Sputter & Cough
Hi, I have a 89 YZ 125. I had a top and bottom end job done
along with PC pipe and silencer. I got the bike used and had a
blown engine at time of bike so it went right to the shop. My
bike accelerates well but has a sputter and cough when run at a
constant speed. For instance, 1/4 or 1/2 throttle in second
gear. I have tried different jetting, spark plugs, fuel mixes,
clean carb/air filter,and a new stator coil. My plug looks
pretty good, dark tan. Any other suggestions or jetting
combinations to try?
Thanks.. Sean.
You need to run the factory recommended
spark plug (or one that is one heat range hotter) and
concentrate on the jetting. I hear of far too many people who
only change the main jet when they try to rejet. First step in
rejetting is the lower speed circuits (pilot jet and air screw)
and then adjust the needle position. Finally, the main jet is
changed but only after the other circuits are correct. It sounds
like your pilot and/or needle are too rich. As always, make sure
the silencer is in good condition (fresh packing and the core is
clean and unobstructed) before doing any jetting changes.
MX Tuner
False Neutrals
Year 1996
Make Yamaha
Model RT 100
My Problem: When shifting through the gears after the bike is
well warmed up it tends to shift into a false neutral, instead
of the next gear(this all gears (5)). The problem seems to get
worse when the engine oil falls low but even when full, the
problem still occurs. My first suspicion was that perhaps the
oil I was using wasn't good enough so I went from using 10-30
like the manual and started using 75 motorcycle oil, but still
the same problem. Then I thought it could be bent posts in my
transmission, I had that problem with my DS 80. Yet after 3 days
of engine work and the price of gaskets I still have the same
problem. I have checked with the local Yamaha dealer and they
told me that they hadn't heard of anyone else having the problem
and that the bike usually had a nice gearbox. So I am know
stumped. Although this does not really effect the performance of
the bike to much one or twice it had done it going up a steep
hill, which does not lead to good things. If you have any idea
please help.
PS:The bike has done this from or almost from new (bought new in
98) and usually tends to do it during high RPMs
Thank you for your Time
Mike Mehak
Sounds like one of two things. Either
the gear lube you're using or a clutch problem possibly. In your
RT, I'd use Mobil 1 15w50 synthetic automotive engine oil. This
is cheaper than most of the motorcycle specific oils and much
better in giving a smoother shift. Type F automatic transmission
fluid also works extremely well but may need to be changed more
often if the clutch is slipped excessively. The other thing I
would make sure of is that your clutch is operating properly. If
the clutch basket or hub have any grooves in either of them, it
can prevent the clutch plates from disengaging fully. The basket
grooves can be filed out but the hub may need to be replaced.
The dragging that occurs when the clutch doesn't fully disengage
can give some shifting problems. If the clutch cable is
stretching, it can also prevent smooth shifting.
MX Tuner
Stuck Shifter
I have a 1989 CR500 I went riding it ran great no falls no
problems went to go riding again could not shift gears it ran
fine in the gear it was in clutch worked fine was able to get it
into 2nd which was done with all my might ran fine clutch worked
fine . I have taken off the clutch basket looking for broken
parts do you have any ideas about where to look do I need to
split the case and look at shifting forks or could it be
something simpler Thanks for any help
Larry
The shift linkage attaches to the end of
the shift shaft right under the clutch. The linkage engages with
the shift drum and turns it in whichever direction you're trying
to shift. You should be able to watch this occur with the clutch
basket removed. You can move the shift lever and watch the shift
drum rotate when it is operating normally. Even if you had
something binding in the center cases, the linkage should move
some. If it doesn't move at all, the problem lies within the
shift shaft and it's linkage under the clutch basket. You'll
need to move the transmission shafts to get it to go through all
the gears. You can do this by spinning the rear wheel as you
move the shifter.
MX Tuner
Three for the Price of One
Hello. I have a 1982 RM125. I just want to know if you have any
solutions. First of all, it has been bored out until you have to
put a piston that is made for a Yamaha 125 bored 25 over. Other
than that everything seems ok. I have been through the carb and
ignition system and everything seems right. I have put a new
piston and set of rings in. When I try to start it, it starts
and runs really really good for a few seconds and then pukes
out. I can also keep it running if I keep a hand on the choke
lever and whenever it starts to die flip the choke on. I was
wondering if my carb isn't big enough or something like that.
Also. I have a 1993 XR600R that runs really hot. Whenever I ride
for just a few minutes it gets hot enough to instantly boil spit
if you spit on the motor. I was wondering if that is normal for
the big XR's or if I have a problem. (The bike runs perfectly
and doesn't mess up when it gets hot).
And last of all. I have a '79 Yamaha DT100 that the coil in the
motor fell against the magnets in the flywheel. I can fix and
replace everything in there but I can't get the flywheel off. I
have tried soaking in lubricants and taping and even leaving a
gear puller on there and spraying with WD40 on a regular basis.
The thing just won't come off. Do you have any tricks to getting
it off? Or should I just scrap the bike?
Thank you.
Jason
Sorry but I'll have to charge you triple
for this
one.
Your RM is suffering from something making it lean. That could
be anything from a base gasket leaking air to a low float level.
First thing I'd do is go through the carb and make sure it is
operating normally.
The XR sounds like it is running about the normal temperature.
If it starts overheating, you'll probably hear some pinging when
the engine is under a load.
You'll need the correct flywheel puller for your DT100. You can
do damage to the flywheel and/or crankshaft by using the wrong
puller.
MX Tuner
Shattered Skirt
Hi, I have a 94 RM 250 and my piston skirt shattered. The wrist
pin bearings where also broken and the power valve was gummed
up. The pieces from the piston skirt scored the cylinder and I
am wondering what would be the smartest and cheapest way to get
it running again. I cleaned up the power valve and it is now
moving freely like it should and the connecting rod looks to be
in good shape. Should I have the cylinder replated,
resleaved(with what kind of sleeve), or should I find a
different jug.
Sleeve technology is better than it used
to be but the best method of repairing a damaged cylinder is to
have it welded, rebored and replated. Sleeving alters the heat
transfer characteristics of the cylinder, and not in a favorable
manner. This would be a good time to consider a big bore kit.
You can get a 2mm oversized piston for most bikes with a plated
cylinder. These are not intended to be bored by the manufacturer
but these have proven to be extremely reliable and provide a BIG
performance boost. In fact, a good aftermarket coating can be
much more reliable than the factory coating (which can, and do
come off).
Eric Gorr would be an excellent choice for your cylinder repair.
Check his Website (www.eric-gorr.com).
MX Tuner
High Elevation Jetting
I have 2000 YZ 250. I ride at an elevation of 6000' to 8000'.
What is the best carb setting for this altitude? I run 40 to 1
Yamaha 2 R. I have a main jet of 168, and dropped the needle one
clip. The air screw is at about 2 1/2 turns out. My bike
sputters through the mid range. I cannot get it to run smooth
throughout the power band. Please help me out.
Thank you,
Jim Ludwick
Butte MT
At that altitude you'll need to lean all
the circuits. Leaned the main circuit and the needle but you've
neglected the most important one.... the pilot jet. You could
try some of the local dealers for approximate settings but
you'll have to fine tune for your bike and weather conditions. I
would try a 42 or a 45 pilot. That should be close to what you
need and would certainly be a step in the right direction.
MX Tuner
Suspension Setup
I just recently purchased a 1995 Yamaha WR250 and would like to
become familiar with how to set up the suspension for my
particular riding style and weight. I'm 6'0" and ride
aggressive woods and power lines in the northeast. I hear talk
about rider sag and race sag but don't understand the difference
or how to set these correctly. Do the fork and shock compression
and damping clickers play into this also?
The Yamaha manual goes into pretty
thorough detail of all the adjustments concerning damping
settings. The sag is also covered but I've had better luck with
a little different method.
Rear sag (also called race sag) is the difference of two
measurements. The first measurement is the distance between the
rear axle and a good measuring point near a seat bolt. You can
use the edge of a fender or any point (you can even draw a line
on the side of the fender with a pen) that you can duplicate.
The important thing is to pick two points that can give
consistent readings. The first measurement should be with the
bike on a crate type stand so the rear wheel is off the ground.
You want to measure the rear suspension at 100% full extension.
The next measurement will be taken with you on the bike. Most
procedures I see have the rider sitting on the bike. The exact
seating position of the rider is a variable that will affect the
readings a large amount. You can eliminate this variable by
standing on the pegs when the measurement is taken. You'll need
one person to balance you while a 3rd person takes the
measurement. Obviously it is critical they measure from the same
two points the first measurement was taken. The difference
between these two readings should be ideally 100mm (4 inches)
normally. But the mid 90's YZs and WRs worked much better with
the sag set at closer to 90 or 92mm. This is set by turning the
spring preload adjustment rings on the shock body. If the
reading is too high (say 110mm), you'll need to tighten the
collar to compress the spring farther to get the reading you
need.
Spring rate is another thing that affects sag. A stiffer spring
won't need to have as much preload to accomplish the sag you
need. One test to see if your spring is correct for your weight
is measuring the amount of static sag. This is a 3rd measurement
with the bike on its wheels with no rider aboard. Ideally, if
the race sag is set for your weight and the spring rate is
correct for your weight, you should have between 15 and 25mm of
static sag. if the spring rate is too soft, you'll have to
adjust the spring preload tighter than it was intended. This
will make the static sag numbers lower (maybe 5mm- I've seen
some bikes with no static sag at all) because the spring, even
without a rider, has more preload dialed in to it. Conversely,
if the static sag numbers are too high (30+mm) the spring is too
stiff for the rider.
Since the sag is intended to compensate for the rider while they
are riding, the rider should be in riding gear (helmet, boots,
etc) since this will affect the 2nd measurement.
MX Tuner
TTR or XR?
I would first like to say what a great thing you are doing on
the Website and I check what u have to say every week.
Hi I am thinking about getting a Yamaha ttr225 or a Honda xr200
brand new and I am not sure on which to get. I weight 170
pounds. I want the one with the most power. Also if you can help
me with these two questions that have been bugging me. Would you
happen to know the top speeds of each dirt bike and if they can
pop a reasonable wheelly. I do not have enough money to buy a
better dirt bike to perform what I want. Also can I get a couple
tips on how to add power to the bikes without a lot of money. If
you can answer me back as soon as possible that would be great,
thanx.
Both the bikes you mention are very good
choices. The XR is a proven design and the Yamaha has exceeded
all expectations for such a new bike. There is no denying the
fact Yamaha had the XR line in it's gunsights when it designed
the TTR line, and like most everything Yamaha has come out with
recently, they have hit a homerun.
In other words, you'll be very happy with either choice. But
when you ask about top speed and which one has the most power, I
can see right now, you'll be wanting more in a short time.
Either bike is excellent for what it is designed but don't
expect either one to last under the abuse you are planning on
putting it through. One option you may want to explore is
spending the equivalent amount of money on a used 125 motocross
bike. They're intended to put up with the abuse you're going to
be putting any bike you buy through. But that also comes at a
price in the way of more frequent maintenance and higher
maintenance costs. Just keep everything in proper perspective.
I've seen guys break the end off the shock of brand new XR 200s
trying to ride them much harder than they are intended. Any bike
will appear unreliable when ridden differently than it was
intended.
MX Tuner
Weak DT 175
Hi there, I own a Yamaha DT175 which I use on a farm. It does
struggle with a few of the hills on the farm so I am looking at
possibly doing something to the bike to make it more powerful.
I've seen other answers to similar questions where you've said
that if you make a bike go harder that isn't designed for it
there will be other problems arise soon enough. I can see where
you are coming from but I am still going to ask my question! How
much extra power is achieved from boring a bike out? Do you know
what the new capacity would be for a DT175? I'm also interested
in doing something to the exhaust. I haven't removed any baffles
and I'm not sure if it is even possible judging by the way a
dt175 muffler is constructed. Do you have any ideas how I can
improve the power for this bike. Or do you think it would be
better off devoting my time to a 250 4-stroke etc. Also is there
any way to adjust the rear suspension travel on a dt175? I think
I may have the wrong bike judging by all these changes I'm
looking to make! Can you help?
Thanks, its great to see this kind of service available on the
web. Hats off to you!
from Tim Davis
The problems that arise from making a bike
faster isn't the mods as much as the bike being ridden harder
than it was intended. You should be able to safely increase the
power output of your DT without sacrificing reliability as long
as you keep it for farm use. Boring can help substantially but
you're limited by piston availability. You might want to check
with a Wiseco dealer to see what they have to offer. Wiseco is
one of the bigger manufacturers of larger than stock pistons.
Another option would be altering the porting of the cylinder.
This can make a very big difference. I would check with Eric
Gorr for all the cylinder work. You can get some info for
pricing and contacting him off his Website (www.eric-gorr.com).
Your cylinder is not a plated cylinder so it will be cheaper to
get bored than a more modern cylinder.
Depending on what year your DT is, I believe the only adjustment
you have is for spring preload. If you are really in need of a
more capable bike, I'd decide that now before you spend any
money on modifying it.
MX Tuner
Loaded RM
I have a 1987 RM 125 and it doesn't get into the power band. It
idles fine. But acts loaded up and breaks up when you try to
wind it out. It goes through spark plugs a lot too. Like every
hour I ride. the plugs are really wet with gas when I take them
out too. They're not carboned up. It just got new piston, rings,
power valve, and porting job.
Sounds like your power valve isn't
operating properly. Either that or you have a leaking right side
crank seal. Is it smoking excessively even after it is fully
warmed up? This is a good indicator of a leaking crank seal.
MX Tuner
Hello
I just got a 1996 Kawasaki KX-80 that's bored up to a 105 and it
idles to slow I wanted to know if there was an idle bolt or how
to turn the idle up
Thank You
Your Kawasaki owners manual covers idle
speed adjustment. You *do* have an owners manual, don't you?
MX Tuner
Rick KX
1993 Kawasaki KX125
my bike is running rich. I have leaned out my gas mixture form
32:1 to 40:1 I have changed the mainjet from a stock 162 to a
155 I have changed the head gasket (I suspected coolant may have
leaked into the cylinder) I have the correct spark plug in and
the right air screw settings
when looking at the bike I noticed that the powervalve was off
of the guide and all the way out... and it had been like that
while I've been running it. I was wondering if the powervalve
being all the way out would make it run rich
I also checked the air filter and took it out and it still runs
rich without the filter..
what happens is with the muffler
it has a brand new top end and is getting proper compression
please tell me what else could be wrong because I am out of
possibilities that could be wrong.
Okay, first off, if your bike is running
rich, changing the fuel/oil ratio won't address that problem.
40:1 is what I'd run your KX at.
Next thing to do for the spooge is run a BR8ES plug. This will
help burn more of the oil before it gets blown out the exhaust.
The power valve needs to be operating properly before you can
expect anything close to proper running to occur. Once you're
certain the power valve is cleaned, assembled properly and
working correctly, then you can look for other reasons. My
initial guess would be low speed jetting. Seems this month we've
had an epidemic of people trying to lean their jetting by
changing the main jet. You'll get a much bigger running change
by changing the pilot jet and the needle position. In some older
bikes the needle can wear making it run richer as it wears. The
tube the needle drops into can also wear. Depending on the
particular carb, this piece may or may not be replaceable. And
as always, make sure your silencer is in good condition (fresh
packing and the core holes clear and unobstructed) before
beginning any jetting changes. In fact, I'd start off with
putting the 162 main jet back in before beginning the jetting
procedure.
MX Tuner
Oil to Gas Ratio - Oil Injected Bike
I recently purchased a 1983 Yamaha MX100. It has the MX100K
engine. We went to the dealer to find out what the oil to gas
ratio was for this 2 stroke engine. They looked it up on the
computer and said not to use pre-mix because it has a tank for
oil injection. We looked over the bike top-to-bottom... no tank.
It appears that it was disconnected some time ago. There are no
oil hoses coming out of the oil pump on the right side case
either. The previous owner did not have bike long, but said they
always pre-mixed the oil. We intend to pre-mix the gas/oil as
well. What would be the proper gas/oil ratio should we use on
this bike (We don't want to look for or replace the oil
injection system... we don't plan to race the bike either, just
learn to ride)
Thanks!
David Allen
Your MX100 should be an excellent bike to
learn on. A good spread of power without being intimidating. I'd
run it at 40:1 mixed with premium unleaded fuel. Yamalube 2R is
one of the best oils available and should be on the shelves of
any Yamaha dealer.
One thing to check, though. You need to make sure the injection
system was properly disconnected. The original oil injection had
oil lines that ran to the cylinder. This fitting needs to be
blocked so it won't suck air. If the oil line is still connected
to the oil pump, it needs to be disconnected and plugged. You
can use the existing fitting but cut and plug the hose going to
the cylinder. In fact the gear spinning the oil pump should be
removed. If the pump runs dry from no oil being pumped through
it, it will eventually get damaged. You can even remove the oil
pump but you'll have to plug the hole in the case where the pump
was mounted.
MX Tuner
Stubborn Swingarm
I have an 89' KX 125 and I took the swingarm off because there
was a small amount of play in the rear end. Anyway I removed the
swingarm and bearings fell everywhere then I really got into
cleaning what was left of the bearing sleeve inside the pivot
hole and I noticed there was nothing left of the race for the
bearings. And now the races are frozen into the swingarm and
I've tried pressing them out banging them out and I cant get
anywhere with this any help is appreciated.
Thanks,
Dave
In some extreme instances I've had to use
a Dremel tool to grind away a section of the outer race. Once
you have a small groove cut out of the race lengthwise, the race
should be fairly easy to remove.
MX Tuner
I am currently in the process of restoring a 1976 yz125, but
I need to order a new head and a new cylinder. I have not been
able to find one at any local salvage yards. Is there a place
that specializes in that type of supplies. I would really
appreciate any information you might have.
Thanks,
Brian Jackman
Your best source of info for your bike
would probably be AHRMA. That is the American Historical Racing
Motorcycle Association. They have a monthly news letter with a
classified section for selling or buying parts and/or bikes.
Start by looking at their Website (www.ahrma.org).
MX Tuner
2000 KX Setup
Hi! I have a 2000 kx250 and I have a few questions about it I'm
5'9" and 140 pounds and I'm am scared to jump the bike to
big because it is unpredictable I could jump the exact same way
twice and 1 time it will nose dive and the next it will air
wheelie how could I fix this and another question how can I make
it accelerate faster and have quicker throttle response with out
losing top end speed also the brakes on the bike don't work good
I lucky if I can slow down a little bit (why would I want too I
don't know I don't use them much) they feel mushy and soft how
could I fix this or what's the problem
Steve
The KX benefits from a straight rate rear
spring. Getting one for your weight would get things going in
the right direction. Normally, how high (or low) the front rides
over a jump is greatly affected by the rebound adjustment of the
rear shock. The fact you have changing symptoms (front high one
time, front low the next) doesn't quite lead me to believe this
is your problem. The shape of the jump face obviously has a lot
to do with this. If there is a lip on the face, it can make the
rear kick, dropping the front wheel. Does it act the same way
consistently over any one jump? That may be the biggest
determining factor in the attitude of the bike.
Getting the jetting correct should give very good throttle
response with acceleration to please most riders. The Delta
V-Force reed cage is an excellent mod for the money. You'll have
to rejet to get the maximum benefit from it but it is well worth
the time and money invested. A good porting job can also give an
excellent gain. Don't settle for one of the cookie cutter
porting jobs the big companies offer. You'll get far better
results going with one of the smaller guys like Eric Gorr. Eric
does outstanding work at a much cheaper price than the big guys.
No, I'm not a friend of Eric's, just a very satisfied customer.
I don't do my own porting. That is a science best left to
someone who knows what they're doing.
Your KX brakes have never won any awards due to how well they
work. First thing to do is flush the brake fluid with a high
quality, high temp fluid such as Motul 600. This should be done
at least once a month or so anyway on your KX. If this doesn't
give the results you want, the next step would be a steel
braided brake hose, routed the same way as a CR. The shorter
hose helps give the lever a firmer feel. Some picky riders have
resorted to installing a CR style master cylinder. Once you get
some better brakes, practice using them aggressively, especially
the front. You'll be amazed at how it'll help your lap times.
MX Tuner
Blaster Break In
I have a Yamaha Blaster that has been just rebuilt. Is there a
break in period for 2 strokes. I was also wandering if I should
run a stronger mix for a while. If so what would you recommend.
Brady Balls
I'd take it easy on your Blaster as if it
were new. This is the safest way to break it in. Just follow the
recommendations in the manual. I wouldn't switch the fuel/oil
mixture. In fact, richening the fuel/oil mixture actually leans
out the fuel/air mixture which you don't want to do, especially
with a new engine.
MX Tuner
I have an 89' Honda CR125. I bought it about 4 months ago and
it had the problem when I bought it. The bike will not kick
start unless I have been riding for 15-20 min and its warmed up.
It will push start at any time and there is nothing to it. I
just run with it about 20 ft. with the bike in neutral and throw
it into first and she comes alive. The motor is ready to ride
with no warm up time at all. I just think the kick start doesn't
make the piston go a full stroke in the cylinder and that's why
it doesn't fire up unless the motor has already been running for
a while. I haven't taken the cover off to look at it because I'm
really not that concerned because if I ever got the bike into a
spot were it couldn't be push started that means I would have
had to ride there and the bike would kick start from there. Also
if you know anywhere on the web there is a full review of my
bike like this web site has of some bike please let me know.
Scott
You're describing classic symptoms of a
worn out top end. You need to replace your piston and rings. I
believe your '89 CR 125 has a steel bore which will need to be
bored when you rebuild it. You'll have to get an oversized
piston for the new bore. Let the shop doing the boring decide
which oversize piston you need. They'll need to measure the
cylinder to determine how much it needs to be bored. The big
benefit won't be from the starting as much as the overall
improvements in the running condition.
MX Tuner
Seizing the RM
My friend has a 1996 RM 250, the bike is in excellent mechanical
condition. Every time he crashes hard the bike acts seized up.
It won't kick over, the first time this happened we assumed it
had seized so we took the top end apart to check out the damage.
There was none - so we took the top end to our mechanic and he
looked at it and was stumped. The only explanation he could
offer is a tooth on one of the gears that go from the kick
starter to the crank broke off and was getting caught in one of
the gears when it was knocked around by the crash. So we pulled
of the cover and inspected it and found nothing not even any
metal particles. So we put it back together and it worked, He
was pretty sketchy about riding for awhile but everything went
well for a couple of months until he crashed really hard again,
we went to the same routine again and found nothing. Everyone is
stumped. Have you ever heard of this or can you offer some more
insight on what could possibly be causing it to seize, but there
be no damage and work fine when we put it back together. Thank
you for you time
Jason
I'm wondering if the crashes may be due to
it locking up. If there is a tooth broken off one of the gears
in the center case area, it may be getting wedged and locking up
the motor. Even if it isn't causing the crashes, it still may be
what is causing the engine locking up. He may be looking at
having the cases split even just to do a visual inspection of
the gears.
MX Tuner
A Long and Winding YZ...
Hello, I have a 91' Yamaha YZ 250. My problem is hard to
describe so bear with me. My bike just doesn't seem to be
running right. Sort of like when an engine is half warmed up and
it cuts out a little when you try to open it up. It idles good,
and seems to accelerate good from right off idle to full
throttle, but if you just go to half throttle and stay there for
a couple seconds and then try to go full throttle it seems to
kinda miss or sputter. It also hates to be even remotely over
revved. Its almost like it likes to be chugged and shifted way
early. What boggles me is that if you don't waste anytime going
from idle to WOT, then it raps out pretty good. Maybe this bike
just runs like this, but I truly think something is wrong. My
friends 88' kx250 and 94' cr250 both don't do anything like this
so I am pretty sure something is wrong. Ok, whew. Now, what I
have done. I have changed out the gas to brand new, mixed 32:1
with Maxima 927. Changed the plug from the champion N2C to what
the dealer told me was the right NGK, a br9es. It actually
seemed to run worse with the new plug, so I put the old one back
in after a while. After doing the 1/8 mile wide open throttle
kill the bike plug test, the insulator was a darkish tan, being
more lighter on one side and fading to a near black on the
other. The plug wasn't wet and didn't have any deposits on it,
and actually looked pretty good. At the same time though, I do
seem to have excessive light gray/white smoke coming out the
exhaust, and some black slug dripping from the silencer/pipe
fitting and silencer end. So, I have monitored my coolant level,
and it hasn't moved a bit, and I changed oil, rode about 5
hours, and changed it again, and I am 99.5% sure I lost no oil.
I moved on to the carb, and nothing was blocking the main or
pilot jets, and the float looks about level,so I took down the
stats: Main is 350, Pilot is 45, Needle clip is in the middle of
the five positions, and the needle number is 6EJ33-61. What jets
did this bike come with stock? I live in Iowa, not sure of the
elevation here but, what jets do you think I need? Anyways, next
I took out the reed cage and noticed that the bottom reeds had a
black, "carbonish" stain to them (kinda like what a
carb on a car looks like when it backfires through the carb).
The top reeds where perfectly clean. Is that normal? What could
have caused that? There was no deposits on the bottom reeds,
just a discoloration. Two of the reeds (one on the top, and one
on the bottom) have very small chips in the very outside edge in
them. The chips appear to be past where the reed seals, so I
don't think that is a very big deal. Either way, I have new
Boyesen reeds coming in the mail. Now, running out of things to
check, I pulled the left side cover and couldn't get any
horizontal movement from the crank, which reaffirms me that I
don't have bad crank seals or bearings. The only thing left I
can think of to check is my power valve which I am not sure how
to check. I think it is on the right side, like the one on the
95 yz125 I had, but there is a little cover on the left side
too. How do I check to see if this is dirty or functioning
properly? I hope I haven't forgot anything, I have been trouble
shooting this for a while now. I haven't done a compression
test, as I haven't seen my gauge for about a month now, but my
foot and previous experience tells me it has plenty. It does
pull hard when it isn't missing. What do you think is my bikes
problem??? I was thinking of dropping the needle a clip, and
maybe trying a b8es plug. I don't want to burn a hole in the top
of the piston though..how do you know when you are using too hot
a plug? Thank you very much, and I anxiously await a response
from you. Sorry so long.
Sincerely,
Frustrated in Iowa
First of all, thanks for being through.
I'd much rather have to read through a long letter than guess at
any number of variables.
Okay, let's see.... first of all, I'd run a BR7ES plug unless
you run at continual high rpm situations like dry sand.
Otherwise the B9 is way too cold. One indication a plug is too
hot of a heat range is tiny silvery spots on the electrodes. The
B7 series plug will work fine for you.
The Maxima 927 is excellent lubrication oil. Certainly one of
the best available for lubrication protection. But it has its
drawback. When it burns it leaves deposits. These deposits need
to be cleaned off internal parts frequently. This makes it a
good choice for top pros who tear their motor down every week or
two but not a good choice for the weekend warrior like yourself.
I'd recommend either Honda HP or Yamalube 2R, either of those
mixed 40:1. This may be what is creating your problem. It almost
sounds as if your power valve is beginning to stick. This is
where the cover on the right side of the motor comes in. You'll
have to remove the pipe to remove the cover but you need to
watch the linkage with the engine running. Once you remove this
cover, reinstall the pipe so you can run the motor. You should
be able to slowly rev the motor and watch the linkage begin to
move at roughly half way through the rev range. In other words,
it should open the power valve at about half throttle with an
unloaded engine. Once it begins to move, it should more or less
open fully and stay there until the revs drop back down. If
there is any hesitation in the valve opening, it may be
beginning to stick.
Your reeds don't sounds like a problem yet but the fact they are
beginning to chip indicates they are ready to be changed. The
discoloration you have is normal.
It's hard to give exact jetting numbers. It is far more accurate
for you to rejet for your local conditions. A call to your local
Yamaha dealer should give the stock jetting specs. You can
expect to go leaner than a 45 pilot and fine tune with the
needle position. Just be sure to start with the lower speed
circuits first and go up from there. And, as always, make sure
the silencer is in good condition (fresh packing and the holes
in the core are clear and unobstructed) before doing any jetting
changes.
MX Tuner
The Silencing of the CR
READ SOME OF YOUR QUESTIONS & LIKE THE ANSWERS. SO HERE'S
MINE.
I OWN A CR 250 R 1995 ROAD REG'D
MODS INCLUDE:
LIGHTING KIT
LARGE 10 LTR TANK
CRANK WEIGHT
POWER VALVE MOD KIT ( GIVES LOADS BOTTOM END POWER)
DEP SPORT ENDURO LDB(LOW DECIBEL) SILENCER.
DEP SPORT EXPANSION CHAMBER
SINCE PURCHASE I HAVE REBUILT ENGINE INCLUDING NEW GEN HONDA
PARTS PISTON RINGS, MAIN BRGS, CRANK SEALS & DONE SOME OF
MODS FOR TRAIL / ENDURO USE.
I CHOSE THIS BIKE OVER A CRM / BIG 4 STROKE (XR400 ) DUE TO
CHEAPER , MORE POWER , LIGHTER. HOWEVER I HAVE SOME CONCERNS RE
RELIABILITY / MAINTENANCE COMPARED TO CRM. I USE IT FOR GREEN
LANE TRAIL / ENDURO SOME ROAD USE BETWEEN TRAILS.50 MILES
APPROX. EVERY FORTNIGHT.
WHAT SORT OF MAINTENANCE REQ'D. E.G. REPLACEMENT RINGS / PISTON
DE COKE PVALVE ETC? MANUAL RECOMMENDATIONS SEEM EXCESSIVE
ALTHOUGH IT IS NOT SUBJECT TO SAME THRASHING ROUND MOTO CROSS
CIRCUIT.
ALSO I HAVE ATTEMPTED TO MAKE THE CR QUIETER BY FITTING LDB
SILENCER HOWEVER STILL CONSIDERABLE LEVEL OF NOISE STILL FROM
ENGINE / EXPANSION CHAMBER PARTICULAR WHEN POWER VALVE OPENS.IS
THERE ANYTHING FURTHER THAT CAN BE DONE TO MAKE THIS QUIETER? MY
MATES CRM IS A LOT QUIETER.(DOESN'T SCARE THE HORSES &,
SHEEP & RAMBLERS ).
I AM CONSIDERING GOING FOR AN XR 400 IN FUTURE IF I CANT SORT MY
CONCERNS WITH THE CR.
I KNOW IT IS NOT DESIGNED AS A TRAIL ENDURO BUT A LOT OF GUYS
SEEM TO USE THEM FOR THIS OVER HERE AS I SAID BEFORE CHEAP ,FAST
& LIGHT.
WHAT IS THE DIFFERENCE RE CR & CRM ENGINE DESIGN RE
RELIABILITY ETC.
REGARDS
TONY
We don't have the CRM here in the US so
I'm not familiar with the differences between that and the
straight CR motor.
The maintenance requirements listed in the owners manual are
intended to keep the bike in top condition for the purpose it
was intended for, which is racing at any level. That being said,
most owners stretch the service limits far beyond what Honda
suggests. If the rings are run past their service limit,
performance will slowly deteriorate and it can become difficult
to start easily. If the piston is run for too long, it can
develop cracks and pieces break off (yes, even the Honda genuine
pistons). This is when things get very ugly and expensive fast.
Wiseco makes a very durable piston that should last for an
entire year without worry of cracking.
Concerning your noise issues. A single wall pipe will make
substantially more noise than a double wall pipe. This is not
the exhaust noise but the sound being transmitted through the
walls of the pipe itself. Some pipe guards can help reduce this
type of noise. E-Line makes a carbon fiber guard which does and
excellent job of protecting the pipe and also helps quiet some
of the noise. The CRM pipe may be a double wall pipe. You may be
able to find a used one to see if it fits your CR.
MX Tuner