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