Don't Ask: Your Off-Road Dirt Bike Tech Questions Answered (June)

You have been duly warned, so don't snivel

Jun. 01, 2010 By Rick Sieman
If you choose to email a question to this forum, then you must conduct yourself accordingly. Therefore, the following rules are in order:
1. Do not write your email to me IN CAPS. If you do so, I will print out your question and do terrible things to it.
2. Do not request a personal e-mail response. Since I get thousands of questions each month, trying to answer them all would cut deeply into my leisure time, which I value more than your current state of confusion.
3. Try to spell at least in a semi-correct fashion. If you choose to mangle the English language, expect no mercy from this quarter. You might be mocked severely.
4. Do not ask for me to send you copies of my many manuals and literature. I am not in the library business, nor do I want to spend the bulk of my day at the copy machine just because you're too lazy to ask your dealer, or look around a bit.
5. Don't bother me with truly stupid questions, like how to get 50 more horsepower for a buck and a half
6. Now that you know the rules, think carefully and have at it!

Oh yes ... I'll leave your e-mail unedited, for what it's worth.

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SUBJECT:  MESSAGE FROM OUTER SPACE
i have a 1995 honda cr 125 havent been able to ride much but when i do it runs great til today... i pulled the plug after catching in gear and it feeling like a fouled plug and it wasnt fouled it did have little oil splotches on it from the crank i havent taken it apart yet would like some help fast so i can go ride it this bike has around tweenty hours on the top checked the piston regularly and it looked fine threw the exaust port it has boysen reed valves and i myself have put all but mabe four hours on this bike when i got it 2 years ago the paint on the frame wasnt even worn off and i have never been shown off on a kid on another 125 or sometimes bigger cc on the bike please help
Jollygreen
Roanoke, VA

What kind of an answer am I supposed to give when the information I receive is a garbled mess of ill-written crap? No punctuation, no caps, no real facts as to what happened. You, sir, ought to be ashamed of yourself. Feel free to write back if and when you ever decide to do things in a reasonable fashion.

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SUBJECT:  GLUE-ON CASE FIX FOR A HONDA 250
i just bought a 1994 CR250R Dirt Bike and i dont know alot about dirt bikes but i bought this one for my boyfriend when i bought it i was told there was a "small" (it turned out to be in between the size of a quarter and a nickle...) well it was covered with J.B. Weld and aluminum foil, its on the left side of the engine case on the bottom. My boyfriend took all the gunk off of it about 3 months after we got it and found out how bad it was is there any suggestions you could maybe give us im clueless on the matter and i found this site and hoped you could help. So should i just buy a new engine(if so where?) or could we reweld it and make sure there is no leak(if im saying it wrong pls tell me how to do it if possible)? IDK ill leave this one up to you... Please Help im very desperate(with the bike that is lol) THe bike is a: Honda CR250R 1994
HippyChick420
Barrackville, WV

Actually, if the repair was done properly, there's no reason the JB Weld wouldn't do the job. Check the cases for any leaks. You didn't mention whether the repair was done on the trans part of the case or the engine part. If the repair was done on the trans section, you'll see some oil seeping from the repair if it was done poorly. You won't find the same sort of seepage on the lower end near the crank. You shouldn't have to pop for a new engine. One last thing: try not to e-mail in such a sloppy style. You can do better.

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SUBJECT:  KAWASAKI KDX200 SUCKING AIR
hey, ive got a 99 kdx 200 that i bought about 3 weeks ago. the guy i bought it from took really good care of it, an it ran perfect for me about the first 1 1/2 an then the plug came loose an i didnt know an it started revin its self up wide open everytime id try to start it.. i fixed it an it rode perfect for like 1 week. then i tried to ride it 1 day an i wasnt on it a minute an it started missing an cuttin out bout to die so i jus killed it. i tried to start it again an it did the same but it was still kida revin a lil high. so i went an bought new plugs an put in it an about 1 minute after i started it, it did that missin an cuttin out again. but the whole time it was runnin it didnt sound normal, instead of that bing sound it sounded like it was crackling.. ??? this is my first 2 stroke but i do know the simple stuff. im really really needin some help here.... wanna get back out in the woods!! please help me.
Perdue20
Wartburg, TN

When the plug came loose, you sucked air into the cylinder and made the bike run horribly lean. This more than likely caused some piston/cylinder damage, which would make the bike run poorly. Time to take the top end apart and check for damage. Speaking of damage, you have single-handedly set the English language back at least a full decade. That makes three miserably written e-mails in a row. Sigh.

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SUBJECT:  WEIRD YAMAHA MAIN JET

Hi-
I'm in the middle of re-jetting my daughter's ttr230 and ran into a little snag- there is a plastic washer that sits on the stock main jet, the stock jet has a hexagonal shape that the washer fits snugly- the new jet is round and the the plastic washer does not fit snugly to it. Do I need to keep the plastic washer or can I ditch it? It is not shown or referenced in the article... maybe I should try to locate a jet that has the same shape as the stocker, though I specifically ordered oem, so I dunno? Please help, would LOVE to finish this up!
Kris
Shingletown, CA

Wow, I have no idea where you got a round main jet. Everyone I've ever seen has flats on it and takes a tool to remove/replace. Get another jet. Let me know what you find out.

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SUBJECT:  WHICH BIKE IS FASTEST?
hey Rick, i got a quick question. What do you think the top speeds of a stock 01KTM125SX, a 1987CR80R, and a 2003CR250 are? They are all stock and me and my buddy were argueing about this.. I know we bicker over the stupidest things. so all stock down an endless dragstrip. Thanks
Dylanearls
Ewing, KY

All things considered, without changing the gearing at all, the CR250 would be the winner. The CR80 would feel quick but run out on top soon. The 125 KTM would peak out in the mid-60s. Figure about 72 mph for the 250.

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SUBJECT:  ADDING A PIPE WITHOUT CHANGING JETS?

HI,
I have an 07 crf230f and am about to add a pro circuit t-4 full system and a twin air filter to it. I was wondering if I could just change the main jet and maybe tune the fuel screw a little bit and not have to get a complete jet kit, Is there any way I got do that? Thanks
CRF230rider
Glenfield, NY

Nope. Go for the whole jetting kit. Any time you make a big change like the exhaust system, it's a must.

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SUBJECT:  YAMAHA TTR230 STALLS EASILY
Hi
I have a 2007 yamaha ttr 230 I just bought this. When I first turn it on I the bike it sometimes stalls after i return the choke.And then when it is on first gear it putts and putts while riding slow. A friend told me i is the switch on the clutch handel or the carburater needs cleaning. what ckould i be?
thanks.
Emiliano
Stockton, CA

No doubt about it, you have some sort of debris in the float bowl, more than likely water. Clean the carb properly and see if this solves the problem.

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SUBJECT:  SPLIT THE CASES ON A SUZUKIRM 465
I have a 1982 Suzuki 465 RM with a broken kick starter spring. Do I have to split the cases in order to get the kick starter, shaft, gears and spring out? It won't seem to pull out.
Skip
Grass Valley, CA

To get the gears out, you'll have to spit the cases. To simply replace the spring, nope.

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SUBJECT:  TOO STIFF SPRINGS?  WHAT DO YOU DO?
what happens if the springs are to stiff for your weight? what should i do?
Charlie
Iloilo, PHILLIPINES

Before you do anything else, back way off the shock preload and see if this helps. If that doesn't do it, then simply go to a softer spring.
  
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SUBJECT:  BACKFIRING RM 125 BLUES

Hi rick
i have a 1993 rm 125 and it backfires every other kick also it fouls plugs all the time how do i fix that problem. PLEASE!!!!!!! help!!!!!!!!!!!
RM troubles
Wilmington, OH

If you're backfiring all then time, chances are that your ignition timing is way off.

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SUBJECT:  WHAT'S THE MOST RELIABLE FOUR-STROKE?
Rick –
Brilliant to see you still out there. I need some advice of what is the most reliable big 4 stroke engine to fit in a specialist twin shock replica for twin shock racing? I am 50 , 260 lbs ex rugby player. It was not always that way - I started my racing career aged 10 with Dave Thorpe - one of my racing pals at the tme. My last dirt bike was a KTM 620 which I rode in Dubai in the mid nineties . I have only ridden riad bikes since + a few odd MX track days.

In Dubai,I was in a position to have other people fix the KTM and clean it. I can't afford such indulgences now. I plan to have a retro twin shock built (JBR Honda or Curtis Honda) by a UK specaolist. i want yo know waht si the best most reliable open class motor thyat I can buy to have fitted. Mt mechanical curiosity and talents are limited. All the young turks tell me horror stories about the maintainece cost of modern MX 4 strokes.Can you avise?
Dean
Kingsbridge, UNITED KINGDOM

Don't plan on using any of the new four-stroke motors, as they are nothing but short-fused hand grenades. The most reliable four stroke engine that I know of is a TT-500. A close second would be the XR-500.

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SUBJECT:  FLUID FOR A TWO STROKE BOTTOM END?
i have a 2002 kx65 what kind of fluid would best be suited for the crankcase
710 yamaha
Navarre, FL

This may come as a shock to you, but the only lubrication your Kawasaki needs is from the oil in the gas.  It's a two-stroke. 

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SUBJECT:  FORKS FOR A HONDA CRF230F
I have been reading your project Honda CRF 230F article and plan on doing the same to mine, I have found 1979 honda 250 parts bike, would the forks from it perform good or should I keep searching for a set of '84 or '85 cr 250 forks?
Jesse Lachance
Lindale, CANADA

While the 79 forks are much better than stock, the 84/85 forks are superior. 

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SUBJECT:  WORN OUT HONDA CR 250
Hi, this 85 CR 250 Ive got wont idle and the clutch cover is leaking out the water pump housing, oil and gas mixed with coolant,I can smell the oror when i rub my finger in it, right fork seal is leaking, so new seal's are in order, mark,,, on the Carb on this thing? Is it the needle ans seat wearing out plus the float is dragging as it floods and then wont start, neat bike and and arm pulling power too WOOOw, Have 86 Kawasaki KX 500 too, backfireing on starting, Please Hekp ok Mark, thanks Mark,
Kirk C,
Alton, KS

Based on your nearly incoherent babblings, it sounds like your Honda is a pile and in desperate need of a complete rebuild.  Much the same as your command of the English language.

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SUBJECT:  WHICH YAMAHA IS IT AND HOW TO TELL
Hey rick ive got a yamaha it 250 haw can i find out what year it is?
Ronnie
Louisville, KY

Easy. Just squat on down and peer at the steering head. Right behind the front plate, you'll find a tag attached to the steering head. On that tag, you'll find the information you're seeking.

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SUBJECT:  WHICH SUZUKI IS IT?

I have a vin RM3770-12277 and I would like to know the model year for this motor, I am considering buying the bike and it is in a RM250 Frame. Please help, thanks
Rm370Fan2010
Chico, CA

The engine number tells us that it's a 1976 RM 370.

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SUBJECT: WHAT IS IT?
I have a older IT 175 with the number on the steering yoke is 5x8-001689 do you know what year it is? thanks for the help.
Bob
Duluth, MN

It's a  1982 Yamaha IT 175.

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SUBJECT:  SLIMMED DOWN AND SLOWER
Yes Rick, I remember you! I grew up reading DBM and remember well your entertaining articles. Who can forget the Great Yellow Dirt Bike Truck GYDBT? Or the cold start race where nobody would line up behind a certain Spanish bike (word gets around). Some writers have the gift of gab and some have the gift of flab, but you had both :) Just kidding, but I do recall an editorial where you tried to slim down and ended up just buying go-fast parts for the bike, haha. All the best and keep on bikin'.
KTM Ken
Cave Junction, OR

Thanks for the kind words. Actually, I lost about 45 pounds, but am now so slow that it didn't really help.

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SUBJECT: IDLE ISSUES
I have an yamaha rs125dx which has a vm24sh carb and my issue is that went I set it up to the recommended settings the engine idles at around 2 to 3,000 rpm and for me to get it to idle something like correct I have to screw the pilt jet in fully. Today I tried a smaller pilot jet and every time I kicked the bike over it went to full throttle which will not do the new piston and rings any good. As far as I am aware the carb is factory standard and original fit. Is there any solution to this.
Thank you,
Alf
Chorley, Lancashire, UNITED KINGDOM

In most carbs, the pilot jet pulls about 5% of the total flow of fuel.  By going to a smaller pilot jet, you reduced the total flow. I'm assuming that you have some sort of air leak, and by going to the smaller pilot, the engine will try to correct the fuel/air ratio by screaming at high revs. 

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SUBJECT:  WHEEL SWAP FOR A YZ 250
will the wheels and hub off a 06 yz250f fit on an 03 yz 250
James
Anniston, AL

How in the hell would I know unless I had the two bikes in my garage, which I don't? Are you too lazy to simply go out with a set of calipers and measure the bikes yourself?

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SUBJECT: 1979 YAMAHA YZ400 JETTING
NEED TO KNOW / STOCK JET SIZES AND CARBERATOR SETINGS FOR A 1979 YAMAHA YZ 400. PLEASE HELP.
Dean Cline
Rockport, IN

Here you go:

Main jet – 420
Needle jet – Q4
Jet  needle – 6F8
Pilot jet – 85
Slide number – 4.0

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SUBJECT:  RT AND DT360 ENDUROS
I had a 1972 360 enduro. I believe it was an RT360 and not a DT360. What was the difference in the two models?
Doug
Conyers, GA

We turned to Matt Cuddy, the man who knows more about Yamaha Enduros than could possibly be healthy. Here are his thoughts on the RT/DT360 line:

The last real enduro built by Yamaha came out in 1973, and while upgraded with a 21” front wheel, reed valves and a gussied up paint scheme, it was still true to the original Yamaha Enduro design that came out in 1968, down to the frame, motor and basic layout.

The enduro that I liked best was the big one, the 360. And since I owned one in high school, it has a special place in my heart as both an evil handling, ankle exploding terror, and a rock solid reliable motorcycle, that seemed to thrive on abuse.

By 1973 the whole Enduro line by Yamaha was getting long in the tooth, and the competition by Suzuki, Kawasaki and Honda had started to out-do Yamaha with more modern designs, that looked nifty on the showroom floor, but failed to deliver the goods when you took them off road. For those who knew, the Yamaha Enduro still ruled the world of desert races, muddy eastern slogs, and commuting duties on the street. Nothing was as reliable, or quirky as the mighty Enduro. And the 360 was perhaps the quirkiest.

Endowed with a motor that was strong enough to pull street bikes up to eighty miles per hour, the 360 was plagued with some funky designs that you either loved or hated, one being the kick start design that exploded more ankles than land mines in Cambodia.

You had to use an exact starting drill to crank over the 360, or it would kick back, and send your ankle flying into the sharp seam on the exhaust pipe at mach III. This would cause intense pain, shooting stars and loud blasphemous curses to fill the air, as you hopped around waiting for the pain to subside, and circulation to return to your foot.

Many the times a classmate would want to ride my 360, and I would hand over the keys and say “you can ride it, if you can start it.” Not a whole bunch of my fellow classmates got to ride the 360, as they limped to the nurse's office for an ace bandage. It even blew the Stan Smith right off one guy's foot, and left a giant purple bruise on his in-step. Not for wimps.

The '73 360 also shared the same frame geometry that the original enduro used, right down to the crabbed in forks, and over sprung fish oil filled rear shock absorbers. To try and go fast across rough terrain was a dangerous proposition, and the best way to make any time was to hang your butt over the tail light, and let the forks wiggle around with an occasional tank-slap thrown in to keep your concentration in check. Pretty soon you got use to the bad head-shake, and learned that a big handful of throttle would usually straighten things out. Remember I said usually, as in WFO situations with the bike tank slapping violently, all you could do was hang on and pray.

The last enduro also had the rock solid reliability that made the 1968-1973 DT/RT series so popular to the average rider. What other two stroke dual sport could you hop on the freeway with, and after a few dozen gas stops, find yourself hundreds of miles away in Laughlin or Las Vegas Nevada. I regularly rode mine from the Los Angeles suburb of Silverlake, to places like Palm Springs, or Big Bear Lake. Things dual sports weren't supposed to do very well. It never failed to get me back home.

The only thing that needed any adjustment were the ignition points, that would close up occasionally, and get the eyeball adjustment with no ill effects. Try eyeballing the point gap on a Bultaco or BSA of the same vintage, and you'd end up with a big greasy skid mark from the rear tire as the motor locked up solid.

The last true Yamaha 360 Enduro weighed in at around two hundred and eighty pounds wet, and put out 33 horsepower at 6500 revs. The power band was wide, and the bike had enough grunt for slow single track trail work, with enough beans on top for 65+ sustained cruising on the highway. Top speed was around eighty.

Consumable items like clutches, piston rings, and other engine internals wore like diamonds, and the only things that wore out quick were the sprockets and chain, along with the sprocket bolts that you had to keep a close eye on, else they loosen up and snap off on the swing arm.

So here's to the last of the real enduro line from Yamaha. True to a fault, with handling that could only be described as unique, it endeared itself to a generation of riders who learned to live with the quirks, and were rewarded with uncompromising anvil-like reliability. In 1974 Yamaha came out with a totally re-designed 360 Enduro that used the 72's MX frame, weighed 20 pounds more, had an ill-designed motor that holed more pistons than a Bultaco Astro running on LOX. It also handled like a safe falling down a flight of stairs, and had Thermal Flow shock absorbers that were set-up for a '55 Buick Special. Some say it was an improvement. Not me.

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SUBJECT:  GAS TANK FOR A 1974 SUZUKI TM250
Restoring a '74 TM 250. The gas tank need to be restored. Is there a manufacturer who makes a replica plastic or fiberglass tank that is AHRMA approved? And yes, I have seen you race a Rokon, just a few years ago at Hopetown.
Aprilia
Monterey, CA

You can use most any TM125 or TM400 tank on your bike.  I especially like the 125 tank, as it's slimmer than the 250 and still looks the same.  I'm not aware of any aftermarket tank. One small thing: I never raced a Rokon at Hopetown. I raced Maicos and an RM370 over the years.

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SHAMELESS PLUGS: BLACKWATER 100
Welcome to a celebration of The Toughest  Race In America, the notorious Blackwater 100.  Held every year in Davis, West Virginia, the race was designed by Dave Coombs to be a real test of survival. While the race is no more, the tales of this legendary race seem to grow with each passing year.

What we have here, is a collection of hundreds photos, stories and copies of some of the actual programs.  These images tell you more about the nature of the grueling course than the many tales that circulate.

Included in this great collection are stories about the race by Rick Sieman, who competed in this event numerous times.  You'll also find a story and test on the legendary 760 Maico, the first bike ridden by Rick in the Blackwater race.

The Blackwater 100 is a two CD set.  On Disc 1, you'll experience a slide show with some classic bluegrass country music to accompany the images.  Just put the disc in your computer, go to MY COMPUTER and hit the BLACKWATER 100 button on your  screen.  Make sure you turn your sound on for Disc 1.

On Disc 2, you'll find the same images, but these are in Picassa 3 format and literally hundreds of photos are there. This means that you can stop any image, or copy what's on the screen, make it bigger (or smaller) and print out anything you see.  Just go to the bottom of the screen and a very simple menu is there. 

Cost for the CD set is $20 plus $5 for Priority Rush mail.  Paypal, checks or money orders OK.  Paypal address is: superhunky@gmail.com.

Mailing address:
Rick Sieman
36607 W. Costa Blanca Dr.
Maricopa, AZ
85138
Go to http://www.superhunky.com/ for more info on other products, including posters, CDs and the Monkey Butt book 
Email: www.superhunky@gmail.com

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