Donít Ask: Dirt Bike Technical and Maintenance Questions

May. 02, 2013 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 Ö Iíll leave your e-mail unedited, for what itís worth.#

April 2013

March 2013

February 2013

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Yamaha Vintage ID
need help coding these bikes. I think they are 1981 yz125##4v2-005164##4v2-015667 #

Yet Another
vin# r1 11614#ANY IDEA OF YEAR#possible 67-69 350cc///
Vintage R1

any help would be great thanks.

No problem at all with the first two numbers. Both bikes are YZ 125H models, which are 1981s. The second set of numbers was very confusing at first, but I traced it down to a 1968 YR1 350.
I just purchased a XS650 Serial # 447-704361#Can anyone help me to find the year and Model of this bike.#I plan on a restoration##Thanks
Bil Al
The one thing I could find out is that this is a pure street bike. At this point, I lost interest in going further. About the only thing I can tell you itís somewhere between a 1975 and 1979 bike. Just remember when you write, the name of the site is
Would the topend from an mx100 engine bolt on to my 78 yz80 bottom end? if you could answer this for me that would be great.
thank you. chris gano
Nope. Even though both are air-cooled motors, the cases are different.
hi i have a 1984 can am mx 500 which beholds a rotax 486. they other day it locked up, i suspect the bottom end.. i want to rebuild the whole thing, but i can't find any kits anywhere! where can i find a rebuild kit, or is there any other newer motors that a rebuild kit would interchange with? what to do?

Try placing a phone call to Tony Murphy at
Tony Murphy Rotax Inc.#
27701 Largo Vista Rd.
Valyermo, CA 93563
(661)944-1624 Fax
(661) 261-9227

Heís the source when it comes to Rotax parts.
Hey great story Daryl, don't everwant to ride one of those. I still have the RM370 from 1976 , glad they got the bugs out of the animal. sorry you got so banged up on that least you cleared the you know the saying no guts no glory, well I'd say you had the guts so theres your glory man !

The 1971 Suzuki cyclone will go down in history as one of the worst bikes ever made. Even with a huge advertising campaign and riders like DeCoster and numerous Suzukis in the Grand Prixs, it didnít take long for the public to find out what a pile of crap that bike really and truly was. Iím proud to say that the article I wrote in 1971 Dirt Bike magazine was the first one to ever tell the truth about that bike. 

Last month, Lainey wanted to turn his Honda Trail Rider into a race bike. You told him it's almost impossible in so many words.#Rick, I've been a mechanic for 41 years and I know how it can be and easy.

You tell the kid to go to the Honda Shop Service Department and ask the Service Manager if he can borrow the tool to adjust the "power band". ALL motorcycles have a power band, it's just a matter of proper adjustment. Full race would require tightening the power band until the adjustment will not go any tighter and back off 1/4 turn.

Trials competition would be to adjust it down somewhere around "trail"...kind of loose, maybe 2 & 1/2 turns out (counter-clockwise north of the equator, clockwise south of the equator)#

If he's an intermediate rider, mabe 6 & 7/8 turns in from the 1/2 way setting. Elevation plays a key element in adjustment. For every 1000 feet above sea level, loosen 1/2 turn. For every 1000 feet below sea level,tighten 1/2 turn.

There you go! #No charge.

Oh, and don't forget to return the tool to the dealer. Also, a Honda powerband adjusting tool will not work on Islo's or Allstates.
David Fruhling
Just a minute, David. Could it be that youíre pulling our leg?
Just read "Don't Ask!" again and wanted to note my version of "Murphy's Law." Mine's along the same lines as "Multiple Observation Rule."#

Kick starting a motorcycle: For every person watching, it will take 20 kicks. Doesn't matter the make or model. My 540cc TT was a one-kick bike, even after sitting for months (which was rare) A friend shows up and wants to hear it run. Fine. I rode it yesterday.

Kick. Nothing. 19 kicks later, it popped. Good! Next kick is it! I musta flooded it. Just then, the side garage door opens and 4 of my friends walk in. 81 kicks later, it's idling and the fins somehow look to have a little smile bent into them.

San Diego, early '80's. My brother was stationed at Mirimar NAS. I visited. He asked if I wanted to ride his '68 XLCH Sportster (with Morris magneto...uh-oh) He told me, "If it doesn't start on the first kick, try later."#Well, it started first kick. Hell, no problem! I rode to the beach. It's hot and not a lot of clothes are clad on the hard-tails. I stopped at a liquor store for a sixer. Naturally, one person stops to look at the bike when I went to start it (maybe he was looking at the steaming puddle of oil underneath it)#

Kick. Nothing. Well, should I "try later". Hell, no. Look like a wussie? Not I!#

On the 19th kick, it popped. Good! ONE more kick. Just then, a bus load of Japanese tourists unload next to me. The camera lens covers come off! Hell, I'll try for the cameras. Well, 1065 kicks and 6 beers later, it fired. I'm drenched in sweat.

I rode back and said, "Here's your bike. I'm going home."
David Fruhling Again
More from David Fruhling, this time on kickstarting and surviving it. Sort of, anyway.
I was there in 1968-69 and shot 8mm movies of the event. I watched in awe of the dual between Petty on the 500 Maico and Lindstrom on the Husqvarna twin. I will never forget though seeing Dave Aldana coming thru the mudhole on a 250 Ossa WFO with his body hanging off the left side of the bike never letting off and winning the race only to be disqualified for being a pro entering an amatuer event ! I loaned those films to a member of the Antelope Valley ramblers and never got them back.
Mike Sullivan

The Hopetown Reunion of last year was one of the truly memorable events. Since my club, the Dirt Diggers, put the race on, the reunion brought back a real flood of memories.  Itís too bad you donít have a copy of that film you shot, because that would be a real keeper today.
I have a 1985 ktm 250cc dirt bike need to know what kind of oil it takes it is a 2 stroke
You had better go sit down for this answer. My best guess is because the bike is a two-stroke, it takes two-stroke oil. Now thatís just a guess and I could be wrong.
In the process of restoring an 86 Honda CR250 from a barn find, I installed a new top end and removed right side case clutch cover to replace kickstart seal. Reinstalled cover and engine back into frame and now shifter will not shift out of existing gear or into neutral. Clutch seems to work fine. Did not notice anything bent or binding when reinstalling right case/clutch cover. guess Ill be removing cover again but what to look for?
Bart Beddingfield
Right behind the clutch is a fork coming off the shift shaft that lays on top of the shift drum and there is a spring in there that holds a fork unit on the shift drum. When you move the shaft off the support assembly on the shift drum, you might have lost or misplaced this spring that holds the shaft in place.
I used to own this bike back in the 1970's. Still have pictures of it too. Great hill climber and fast off the start because of the gear ratio but otherwise I think I should had stuck with a Japanese models back then.
One day while kicking it the spring behind the case failed spun around and blew a big hole in the case. Parts were hard to find back hen so I fixed it with steel wool and goop and when it hardened it worked OK. Had to jump start the bike after that. I sold it soon after and I think I lost a lot of $$
Bruce Kendall


A decent running 250 Cooper is going for about 1500 to 1800 right now, so you didnít lose a whole lot. A bit of advice for anyone who punches a hole in a case like you did. Fix the hole with JB Weld. Itís a two-part epoxy thatís metal-based and itís really a miracle worker.
i have a 1982 kdx 175.i took off the cylender head down to the piston.i moved the crank up and down and seems to be ok,but when i move the crank back and forth or side to side and it has play.what does there a problem with the bottom end or is that normal?
Freddie Martinez

Side-to-side play on the crankshaft is no problem. The real problem is when you have up-and-down play. If you grab the rod and tried to move it up and down and you get anything in all in the way of looseness, you have a real problem. On most crankshafts however, you have a few thousands worth of play from side to side.
Bought a basket 78 IT250, needs a few parts to finish off, rear swing arm bushings, has smaller DT front brakes so need new cable or drill and tap. Issue is, been a while since I had an old YZ, pulling in the clutch with the motor not running and in gear, should the bike roll?#Seems like it is in gear with clutch engaged, bike probably hasn't ran in long time, looks like it has a new case as there are no numbers stamped into case.#

Looked at a 78 clutch basket on eBay, it had grooves on fingers that looked like they are made that way. It what was possible issue I found on web, unless something else could be causing this... any thoughts?
In an ideal situation, you should be able to pull the clutch in with the bike and gear and be able to move the bike freely. In the real world, itís going to drag a whole bunch and some cases, wonít move at all. When the bike is fresh and new, this should work just fine. But as an old YZ or IT gets older, the clutch action deteriorates. You can make it better for a short while by putting new plates in and making sure the cable is fresh.

I have a 96 Rm 80 want to change to pre mix gas do I need to buy a block off kit or just drain oil tank and people mix gas. thanks wade

This might come as a real shock to you, but the 1996 Suzuki RM 80 runs premix as is. There is no oil injection, no oil injection tank and no facility to put any sort of injection unit on the bike. If youíre like most rational people, youíll run anywhere from 32:1 to 40:1 gas/oil ratio. However, itís obvious that youíre not like most rational people. You sir, are a dummy.
Hey I have a 1999 Kawasaki kx 125. I have a new shock for it but the spring colour is gray, I also have a purple one. I have been told that the spring colour is according to weight. I weigh 140lbs. Which one is softer and the one I should use or do you know where I can get a chart. Thanks.
100-135 pounds bodyweight Ė 5mm Std0.  38/0.40 -Light105mm5169-104.4/4.7/4.9ēLight97mm12102-1/4150psi

135-160 pounds bodyweight -  5mm Std0.39/0.41ēStock105mm5169-104.6/4.9/5.1ēStock97mm12102-1/4150psi

160+ bodyweight - 5mm Std0.40/0.42ēHeavy105mm5169-104.8/5.1/5.3ēHeavy97mm12102-1/4150psi
why you such a prick in your responses?

Mostly itís because a huge amount of the email questions that I receive are truly dumber than a pile of pig crap. Thank you very much.
I'm breaking my KTM 1986 250mx and will be on eBay UK in the next few week's I'm on Facebook under milesy Murphy if you have any questions.
Miles Murhpy
I might break my 1985-6 ktm250mx just gauging interest
Please refer to the above email and maybe you will see why I have little tolerance for truly stupid questions. Iím very happy that youíre going to break your KTM in, but what does this have to do with anything in this column and why should readers care? Therefore, Iím going to exercise my option of being a real prick.
have vin no; 1G8-008610 u have listing but not to this high would it still b same bike
According to my rather extensive files, the bike in question is a 1976 YZ 125X. That serial numbers series starts with 1G8 Ė 000101. For all of you people who are curious about the various IDs of the Yamahas, I would suggest that you please include a description of the bike with your request. For example, is it a dual-purpose bike, a motocross bike, whatever? It will make my life worlds easier. Literally dozens of sheets of paper are normally searched for the correct make and model.
My sons 1990 xr 200 all of a sudden stopped shifting into any gear. I pulled the right side cover off, and sometimes you can see the shift forks working correctly, and sometimes not. I had a lot of the parts out, and they appear to not be worn, and i am at a loss. Any ideas?
Chances are very high that something connected to shifting pawl broke or came loose. If all the gears appear okay, thatís usually the problem.

Yamaha made this 1 ½ hour movie back in 1970.  While nowhere near the quality of On Any Sunday, it has a whole bunch of great footage from the Ď60s up to 1970.  Most of the movie covers off-roading, but there is chunk of road racing and flat tracking.

The best stuff is the old desert and scrambles/motocross racing. Excellent!  Even though itís a Yamaha promo, thereís a lot of shots of J.N. Roberts and other legends of that era.  Itís a neat DVD and one that youíll watch more than once.  Cost is $10, which includes postage in the US. 
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