Donít Ask: Your Dirt Bike Tech Questions Answered

Jul. 01, 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.#

Have a question for Rick ďSuper HunkyĒ Sieman? E-mail questions to editor@off-road.com, Attn: Donít Ask.

Previous Donít Ask Columns
June 2013

May 2013

April 2013


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SUBJECT: BULTACO WITH IRZ CARB
I have a bultaco matador it has an irz carburetor and I can't find anything about it I need a float bowl gasket and a pilot jet for it do you know where I might find some info?
Richard

Most older Bultacos came with an Amal carb made in Spain, usually a side float model. The IRZ carb was used by Ossa a lot, and you can get jets or information on the IRZ from Keith Lynas at Ossaplanet. Email: KLynas.aol.com or www.ossaplanet.com. Tell him that Rick sent you.
 
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SUBJECT:  WHICH BIKE FOR ME?
Hello,
I am wondering about what size bike I should ride. I am 13, 5'1",#and weigh about 90 pounds.. I was thinking about purchasing a 90cc. Any suggestions?
Jackie Hopkins

Itís really hard to give an answer to a question like this. For example, do you want to use the bike for racing, trail riding, or just all-around off-roading? Are you good athletically, fairly strong for your size, or just average? All these things will determine what kind of bike you should have. Letís assume that youíre an average strength person for your size and that you want to use your bike for a little bit of everything. A Yamaha TTR 90 is just about the perfect starting point. If you are thinking about racing, almost any 80cc Japanese motocrosser will do the job. Stay away from all the Chinese crap on the market.
 
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SUBJECT:  BULTACO WITH FORKS ON THE REAR
SuperHunky, Man, you have no idea how you and Dirtbike mag helped me as a kid growing up in Virginia! I'm now 54 years old...started working/competition in 1972 at AlliedCustomCycles (Maico,CZ,Husky,Bultaco etc.) in Richmond...raced#motocross and competed in trials throughout Va.## My intrest in motorcycles have carried me thru the years and for the#past 14 years I've been a master BMW tech at Morton'sBMW in#Fredericksburg Va. We actually sponsored a David White (my friend of#30+yrs) and won the prestigious VCHSS (Va Championship Harescambles#Series) senior A class 2010 championship with a 450 BMW!! From what I gather THE FIRST BMW to win a major dirt bike competition in the US## ANYWAY, my question to you...put your memory cap on!!!##  There was an article (I think in DirtBike Mag.) in the 70's that#showcased a Jim Pomeroys tricked out Bultaco with front forks modified and fitted as rear shocks.

Was this a Factory mod.?...or was this a US mod. from his Stateside#mechanics??  Any Idea how many were made..and what happed to#it/them???

THANK YOU SUPERHUNKY,
PleezeReply 
Dewey Keeton
Louisa , VA
 

Luckily, I know a little bit about that bike. At the time, Pomeroy rode for the Bultaco factory, and his mechanic was a man we called The General. His real name was Jon Miller. Anyway, he was the man who decided to put the forks on the rear because the standard suspension on the Bultaco was not up to the task. As per usual practice, the Bultaco people went nuts. The bike was never put in production and they never allowed the bike to be campaigned because it didnít come from them. The bike was a one-off and that was it.
 
 
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SUBJECT: MAICO LOADING UP SOUNDS
In 1970 I was 12 and had started my youthful endeavor as a 125cc motocross racer. I can remember while watching my brother on his 250 Pursang on the line a strange noise. It was usually Maico's making a strange bong- bong -bong sound and spewing copious amounts of smoke. The riders would lean the motorcycle  to the side and after a few moments the bike would clear and off they'd go.What caused this? My guess is the bottom end loaded up with fuel mixture and leaning it over leaned it out. Your answer  O ' Hunky is awaited. 
Thanks man 
Randy Keller
 

 
I had some early Maicos back then and went through exactly the same thing that youíre describing. Hereís the inside scoop on all that. The Maicos and Bultacos all came with carburetors that were jetted way too rich down low. In fact, the Bing carburetors on the Maicos didnít offer any smaller pilot jets than came in the carburetor stock. That meant that you were stuck with the overly rich jetting down low. By leaning the bike way over to one side, the pilot jet no longer sat in the fuel trapped in the float bowl and therefore the fuel mixture was able to lean out properly and the bike would then start to run clean. Most savvy Maico riders of that era would just put on a Mikuni carburetor to deal with the problem properly.
 
 
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SUBJECT:  87 SUZUKI RM250 WONíT RUN
I have a 1987 Suzuki rm 250 and im getting spark and compression but its not wanting to fire up I have a 1987 Suzuki rm 250 and im getting spark and compression but its not wanting to fire up can u help me solve why its not
Cade Bodkin

You need a number of things for any motor to run. These things are proper compression, mechanical integrity, fuel, spark and correct timing. If any of these things are not working properly, chances of your bike starting and running are slim or nonexistent. The very first thing I would check for before you go crazy, would be to make sure youíre getting fuel when you need it. This means taking the carburetor apart and checking your float bowl for crud in any of the jets. As long as you have proper fuel flow, you should then turn your attention toward timing. Thatís right, the spark that you have should happen at the correct time. Before you take your bike into a shop and have them go through it, check these two things thoroughly. Chances are the problem is here.

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SUBJECT: RELUCTANT NUTS
Hello!#We have a 1989 Honda NX125 dirtbike that we are tring to change the clutch pads on. We have all the parts and tools that are needed but can seem to get the lock nut off. Do you have any suggestions?
Kayla
 
Whenever I have a nut that I want to get loosened, I find that a little bit of heat usually does the trick. You donít need a welder, but a simple propane torch will do the job. Just heat up the nut and youíll find that it should come loose.
 
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SUBJECT: HUSABERG WONíT RUN
I recently purchased a 1994 husaburg 501 and can't get it running I have cleaned the carb all the lines checked and I am getting spark. Really wanting to get this running I'm low income just wanting to ride can you please help. #Thanks Josh
 

 
Like I always say, you need a certain number of things for a motor to run. Among those are fuel, compression, spark (with correct timing) and mechanical integrity. By mechanical integrity, I mean that there should be solid components and no air leaks. If you have all these things happening, you should be able to get the bike running. The very first thing I would do if this was my bike would be to take the carburetor apart and check for fuel flow or clogged jets. Next you should check the compression on the engine. If itís low, starting becomes very difficult. On the mechanical integrity side, you want to check for air leaks anywhere in the entire system. Lastly, I would check the timing. Do all these things in the order that I gave you and you should be able to stumble on the problem.
 
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SUBJECT: WHAT IS IT WITH ALL THE YAMAHA ID?
looking for the year and model of my sons newly aquired dirt bike its a yamaha and the numbers on the forks is 4v5-020655 want to restore to working order
Jess
 
The bike in question is a 1982 Yamaha IT250J.
 
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SUBJECT: TOO MUCH INFORMATION
1M1-100632. Can you please tell me what year model cc Thank u
 

 
Such a wealth of information! Would it have strained your mind to tell me that the bike was a Yamaha? Since we get such an overwhelming number of questions about Yamaha ID, I figure thatís what it must have been. According to my unbelievably accurate files, the bike in question is a 1978 D250E Yamaha. In this particular model run, the engine numbers start with 1M1 Ė 100101
 
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SUBJECT: YOUíRE NOT TRYING
I"m looking for a pdf repair manual for a 1972 jt2 mini endure
Rob
 
If youíre looking for one for free, lots of luck. However, if youíre willing to pay a small amount, I found several on eBay with a minimal search.
 
 
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SUBJECT:  COMMENTS ON THE DEATH MACHINE
Re: Death Machine. I'm digging on the "Death Machine" power bicycle featured in the June "Don't Ask!" I like the muffler mounted to where you can fry your balls in cold weather.

The rear mounted gas tank may come in handy for flaming loop-outs.#To enhance performance, I'd continue the fairing with full body work. Just rivet it to the existing fairing. Might cut into any turning distances but who turns at Bonneville?

I'd like to see some "BMX Action" or some "Freestyle BMX" with this fine unit!
David Fruhling
 
We drew quite a bit of email on the Death Machine featured in the June Donít Ask. Most of the people thought it was a complete put on, but we have to assure you that someone actually made this thing and rides it. All we can do is shake our head.


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SUBJECT: THOUGHTS FROM A TM400 RIDER
TM 400 I had one. Japanese answer to the MAICO MC 501! I broke my knee cap on that bike and tibia. I hope i never see either bike again! Extremely powerful and both bikes were deadly on the race tracks! TM 400 Cyclone was no toy this was a factory racer as were all the Maico's. Another nightmare from hell was the Honda 250 Elsinore Silver tank#green striping! Stay the hell away from that bike! I watched that go after a TM 400 cyclone and Maico radial fin i believe it was a 490 Magnum ! THat dont make bikes like this any more all liquid cooled garbage!#Back in the 70's i used a JOFFA MOUTH GUARD with the plastic dental guard you put in your mouth came with plastic strap for the mouth guard! I miss the 70's ! Bikes back then were deadley, dangerous, loud expansioned chambered! The sound from these bikes music to my ears! Easey Rider ?? Opening scene ha ha!!
Atkin
 

 
We have to enthusiastically agree with you that the TM 400 Suzuki was one of the truly awful bikes of all time. However, the 501 Maico properly set up was a wonderful bike. Also, I had a 250 Elsinore back in 1973 and it was quite a good bike once you got decent shocks on it.
 
 
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SUBJECT:  WHICH WAY TO GO?
I am trying to split the case on a 1983 Yamaha yz 490 the crank nut is that a normal right handed thread or is it left hander.
Thanx
Rich Evans
 
We referred to Matt Cuddy on this one, as he had a 1986 YZ 490 and he assures us that it was a clockwise thread, a right-hander. The Yamaha YZ490 is a right-hand thread on all shafts. Suzuki uses left on the right-side crank. Ossa uses left on both right side shafts but not Yamaha. Amazingly, Matt is still alive in spite of owning that wretched 490. You would be well advised to turn it into a planter instead of riding it.


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SUBJECT: 1978 HONDA XR 75 ...PISTON RINGS
I have 1978 Honda xr 75. I can't find anyone that has piston rings for it. The piston size is 1.985. I can't even find a after market piston kit for for the bike. The Honda dealers are telling me that Honda discontinue the rings and can't find a after market piston for that model. I would like to get the bike running. I'm knot sure where to look or what to do?
Thank you
Mike

Once again, I must say that youíre simply not trying. I went on eBay and within five minutes found dozens of sources for pistons and rings for the XR 75.
                                  
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SUBJECT: BOGGING 1980 YZ 250
Now for some bike help if you are willing. I just finished a 1980 YZ250. Has a DG pipe, stock porting, 5 speed gearbox from an 81, 7mm reed spacer  and I added 6 ounces weight to the rotor. Is it true that I will never have a smooth power transition from slug to rocket in 100 rpm?  It has stock sprocket gearing for the 81 and I wonder if adding 2 teeth to the rear will let me get it on top sooner. Once the revs drop and you clutch it to get it up, it takes of like a rabbit but the power starts just above mid range to get it screaming again. Like towing an anchor on the bottom.

Any help would be appreciated or just a good laugh as I read these things were like this anyway. Did Hannah develop the motor?
Thanks Rick and I hope all is well with you,
Gary Moore

I had a 1980 YZ250 that I raced for the entire year and I did experience a bogging in the motor that drove me nuts. I traced the problem down to the reeds being worn out and not seating properly. I installed Boyesen reeds in that bike and the problem went completely away. One thing you should be aware of is that the 1980 model had low-end and midrange power out the kazoo and not a whole lot on top, so take it from there.

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SUBJECT:  YET ANOTHER YAMAHA I.D. QUESTION
Hi,
I recently picked up a basket case project bike and need to determine the year of the motor. I was able to contact the dealer for the frame year but they couldnít help me with the motor number. the frame is a 1982 yz490j. the 10 digit number on the motor is 2WH-006722..can you tell me what year this motor is?
Thanks,
Bob Lewis
 

This one was a real tough ID. As it turns out, the motors starting with 2WH were found with a 1988 YZ 490. How you ended up with a 1988 motor in a 1982 chassis is a strange one, but not any stranger than the YZ 490. At this point in time based on what we know about that bike, your best bet is to either burn it to the ground or sell to a passing gypsy, because that is probably one of the worst bikes ever made.

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SUBJECT: HONDA 230 L & F SWAPS
I have a 2009 CRF230L which I would like to add performance upgrades like you did on the CRF230F such as open up the air box and install a DRD or Big Gun exhaust.#Can I use the same carburetor jet sizes as you used on the CRF230F?#Thanks,#Wil Smith
 

 

You can put the CRF 230 F jets directly into the carburetor of the L model. As far as the exhaust goes, I took a look at the bike and it appears that the mounting is the same. If you have any problems please let us know.
 
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SUBJECT: VINTAGE HUSKY "BOGGING" QUESTION
Hi rick!
I've enjoyed reading all your messages throughout the years, and hoping you can help me a little. i'm an older district 37 racer that recently purchased a "barn find"1972 husky 250wr that i restored from the frame up. the problem i'm having is that after all the work that went in to this bike, i can't seem to correct the low-end bogging that takes place under a load.

here's what i've done so far to correct that problem, but to no avail: new top end, changed the carb. from the stock bing to a mikuni, checked for air leak--ok, tried re-jetting from extreme low to extreme high, new fuel at correct mixture, cleaned and repacked silencer, new points, good spark, although the spark itself wasn't completely a nice blue color.

the motor still smokes quite a bit even after cleaning it out, but i keep think that "it's an old two stroke" and that most all of the older vintage two strokes did that.  i owned and raced this very model back in the seventies, and always had good luck, but i'm now at my witts end with trying to figure out what my next move should be?? sorry i'm so lengthy here rick, but maybe my next move should be a "harry carry"
      
thank you in advance.
Kathy Winkler
 

The one thing that you didnít mention is crank seals. On an older bikes like that, chances are the crank seals are shot and if theyíre shot, the trans fluid would get sucked through the seals into the lower end giving every illusion of rich jetting. Check those crank seals and get back to us on that.
 
 
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SUBJECT: I DONíT LIKE YOU!!!
Hey I donít like you or just about anything you have to say. You are nothing but a smart ass and you give nothing but smartass answers to people who ask you questions. Sure maybe some of the people donít know a whole lot but after they asked you a question they still donít know whole lot. So why you just go stuff your head in the ground and get a real job huh.
Marty M.
 
Marty, I get hundreds of emails every month, many of which are truly stupid. I try to take one or two of these out and print them, mostly for the amusement of the readers. I humbly suggest that if I bother you so much, do your reading somewhere else. Now go away and stay away.

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SUBJECT: TRULY DUMB EMAIL FOR THE PERSON ABOVE
I cant get my bike started most of the time unless somebuddy pusehes me or I park on a hillÖÖ what could be the problem do you think???
Allen
 
Your powerband is probably broken.

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SHAMELESS PLUG
My new book, THE LAST RIDE, is at now out. It's fiction and starts in 1969, when an 18-year-old kid just out of high school gets a chance to ride his Yamaha 250 DT1 from Pennsylvania to Los AngelesÖ all off-road.  His adventures are truly amazing.

The book then jumps 40+ years where the same person, now in his 60s, wants to get that old Yamaha back in his possession and return it home by riding it all off-road across the country again. The book is $15 plus $2.75 for mail anywhere in the US (or $5 for Priority Rush mail) and for more information, the email is: superhunky@gmail.com
Paypal address: superhunky@gmail.com

Have a question for Rick ďSuper HunkyĒ Sieman? E-mail questions to editor@off-road.com, Attn: Donít Ask.

Previous Donít Ask Columns
June 2013

May 2013

April 2013

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