Don’t Ask: Off-Road Dirt Bike Tech and Maintenance

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.

Other Don't Ask Columns:

February 2011

January 2011

December 2010

EDITOR'S NOTE: For those unfamiliar, Rick Sieman has been a staple in the dirt bike world for decades, and his legend recently received honorable mention in a Racer X column by Davey Coombs. Check out the link to learn a little more about "Super Hunky."

http://www.racerxonline.com/2011/02/17/the-list-ten-best-nicknames

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SUBJECT:  ROD KITS AND TIRE CHOICES

Dear Super Hunky,
This is so cool that I found you here! After an 18-year hiatus I have finally gotten back in the world of MX by purchasing a near mint 1989 CR250 completely disassembled in boxes for $200. I'm pretty good with 2 strokes and look forward to rebuilding the bike from the ground up-where it's needed of course.

Here's my questions: #1-the big end bearing has been thrown so I either need to have a new one installed or see if HotRods offers one. If they do make one for my year would it be an upgrade of the original, or is the stock shaft of better composition and quality?

#-2 Back in the day I swore by Wiseco pistons but now I notice there are a couple of other brands[Namura and another I can't recall]out there. Are the other brands any good? They seam to be about half the price of the Wiseco but that doesn't really mean anything to me because I prefer quality.

#3-the forks are badly damaged by our salty air[I live 60 miles off the coast of Alaska in Canada on an Island called Queen Charollotte Islands] and need to be replaced.If I remember correctly the only problem with this machine according to Dirt Bike magazine was poorly under sprung and harshly over damped suspension.If I am correct,and I need to replace the forks anyways,is there another bike that has compatible forks that I could replace these with?If not could you suggest a spring kg for the front and rear?I'm a 185 pounds lower intermediate rider that rides some trails and doesn't race,purely for fun.aside from that is there anything else I should know? does the jetting work for sea level? Except for some matching and smoothing of the castings on the exhaust and intake ports the machine is stock, aside from what I've already told you.

One last question: back in the day I used a Dunlop K695 out back and a Bridgestone M23[or maybe a 22-my memory fails me]up front with great results. Are these tires still available or even relevant today? If not could you please suggest something as good or better? Lastly, please don't rag on me for purchasing this bike. It didn't have enough hours on it to have even a light layer of carbon on the HPP's and the cylinder still has the cross hatching on it. I have no idea how it came to be. Plus it reminds me of a really great time in my life,and of a really great time in MX! Thank you for any advice!
Dale Piwek

I've heard plenty of good things about the Hot Rod kits and the price definitely is better than OEM parts. About the only real problems that I've heard with the kits are with the Honda 250 and 450 4-strokes, so take it from there.

I've personally used Wiseco pistons throughout the years with great success and don't know anything about the new piston that you mentioned. So if it was my bike, I'd stick with the Wiseco.

Before you go crazy with the forks, consider changing to a lighter fork oil and run it about six inches from the top with the forks compressed and the springs out. That should help considerably.

Those Bridgestone tires used to work really good on hard-packed terrain back in the day. I don't think they're available anymore, but it's certainly worth investigating. You might give the new Maxxis tires a try. I've used them and like them.

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SUBJECT: 1973 YAMAHA 360 REVERSE?

Dear Rick,
I have a 1973 Yamaha 360 Enduro (RT-3) that occasionally will go backwards...(no, I'm not on any mushrooms or ??). Yes, the bike actually moves in the wrong direction! Being a rider for over 50 years, I'm not trained to go in that direction. Watching the dirt being thrown towards the front tire on takeoff usually tells people that I do not have a brain tumor. If I shut off the bike, let out the clutch in gear and push on it (lightly) forwards, I can fire it up and proceed in the normal direction......forwards. I don't think the tranny has reverse, is the engine running backwards?

This has happened more times than I wish to deal with.  I wonder if it will someday finally refuse to go forwards and leave me having to ride it in the wrong direction? I've asked everybody for help and have only had strange looks gazed upon me. Could the bike be in a time warp? If I ride it backwards, will I once again be 21 years old and fresh as a new pup?

I ride in the Trinity National Forest  (Northern California) and can get quite a few miles from home. I would hate to have to walk out, as that's another hobby. I would appreciate any help with this issue.......it has everyone stumped.

Thank You,
Swamp McGinnis

Dear Swamp,
 
1973 was the year Yamaha dabbled in time travel. Since most of the Enduro line was so slow, they figured if they could warp time by throwing the universe into reverse. The bikes would be at the start-finish line before the race even started.
 
But it didn't work out, and it just made the bikes run backwards.
 
What you have there Mr. Swamp is a case where the points have closed up on you, bringing the ignition spark too close to top dead center, allowing the motor to run backwards. Open up the points a tad and you should be OK. Also, when the points close up, you will get pinging and detonation, along with a very high idle.
 
And after a long ride if you find yourself back in 1990, the time-warp gizmo has started working. Check out the story on the RT3 somewhere in this fine website.
 
Cheers,
Matt Cuddy

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SUBJECT:  IN PRAISE OF THE KAWASAKI KDX200
as a owner of 14 kdxs and 2 84 kx 250s and kx500- the kdx is a do anything powerhouse and is heavy compared to 10k new machine but these bikes can be lightened and disc brakes mods off kx and are rock solid at 90mph and stabile and reliable and are worth up to 2000 used parts are available and very interchanchable and very competetive to this day as my 84 kx 250 and 500 smoke bikes 8k more then them so called beaters so buy that kdx 450 very rare and powerfull!
ken krajewski

The Kawasaki KDX 200 is definitely one of the finest bikes ever built and quite possibly the best Kawasaki that was ever made. They quit making the bikes in 2006, which is a real shame, as the four-stroke push of the company had just about destroyed a bunch of good two-stroke bikes. I had a 1990 KDX 200 when I lived in Baja and I put 12 years of hard riding on the bike with no real mechanical problems. I'd simply replace chains, sprockets and tires as needed. The oil was changed in the gearbox regularly and the air filter was kept clean.

When I sold the bike, it had a loose piston and rattled quite a bit and was smoking considerably, but still running fairly strong. I just recently bought another 1990 KDX 200 and have it sitting in my garage. It's a fantastic trail bike. One of the things that I highly recommend is going from a 13-tooth counter shaft sprocket to a 15-tooth. Now this might seem like a huge jump in the gearing, but the bike pulls it perfectly and you can still use second gear in tight situations. One other thing you might consider doing to your KDX is installing Boyesen reeds.

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SUBJECT:  YZ VS KX POWER?

Ya we do a lot of riding when I was younger I had yz 125 about 5years ago....so now I bought a 03 kx 250 and what I figured out is that my friends yz 250 had a lot more power..when I ride my bike and get comfortable with it I jump on there yz and you really feel the difference In power the zy got alot more when you get on the gas it is there...now for when I was just getting back on a bike the kx was good but now I wish I would of got the yz..then I thought it was just his bike that was fast but then I jumped on another friends yzand it felt like it had even more...so know I'm wondering if it is just my bike???
Chris Myers

For some reason, YZs just seem to have snappier power than KXs. There are those who would disagree with me, but as my sainted grandmother would say, bite my shorts.

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SUBJECT: JOINT PROTECTION

Hi Rick-
Love the site, retired biology/ English teacher..appreciate your critique of language abusers..62 yrs old..have three restored SL125's.. yeah, I read the mag article! Any bolt on later forks to improve travel, that utilize the Sl hub? Maybe just better front springs? Same for rear..better shocks.. couldn't find shocks at Works Performance.. I'm primarily a trail rider, 5'9', 155 lbs..

I have six bikes, and am restoring a JT-2MX for my 6 wk old grandson.. In the past , I owned new a PE 250, an MR250(stolen right after I bought it), a DT175 and an SL350. Wish I had them all today! My road bikes are a Triumph Bonneville and 77 CB400F.

Also, what is the best elbow and knee armor for enduro/trail in your opinion? Too many choices!

When I was in my 20's, we all sat around and read Dirt bike magazine..still have a few..here in NY, we went to Unadilla and watched Roger D, Brad Lackey, and Gerritt Wolsink (sp?)..still have old 8mm of them somewhere..
Thanks in advance,
Thanks in advance
John Coryea

I can't believe that Works Performance didn't have a shock for your bike. Contact Gil directly at 818-701-1010 and I'll guarantee that he'll find something that'll work. I've always used the regular old kneepads that came with my leathers and never used any elbow protection, so I can't help you there.

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SUBJECT:  LOOKING FOR A HONDA MT250
In Regards to story on site, but might be useful for you ...

I am looking to buy an MT250 if it's running-and you have a title.

Please email me at  ********** with photos and price. Thanks.
Mick

Since we are not a source for buying and selling dirt bikes, we can certainly recommend Marks Vintage Motorcycle Swapmeet (http://www.vintagemx.us/). They have literally thousands of vintage motorcycles for sale and will meet your needs quite easily.

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SUBJECT:  KILL SWITCH FOR YAMAHA TTR90

I am trying to install a pro design kill switch on a 2007 TTR-90 dirt bike. It comes with to wires one longer than the other. I know one is for the ground but the other wire don't know where it installs. If you can e-mail back with some instructions or pictures i really appreciate it, thank you.
Eddy

Since I don't have a Yamaha 90 in front of me, I would do what any good mechanic would do, and that is find out which one of the two wires is hot and which one is the ground. All you have to do is hook up your kill switch and put the two wires in any order that comes to your mind. Then, by holding the kill switch down in the close position, see if you have any spark in the plug. Then switch the positions of the two wires and do the same thing again. The one that works is the one you should stick with. Now that wasn't so tough, was it?

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SUBJECT:  1982 HONDA CR80R WITH MAJOR PROBLEMS

i have a 1982 Honda cr80r i bought it and when i bought it it ran fine. but i had to get a few parts to get it going such as chain and tire. so i didn't get to test ride it before i bought it. when i got all of the part i rode it and it topped out at 20 mph in 6th gear. i took the clutch apart and flushed it, nothing was broken. i think it might need knew reeds. what do you think?
Kevin

Let's see if we can get this straight. You bought a minibike and you never really got to ride it and you said it ran fine. I don't quite get this part. So you finally got to ride the bike it topped out at 20 miles an hour in top gear. That in itself should tell you that you have major problems. But what do you do but take the clutch apart and flush it out?  And your consensus opinion is that it might need reeds.

I hate to be the one to break it to you, but don't have much more in the way of skills than the average German Shepherd. Get a manual, force yourself to sit down in a nice quiet place and read it, and then you might learn a thing or two that you'll have to do to your poor unsuspecting bike.

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SUBJECT:  IN SEARCH OF KTM PARTS

Hi mate,
I have the pleasure of owning a 1994. 550,use,mxc. I live in west Australia.my dilemma is parts.iv been waiting for a ring set + spare piston. For 8 months, tried Austria and U S A .I'm still bloody .waiting, whot I need is advice on who is the best/prom supplyer for parts, please help me u need my 2stroke fix .cheers rusted
Rusted

Here's the phone number for Kay TM USA. They absolutely should be able to help you find whatever part you need for your bike.  951-600-8007.

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SUBJECT: CR85 IDLE ISSUE

Rick “Superhunky” Sieman;
I have a challenge on a 2004 CR85.  I have been building bikes for years but this one has me stumped. The situation concerns the idle circuit.  If I adjust the slow speed jet mixture to achieve a nice clean response, i.e. not rich, ~ 2.0 turns, if I rev the motor the idle walks up,  if I adjust the idle down it will drop suddenly to barely idle.  Then if the slow speed mixture is set to about 1 turn to fatten it up then adjusting the idle on a somewhat erratic (fat)mixture the same goes adjusting the idle several turns in achieves a very, very low idle where it will sit until rev’d as if it’s loading up, clean out and rev out for a bit then drop or if real fat drop completely to the very slow idle. The issue is there is no in-between either - 1,000 rpm or 200 rpm.  

So here is what I’ve tried to do to resolve this problem. Note some are not likely relevant but gives you an idea of the level of effort.. 

1.       Two motors do the same thing 85 /105
2.       Round slide (04) & Flat slide (05) Carb.
3.       Jetting – Various Slow Speed Jets, Optimum response ~1.75 /2.0 turns
4.       Checked Float Level, jetting circuits
5.       Rebuilt 105 Motor – Complete (bottom & top) New everything, seals, crank, bore and top end.
6.       Replaced (New) Carburetor  - No change, Re-checked Float level, jets, circuits etc.  Re-jetted
7.       V Force Reeds New – Tried Stock Honda reeds too.
8.       Swapped Mag.  Ignition Only
9.       Different Exhaust Systems FMF/JEMCO – good seal, re-pack muffler
10.   Different Air Filter
11.   Checked Fuel Flow
12.   Checked Throttle cable
13.   Checked for air leaks, base gasket, carb boot, left crank seal,  etc.
14.   Used various Fuels (VP 4.4 and TRICK)
15.   Changed Head –CR 105
16.   Compression Test - 180 Psig
17.   Dyno  RWHP - ~25.4 HP ( Good Power/Torque curve)

About only thing I can think of is the black ignition box and carb. boot are common between all testing. Any idea’s ???
Clint

My first thought was an air leak, but since you seem to have checked all those possibilities, we can write that off. My next thought was a pilot jet is not seating correctly and the gas is going past the pilot jet. Failing that, you might check to see that fuel is not going past the main jet and giving you those false readings. There should be a little brass or plastic fitting right underneath the main jet that prevents the fuel from going past there through the area where the needle jet sits. This might sound far-fetched, but it's worth investigating at this point.

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SUBJECT: 2003 KTM 200EXC

Hello Rick. I bought my son an 03 200EXC last summer. The bike needed some TLC, but was priced right. While replacing the front wheel bearings, I found out that the front end was from an older model (98-02?). 43mm forks, smaller axle, etc. Now, these forks are about as harsh as I've ever ridden, unless you're really hammering them. Are these worth a re-valve, or should I find the correct 48mm forks? Along with the clamps, wheel, and brakes? I have heard that some of the WP forks were outstanding, while there are others that cannot be fixed.  Any help would be appreciated.
Thanks!!
STEVE KAILHOLZ

Rather than spending a lot of money, try putting softer fork springs in, lighter fork oil and less oil volume. Also, make sure that you don't have excessive air trapped in the fork tubes. Bleed them first before you try any changes whatsoever, then start with the springs and the oil viscosity first.

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SUBJECT:  SUZUKI RM 250 FUNNY NOISE

I have an '06 RM 250. Just did complete top and bottom end as well as recoating of cylander.  Anyway all of sudden bike makes a whirring sound.  Never had before.  Bike runs and feels great just annoying noise.  No differance with clutch pulled in or not.   Sound increases(as loud) in line with higher rpms.  What could be causing this noise?  My boyfriend aslo has RM 250 an 02 makes same noise.
Janine Barrett

It has all the sounds of a water pump bearing that’s wearing out.

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SUBJECT:  HONDA CRF230F TOP SPEED?

I know youve probably recieved more questions regarding 230's than any other bike, but I have an extra stupid question for you: What is the top speed of a stock-geared 230 Honda?
 
Thanks for the time!
Thomas

A stock CRF 230 Honda should top out right around 70 mph under ideal circumstances.

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SHAMELESS PLUG:
DIRT BIKE MAGAZINE CD SET
Get the first four years of DIRT BIKE Magazine on discs. Those early copies are getting hard to find and the ones in the first year (1971) are going for big bucks. Here’s what you get:

*   Every issue from June of 1971 through all of 1974. That June ’71 issue was the very first issue. I worked on all of these magazines until that last issue in 1974. You’ll see a big difference in content in that last issue and the ones that preceded it.

*  Every issue has every page included. All the color pages are reproduced in color. You can print out every page if you want to, since the issues were produced in Picasa 3 format.

*  Or you can put it in your computer (or CD/DVD player) and simply enjoy a slideshow of each and every year. There are seven discs included in the package. Each disc contains one-half of a year (six issues) in order. This comes to about 4400 pages total.

Here’s how to work the discs: Pop a disc in your computer and open it. An icon saying PICTURES will appear. Left click it.

Another icon will appear naming the disc (ex: DIRT BIKE 2nd HALF 1974). Left click it. This will bring up a bunch of dates/icons. Left click on the first one.
This will open up Picasa 3 and the first page of the magazine. Go to the bottom of the photo with your cursor and this will reveal the tool bar for Picasa 3. It’s self explanatory. You can make the page bigger or smaller, rotate the page, edit the page in Picasa, advance to the next page, make a slideshow out of the magazine by clicking the arrow in the middle, or simply print the page out by going to the down arrow (far right), click it and follow the directions.

The seven disc set costs $70 plus $5 for priority mail.  So get your very own piece of history.  http://www.superhunky.com/   go the STORE for details.