Vintage Dirt Bike Q & A

I'm in there process of getting my 74 CR250M out of moth balls. So far, I've drained the gas tank, removed the carb, disassembled, and soaked and cleaned it. I reassembled it, reinstalled it, put in fresh gas, and to my surprise, it started on the 3rd kick. (I had forgotten how back pressure the kick starter has, and what then can do to your foot or leg.) When I reassembled the carb, I must have put the float needle valve in upside down, as without the engine running, and the fuel on, it would come out the overflow. I know I need to drain and replace the engine oil, but what oil do I replace it with? I may need to add oil to the forks, I think I'm supposed to use ATF, but I'm not sure. What ratio should I run gas/oil, and what brand oil is recommended

There are a few thing I need to replace, 1st I need to replace the original front sprocket (teeth are missing), I would like to drop a tooth or two, as I plan to trail ride with my son. The original air filter has dry rotted, the grips need to be replaced, and the front fender is cracked. Any suggestions as to where to locate the needed parts. I'm mainly planning to trail ride with my son, and showing him the old man's still got it...

Any suggestions/tips to help get me get back onto the trails would be appreciated

Howdy,

Check your ignition timing if you are getting excessive kick back. I believe the stock specs call for 2.3mm BTDC. Try backing off to 2.0mm and see if that helps. (I run mine between 1.7 and 2.0mm but I have a PVL ignition.)

Unlikely you put the float bowl needle in upside down as... well.... unless you really use a lot of force it just won't go in that way. More likely the needle is scratched, has some crud on it, or has hardened and won't seal against the fitting in the carb body. Or you have debris wedged up in there that's not allowing a seal.

For engine oil I use regular old automotive 20w/40. Takes about .8 qt. There is a dip stick on the filler hole. With it unscrewed fill the case with oil until you get oil up to the hash marks on the stick.

Gas/oil ratio depends on what brand oil. I use Gold Spectro at 40/1.

Front sprocket can be obtained either from Sprocket Speciaties at http://www.motorcyclesprockets.com or from Western Hills Honda at http://www.westernhillshonda.com . Western Hills is a good source for old Honda parts in general.

Air filter can be obtained from Dave Boydston at AMS. http://www.amsracing.com

As for grips, unless you want the original grips just pop into your local motorcycle store and use whatever suits your fancy.

For a front fender you'll probably have to look on EBay.

Front fork oil use either ATF or a 10w or 20w fork oil. (ATF can be a little rough on the seals but generally works fine.)

HTH,

Loren

thanks for the input. I really appreciate it. Its been idle for a while, so I hope all it needs is the fluids replaced, and a few minor repairs, and it will be time to get it dirty...

I'll let you know how it goes.

Dave still has the front fenders listed on his Web Site. Follow the Fender Link. That's where I bought mine. Nice friendly service. It's a plastic reproduction, not N.O.S.

http://www.amsracing.com/a.htm

I've tried everything I can short of replacing the float valve, (which is on order), but I've been unable to get the fuel to stop coming out the overflow. When I took possession of the bike the choke lever was coming out the carb. I reinstalled and it seems to work, as with a cold engine, choke on, it will start on the 2nd or 3rd kick. Is there a special way the choke needed to be reinstalled, as I just put it back together, the best I could. It just seems to run as if the choke is still on after it warms up. I'm assuming this is caused by the bike being flooded with too much fuel. I hope this is will be corrected when I replace the float valve. Does anyone have any other suggestions as to what I should try to correct this problem.

Any and all suggestions are appreciated.

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74 CR250M, bought new in 74, still stock, except for the new 36mm Carb, and proform exhaust.

I took the carb to my work bench, where I completely disassembled it, when I removed the seat for the needle valve, it became apparent as to the problem. the "O" ring, or what was left of it, was allowing the fuel to flow past the needle valve. I tried to repair it (without parts), and reinstalled, only to see it is now much worse then before. At least I found the problem, and as soon as the repair kit arrives, I can get this beast ready to ride again.

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74 CR250M, bought new in 74, still stock, except for the new 36mm Carb, and proform exhaust.