Vintage Dirt Bike Q & A

well first of all the bike is 100% stock except for a .040 wiseco piston and rings. all the bikes specs are stock, including the timing.

the previous owner started messing around with the carb jets and screwed the jetting up. the bike at idle kind of winds out, like how the engine runs when you are running out of gas.

at half throttle the thing sounds like a machine gun and pops huge smokeballs out the exhaust one after the other, it looks lke a coal locomotive and the smoke lingers behind for a while.
i am use to 2cycle smoke but i have never seen an engine that smoked like this using 31:1. i swear it looks like a coal locomotive!

at wide open throttle the bike runs like the choke is on, but it isnt. and there is again massive smokeballs comming out of the exhaust. somtimes it even makes these person sized smoke rings you can walk through. its really crazy.

i have extra jets for the bike but the previous owner tried drilling some of them and i dont know which ones. so if anyone has a 74 250 and could recomend some jets for a stock bike, i would most appreciate it!

also what kind of carb does my 74 come with? its a kliehn but i cant figure out the model.

While it would not do any harm to rebuild the carb and check that all the jetting is stock, I would also check that the crankshaft oil seal on the primary drive side is not allowing transmission oil to be sucked in and burnt. I had this happen on a RM250C2 and it ran very badly (like the choke was on) and smoked (white) until the seal was fixed...

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Is the bike a CR, MR, or MT? I'm thinking a CR or MR if you're premixing. The MT has a 28 mm type PW carburetor. There should be some numbers and letters stamped on the intake end near the choke lever base. The carb must be removed to read them. I would try to order originals from the Honda dealer. The needle will come with a needle base. Replace both. You may also want to replace the main and pilot if you think they have been drilled out. These things are sensitive. You don't want to clean them with steel wool or sand paper. I found my original 2 part Honda needle jet on E*bay in original sealed packaging with correct part #. What a difference. Runs sweet with no more blue smoke.

I too have a 74 CR250M. I too was having carb problems. If you need to get repair parts for the original carb, call Jeff, at Western Hills Honda. He will be able to get you the parts your looking for, and explain what needs to be done to get the bike running again. Their address and phone number are:

Western Hills Honda / Yamaha
3110 Harrison Ave.
Cincinnati, OH 45211 USA
Phone: 1 513 662-7759
Fax : 1 513 662-7912

http://www.westernhillshonda.com/

Good luck, let us know if you get her running again

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

thanks for the help guys. im going to go ahead and get new carb jets and needles. i am sure the original jets have been drilled out.

the reason i use premix is because the stock oil pump failed and cost the previous owner an engine. he removed the oil pump after that. i dont blame him, i am leary of oil pumps myself. all the new bikes dont have them.

by the way the bike is an mt 250. whats the difference between the various models?

how hard is it to check the crank oil seal? that sounds like my problem. the thing just smokes so damn bad, its like a coal locomotive! i assume i need to pull some parts off the tranny?

anyone want to buy this thing before i start wrenching on it? its got a fresh top and bottom end. its never been raced. got 9K on the odometer and i can get the title so the bike is street legal. its got the right lights and crap for road riding.

MT is the a tamed dual sport version of the CR. Different porting/cylinder, smaller carb, all the trick CR parts like alloy rims and tank are missing, seat built for two, that kind of stuff. The electical/coils/stator is different too as it needs to power lights. MR is the trials version IIRC. I have a cylinder/head/piston from one. Looks like they are closer to the CR then MT.

Three things: My MT had the same problem people are talking about with the crankcase/transmission seals people are talking about. It also had a eaten the top piston ring so low compression. Symptoms exactly like you describe. One thing to check is how hard it sucks at the carb. Pull the plug and with your hand over the carb intake you should be able to kick it over by hand. If there is little or no vacumn then seals are gone.

Fixing it with a manual in hand took a while but wasn't bad. Maybe $250 in parts off of eBay. Mine was converted into a CR wannabee before I got my hands on it. I did not restore it but left it w/o any road features and just made a simple wiring harness. FWIW: My S.O.'s little brother who used to race a CR said it felt a lot like a CR. Power in a well tuned one is good'nuff.

*IF* you do sell it there seems to be a good market for registered/tittled MTs of that time period. They still aren't as expensive as a CR but I have seen them go for well over $1,000. Of course that would mean you would have to fix it and have all the orginal parts on it

$250 to fix a crank seal isnt worth it to me, not for a $500-$1000 bike anyways. its a nice bike but id rather put $250 into a downpayment on one of them new xr650 street legal enduros. no offense to you vintage guys, i dig vintage bikes and actually all bikes but i think i would be happier with a modern monoshock enduro like an xr.

somebody buy this thing from me. i have all the original parts including the oil pump. the bike is stock except for the jetting and a wiseco piston.

it runs like crap but now we know why! the trans is great shifting, shocks and forks work great. the engine starts right up on the first kick but that crank seal makes it run real bad.
i can get the title for it no problem. take a couple weeks at the most. the guy i bought the bike from lost the title so i have to get him off his @$$ and go get a replacment one from the department of motor vehicles. no big deal there.

email me at mailto:smithjoe@adelphia.net or call 561-791-3419
ill be gone for a week, going to a bike show over thanksgiving. i should be back home first thing in december.

If you need a crankshaft seal on the primary side you will have to split the case to do it.a gasket set is about 40 bucks and the seals and bearing kit from vintage elsinores is 49.95,fyi the seals and bearings and gasket kit except the head gasket and the carb joint gaskets from a 73-74 CR250 will work on your bike and cometic makes head gaskets for the mt 250.the top end gasket kit from a honda 250 odessy will work also as it and the mt 250 top ends are identical.one way to check if you dont have a leakdown tester for a bad primary crank seal is drain some of the transmission oil out and then start the engine but DO NOT RIDE THE BIKE with no oil in the transmission and run the engine for a few minutes.if the smoke goes away and or it acts like its running lean you found your answer.as long as you dont ride the bike or run it any longer than you have to it wont hurt the tranny a bit.both main bearings are lubed by the gas/oil mix or the oil pump if its still on the bike.if you do the job yourself you are looking at between 80-110 dollars in parts and about 15-20 dollars
for a manual.I would strongly recomend the haynes manual if you can find it as they tear down and rebuild a mt 250 and it has color photographs
of the teardown.I hope this info helps you out some and I have had my MT 250 since 1990 and still have it to this day.its a very depndable and fun motorcycle if its taken care of and it has loads of personallity that you wont find in a modern 4 stroke machine.good luck.

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(2) 1968 DT1 1970 RT1M,1970 DT1C 1971 RT1B Enduro 1974 MT250 1974 DT250A (2) 1975 DT400B 1974 DT100,1978 DT175
1975 CR250M1 1979 CR250R 1979 Kawasaki KZ400H1 Jesus is Lord!!

i pulled the elsinore out today and gave it a good once over. i kicked it over and it started right up. i got to thinking that if the dmv lets me put a tag on this bike maybe i will go ahead and tear the motor down and fix that seal and keep the bike.

but i have more questions, is there a way to put an electronic ignition on this bike? i HATE points. i really do. i grew up on poinds ignitions and im at the point in my life where i refuse to own a motor which uses points.
i know theres some universal points conversion kits for lawnmowers. does anyone think this would work for my elsie?


what kind of performance upgrades are there for this bike? i would plan on using it for road use only, so i dont need bigger suspension or anything, but a exhaust would be sweet. id like to get a smaller rear sprocket and a larger front one too so i can cruise at a lower rpm.

and whats the deal with the cylinder head? theres 2 sparkplugs going into the head, but only 1 coil and only 1 spark plug wire. isnt that a little funky?

you are right about it having loads of personality. i am so use to running my 4 cycle 125 bike that when i got on this ensinore today and popped the clutch in second the elsie hooked up got traction and threw me right off the bike and onto my back.

it sure does have personality.

I use the PVL ignition and love it. http://www.pentonimports.com/ But it's more than a little pricey. Close to $400.00. Maybe you can find a used one on EBay or somewhere.

Loren

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Those who can make you believe absurdities can make you commit atrocities.

Loren Davis
51y

ah man $400 :\

if i get the rest of the bike fixed up ill probably end up buying that ignition. like i said i hate points.

guys im sorry for this but i just found out my bike was actually made in april of 73, not 74 as i had originally said. does this change anything as far as parts are concerned? can i use cr engine parts now?

Mine has an after market pipe and I have seen them forsale rarely on eBay. Expect to pay ~$100-$150 if you find one.

From what I understand the entire top end from a '73 CR250 from the case up will bolt right on. The CRs changed bolt patterns/layout in '74 or '75 and would not be compatible.

A pipe does wake up the mt 250 quite a bit.I put a krause pipe that was made by jemco on my bike a few years back.its a midrange pipe and it helped all around and gave it a good 500 rpm on top and it doesnt flatten out as early.a pipe and the carb jetted right really wakes up the bike a bit.a 73-74 cr 250 top end will bolt right on and you will need a pipe,34-36 mm carb and you will have to rig up a air filter arangement as the stock aircleaner assembly wont work with that large of a carb.the stock top end could be ported as it has lots of room for improvement and a 30 mm mikuni installed instead of the stock 28 mm kehin carb.other things to consider is fitting it with the triple tree and forks from a 74-76 cr 250 and works performance shocks and the aluminum front and real wheel and brake assemblies from a 73-74 cr 250 on the rear and the front from a 73-76 cr 250 will lighten the bike up and improve its off road capabillities quite a bit.these parts can be found at junkyards fairly easy.as for a electronic ignition such as a pvl it will bolt on but it does not have a lighting coil to charge the battery and run the headlights.I would look into a ignition system from a honda oddesy 250 81-84 and see if that can be fitted.it has a 12 volt lighting coildl on it so you would have to convert to a 12 volt system on the bike.the points ignition is pretty reliable though so if it was me i wouldnt worry about it.

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(2) 1968 DT1 1970 RT1M,1970 DT1C 1971 RT1B Enduro 1974 MT250 1974 DT250A (2) 1975 DT400B 1974 DT100,1978 DT175
1975 CR250M1 1979 CR250R 1979 Kawasaki KZ400H1 Jesus is Lord!!