ET-250 primary clutch replacement

E

ET250MAN

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Nov 26, 2006
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I've got a 1978 ET-250. I'm looking to replace my primary clutch. It rattles way too much. I took it apart and its too sloppy on the shaft.
What clutch should I put in? I need to know specific mfg & model number of clutch. I'm having trouble finding one that will fit this sled. Thanks!
 
Yes. I'm really looking for somebody to tell me exacty what clutch will work. Not just "go look over there someplace..."
 
Its either going to be this one,

206094A 94C CLUTCH - 30MM 1:10 tapered bore. Adjust to belts 1-3/16" thru 1-1/2" wide. Comes with kit #205828A pre-installed. Stock #206094A thus accepts both 1-3/16" and 1-1/4" wide belts, just as it comes - right out of the box. Also contains six pucks #205918A and orange spring #205583A. Since the majority of snowmobiles, including those with engines such as Kohler, CCW (Kiritz), JLO, Hirth, Tohatsu, Kawasaki, Sachs Kiehaefer, Mercury, Xenoah, Suzuki, Yamaha, etc. have a 30MM - or occasionally a 25MM 1:10 tapered crank, this is the most popular DUSTER clutch. Also for FL 350 Odyssey.

OR

212629A 94C CLUTCH - 30MM 1:10 tapered bore. For 1-1/4" wide belts - contains 6 pucks #205918A and red spring #212631A. Limited application. This clutch is ONLY for those Yamaha models built from about 1974 to the present, which require a gear attached to the back side of the clutch for driving oil injection system. Included among the models, most Exciters, etc. This COMET clutch DOES NOT interchange with nor fit all Yamaha "geared" models. If there is any question of it, check with your Yamaha dealer.

You will have to ask your dealer on which one it's going to be but it will be one of those two.
 
Nope your wrong.

After taking the clutch apart I now see why there is no replacement clutch available. There is no tapered crank. Its got a spline on it and the outside clutch sheave slides on the crankshaft itself.

Basically if you have too much clutch play you have to replace the outer sheave and your entire crankshaft!

This is the case for 1977, 78, 79 and maybe even 1980 ET-250's.
This is a warning to you guys with early ET-250's...
Keep your clutch properly lubbed up!
 
if my memory serves me correctly the 1980 version had a tapered crank and a fixed ramp style clutch similar to the arctic cat design. back in the day we had a 77 and a 79. the 77 became a real demon in the junior stock drag race scene after my father cut the end of the crank off and machined a taper on it to accept a srx style clutch.
 
I think the 1980 ET-250D has a splined crank. There's one on ebay right now that appears to be splined. The guy assures me its and 1980.

I like your idea about machining to a tapered shaft. I thought about doing this myself but didn't know how easy it would be to cut threads for a bolt inside the end of the crank. So is there enough shaft to make it exactly like the later tapered ones?
 
hmph. we have a powerblock clutch on my dads 1979 et250. dont think they changed the crank either to put it on. dealer did put it on though so idk if it is splined or not.
 
i just spoke with my dad about the old 250. when he cut the spline off the crank he first drilled the end as deep as possible to keep the hole centered. it took several cuts to make it down to the taper and get a mounting hole in the end of the crank. this was all done on the bench without taking the crank out of the motor. however, the taper is not the same as modern clutch. he cut the srx clutch in a lathe to match the taper on the 250's crank end. maybe a tapered shim could be machined to adapt a new comet to it. i'll look in the garage to see if i still have an arctic hex drive clutch w/ the oil injection ring on it. it needed new bushings but worked well trail riding
 
Could the entire engine have been changed out? Maybe the sled is newer than you think.

Check the diagrams on yamaha's web site and they show a splined crank for that year.
Could that power block be splined too??
 
the 1972 gp needed the same crank surgery as the 250 to adapt a duclo power-blok. this was in the mid 70's so things may have changed. i do have the arctic clutch but the shaft is froze up. good luck w/ the enticer. my brother and i put many hard miles on those things back then and my son rode his thru the u.p. for a thousand miles till he out grew it.
 
We have cut the cranks on several of out 292 Yammie engines that we use for racing. The one I had done now runs a polaris p85 primary on it. You could use any clutch comet, cat, what ever. This has worked very well for us and I dont see why that cant be done to the 250 motor

Eman
 
clutch

Hey there I race a et250 in vintage races its a 1978 yes it is splined. There is no aftermarket clutch that is available. You will have to search the salvage yards I only have one extra and we need it as a back up. Im very sorry that you have not had luck finding one. It helps me cause Im the parts manager for a Yamaha dealer. If I can help let me know.


Randy :dunno:
 
I just bought a new Powerbloc ALT 3713 for my 1978 ET250 with a spline shaft. It screws onto the shaft via the 28mm threads used to hold the inside sheave and idler bearing on and seats on the taper that the factory sheave was pressed onto. The spline is no longer used. CVtech no longer makes this ALT 3713 Powerbloc but you may get lucky like I and find one with dust on it in your local recreation supply shop. Anyone who has this clutch or has info on setup please help me! The secondary is not working proper with it yet. I have the factory 50mm X 4mm secondary spring with 40 degree twist and it won't shift. Is there a lighter spring available? I have tried many primary springs and weight combinations with no success. The belt is adjusted for full shift-out and .43 offset. There is no bog or load on the 250. It reaches 40mph in a snap and stops shifting in almost all combinations of primary weight and spring. Its like the secondary is getting stuck. It stops shifting and then the RPM tops out. The primary spring has sufficient room to fully compress and shift-out will occur if the track is lifted and free run but will not shift-out on the hard-pack track. Any suggestions would be greatly appreciated. Thanks
 
Last edited:
1978Yamahammer said:
I just bought a new Powerbloc ALT 3713 for my 1978 ET250 with a spline shaft. It screws onto the shaft via the 28mm threads used to hold the inside sheave and idler bearing on and seats on the taper that the factory sheave was pressed onto. The spline is no longer used. CVtech no longer makes this ALT 3713 Powerbloc but you may get lucky like I and find one with dust on it in your local recreation supply shop. Anyone who has this clutch or has info on setup please help me! The secondary is not working proper with it yet. I have the factory 50mm X 4mm secondary spring with 40 degree twist and it won't shift. Is there a lighter spring available? I have tried many primary springs and weight combinations with no success. The belt is adjusted for full shift-out and .43 offset. There is no bog or load on the 250. It reaches 40mph in a snap and stops shifting in almost all combinations of primary weight and spring. Its like the secondary is getting stuck. It stops shifting and then the RPM tops out. The primary spring has sufficient room to fully compress and shift-out will occur if the track is lifted and free run but will not shift-out on the hard-pack track. Any suggestions would be greatly appreciated. Thanks
Click to expand...



Are you still having trouble wit your secondary? I'm curious how this panned out for you.
 
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