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Old 12-05-2008, 01:19 AM   #1
smstavinoha88
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Default need help with restoration of 1971 yamaha 125

i have been taking a small engine class at my college and i decided that i was going to restore my uncles 1971 yamaha enduro 125 at1-c. It hasnt ran in 30 years. so we drained the oil and gas and tore apart the top end of the engine. we replaced the rings and put a rebuild kit in the carb. after getting everything back together and polishing it up(it was garage kept under a tarp so excellent condition) it was the moment of truth. after about 4 kicks and some starting fluid we got it fired up. man it purred like a kitten. the problem is when i went to put it into gear it didnt move.. after sitting there working the clutch and going from N to 1st multiple times it started to creep forward. after slowing moving around i got it to go a little faster but once it would hit around 5000 rpms it would feel like it shifted back into neutral no matter what gear it is it. i have been trying this same process for the past couple of days hoping it would work itself loose but so far no luck. it usually takes a couple minutes of playing with it to get it rolling. i have lubed the clutch cable. is it possible its just gummed up inside or does this sound like something serious went wrong?
thanks in advance for your help,
steven
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Old 12-05-2008, 02:55 AM   #2
jordanhoff
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I know that on my MT250 when I got it running the clutch was stuck. Im not sure if this is what you mean, or was part of your problem. It sounds to me like a clutch or shift fork problem. I started by taking the engine case off and taking the clutch apart and soaking it in fresh oil. Also it sounds like it is part of the gears you can try putting a little seafoam in the oil and running it like that for a little bit and then draining the oil, and changing it, but I dont know that any of this will do the trick, because it also sounds to me like it could be bent shift forks, but maybe someone wiser can add to this.

Good Luck,
Jordan
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Old 12-06-2008, 01:38 PM   #3
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yeah i was planning on taking the cover off soon to see if i could notice anything wrong or stuck with the clutch.. i've been leaning to the clutch because that seems like a much easier and less expensive fix compared to say a tranny rebuild which wouldnt be fun.
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Old 12-10-2008, 09:56 PM   #4
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lol this is my first and only bike mine sat for 15 years take the mag cover off then take the part uhat covers the chain (were the clutch cable goes into the case) then u might have to improv on the meck that pushes the clutch purrod (also make sure cover screws are tiht cause th clutch wont activate) if the cablis out wrap wire on it to make it fit better oh an message me if u need more explaning (i shortened cause its hard to type on a psp)
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Old 12-14-2008, 08:25 PM   #5
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oh alright thank you so much. i love this bike it runs like a champ i wish i could really see what its like riding it around but hopefully now i can figure out this whole clutch problem. if i have any questions i'll def. shoot you a message.
thanks again,
steven
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Old 12-14-2008, 09:53 PM   #6
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If it were me I'd pull the clutch cover off and pull it apart and see if maybe the clutch plates are shot. They might be all glazed over and won't "grip". Or the clutch mechanism isn't releasing, either the cable is hung up or the rod is sticking in the engine. Does the clutch lever come the whole way out when you release it?


Usually when a bike sits for a long period of time the clutch sticks engaged.
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Old 12-16-2008, 11:27 PM   #7
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i remember some yamahas had an arm(cable attached to that) on a rod going through the case and that rod would stick if it sat for a long time just take it apart and clean lube all moveing surfaces.
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Old 12-21-2008, 06:28 PM   #8
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alright thanks. i've got it all apart now and am looking everything over.. i'll let ya'll know what i figure out(if i find anything wrong)
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Old 12-24-2008, 01:14 PM   #9
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well i took everything apart and there was quite a bit of build up under the cover and i cleaned all that and it still doesnt want to engage. i even took the 5 inch rod out and cleaned it. that screw you were talking about is that the one that turns when you squeeze the clutch? if so would you want to tighten it or loosen it?
thanks again,
steven
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Old 12-24-2008, 02:37 PM   #10
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try loosening it a bit see if that helps.
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Old 12-24-2008, 05:49 PM   #11
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when clutch is properly adjusted there should be around 1/8" of free movement on the clutch lever when its not being squeezed.

saw one bike a kid had tightened the clutch so much it could not engage.
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