79 ET300 Still has bog and labouring symptoms

S

SSJ

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Joined
Sep 11, 2006
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16
Location
New Brunswick, Canada
I'm not sure where to check next! Fixed the choke problem . Starts and stops easy. Changed plugs again. Check impulse line for cracking.(none). Took belt off and turned secondary and primary clutches by hand with no problems .Changed all fuel lines and drained tank, refilled with fresh fuel, and changed fuel filter.The sled sat in basement since 85( it's a 79) and was running fine then.When it idles it seems to run great, but under accelleration it feels like you're driving with the brake on. Hence the bogging and a labouring problem.The carb has been cleaned and new jets installed by the dealer,with a new float in the bowl also. The only thing I havent done is replace or rebuild the fuel pump.I'm thinking the problem is either the pump diaphram or hopefully not a crankcase seal. Anything else I may be missing before I take it to a dealer and dump a bunch of cash into it,I don't have??
 
Do you have a bog where you flutter the throttle or put the choke on for a bit and it recovers? If so then it more than likely has an airleak. It's not necessarily seals but if it has sat for that long, it is a given to change them. Watch out for dealers. The ones who know and respect old sleds are few and far between. Sometimes you will find someone who knows exactly what the problem by the sound and doesn't BS you.
Most of the time you'll get a guy who is looking to sell you crap you don't need.. like coils or new carbs, when the sled has other problems. I could probably fix that thing in no time, for very cheap and I have tools specialized to old Yamahas. One of my sleds had really poor torque on the head bolts which caused a base gasket leak. It was just as simple as tightening the head bolts to proper torque (18 ft lbs). Another thing is the intake. A leak in the gaskets or poor torque there can cause a bog too.
 
The bog happens as soon as you accellerate as well if you try and flutter the throttle. It does seem to change while picking up speed. Like I said earlier, it's like trying to drive with the brake on. I'm well aware about dealers doing more than required. I'm an ex service writer myself, in the automotive buisiness.The dealer here is notorious for that kind of thing.Where you are so close to me and I occassionally get to Moncton, maybe I could bring it down for to you and have a look at.The season being over soon too, I'de have a better chance of getting it there this spring sometime. Let me know if you'de be interested in looking at it, and I'll see what i can do to get it to you . Thanks
 
Are you 100% sure that they put the correct main jet back in. This also sounds like a transition problem between low and high speed. Changing your needle position may help.
 
I think that carb would be a butterfly/float type if it is correct. Well, my Exciter was running really nasty there the first time I fired it up this year. It didn't have any power but it was smoking and loading up something terrible. Water got into the gas and the inlet area which made it run terrible. Is your bogging causing alot of smoke as if it is running rich or is it fairly clean?
 
Yes it is a butterfly/ float type carb, and yes it does smoke alot. But the tank has been drained and cleaned and all the fuel lines replaced with new.The rubber joints on each end of the carb are new also.I don't know where the moisture could be coming from if that is the case. The fuel filter has also been replaced. It sounds like it's doing the same thing as your Exciter was.
 
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Hey ya sure the belt deflection is correct on that thing and is allso the correct belt?A loose belt will cause a nasty bog and make sure its not one of those ultramax 3 belts.There to soft of a compound and will cause it to bog allso on the enticers
 
Lots of good advice here. Amost too much, but season is almost over and I'm just going to put the sled away and start a teardown and rebuild. No hurry now and I'm sure I'll have it running like new again for next season. Thanks to all for your help.
 
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