It has been several years since I rode 2 strokers. I just purchased a 95 400 Scrambler, replaced the clutch cover right off and changed the fluids (looks like they were never changed!). I notice a loud knocking sound during idle. I cannot determine if it is coming from the exhaust or the motor. Would anyone recommend a top end rebuild? The bike has good power, but I don't have anything to compare it against. I also notice on the clutch system that the ?primary? (front mechanism) seems to wobble a bit at low rpm. Is this a concern I should look into? Thanks for any help with this!

 

They all have that knock I wouldn't worry about that. The wobble in the drive clutch there is an inner bushing that could be worn. Typically this is a item that a dealer has to change. It takes a special tool to take the clutch apart. If its not hitting the plastic housing I wouldn't worry too much about it also.

 

Wow, quick reply. Thanks !! Every once in a while it hits the cover during idle maybe 2-3 times per 5-10 seconds of idle. Another question if you don't mind. Do these motors have a hard time tooling around at low rpm? I have been afraid of fowling my plug while chugging through my creek. I notice that it seems to load up, but once I open it up, it clears up. Do you run yours at low rpm much? Thanks again for your quick response to the first post!

 

yeah well most 2 strokes you have to ride them ***** to the walls otherwise they will carbon up. just keep it in a lower gear at a higher RPM and you will be fine

 

how is he going to keep it in a lower gear?dont worry about running it at low speeds,there has been many days i was riding and barley moving through the trails,ive only fouled 1 plug in almost 2 years..look over your pipe,it could be hitting your engine case,i had a fmf pipe on mine and it hit the motor all the time and made a knocking sound..

 

That sounds like it could be my problem, could you do anything about your pipe? I still have the stock (3 piece with springs) pipe....

 

I had a 2000 Scrambler 400 4x4 and the aftermarket pipe hit the frame in the front. Once the carb is jetted correctly I never had issues with fouling a plug, a quarter turn out on the air screw may be all you need.

 

maybe time for a boring and honing,with time and use the cylinder clearance become loose so it make the engine rattling,that why those engine like wiseco pistons cauze of the more "tolerant" clearance,,
you should look if that jug was ever bored yet since it's old.