'77 RD 400 tuning

[mikeges335]

My '77 RD 400 runs. but it seems to rev really high and when i give it gas it takes a long time before the rpm's come down. I know it is supposed to rev high because its a two stroke, but it seems to be reving too high. Any suggestions?

Thanks,

Mike

 

[stik70]

My '77 RD 400 runs. but it seems to rev really high and when i give it gas it takes a long time before the rpm's come down. I know it is supposed to rev high because its a two stroke, but it seems to be reving too high. Any suggestions?

Thanks,

Mike

If it takes awhile to rev down, its sounds like a vacuum leak which could be cracked intake boots, dry crank seals, or loose manifold to head or manifold to carb. Something to look at anyway.

 

[mikeges335]

thanks for the input. It is leaking air somewhere.

 

[chrisf]

If that's the case, it will never run right until that's fixed.

--Chris

 

[killerdwarf]

Check to see if you have about 1/8" free play at the throttle, and the same free play at each throttle cable where it enters the carb. Make sure none of the throttle cables is hanging up. When checking for air leaks I like to use chain lube. Instead of raising the idle, chain lube lowers the idle, and will stall the engine. I find it to me more precise in locating leaks. Does the bike seem to be blowing alot of smoke out of the right side pipe? If not, that side seal is good, provided there's oil in the trans. To locate a leaking ign. side seal, pull the timing cover off, and inspect for any signs of oil. Oil in the ignition area indicates leaking seal.

 

[mikeges335]

The right side seems to be normal. Thanks for the tips Great Stuff!
Thanks
Mike