my 2002 Skorpion won't rev past 3500 rpm

[edfmaniac]

It's a mechanical linkage and the adjustment is in between the two carbs. Can't remember the factory recommendations for setting the delay but you do want some. That insures the idle circuit is only trying to compensate for air running through the left side carb. I set mine so that I could just barely twist the throttle before it engaged. You can also set it easily with the carbs off. You want the butterfly valve to be parallel to the air stream at wide open throttle. If you set it to open too early, it will go past parallel, reducing the max flow through the carb.

[breakwellmz]

Thanks.

A good old mechanical linkage eh.
I thought it may have been something `clever` like primary carb vacuum operating some sort of mechanism.
Saying that, Yamaha must have be able to reduce costs a fair bit by replacing this dual carb system with injectors when they introduced the `new` XT660(As well as losing a valve)Although i understand they don`t run as well at low speeds.

Cheers

[dandywarhol]

I owe you folks a huge apology and also many thanks for helping me understand whats going on/wrong with my 660.
I don't want to go on and on about something which isn't an MZ but sharing a common engine with the SZR was why I joined up here.

I've only used the bike for a few weeks and keen to sort out a few minor problems - the carburetion being one. I couldn't understand the engine breather system on my engine and thanks to edfmaniac and others I've got to the bottom of it.
A previous owner had joined the crankcase breather pipe directly to the secondary carb breather via the coarse filter barrel. When I disconnected the 2 parts of the pipe it was obvious that the engine breather pipe was just the right size to fit onto a stub on the airbox I then reattached the carb breather pipe, with mesh filter, and let it dangle down the side of the engine.
Road test time and what a difference! I hadn't ridden a 660 before and used to twins. I thought the low/mid speed jerkyness was "characteristic" of the engine but in reality a PITA. It was never smooth when opening to full throttle quickly and was rough running below 3000 rpm in any gear. Now it picks up cleanly from just over 2000 and just about peaks at 7200 rpm in 5th. What a transformation! It also seamlessly goes from primary to secondary throttle on wide open throttle cleanly now, rather than fart, pop and rattle my bollox off the back of the tank!

Please ignore all the crap I was spewing previously about the carb feeding air from the crankcase, clearly not the case and it was through discussion and debate on here that helped me sort it . Thanks very much. For anyone interested, here's some before and after pics.

Original plumbing, pipe from secondary carb connected via filter to crankcase


Original plumbing showing pipe down the back of the engine


Crankcase breather pipe now attached to the botton right of the airbox

[breakwellmz]

I GOT I WRONG AS WELL!!

The open ended tube in the middle of the top picture comes from the carb diaphragm not the one from the crankcase(On the left)
Note to self-wear your specs when you go to the garage!