Revving high when started

I just got my kz650sr started last night, it seems to run alright but its revving really high(3000 rpm) thats with full choke. I let it run for a bit and slowly started taking the choke off. At first the RPM's got higher (4000) then they dropped off to about 2500 at about half choke. If I take the choke off anymore it stalls. What could my problem be

Pwallace30 wrote:

I just got my kz650sr started last night, it seems to run alright but its revving really high(3000 rpm) thats with full choke. I let it run for a bit and slowly started taking the choke off. At first the RPM's got higher (4000) then they dropped off to about 2500 at about half choke. If I take the choke off anymore it stalls. What could my problem be

Doesn't seem so unusual.

IMO it's good practice to remain very attentive to rpm and choke manipulation during warm-up so as not to over-rev a cold engine.

When fully warmed up, it's not supposed to stall when taking the choke off, as this would mean it won't idle without any choke. So if that is the case, the problem might be any of several things which could cause an excessively lean condition at low rpm, or possibly something not carb related.

Good Luck!

Alright thanks, just seemed to be revving to high, guess i'll let it warm up a bit longer and see if I can get the choke all the way off.

Check your throttle cables and make sure that they are not getting pinched up somewhere. It might be a good idea to give us a bit more information on how the problem started including any recent work you might have recently done to the bike.

Cheers-Colin Firth-Ontario Canada
1977 Kz650 Custom. 810 Wiseco big-bore kit, Mikuni 29 Smoothbores, GPz750 cams, intake valves tucked inside a ported, milled and polished 650 head. Lottsa other goodies in a stock looking package.

1982 Ferrari 308 GTSi - Rosso Corsa Red With Tan Interior. Twin to the Magnum P.I. car.

I bought the bike off of a guy who had it stored in his home office for 20 years. I just got the bike running a couple of days ago and notcied that it is revving high at idle. I dont see the throttle being pinched or caught anywhere. Could someone tell me what RPM there KZ650 is at with full choke?

that is kind of normal, they are also a bit cold tempered, mine are anyway, sometimes it can take 5-10 min ,before the are warm and running right.
did you go thru the carbs ?

I havent taken them apart, but I did drain the bowls and the fuel seemed to be flowing freely.

you may have some plugged up ports inside the carbs, since it sat so long a through cleaning is needed, along with a complete tune up

The start up rpms described are very normal. The only thing that was mentioned that is of concern is the fact that when the choke is taken off all the way, the bike dies. This indicates either the fuel level in the bowls is not right or the pilot system needs cleaned. It could also mean the fella is coming off choke too quickly and the bike isn't warmed sufficiently.

I dont have my fuel system completely hooked up yet (cleaning the tank of rust) so I havent been able to run it for an extended periode of time, so yes it could just not be warmed up. Thanks guys