Returns to idle slowly (650 with Dellorto)

Lanttola · Mar 12, 2011

Bike is a 650 with a dellorto carb. It runs good othertwise, but if you rev it, it stays on 3000rpm for a while, then drops to normal idle of 2000rpm.

Jetting: some drilled main jet (just under 2mm), needle clip pos. 3, needle K51, DR272, pilot jet 40, and air screw 1.5 turns out.
I tried to turn the screw 1 turn out and 2 turns out but it didn't help. Could it be that i need a bigger idle jet because it's a little cold, about -2 c degrees?

logjump · Mar 12, 2011

My 501 with a dellorto would occasionally get a sticky film built up on the slide which would give it the same symptoms as yours. The sticky film wasn't allowing the slide to drop all the was down to the idle position. Check that, and clean if necessary. Believe it or not, this was due to a slight head gasket leak. Yes, the bike was losing some coolant as well.

• Also, make sure your throttle cable is clean and has lubrication as well as the cable routing is good and isn't pinched.
• Make sure your throttle tube and handlebar are clean and move freely.
• A rubber intake manifold leak may also give your bike a strange idle.
• Pull your air filter and wipe up the pool of oil that may be resting in the bottom of the rubber intake elbow.
• Remove the carb jets and make sure there's no specks of dirt hung up.

Hope this helps.

log

Lanttola · Mar 12, 2011

I forgot to mention the carburator was just cleaned inside and outside. I tried to lower the idle to 1700rpm and now it works just fine. Strange thing but i don't mind as long as it stays that way...

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Returns to idle slowly (650 with Dellorto)

Lanttola

logjump

Lanttola

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