GS1000 overbore to 1063 Wisco piston upgrade

[Anonymous]

Have 1063 piston kit in my 79 GS1000. K&N oval filters. Stock jetting. Engine will idle after warm up. But after that, when the throttle is opened up engine will not idle back down to 1000 rpm,s. Wait for two or three minutes and sometimes it will come down. What should settings be on pilot mixture screw? need advise to help solve my situation. All throttle cables are set up according to Haynes manual.Stack jets are 95's. Thanks for the help in advance.

[Anonymous]

Is this right away? or after warm up for a while?

Is this right away? Or is this going on after the bike warms up for a good while? Sounds like an intake leak, but I don't know much about top end rebuilds. The problems that could arise with that are beyond me.

[Anonymous]

My bike was doing this until I synchronised the carbs and adjusted the valves. There were many discussions of this topic in the Tech forum last spring.

Steve

[KEITH KRAUSE]

Re: GS1000 overbore to 1063 Wisco piston upgrade

Have 1063 piston kit in my 79 GS1000. K&N oval filters. Stock jetting. Engine will idle after warm up. But after that, when the throttle is opened up engine will not idle back down to 1000 rpm,s. Wait for two or three minutes and sometimes it will come down. What should settings be on pilot mixture screw? need advise to help solve my situation. All throttle cables are set up according to Haynes manual.Stack jets are 95's. Thanks for the help in advance.

I have a '79 1000 with 1085 Wiseco,K&N ovals,but I also have a V&H 4-1.
You are running very lean. You need to re-jet or risk burning a hole in your pistons,etc. Going to the K&N's REQUIRES you to re-jet. It also sounds like you may have an intake leak, but it could also be a poor carb synch' or sticking slides.
For the possible intake leak, check/replace the manifold o-rings, put some hi-temp grease on them and torque to about 6 ft/lbs. Check the manifolds too and the rubber boots on the filter side. Tighten the clamps. Oil your filters correctly.
Check your slides for smooth operation. Synch' the carbs, VERY important.
As for re-jetting, I use a Dynojet kit. But if you stay with the stock needle,
try lowering the needle clip 2 grooves, which will raise the needle and richen your mixture. Try adjusting the pilot screws (underneath) out a 1/2 to 1 full turn. Be careful, if they have never been moved they can be stuck. Adjust your side air screws for the highest rpm, once warmed up. Turn 2 at a time in 1/2 turn increments and listen for the highest idle, repeat for the other 2. If the pilot screw adjustments are not enough, try a 17.5 pilot.
As for the main jet, do you also have a good 4-1 pipe or stock exhaust?
If stock, I would try a 115+ main and if a good 4-1 pipe, 125+.
This should get you started. ANY richening at all is better than running the stock jetting!!! Remember, you must re-synch' everytime you move the needles. Test and do what the plugs tell you .
Let us know how it goes. We all learn more if you share results.

[Anonymous]

Thanks for the help.