idle rises after a ride

i have to keep fidling with the idle when 1st start it its too low after a ride its too high and when i rev it hangs but when i adjust the idle down and rev it its all good but of course next time i got to start it cold its to low ..i do let it warm up to adjust the idle rite after having it on choke . one thing i did notice this time starting it up cold is the choke worked but didnt have as much effect as usual only thing that has changed since last start is i installed a fuel filter wich there seems to be more power and pick up since riding though ..this all started happening a few rides ago b4 filter instalation when i took it on the highway for 20 minute ride proberly the farthest i have taken it so far any ideas? also the carbs where leaking when i forgot n left it on petcock for the 3rd frekin time but i was hoping that was due to draining the tank to empty and the starting it without a fuel filter wich i got a fuel filter and fresh fuel to try flush out the posible dirt messing with the float needle but anyway the idle was erratic cpl of rides b4 draining the tank n starting it

 

You may have a vacuum leak (only shows up when hot) check with propane is best way or carb cleaner around intake boots . The other possible your synch is off slightly ( I had similar problem adjusted synch and this cured problem have not touched idle knob since 1100 rpm steady hot or cold)

 

My Kaw 750 did this, the intake manifolds/boots were leaking. Idled okay cold, would vary once warmed up. FWIW, I didn't have any luck with the propane test but once I sprayed the intakes with starter fluid she revved right up. I did the RTV repair on those and it's holding up fine.

 

+2 on a vacuum leak.

+1 on using carb cleaner or ether to test.

 

If the intakes are suspect, here's a quick explanation on what is happening. When the boots are cold, any cracks will have minimal effect since they contract when cold. once the engine warms up and the heat transfers to the intakes, they will expand therefore opening up the cracks and allowing more air in.

What kind of petcock? Regardless of the type, the carbs should never leak gas and this would indicate an issue with the needle valve and seat not closing properly and not an issue with the petcock.

 

thanks guys i wanted to replace the boots anyways ....yep i new they shouldnt be leaking regardless im just hoping a fresh lot of fuel and a filter might flush out the gunk but i spose i have to pull the carbs now anyway to sort out the air leak

 

Find the vacuum leak before you pull the carbs, that way you know you've eliminated it by doing the necessary work.

 

yeah prob the way to go that way i can just chuck some silicone on it i still have to pull the engine to weld a new bar the frame im not ready to do that yet so il just find the leak patch it up can ride it till i got the funds for the engine pull hopefully it is one of the boots i want to replace them anyway when i do engine pull cause there quite perished looking ...so once i do the engine pull i have to pay 200 bucks to a fabrication company proberly about 200 bucks boots with gaskets prob about 100 bucks for plastic side covers then 50 bucks for various paint and strippers and another 50 for metal polishing gear may aswell give it a birthday if im going to pull engine bit like jumping in frosty water maybe tomorrow lol

 

Why are you pulling the engine? Do you have a frame problem?

 

yep rusted a long the kickstand side from engine mount to behind kickstand ultra thin metal and rust the welder i got a quote from was trying to convince me it wasnt worth doing because the rust could be elsewhere in the frame but i read the bar along the kickstand wasnt rust treated for some reason on these bikes and its a common area also it makes sense because any water making its way into the frame would migrate to that side of the bike whilst its on the kickstand

 

It's worth doing. This is one instance where you're at a disadvantage; being reqired to have frame repairs done by a certified shop. Even in the most safety-stringent U.S. states you can do the job yourself as long as it passes inspection.

 

im not capable of doing it and i wouldnt trust a back yardy around here to do it either there not very technical the as it is the fabrication company qouted me verbaly 200 i asked a guy advertising panel repairs on the side he wouldnt have been qualified he just tack welds patches on car body work by the look of it but he said he could do it for me for 450 so im better off just going to the professionals at elite fabrication they might even give me an engineering certificate