throttle or carb problems
#1
10-17-2007, 12:33 AM
throttle or carb problems
the throttle on my '78 kz650 is going crazy. when i clutch between gears it revvs up to about 4 grand and stays there for a bit, then eventually goes down to idle and dies if you let it idle too long. its definitely not me doing it by accident. i know that someone who owned the bike before me had the bright idea of boring out the carburetor jets to get more fuel, but now it runs too rich. do you think that could be why the throttle cranks by itself like that? i ordered some pod filters to replace the intake box, with hopes that getting a little more airflow will help smooth out the mixture. is there a way to turn down the fuel ratio on the carbs? any suggestions would be helpful! thanks
#3
10-17-2007, 12:54 AM
RE: throttle or carb problems
Don't know if this would cause the problem but..........
My '81 KZ 750 LTD was having a problem...............
It would run fine for a while and after a few miles, once it was warmed up, it would lose power.
The problem was improper suction of fuel from tank into the carbs.
The mechanic removed the valve /switch that controls flow from tank to carbs and rebuilt the
mechanism inside (it is located directly under the gas filter inside the tank)
If this isn't functioning properly, couldn't it cause the flow of gas to increase and decreas randomly, causing the revving
and stalling you describe?
Maybe someone knows more about this than I and can describe it better.
Good luck
My '81 KZ 750 LTD was having a problem...............
It would run fine for a while and after a few miles, once it was warmed up, it would lose power.
The problem was improper suction of fuel from tank into the carbs.
The mechanic removed the valve /switch that controls flow from tank to carbs and rebuilt the
mechanism inside (it is located directly under the gas filter inside the tank)
If this isn't functioning properly, couldn't it cause the flow of gas to increase and decreas randomly, causing the revving
and stalling you describe?
Maybe someone knows more about this than I and can describe it better.
Good luck
#4
10-17-2007, 12:58 AM
RE: throttle or carb problems
Actually, it's running too lean. Engines like to race when they have a lean A/F ratio. Too much gas causes them to bog down. Small engines such as motorcycle engines tend to have more dramatic aftereffects from small changes like an aftermarket pipe, or a modified airbox. It is also very possible your float bowl levels are way too low. That too would cause a lean A/F condition.
#5
10-17-2007, 01:00 AM
RE: throttle or carb problems
ORIGINAL: davehayward1
Don't know if this would cause the problem but..........
My '81 KZ 750 LTD was having a problem...............
It would run fine for a while and after a few miles, once it was warmed up, it would lose power.
The problem was improper suction of fuel from tank into the carbs.
The mechanic removed the valve /switch that controls flow from tank to carbs and rebuilt the
mechanism inside (it is located directly under the gas filter inside the tank)
If this isn't functioning properly, couldn't it cause the flow of gas to increase and decreas randomly, causing the revving
and stalling you describe?
Maybe someone knows more about this than I and can describe it better.
Good luck
Don't know if this would cause the problem but..........
My '81 KZ 750 LTD was having a problem...............
It would run fine for a while and after a few miles, once it was warmed up, it would lose power.
The problem was improper suction of fuel from tank into the carbs.
The mechanic removed the valve /switch that controls flow from tank to carbs and rebuilt the
mechanism inside (it is located directly under the gas filter inside the tank)
If this isn't functioning properly, couldn't it cause the flow of gas to increase and decreas randomly, causing the revving
and stalling you describe?
Maybe someone knows more about this than I and can describe it better.
Good luck
#8
10-17-2007, 02:22 AM
RE: throttle or carb problems
i'm not much of a mechanic and i've never worked on a bike before, but i do enjoy getting my hands dirty. is there any way to adjust and sync the carbs that i can do without paying someone alot of money to have it done at a shop?
#9
10-17-2007, 02:23 AM
RE: throttle or carb problems
bored out jets. Good point. so install stock mains and try to get a baseline.
#10
10-17-2007, 02:39 AM
RE: throttle or carb problems
It could be somethingnon jet related tocause the engine to lean out though. It isn't always the usual suspect. Your engine having a hard time returning to idle is a classic example of running too lean. But having said that, it still COULD be something else, but not very likely.