fzr600 gearbox sprocket alignment and other questions

[bubbadel]

Hi, not needed to post for a while, but i would like to know if the gearbox sprocket on all fzr600's are at the same position/spacing, i have had a 3he engine in my fzr400 for about 9 months, but im having serious starting difficulties when the engine is cold, just chugs on basically 2 cylinders (1 and 2), then if im lucky after a minute or 2 it gradually comes to life on all pots, i have good sparks. I was thinking the carbs. I may be buying another engine, either 4jh or thundercat, will the sprockets line up ok? Also will thundercat carbs fit ok, anything i need to do? I know the t-cat has 36mm carbs, foxeye 34mm and 3he 32mm so i would like to have the right carbs for the engine, or can i just use the 3he carbs without losing any power.
Hopefully someone out there will know....Del

[Evilchicken0]

As far as I know the 4JH + T'Cat motor's sproket are in a different place to the 3HE.
I'd stick to the right carbs right engine mainly because you won't have to mess around trying to retune them and that can be a godsend on a project bike.

I'd be inclined to compression test the 3HE motor with a view to doing the valve clearances. I think the tollerances are closing up as the engine warms up just enough to get a seal between the valve and head. If your confident enough you could build the 4JH top end onto the 3HE for a 660cc conversion. I think you need the small ends opening up for the 4JH pistons.

[bubbadel]

I dont have a compression tester, could buy one i guess. Once it clears the chugging it runs fine but the tickover can change and get lumpy at any time. Another thing i noticed is that 3 and 4 carbs have petrol spitting out when i have the airbox off, the slides get quite wet with fuel, 2 and 3 is just a mist when the throttle is blipped

[Evilchicken0]

ahhh - well, sounds like the floats then. Either the valve or the float levels .... or it could be a little O-ring that's broken down letting in to much fuel and blocking up the idle jet with debris.
Easier than a compression test huh ???

[bubbadel]

i did try lowering the float heights on 3 and 4 but still the spitting, i do smell petrol when i'm trying to start it, so i tried with the fuel off, it did start to chug but it may have been a coincidence

[Evilchicken0]

Does the fuel pump run time out when you turn on the ignition, and if you flick the kill switch to off and on again does the pump time out again or stop .... ???
If it times out a couple of times then it might be something like the float bowl gaskets. The pump is trying to get the carbs up to pressure but because the fuels seeping away it can't.

take the tank and airbox off then reconnect the tank and let the fuel pump tick over - have a good look around for any leaks. Then take the carbs off and have a look for any debris, fuel in the floats themselves (makes them heavy so they don't float so high), and then take out and clean the float valves / idle jets etc. The float bowl gaskets can look ok but they get flattened after time and a lot of strips. Change the good carb gaskets over and see if it makes a difference.

Lastly if this doesn't cure it pick up a set from e-bay and try them, you can always resell them and it might prove it's the carbs or not.

[bubbadel]

sometimes the fuel pump clicks away merrily when running, even after i have put a tenner in the tank, which i thought was odd. The pump does timeout when the ignition is turned on, sometimes it just clicks a few times then stops

[Hogdigerdy Dog]

sometimes the fuel pump clicks away merrily when running, even after i have put a tenner in the tank, which i thought was odd. The pump does timeout when the ignition is turned on, sometimes it just clicks a few times then stops

sounds like the fuel pump is ok

it's supposed to do that, when the engine's running it has to keep the pressure in the float bows up
if you just turn the key, it pressurizes the float bows then stops, it doesn't matter how much fuel is in the tank, as long as you've got some in there

mine ran similar to yours, intermittent firing at low rev's, farting and burping all over the place, but once hot and at above 7k rpm it was fine i'd done all the obvious so i then did the valve clearances which were not to far out but needed doing and then balanced the carbs ans since then it's been like a different bike

[bubbadel]

once my bike has warmed up it run fine but is gutless below 2 or 3k, but that i think is due to the engine has been tuned by slipstream and was in a race bike before i bought it, i'm getting another engine anyway because mine has all but lost 1st gear.