Help tuning flatslides in Wellington?

[Dogboy900]

My ZXR 400 race bike has Kiehin flatslides and unfortunately being pretty much a complete mechanical numptie I have no real idea of how to tune it properly.

The bike runs OK while cold and on full throttle but after it is hot at the end of a session on the track it will stall if the revs drop below 2,000. The plugs tend to oil up a bit as well, which leads me to think its probably running rich.
I have a complete set of jets and needles etc just no real idea of what to do with them.

I am thinking a bit of time on a dyno with someone who has some clues about tuning flatslides might help me get the best out of my bike.

Anybody have any suggestions as to where in Wellington I could take it?

Thanks

[F5 Dave]

ok two things,
1st, on a 400 on the track setting the idle high will help keep the weight off the front a little, I know its a bandaid for your problem but worth a point.

2nd they are old & that rattle you hear is the slides vibrating. If you take the airbox off & start the bike the rattle can be stopped by putting your fingers on the slides. Like that from new, But it will wear things quicker.

Yes it does sound rich if oiling (fuel fouling not oil one assumes) the plugs. Check the needles & the needle jets. Any wear or ovalisation will scupper any tuning efforts by spraying big droplets. Can't remember if the FCR needle jets are replacable (PWKs aren't). but with some machining & inserts they could be fixed. You will need to take apart & check with a bright torch. Any slight ovaling is what you are looking for.

Also suspect is the floats aren't leaking, float height & float valve. Any of these (likely valve) will scupper any tuning efforts. Do all this before trying to change jetting. I'd assume that if it has run ok in a past life there has been some wear issues.

[Dogboy900]

Cheers :)

I will follow your advice before going any further.
Have also found some good info on the net now (which was surprisingly hard to find!)

[Dogboy900]

Thanks dude.

[Dogboy900]

If anyone else is interested here are a couple of web pages I found useful

http://www.zrxoa.org/forums/showthread.php?t=181609rl

http://www.ducatitech.com/2v/inside_fcr.html

Lots of pics as well as charts and diagrams :)

Cheers

[roadracingoldfart]

Cheers :)

I will follow your advice before going any further.
Have also found some good info on the net now (which was surprisingly hard to find!)

I have used the Keihin site before and found it really good as a guide and for faultfinding .

www.keihin-us.com/fcr.htm select carb tuning half way down l/h side.

[Dogboy900]

Cheers :)

Only done a basic going over so far but found the idle mix screws were all over the place between 2 and 3 1/2 turns out, different for each one so been playing with them and giving it a good clean out. Will see how it goes at the next test day :)

[bistard]

If its any help,I am also in Wellington & have a ZXR400 with Keihin flatslides on as well & have mucked about with them alot over the years
Send me a PM if required

[Dogboy900]

Cheers, I will see how it goes after the test day and if necessary send you a PM.
Thanks for the offer :)

[Spanner Man]

Hey i think you are on the right track with the carbs, however just something to consider if tuning the carbs doesn't work. In my experience the valve clearances on the Kawasaki's have a tendancy to go tight and can cause hot temp runnign probs, and mostly at low rpm's where the compression is being lost trough an open valve and the engine speed is slow so there is more time for pressure to be lost.

If you can find someone that could check them for you before you spend lots of money on carb bits it would be worth a check as otherwise you might end up tuning your carbs to compensate for this problem. I think from memory clearances should be inlet 0.08-0.12mm exhaust 0.18 - 0.22 used to find that the exhausts were particularl prone to going tight and in those small higher revving 4's, and if they didn't get checked and adjusted the valve heads would eventually fall off. However this was usually after a mindless thrashing over a long period of time and severe lack of maintenance.

Good luck

[Dogboy900]

Cheers.

Will let you know how it goes :)

[Dogboy900]

Well VMCC round three went fairly well and I managed to come.... Not last in F3!!!

The bike is running much better still a little rough on idle when hot, but it's not stalling instantly and being unable to re-start. I think I need to fine tune the idle mix a little but essentially my main problems have been solved by a good clean and adjustment of the idle mix screws

Thanks to everyone who helped out :)