Hello all, after some help with my bike as it's running rich, fouling plugs and won't won't run properly when I try to take it for a ride it then dies and won't start (plugs). I know this usually means a vaccum leak but cannot see where a leak could be. The carbs have been taken apart and cleaned with all new seals throughout from litetek and new rubber boots on the block. Float/fuel levels checked and within spec. I've got the vaccum lines set up as suggested on here when removing the vaccum valve. 1&4 to petcock and 2&3 blocked off. The top breather on the carbs is not connected to anything. The bike had low comp on #2 so have had the head off and fixed a buggered valve. So have had the head off and fixed the valve. The issues im having are the same as before I had the head off so nothing's changed. Had a set of vaccum gauges on it last week and synced the carbs. The vaccum gauge did rear between 10 and 20hgcm which on the gauge is a red area that says "late timing or vaccum leak". Before I changed the rubber boots on the block I had taken the bike for a quick ride and it wouldn't go past ~12k rpm with a wide open throttle and if I went up a hill would not make it up and eventually bog down and die. I've run out of expertise and hoping someone has some ideas. I'm about to get a new bank of carbs or sell the thing.
Did you replace the needles when you rebuild the carbs ? . It definitely sounds like a carb problem more than anything . A vac leak will usually result in high idle lean condition or a carb that is wayy off balance. The wasted spark system in these things is quite annoying because for instance if one carburettor has a fault it will foul the sparkplug which will stop that cylinder firing and also the one that's on the same coil from firing .
A vacuum leak would mean extra air in the mix, so you'd get lean looking plugs. Fouling is excessive fuel, or not enough air. My go-to on these Keihin carbs for excessive fueling issues is the o-rings on the seats for the float needle. The o-rings split and the seat/needle combo is no longer in control of fuel flow. Other than that, you've had the head off, you checked and adjusted the valve clearances while you were in there, riiiiight?
Just a warning, our float valve seat o-rings are made for the genuine Kawasaki part not Keyster version. Keyster use their own size that only suits their part. https://www.litetek.co/Guide_OR-032_Fitted.html
@TonyZXR I did not replace the needles, only all the o rings and seals as well as the seats and float needles. @GreyImport @Linkin @maelstrom Forgot to put it in there, float seats and needles replaced so brand new o rings (bought the same as what is in the link above) as well as valve clearences all checked and brought within spec. Would something like this be my next best bet? https://www.motorcyclespareswarehouse.com.au/products/kk-0174ns-carb-repair-and-parts-kit Thanks for the replies
maybe put some smaller main jets in the carbs & see what affect that has on the plugs and how it runs. standard on a C model is 122:125:125:122. maybe try #115 across all 4 carbs. What happens when you run the petcock on P (prime) instead of using the vacuum diaphragm to meter fuel? What plugs are you running? What number is on the TCI unit?
Took the carbs out and made sure they were clean. Found that the mechanic that had it had put 120 jets across all four carbs. Adjusted the float levels as they were sitting between 11-12mm. Now sitting closer to 14mm. Seat and needle are brand new and o rings are fine. Put it all back together and it started up and was idling like new. When I raised the revs to about 8k I could hear the exhaust note was popping almost like it was missing on one cylinder but would still rev out to redline. Took it round the block and it wild get to ~8k and not go any further, sputtering etc. About 1km later it just shut off. Wouldn't start for about a minute, placed petcock on prime and could get it to start begrudgingly. Got about another 100m and the same...all the way home. Seeing as it idles fine could it be a spark issue? As in during higher revs the coils are not giving enough juice for a proper spark to ignite the fuel leading to excess fuel and then fouled plugs?
CDI is a 21119-1316. I assume TCI and CDI units are the same thing? Plugs are what the manual states CR9E
TCI & CDI units are not really the same thing, but they perform the same function. I'm assuming your bike has a 240kph speedo since it has the 21119-1316 TCI unit. That unit is used on the Balius as well as the Malaysian ZXR250C (C7). All non-Malaysian ZXR250's have a 180kph speedo and the ZXR250C models use either a 21119-1322 or 21119-1384 TCI unit. In my opinion, none of this should be causing your issues, however I have attached the ignition map for your TCI unit. It may help you with your ongoing diagnosis. Do you need to use the choke when you attempt to restart it after it conks out? What's the Engine Number? I'm wondering if you might have a Balius (ZR250) engine with ZXR250C 'bits' or vice-versa.
