Hi guys, I had gotten my jetting dialed in a couple of months ago and had very linear, smooth and power response. Specs: 5K feet ASL, 126 dynojet main, needled in 4.5N, stock 35 pilot, 2.25 turns on the fuel screw.

Up to a couple of weeks ago the jetting was fine. Then I snapped my cam chain, replaced it, adjusted valves to spec. Exhausts were too tight: .127mm and .140mm. Intakes were already in spec: .178mm and .152mm.

Could this cause jetting changes? It is very slight but there. A hesitation almost sputtering between 4k and 5k rpms, cruising or going to WOT at those rpms. Doesn't want any choke except to start in the morning.


Thinking of other causes: Temperature here hasn't changed much in the past couple of months. I disassembled and cleaned the carb before installing it after the cam was put back together. I did not clean the tank, which sat unused for a week, so I may give it a rinse and clean the carb again just to be sure.

cheers

 

I can't recall...did you post a report of your cam chain snapping incident? I'm thinking your engine's performance change has something to do with the issue of your cam chain snapping. Unless your valves had been way, way out of adjustment, I don't think you should detect much of any difference. Of course I'm assuming you got everything back together correctly when installing the new cam chain.

 

Very short post: https://www.kawasakiforums.com/forum...lx-sohc-42865/

Everything was put back very carefully and quadruple checked. The bike is running great really. If it was a 9/10 in jetting before, now its a 7.5/10 and just in that rpm range. The rest of the rev range is great, pulls strong, idles smooth, starts easily. I hope maybe it was just dirt in the tank and a cleaning of that and the carb solves this.

 

OK, I recall that post now. neon, I'd be amazed that you actually got out of that incident without something else being damaged in those episodes, and without being there to examine it personally, I'd suspect valve/top end damage of some kind that is now causing your "difference" in how the bike is running. I think you need to do a "leak down" test first.

 

That's another big possibility that I'ved considered but obviously hoping it's not jaja. I'll see if a local shop can do it as I don't have a a tester or compressor.

 

I hope you find nothing and that the change is just coincidental due to a minor issue like crud in the carb or such. Still, when one has a problem pop up, he should always look to the last thing that occurred on the bike, was serviced on the bike, or that was replaced on the bike. Let us know what you find.

 

Here is what was done between before I had this issue:
Cam Chain snapping and Replaced
Exhaust Valve clearance adjusted: from .127mm and .140mm to .229mm and .178mm
Air Filter Cleaned, I had it way over oiled it was dripping slowly into the airbox. Now it just has a light layer and cleaned excess with paper towels

Here are my changes and effects

Fuel screw from 2.25 to 2.75: It was starting super easy before this then started struggling, with the change to the fuel screw now it starts real easy again

Needle from 4.5N to 4N: Much worse mid from 4k to about 7k rpms. Top and bottom unaffected

Needle to 5N: Nearly the same as in 4.5N, hesitates or wants to stall when cruising or revving up anywhere from 4k to 6K.

Something else I noticed after riding and with the engine off the exhaust header pings for a few minutes, as if it is cooling down. It never did this before. The pinging and the leaner needle being worse are making me think that it is running lean.

I'm beginning to think you may be right about some damage to the valves TNC. Besides that or an air leak somewhere, what could cause this? Could valve damage be present even if it starts so easily with half a second of pressing the button? Could a valve issue be present at only mid range rpms while pulling strong at the top same as before?

cheers

 

No, usually a bent valve is pretty much constant, resulting in a motor that won't start...at least on a single...or runs like crap throughout the range. There are 4 valves and depending on the extent of the damage...usually to two valves...results can vary. I don't know...the more you've described, the less it sounds like bent valves.

 

Ok, so I got a can of carb cleaner and sprayed several parts with the bike idling. Spraying the throttle valve spring made the engine die. Started the bike again and double checked, same result.

I looked and there is a seal/grommet sort of thing there. Of course the screws on the butterfly valve are strange JIS or something that I don't have on hand.

Question:
Is that seal/grommet sold by itself? Where?
Is there anything I can put over it that will seal it or at least help until I get a replacement?

So this is better than bent valves but I don't think I can get that part here soon, if at all.

cheers

 

Not exactly clear on the part you're describing. Likely it's only available from Kawasaki since it sounds like a carb part.