Topic: kawasaki boging

[bountyhunter]

guys working on a v twin 18 hp with single carb the motor idles good! but when you open the carb up off idle it stumbles or cuts out for 1-2 secs. then catches and revs up fine! if i keep rpms up ta say 2500- 3000 then open it up will rev normal! i dont think its in the carb. ive richened idle up to were it shouldnt stumble (on the rich side) could maybe it have a valve that not sealing 100 percent  any more!! also it has a couple of race seasons on it before we got it!! they had valve lash set at .20 i put it back to .006! oh the air cleaner was basicly junk prob let some dirt in because it was ripped!!  darn I hate it when people dont keep things up!! it doent smoke!!

[Rooster]

Thats a typo right, valve lash .20?
You sure that wasn't .02?

[bountyhunter]

yep!!    .020 not.2 thanks!! that would be bad!!!

[Rooster]

Lol...I was thinking....NO way ...and it's running?
That'll put a little rickity tickity in it!

[mightymowe]

I would try cleaning the carb again to get rid of the bog,it probably still has a piece of dirt in it.

[Flipper]

Your stumble problem is caused by the jets and the carb itself. They are too lean. The 18hp Nikki carb throttle does not open all the way 100%, if you can, Get a externally vented carb from a 25hp Kawi (FH721), that carb opens all the way.  Replace both lower main jets with #140’s and start with #48’s for both slow jets. This will smooth out the "Hit" from idle to full throttle. If you are using a bigger cam you might step up to #54’s or #56’s. Isky & Dyno make cams for the Kawasaki FH-V series. Also, remove the choke assy. Using stock valves, I set my Valve Backlash at 10,000 to 12,000 with the high lift-high duration cams. George sells an air filter adaptor and the large oval K&N filter that works great.

[bountyhunter]

Joey I think we talking about 2 differant motors the one Im working in has a one bl. mukini carb can remenber what the model# of motor is its the smaller cu inche one!the motor is stock as far as I know! do ya know how much dyno gets ta grind cam! oh I think idle jet is under soft plug!!(welch) has any body worked on one of these carbs before it might be like ya said just lean because its a emition carb the day we tryed it it was 40 degrees out prob if it was 8o plus it might not be so bad! the carb is super clean!!!

[mightymowe]

On the Honda carbs the low speed jet is that plastic piece that pulls out after you take out the plastic screw that sets your idle speed.

[Mike Gentry]

It's got to be in the carb ......... i don't think a valve would cause and "Off Idle" stumble 

[fordman21]

Check the intermediate curcuit or port, it might be plugged or need to be enlarged.

[bountyhunter]

OK update switch motors same carb motor runs good Im betting that if I take motor apart theres going ta be valve bad!

[mightymowe]

If you have a bad valve you should notice that on a leakdown test or even a compression test.Could it be that you got the valves lashed wrong and one is not closing.

[The Tank]

It hasn't been in racing conditions of course but I've had a lot of trouble on the Nikki carbs on just grass cutting mowers so I would say it's in your carb as well.

[bountyhunter]

No he found a other engine so switch used the same carb!!1 and it runs great!! it is a mikuni carb

[The Tank]

No he found a other engine so switch used the same carb!!1 and it runs great!! it is a mikuni carb

Good! I like the mikuni carbs much better than the nikki brand. They seem to be alot more durable and easier to work on to me.