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H2B RH cylinder misfire
http://www.kawi2strokes.com/forum/viewtopic.php?f=14&t=12996
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Author:  mraxl [ Tue Aug 08, 2017 11:13 am ]
Post subject:  Re: H2B RH cylinder misfire

If it were me, I'd set airscrew out 1/2 turn (with #37.5 pilot), sync carbs, remove air filter, and see what it is like.
Keep in mind that it is normal for H2's with this setup to "buck" at steady 1/8-1/4 throttle.
Mains should probably be at 115 or so... not knowing what compression you have.
Probably need higher octane fuel than what is available at pump.
Plug reads can tell you a lot if you do it properly.
http://www.kawatriple.com/manuals/carbtune/carbtune.htm

Author:  DGA [ Tue Aug 08, 2017 12:42 pm ]
Post subject:  Re: H2B RH cylinder misfire

mraxl wrote:
If it were me, I'd set airscrew out 1/2 turn (with #37.5 pilot), sync carbs, remove air filter, and see what it is like.
Keep in mind that it is normal for H2's with this setup to "buck" at steady 1/8-1/4 throttle.
Mains should probably be at 115 or so... not knowing what compression you have.
Probably need higher octane fuel than what is available at pump.
Plug reads can tell you a lot if you do it properly.
http://www.kawatriple.com/manuals/carbtune/carbtune.htm

I'll try that then later this afternoon, no harm trying. Main jets are a 107.5 now, I have tried to keep the revs down until I get the bottom end closer to being right. Fuel here is 92 or 93 octane, but all gas stations have a single pump hose, so you just know the last car there got 87 octane, and you get at least a hose full of that crap before the 93 starts.

Author:  mraxl [ Tue Aug 08, 2017 2:16 pm ]
Post subject:  Re: H2B RH cylinder misfire

If you double the thickness of the cylinder base gasket it would reduce the compression to a point that 92-93 octane fuel could be used without problem and give you some extra umph.

Author:  DGA [ Tue Aug 08, 2017 6:10 pm ]
Post subject:  Re: H2B RH cylinder misfire

I synched the carbs, they weren't right, but not terrible. I have had to fight with the throttle cable, I can hardly get any slack in it and I don't like the junction box, plastic. It's like it's an H1 cable or something, it is new.
So I set the idle mixture screws at a half turn out and rode it. It's blubbery rich at low speed like that, certainly is not better, so I went a few turns out and it's an improvement, but not right. At partial throttle, like it should be on the needle, it seems rich so I might try setting the needles to mid position and try again tonight.
Added pics of the intake and filter, no way that filter is a restriction, and see how the intake is, i"m sure it's an H1B one, we had about 9 H1s in NZ and this was the only H2 and I think there was a mix of parts in the crate.

Author:  DGA [ Tue Aug 08, 2017 7:07 pm ]
Post subject:  Re: H2B RH cylinder misfire

I lowered the slide needles another notch to the middle position. It liked that, and then the idle was too lean, so will go another notch leaner and richen the idle a bit and try it.

Author:  DGA [ Tue Aug 08, 2017 8:17 pm ]
Post subject:  Re: H2B RH cylinder misfire

Went all the way down on the slide needles now (clip to the top), and that let me then go rich on the idle screws to 3/4 turn. It's still hard to get off the line, anything under 3000, could still be lean at idle, but it's brutally fast in the midrange now, from about 3000 to past 6000, then flattens off. I have 107.5 mains in it, I will get some 110 and try that.
Strange that it needs to be so lean on the midrange. I'm now seeing the head pipes go a darker straw and they seem to be even in colour.

Author:  mraxl [ Tue Aug 08, 2017 8:54 pm ]
Post subject:  Re: H2B RH cylinder misfire

Where is your float height set?

Author:  DGA [ Wed Aug 09, 2017 1:05 am ]
Post subject:  Re: H2B RH cylinder misfire

I have not checked the float heights. I will when I pull the carbs to change the idle and main jets, which are on order now.

Author:  mraxl [ Wed Aug 09, 2017 6:51 am ]
Post subject:  Re: H2B RH cylinder misfire

If float level is off it could cause a rich condition with everything else set right.

Author:  DGA [ Sat Aug 12, 2017 10:51 am ]
Post subject:  Re: H2B RH cylinder misfire

Could I get confirmation that the needle jet listed for the H2B on http://kawtriple.com/mraxl/carbspec.html is meant to be a 171 Q6 and not the listed 171 O6, which does not seem to exist per JetsRus? http://www.jetsrus.com/a_jets_by_carbur ... mikuni.htm There is only one O range needle jet listed and it's an O8. I have ordered three 171 Q2, which is two sizes leaner than the 171 Q6 stock.

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