High RPM Blowback, and Lean.

Ed - Dead Possums /

So I am tuning up this new Carb and getting lots of fuel blowing out when I'm at WOT. More than i'm used to on other builds I've done. More at wot/high rpm than at low rpm. But my plug chops say that I'm running lean. If i upjet won't i just be blowing more fuel out?

70cc TCCD

high torque head

case/intake matched

needle bearing crank

16x40 gearing

boss circuit pipe

Timing at 17mm on flywheel

Custom intake

17mm PHBG

no air filter

65-starter(too rich)

42-idle

70-main

262au-atomizer

au-bushing

50-slide (edited)

Re: High RPM Blowback, and Lean.

Probably Fred /

Boss circuit pipe ?

What needle?

42 idle is kinda high

70 main seems low

K&n filter will help

Boost bottle will help too

Re: High RPM Blowback, and Lean.

Ed - Dead Possums /

Sorry, Tecno Circuit pipe

W6 needle.

I know now after a bit of riding that the idle 42 is too big.

Air filter, I have a malossi in the mail already.

As for the main, my elevation is only 1000ft. I have a 16mm phbg that runs a 62 main jet. Also seems low to me, but even my plug chops a bit rich.

I have a boost bottle, I might try that too!

Re: High RPM Blowback, and Lean.

Luke “Funkenet” Hosfield /

K&n filters also get clogged with fuel. Would be recommend.

Re: High RPM Blowback, and Lean.

Luke “Funkenet” Hosfield /

I get blowback like crazy on a 19 phgb and kstar pp but it's in the low rpm range.

Re: High RPM Blowback, and Lean.

Probably Fred /

Lower elevation higher jet

Re: High RPM Blowback, and Lean.

Ed - Dead Possums /

Yeah... I know. Don't know why I'm running small jets. I've started with much bigger and worked my way down.

Re: High RPM Blowback, and Lean.

Ed - Dead Possums /

Fixed all this with a 60 starter, 37 idle, 72 main, needle, second from top, and malossi filter..could maybe go back down to a 70 with the filter. Also installed the boost bottle. Not sure how well it works, if any, but the acceleration is perfect and smooth. Very quick, great midrange, and still hits 51mph at about 10,000 RPMs!

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Re: High RPM Blowback, and Lean.

That bike is filthy. They oughta lock you up.

Re: High RPM Blowback, and Lean.

Ed - Dead Possums /

Yeah you like!

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