[Dave Holstein]

Don’t go to 40:1, you will stick it.

20:1/24:1  110  using redline is what my race series runs.

Clip is second groove from the bottom.

185 – 195 main

132.5 – 133 pilot

Should get you started in the right direction.

[Matt Dixon]

They usually wont idle thats normal, dont read the plug unless you are driving it hard and then chop the engine(let it die and coast in after driving it hard).

Pilot

If you gas it and it blogs before cleaning itself out and taking off its to rich

If you gas it and it hesitates before taking off its to lean

Main

If you rpms are down at the end of the str8 your to fat

If you stick it at the end of the str8 your to lean ;-)

Follow Daves advice and you will be in the ballpark and having fun in no time

[James McMahon]

Are you sure it’s not just falling out of the powerband? What RPMs is it faltering at? It’s normal for these motors to feel like someone cut the ignition at lower RPM, they dont make anything until 9000ish. You can kinda guess your main jetting by the top RPM that the motor stops pulling at, but that actual RPM depends on your setup.

Tuning wise….

Run 24:1. Do not pass go, do not collect $200.  Nobody is jetting these on 32:1, so get that variable out of the way.

Change nothing else until you are running with that. Many 80’s are fairly highly strung so proceed with caution when lowering octane. To be honest,  stick with a leaded racing fuel if you can. 91, even with stock ports and head is going to be sketchy if you have a kart racing pipe on it. Lead is verykind to the bearing surfaces in the motor. Run a racing oil too, not some random road motorcycle stuff.  Motul 2T is a popular synth, Maxima 927 is a popular castor.

If you have a pumparound carb, ensure both sides of the fuel pump are clean. A weak return side will cause it to run rich.

B10 is fine, again those motors are small but tend to have high specific output.

[Manny Dial]

Thanks for the responses.  It currently has Maxima 927 mixed, so I will do the 24:1 suggestion next and keep the B10 and 100 oct.  It could very well be me being timid, not riding it hard enough.    I’m not use to hearing the rpms run up so high since I’m only accustom to car track racing (sub 8000rpms).   I’ll downshift thinking my rpms are high enough, apex, throttle out but it’ll feel flat and no response at all from the throttle for a few seconds before pulling hard.  So maybe on my next session I will really try winding it up and keeping it up there to see if I notice any change.  I’m thinking this might be the case since I notice no breakup at all when it pulls or while cruising around corners.  Will post again when I find out more.

[Michael Taksa]

It’s doing what it is supposed to do. 24:1 ratio and keep the revs up, as high as you can after warm up.  Anything below 8K RPM will foul the plug, I am surprised it idles at all.

[Steen Carstensen]

The Maxima 927 is a good oil, but will gum up your engine. Do yourself a favour and buy Motul Gran Prix 2T, will keep your engine a whole lot cleaner.

[Manny Dial]

Decided to start a new thread in the proper section (sorry about that) since it’s a different issue.

 

https://new.ekartingnews.com/forums/topic/cr80-shifter-bogs-out-of-hard-lefts/

 

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