Jetting Recommendations

[Greg]

Feb 25, 2010 14:33:37 GMT -5 90GTVert said:

Never thought about wheels from a 150.

Nice selection of jets.

As far as I can tell, all 13" wheels are rear disc. So yeah, more of them on 150s.
Doesn't your friends Roketa have rear disc? You can take the Roketa and swap rims and rear brakes. He'll never know. I believe you said he never rides it. hehehe
That Roketa has many of the same features as my 50cc scoots.

With the jets, I was going to stop at 95 but what the heck, it's only 6.00 more for 2 each of the last three.

[90GTVert]

His has 13" wheels with rear drum brakes.

[Greg]

I'm all set to get back to tuning.
It tried the 90 and it felt even stronger than the 88.
I put in the 92 and at first it seemed stronger pulling than the 90.
When I went to do a plug check, the wire came out of the plug boot.
I may have been slightly misfiring with the 92.
I think I need a new plug for a plug chop. The misfire has created what looks like a salting on one side of the porcelain.
Rain came so I had to stop. Looks like the next opportunity will be Monday.
Can somebody point me in the right direction to accurately diagnosing a plug?

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[90GTVert]

First off, good idea for a simple jet organizer.

I used to think I knew how to read a 2T plug, until I tuned a lot more. It seems like I get varied results. I've had a couple of setups that got black plugs when they were running the best. Mostly they seem to be a caramel color though. I think you are going the right way actually running it with these larger jets to get the most performance. If you wanna be on the safe side just go 1 jet higher than what gives the best power. That's what I do these days. If I see a white plug or close to white though, it's getting richer whether it runs great or not.

One thing that many tuners use to get a better idea of the tune is the piston. They are looking for the center area to be black and the edges to be caramel I believe. They often say that the black area should have little recesses caused by flow from the transfers passing over the piston that will kind of make a butterfly pattern. IIRC, A. G. Bell states that the combustion chamber and piston crown should have a dry brown to black coating if the tune is correct. He also looks for a tan or brownish spark plug.

[Greg]

Yesterday, I lost 5mph going up my "measurement" hill (going up at 25 instead of 30).
The temp was about 10 degrees warmer.
I downshifted to a 90 main jet and got my 5 Mph back.
I'm starting to know what it needs to keep her in tune.

On a different subject, I finally put the BBK on the blue M80 today.
I went with stock airbox and changed jetting from 68 stock to 75 to be safe. I really like hearing the exhaust, it is not obnoxious. It's running great but I need to give it some more run time and check the plug.
One other difference is the blue scoot has 5 gram sliders (red scoot has 6 gram and both have 1500 contra springs).
Definitely way faster off the line, runs at higher RPM but I don't know about top speed yet. It feels slightly slower at top speed, but I really have not pushed it.