Strange Tuning Problem

I was previously running the CNS carburetor on my 70cc Thatsdax engine and tried tuning that to no avail. I then gave up and went back to the NT carb and ordered a 71 and 72 jet from dellorto direct. I tried a 71 first and it didn't seem to make much a difference compared to the stock #70 although the engine did seem to run more smoothly. I checked the spark plug and it was still very oily and dark.

Today, I swapped out the 71 for the 72 size jet and it seemed to run a bit more smoothly and the engine started to 2 stroke more often (it didn't much with the stock and 71 jet). I checked the plug again right after running the engine at full throttle and it was still very oily.

I then checked the air filter and it was saturated with oil so I cleaned it. The only other problem that I can see is that I have the spark plug (An NGK B5HS) gapped to .015" when it may run better with a wider gap. Should I look at switching to a B6HS since it's warmer out? I haven't run it since cleaning the air filter so that might help. Please let me know what you would do.

Thanks,

Techbiker

Nougat said:

.015 gap is really narrow. I know a lot of people say a lot of things about gaps, but I've never heard anyone going that low. I run at .026 without incident. Cleaning the air filter will surely help.

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I will go ahead and regap the plug to .026. Should I go ahead and swap out the B5HS with a B6HS (I live in Georgia and it's getting up into the high 80's)?

Thanks

The NT carburetor actually takes PHBG jets. Just go to Dellortodirect to get any jet size. The only downside is that shipping is a flat $10 fee. I couldn't find these jets on any other site though so there really isn't much choice if you need new jets.