Speed,Combat,Scale,Racing > F2C CL Team Race

Black exhaust goo?

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frank mccune:
     Hi All:

     I was running my MVVS D7 today and the exhaust goo was jet black! I adjusted the needle valve and backed off the compression to where the engine was under compressed and missing.  No matter what I tried, the exhaust goo was sill very very black!  The engine started very easily and ran flawlessly.  Could it be bad fuel? Any suggestions?

                                                                                                    Tia,

                                                                                                    Frank McCune

john e. holliday:
What fuel mix are you using?  I know from experience that over compression will cause some black crud to come out, also old kerosene.  The kerosene should be clear like tap water.

Russell Shaffer:
If you are using a muffler, a loose one will make lots of black stuff from aluminum wearing.

Motorman:
If you are using ether from a spray can it has a top cylinder lube in it that burns at a very low temp and comes out black as coal even if your engine is rich and undercompressed with a light load prop. It's not a problem but your engine will coke up a little faster.


MM

RknRusty:

--- Quote from: Russell Shaffer on October 13, 2016, 10:28:51 PM ---If you are using a muffler, a loose one will make lots of black stuff from aluminum wearing.

--- End quote ---
A rattling through-bolt in the muffler will do it too. So will one or more loose engine mounting bolts. Black exhaust goo is always alarming, but I hope it turns out to be something simple just vibrating.

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