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Black Smoke

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RobertTheFrogOwner

Freshman Member
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Ok,
I've been lurkin' for quite some time now. And learnt a lot. But not everything, so here's my question:

I own a frog(bug)eye (FYI it has 2 S.U. H1 carbs) Occasionally, when the engine is warm I get some black smoke from the exhaust. I tried adjusting the carbs and for a while that worked. But then the front carb started leaking gas and I replaced the gaskets on both carbs (and those gaskets needed to be replaced) I noticed that the jet on both carbs now goes 'all the way up into the carb' whereas this did not happen before I replaced the gaskets. After re-adjusting the carbs I still get the occasional black smoke. What can be the reason for getting black smoke from the exhaust (other than too rich mixture because of wrong adjustment of the carbs)? Any help would be appreciated (as the s.o. is asking why we can't go for a ride
rolleyes.gif
)
 
Robert,
When you replaced gaskets did you replace the needles or main jets also? The needles could be the wrong ones or the jets could be too large. Eg. .100" jets installed instead of .090".

Make sure that the jets are returning fully to the up position after using the choke for starting. Sometimes the new jet packing causes the movement to be too stiff for the return springs.

Other than that mixture adjustment or incorrect float adjustment are the most likely problems.

Good luck.
D

[ 08-22-2003: Message edited by: Dave Russell ]</p>
 
Do you have a fuel filter? Often there is junk in the fuel system and it will stick the needle valves or Grossde jets open. Fuel will just pour into the engine and cause the black smoke. A modern fuel filter will take care of this little problem. Get a good $2.00 throwaway filter like a wix 1101 not one of those $10.00 chrome dealies. They tend to let more junk through than the throwaways.
 
Dave,

No I did not replace the needles nor the jets. Before replacing the gaskets the jets did not return to the full upward position after using the choke. Now they do. So I'll check mixture and float adjustment. Thanks.

Thom,

I do have a fuel filter installed. Thanks anyway for the tip.
 
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