Runs rich and then becomes lean

[Hell on Wheels]

The gas cap wore the more I used it. And now that I test it, it vents. Never had fuel delivery issues. I would notice from the gas in the fuel filter.

 

[Hell on Wheels]

Oh yah, I also modified the spigot to 1/8 in from 1/16

 

[Jag]

I guess I would recommend checking your intake for leaks then fixing them with permatex ultra black

 

[Hell on Wheels]

Turned out to be a massive intake leak. Seems the intake rattled loose. Time to downjet again.

 

[Jag]

Lol

 

[Hell on Wheels]

Back at it again. No intake leaks this time. Resized the jet and it runs rich then turns turns lean. Anyone ever have issues with single jet carbs not delivering enough fuel at WOT??

 

[Jag]

Check for leaks everywhere else

 

[crassius]

sometimes see that when airflow isn't enough to lift fuel at full throttle because at something less than full throttle, motor is pulling as much as it can already so opening throttle more doesn't bring more air

velocity stack can help, but mods to increase motor's flow is the usual fix

 

[Hell on Wheels]

sometimes see that when airflow isn't enough to lift fuel at full throttle because at something less than full throttle, motor is pulling as much as it can already so opening throttle more doesn't bring more air

velocity stack can help, but mods to increase motor's flow is the usual fix

Hmm, what else can be done to increase flow? The only things I can think of that I could do much of anything is slope the stock exhaust pipe inlet more, grinding the piston window a little bit higher so intake is fully controlled by the Reed (right now intake fully closes only at bdc and opens up immediately after), and maybe widening the transfer ports. I could try going to a bigger carb (my top speed right now is about 34mph on flat asphalt with a 41 tooth, I believe it equates to slightly more than 6500rpm). The ID of my current carb is 16mm.

 

[Hell on Wheels]

Note: to regain power, I need to shut it off for a few minutes. Decreasing throttle and chokeing doesn't help much. Also. I've done nothing to compression.