cub problem

[dubbin337]

I recently got my cub motor running that i bought from jeff over at fast and this thing really flys. He set me up with 168 mains, 48 pilots with cel needles for my 35 mm pwk's and it seems to be running perfect but every now and then in the middle of running wide open the motor will just cut out for a second or two and just come right back running great again. I cant figure out what would be causing this because the motor seems to be running so good. Do i need to upgrade my pingle valve for better fuel flow? One of the carbs also seems to leak a little from the over flow tube comming off the bowl, i wasnt sure if this might have something to do with it too. Any ideas of what might be causing this?

[trex banshee]

if i were you i would just call jeff since you bought everything from him he will probably be able to help you out.

[dubbin337]

Yea i was going to give him a call on monday, i just wanted to see if anyone on here had any idea of what might cause this.

[trex banshee]

ah i see well the only thing i might thank of off the top of my head is maybe you have a bad connection on your coil? but if that was it, it probably wouldn't run at all but it is worth a try.

[FASTOYS]

Here are some things to check : would be the float settings, plugged fuel valve or jacked up gas cap vent (i dont even run one), possible wiring/ignition problem causing intermittent miss?!! Did you do a wide open plug chop and cut the plug to look at it? Call me if none of those fix it and i will try to help you figure it out.

[rocketboy]

168 is a fat main ... it may be running too rich on top and sputtering .

[wesw]

try a 55-60 pilot, cel 5th clip adn 150 main and work your way around it.

 

168 is awfully fat

[FASTOYS]

We have done several with 168 mains and they have a 2mm smoke ring on the plug and run great. Wesw, I think if he listens to you i might be selling him some pistons!

[2bzy2p]

LOL thats what i was thinking,, is that how u break your motors in??? always start phat and go down.. safest thing for me!!

[wesw]

hmm

 

talked to couple people and did a lot myself

 

155 mains were witha 4mm cub dyno tested.

 

but i dont know nothing.

 

your richen the bottom, and run a good needle you wont need a big main.

[dubbin337]

Actually i thought it was running a little lean on top because after running WOT in 5th gear, because i didnt have enough room to make it to 6th, the plug was a little on the lighter side and the motor seemed to have a slight crackeling sound when i had it wide open. The bike never really sputters, it runs really strong, its just every once and a while it just cuts out for a second and its never while holding it wide open, it only happens when getting back on the gas after a shift. Thanks for all the input.

[odaen]

are you running T5's, pc's, or FMF pipes? that would explain the bigger main jet than normal. if you are running CPI's or shearers, sounds like you might be a tad rich on your main.

 

I run 160 mains, CEL needle, and 52 pilots in my 39's and it's a tad fat on the main at sea level.

[dubbin337]

Im running small bore shearers on a 4mil cub with 19 cc domes and i also run vp c12 if that matters and i am also at sea level.

[Buttermilk421]

I'm running 148 mains, with BEL needles on my 421 Cub with CPI s.b. inframes. Been almost a year now, with no problems.

[RNBRAD]

I run 160 mains CEL needle mid clip and 55 pilot. I run 165 mains in cooler temps this time of year. 421 cub.