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jetting cubs....


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i had dan from patriot do me a set of cub cylinders. i have a 4 mil long rod with v force reeds and cool head running on race fuel. i haven't got it all together yet and running but i took apart the carbs to make sure everything was the same and he has 78 pilots in them. isn't that a little high? the mains are 150. these are 35 mm keihn carbs. i haven't got it running yet but i waondered if anyone else thought that pilot size was a little large. any help would be great

 

mini

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yes thats way too big and the main is way too small, especially for the cub cylinders. pilot will be in the 45 to 50 range and mains in the 158 to 165 range depending on elevation and pipes. usually a pilot that big is more for the single cylinder 2 strokes like the cr500. my 40mm keihin carb for my cr500 used a 65 pilot or so...

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it also depends on what needle you have. if its lean down low on the L1 spot then you will need a big pilot

 

 

find or see what needle it has in it

 

also my bike that last time it had it dyno jetted it had a 152 main and was still rich, by the time i get the fuel right down low, the guy told me i will need probably a 145 main. thats in ks, 900 ft elevations, 60 ish degrees

Edited by wesw
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i wasn't as much worried about the main as i am the pilot. i haven't ever really messed with pilot or airscrew so i don;t know how to tell if it is right or not. i can't beleive he would have that jetting in there if it wasn't close but i looked at the pilots and they seem huge. i don't know if its way to big or not and right now i don;t have spark. i got the motor in and on the 3rd kick it stumbled like it wanted to start and then i pulled plugs and it would spark every 3rd kick or so, and now i have no spark at all. i don;t know if it is something dan did when he had it all apart or what, but when i pulled the motor everything worked fine and now i have no spark. so i need to figure out why i dont; have spark first then work on the jetting, but how can i tell if the pilot is right or not?

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id ditch those pilots first ,thats not even close i bet <_< id run a 50-55 pilot if it were me to see how it responded .easy way to check pilots is by doing the choke trick and watching for how it starts and if you need to choke it or if it bogs off idle or hesitates,yours will most likely bog like holy hell off idle , that is if can even start with pilots that big :blink:

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that main is not that small, mine is 148.  Dan wouldn't set him up with too lean of jetting.  He may of put in a rich needle or something.  Dan was talking about  145 mains with 35pwk's over on planetsand with 4 mil cub.

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damn 148??? where you located at? your elevation must have something to do with that..around here thatll get you 2 nice pistons with holes in them..

 

minishee, where you located at?? and also, those pilots are way too big. start at a 50 and see what happens.

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Does anybody have a running Cub with these parts?

 

68mm Cub, 4mm stroker, cool heads, 35mm PWKs, vforce reeds, timimg plate set to 5 degrees

 

We're at 300 ft above sea level.

 

We can't get this thing to idle. We've got 160 mains, 55 pilots in it right now.

 

Does anybody have settings that will work?

 

What about the needle? Size of pilots and mains? Starting point on the mixture screws?

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damn 148??? where you located at? your elevation must have something to do with that..around here thatll get you 2 nice pistons with holes in them..

 

minishee, where you located at?? and also, those pilots are way too big. start at a 50 and see what happens.

369430[/snapback]

 

 

im at sea level and the temp is 70 to 80,needle in the middle. even after holding it wide open for a while, like a jet ski, the cylinder temp is only 155 f and Dan told me not to worry about any melting problems unless my cylinder temps were close to 190 f. It makes hella more horsepower now and I may go leaner when I get to the dyno with a/f meter. My plugs are still showing richness with the 148

Edited by 1800bigk
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Does anybody have a running Cub with these parts?

 

68mm Cub, 4mm stroker, cool heads, 35mm PWKs, vforce reeds, timimg plate set to 5 degrees

 

We're at 300 ft above sea level.

 

We can't get this thing to idle.  We've got 160 mains, 55 pilots in it right now.

 

Does anybody have settings that will work? 

 

What about the needle?  Size of pilots and mains?  Starting point on the mixture screws?

369475[/snapback]

 

what is your outside temp? 55 is too big for warm weather drop down to a 48 and try.

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you need to find out what needle you have. that makes a huge difference of what you stuff should be.

 

if you have a needle thats lean down low your going to need a big pilot hopefully he didnt put a lean needle in.

 

 

find out what needle it is

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Does anybody have a running Cub with these parts?

 

68mm Cub, 4mm stroker, cool heads, 35mm PWKs, vforce reeds, timimg plate set to 5 degrees

 

We're at 300 ft above sea level.

 

We can't get this thing to idle.  We've got 160 mains, 55 pilots in it right now.

 

Does anybody have settings that will work? 

 

What about the needle?  Size of pilots and mains?  Starting point on the mixture screws?

369475[/snapback]

 

i have almost the exact same setup but my timing is at +7 which i would recommend you advance to. your pilots are too big. try a 45 or a 48 and it should idle fine. my jetting is 45 pilots with 162 mains. runs great and idles perfect. cant remember which needles but the clip is in the middle. im at 1000 feet above sea level...

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i have checked all the connections and my cdi and coil both work on another basnhee but it still wont work on mine. i haven;t got ahold of dan yet but hopefully soon i will and he can help me out and explain the pilots.

Edited by minishee
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