jetting 421 cub

[sped]

Im trying to jet my new cub motor. 45 pilot, air screw 2 1/2 turns out, needle EEJ on the third clip from the top, elvation sea level(oregon dunes),and main jet 170. From the plugs 1/2 to wot seems to be running lean. Should i go back to the stock pwk needles or just put some bigger mains? The lower throttle ranges plugs are golden brown. Am i missing something

Edited July 9, 2007 by sped

[dajogejr]

I don't know about that needle...I ran CELs in mine when I ran gas on my 4 mil cub.

It ran very crisp...and I think I had a 158 or 160 main.

If you're at 2.5 turns out on the air screws, you probably want to run a smaller pilot.

 

Have you checked the motor for leaks? Compression test? Tested the electrical?

[BigRed350x]

I was at a 42pilot, 148 main and a CEL or CGL needle on the middle clip and around 1.5 turns out. But I ride at 7200 to 8500ft.

[bansheeseat$$]

The EEJ needle is a rich needle.With your screws turned out that far more then likely a 42 pilot will be what it needs.However sense you are running 170 mains I would be concerned with air leaks around your crank seals and base gasket.Like Dave mentioned about air leaks.I would highly recommend a leak down test.It is real common for the cubs to leak air around the base gasket area and the keyway on the primary gear on the crank.

[sped]

so i will retorque everything and while the bike is running spray some starter fluid to see if the idle raises. i will post my findings. thank you guys

[dajogejr]

so i will retorque everything and while the bike is running spray some starter fluid to see if the idle raises. i will post my findings. thank you guys

 

My cub was actually uneven from the factory. The top and bottom had to be slightly decked to get it flat.

It's part of the sand blasting/finishing products from Millenium, the platers.

 

I assembled my motor 3 times before, more and more carefully each time and it was still a problem.

Get a leak down tester to make your life easier...

 

Bob from R&B Racing sells a nice kit for 50 or 60 bucks...you can PM him here @ machwon.

Great guy to deal with.

[sped]

i saw the thread on the homemade tester on this forum. Going to use the same idea with a mityvac. It should do the trick. Going to try that tommorrow and post.

 

You are scaring me with the uneven cylinders hopefully not the problem. Thanks for the heads up.

[sped]

I retorqued the barrel and head. performed a leak down test. It held 6 psi for 4 min with no drop. I think maybe it was leaking from the base gasket ,because a couple nuts were loose.

Going riding this weekend we will see what happens.

 

 

thanks again for your guys help.