Cub Timing, Compression, Jetting

[dajogejr]

Sorry for now browsing this whole thread.....

 

Question...are these short runs, or are these long, wide open runs in top gear?

 

If it's long runs...it's possible you're sucking your float bowls dry...that'll melt a motor in a hurry as well.

 

What does your fuel supply look like? Pingel or stock fuel valve? Have you drilled your gas cap or at least removed the check ball?

[SpeedRacer88]

Long runs once I hit 6 they fly by like they got another gear and I wasn't even wide open when I blew the topend and I have a regular fuel supply un modded

Edited August 8, 2011 by kadillacman

[SpeedRacer88]

I had a leak down test done to it the same day it was jetted I shipped it down south in my half empty u haul it blew on the second ride but to be honest it was acting weird the first day I pulled it off the uhaul I was jus too happy to be home to even think to worry about it I ride the same kind of trails I was riding before

[dajogejr]

You starved the motor of fuel.

You need at the very least a dual outlet pingle.

100% perfect jetting doesn't mean anything if there isn't enough fuel in the bowls.

 

My advice...and this is overkill...is get a dual pingle and larger float bowls.

 

You can NEVER have too much fuel supply. And if you have the stock gas cap...take the little screws off the bottom and remove the check ball... It needs to breath through that vent.

[SpeedRacer88]

Thanks any advice on wat I can do for a lil more hp? To be competitive against those bikes?

[dajogejr]

They were going by you in 6th gear because you were running out of fuel.

Fix it as is before you go looking for more power.

 

Then...work on traction. You have damn near the same power to weight ratio as those bikes. A healthy 4 mil cub is around 80ish or so HP.

An RM250 is 40ish. But half the weight....

 

If you get traction, you should be able to beat any 450 based 4 wheeler....unless it's WAY done up.

 

Where they're beating you is handling and traction. My buddy had an 04 450R with damn near everything done to it. When I could actually shift my 4 mil cub on gas (didn't have an override tranny) it wasn't even close.

 

Of course, this was at the dunes with paddle tires.

[SpeedRacer88]

I'm talkin bout 450 dirtbike I'll try what u said first tho

[dajogejr]

A 450 dirt bike is still only in the mid 40s...and it weighs just a hair more than a 250.

 

They just get traction....period. And they're lighter and geared different.

[SpeedRacer88]

What's a good gearing u think I'm at 16/40

[locogato11283]

You don't need more power. You need more traction. There is no reason you shouldn't be stomping both of those bikes.

[SpeedRacer88]

You don't need more power. You need more traction. There is no reason you shouldn't be stomping both of those bikes.

Tire recommendation?

[SpeedRacer88]

Tire recommendation

[dajogejr]

10 - 12 paddle tires and put it in sand.

 

Because of the lightswitch power band on a cub...good luck getting a set of knobbies to hook up no matter what the surface.

 

On my 4 mil cub with a 6 over arm I could fry holeshot XCR tires in deep, nasty grass...whereas normally it'd hook so hard it buck you off the back.

 

That thing is hitting like a freight train and it needs tires, suspension, gearing and the ability to shift to get it all to the ground.

 

Good luck....

[TNTS355]

What's a good gearing u think I'm at 16/40

 

I think you should be at 14/41, more outta the hole gearing. If that doesnt work try a 13.

[dajogejr]

I think you should be at 14/41, more outta the hole gearing. If that doesnt work try a 13.

 

No offense, but I think that's going in the wrong direction.

I think it'll blow the tires off even more than he is now.