Question about 7mill crank.

[bansheeqc]

Hi everyone!

 

I have a couple of question about 7mill (115 rod)crank on stock cylinder.

 

-For drop a 7mill crank on my case, i need to trench my case (i think)?

 

-I'm able to run cylinder without a plate welded on the top of the cylinder?

 

-I'm able to run cylinder without base plate with custom cut dome for the stroke?

 

In fact, what is the difference between drop a 4mill and a 7mill crank except the case trenching and the porting? (for a stock cylinder motor).

 

 

thank you everyone

 

bansheeqc

[tony cub]

Hi everyone!

 

I have a couple of question about 7mill (115 rod)crank on stock cylinder.

 

-For drop a 7mill crank on my case, i need to trench my case (i think)?

 

-I'm able to run cylinder without a plate welded on the top of the cylinder?

 

-I'm able to run cylinder without base plate with custom cut dome for the stroke?

 

In fact, what is the difference between drop a 4mill and a 7mill crank except the case trenching and the porting? (for a stock cylinder motor).

 

 

thank you everyone

 

bansheeqc

yes

yes

yes

youll feel the diffrence between the 4 and the 7(with the right porting)

Edited January 20, 2009 by tony cub

[locogato11283]

unless you already have a 7mm crank, go with a 10mm.. its the same money and more power.

[tony cub]

unless you already have a 7mm crank, go with a 10mm.. its the same money and more power.

that sound a hell of alot better!!!

[2001Stroker]

unless you already have a 7mm crank, go with a 10mm.. its the same money and more power.

Yea, he talked me into that too. I'm glad he did.

[blowit]

Hi everyone!

 

I have a couple of question about 7mill (115 rod)crank on stock cylinder.

 

-For drop a 7mill crank on my case, i need to trench my case (i think)?

 

-I'm able to run cylinder without a plate welded on the top of the cylinder?

 

-I'm able to run cylinder without base plate with custom cut dome for the stroke?

 

In fact, what is the difference between drop a 4mill and a 7mill crank except the case trenching and the porting? (for a stock cylinder motor).

 

 

thank you everyone

 

bansheeqc

 

 

Yes, a 7mm will work but must be done carefully and correctly. We will not do a 10mm crank on stock cylinders any more because they just suck compared to the cub motors from lack of transfer volume/flow. ie, you can't feed it very well. They also suffer big time from port timing being way out of the bubble for optimal performance. In our opinion, the 7mm is the largest sensible crank for the stock cylinders.

 

Brandon

[4stroker]

Yes, a 7mm will work but must be done carefully and correctly. We will not do a 10mm crank on stock cylinders any more because they just suck compared to the cub motors from lack of transfer volume/flow. ie, you can't feed it very well. They also suffer big time from port timing being way out of the bubble for optimal performance. In our opinion, the 7mm is the largest sensible crank for the stock cylinders.

 

Brandon

 

i agree. with a 10mm you will have to run a spacer plate to stop the piston being pushed out the top of the barrel, and unless you resleeve the stock cyls to optimise the transfer timing it wont work very well.

 

after all that work is done, you might as well have started with a 10mm cub.

 

so while the cranks might cost the same, the extra work required to make a 10mm work well does not make it feasible.

[locogato11283]

in that case then, if you dont wanna run cub cylinders, i would stick with a 4mm motor. the gains youll see from going to 7mm arent gonna be worth the extra hassle and money in my opinion.

 

the 4mm motors can make great power and setup properly will run right along with 7mm motors anyway.

[dajogejr]

If you already have the 7mm crank, get domes cut.

If you haven't purchased a crank yet, get a 4. Less work, hassle, headache and no trenching.

 

In terms of cubs....yest, get a 10 over a 7 UNLESS you already have a 7 mil crank...or unless you race at a specific venue where the size limits of the class puts you less than a 10 mil...and you need to compete.

 

Here's a trick if you have a 7 mil crank, buy a 10 mil casted cub and have the bottom decked....

 

Stock cylinder 7 and 10 mil motors do run, but they are a LOT of work....period.

[bansheeqc]

Thank you everyone.

 

I really want to stay with stock cylinder and have the sleeper look,

 

I want a hard running bike, with the appearence of a stock motor.

 

I dont have 7mill crank now, but i probably buy one soon. I already have a 4mill bike, and i want to try something different.

 

 

bansheeqc

[locogato11283]

so what exactly do you want?

 

you have a 4mm cub now or a stock cyl motor?

 

the 7mm really isnt gonna be worth doing, and i think youre going to be disappointed with all the time and money you put into a 7mm stock cyl when it doesnt run that much better than your 4mm bike.

 

its your money in the end, we are just tryin to keep you from wasting your hard earned money..

[dajogejr]

I agree... 4 to 7 just isn't worth the money.

4 to 10 is.

[locogato11283]

I agree... 4 to 7 just isn't worth the money.

4 to 10 is.

 

word.. best thing i couldve done going from a 4mm cub to a 10mm cub..

 

now only if i could figure out how to rebuild my kicker..

[bansheeqc]

now only if i could figure out how to rebuild my kicker..

 

What what do you mean

[2001Stroker]

now only if i could figure out how to rebuild my kicker..

 

What what do you mean

That's between him, BigRed350x, and gregrob. Kinda of something that you have to be following to understand.

 

I didn't see that you wanted to keep the stock cylinders. So yea, you'll be happier with the 4mil over the 7mil. Alot of hassle, for not much more power. I'm using a Cheetah PV cylinder for my 10mil.