440 kit rebuild

[hotrodbelair]

i wrecked my 440 and while im waiting for a new frame im gonna rebuild my engine what can i get for it to where i can get more power but keep it relible. i bought this quad from my brother it has 440 standard compression and stock head. it still runs right now just the front of the frame i tore up pretty bad

[mikeboone]

Bump the compession up to 10.8:1 and maybe a Hotcam? Labor will be more than parts

[hotrodbelair]

would i need to get better head studs if i bump up the compression

[mikeboone]

Originally posted by hotrodbelair
would i need to get better head studs if i bump up the compression

No, running under 11:1 will be very safe and long engine life. Stock crank and stock headbolts will be fine. If properly reassembled you should have no problems. You should also be able to run premium pump gas; not race fuel.


You can do endless things for more power but they will costs much more up front and require more maint. The best bang for the buck cams are the Hotcams.

Some of these "440" horror stories are caused by the owners. With the 89-89.50 mm motors the oversized sleeves run into thr two dowel pin holes on crankcases. Either the sleeve must be notched or the two dowel pins shaved slightly for the cylinder to slide down onto. If the cylinder isnt fully seated the studs will pull when the acorn nuts are tightended to specs.

[hotrodbelair]

should i go with stage 1 or stage 2

[Chino886]

Originally posted by hotrodbelair
should i go with stage 1 or stage 2

The stage 1 cam makes more midrange, and top end then a stock cam, and is more biased towards the middle. The new stage 2, also makes more midrange and top end power, but is more biased towards the top, but does not loose any bottom end. The stage 3 (old stage 2), is basically a top end cam, and does loose some bottom end power. Let me know if you have any other questions.

[hotrodbelair]

on mine i had stock gearing. what do u think would be the best gearing for it i would like to go a little faster but dont want to lose alot of power

[hotrodbelair]

ok this is what im thinking bump the compression to 10-1 and a stage 2 hotcam. does anyone know of how much power i will gain i heard a basic 440 kit will get around 40 is this right

[Chino886]

Originally posted by hotrodbelair
ok this is what im thinking bump the compression to 10-1 and a stage 2 hotcam. does anyone know of how much power i will gain i heard a basic 440 kit will get around 40 is this right

I would go higher than 10:1, that is not very high comp, you will not have as much power with the lower compression. I would go with Mike Boone suggestion, 10.8:1, I have a JE 10.5:1, no problems.

[hotrodbelair]

mike was saying anything under 11:1 was safe does that mean 11:1 would be good or should i go with 10.8:1

[Chino886]

Originally posted by hotrodbelair
mike was saying anything under 11:1 was safe does that mean 11:1 would be good or should i go with 10.8:1

I would go with a JE or Ross 10.8:1 thermal coated. I stayed under 11:1 because I heard that is the point that you need to run race gas.

[hotrodbelair]

mine is a 440 kit when i order a piston for it do i go with 435 or what

[Chino886]

Originally posted by hotrodbelair
mine is a 440 kit when i order a piston for it do i go with 435 or what

I could call up Colby at C & D Racing the site sponsor, you will get a good deal and his customer service is unbeatable. you will learn a lot from him even if you don't buy anything from him.

[400exrider707]

Originally posted by Chino886
I would go with a JE or Ross 10.8:1 thermal coated. I stayed under 11:1 because I heard that is the point that you need to run race gas.

YFZ's and LTZ'S are over 11:1 compression from the factory and run fine on pump gas. 12:1 is where race gas must be used or at least mixed. I have a standard bore 11:1 and love it, I too would also suggest going higer than 10:1, I dont think it will be enough of a gain for the hassle of tearing it down and rebuilding it.

[Chino886]

Originally posted by 400exrider707
YFZ's and LTZ'S are over 11:1 compression from the factory and run fine on pump gas. 12:1 is where race gas must be used or at least mixed. I have a standard bore 11:1 and love it, I too would also suggest going higer than 10:1, I dont think it will be enough of a gain for the hassle of tearing it down and rebuilding it.

I think the 11:1 holds true for air cooled engines....I think.

[TRXRacer1]

Originally posted by 400exrider707
YFZ's and LTZ'S are over 11:1 compression from the factory and run fine on pump gas. 12:1 is where race gas must be used or at least mixed. I have a standard bore 11:1 and love it, I too would also suggest going higer than 10:1, I dont think it will be enough of a gain for the hassle of tearing it down and rebuilding it.
You're compairing apples to oranges. Heat is the reason you need race fuel not compression. That's why in a liquid cooled motor like you pointed out you can run pump gas at 11:1. The liquid cooling keeps the added heat from the compression at bay better then an air cooled engine will. As Chino 886 said, 11:1 in an air cooled is about max for 93. Even then you should keep an eye on it. In certain conditions that might not even be enough.

[Chino886]

Originally posted by TRXRacer1
You're compairing apples to oranges. Heat is the reason you need race fuel not compression. That's why in a liquid cooled motor like you pointed out you can run pump gas at 11:1. The liquid cooling keeps the added heat from the compression at bay better then an air cooled engine will. As Chino 886 said, 11:1 in an air cooled is about max for 93. Even then you should keep an eye on it. In certain conditions that might not even be enough.

you also need to be careful when people talk about premium gas, here in the midwest premium is 91, others it is 93. I don't trust running 91 in my bike.

[hotrodbelair]

i have about 600 to 800 dollars to spend on the motor in my 440ex im gonna bump the compression up to 11:1 put a stage 2 hotcam in it then i was thinking of making it a stroker what all do i have to do to do this. i was also thinking what all would i half to do if i bump the compression to 12:1? just put stronger headstuds in it? if i half to run race gas i have a friend that races latemodels and they have race gas at the shop.

[hotrodbelair]

anybody what would i half to do to make it a 450 or maybe a 460 stroker. get a different crank and rod or could i send my crank in and get this done