questions and thoughts on 426 hybrids...

[800screws]

i've tried to get some answers with no luck... i was wondering on running a 426 engine in hybrids, how do they compare to production engines and the crf hybrid's-down on power? also how much in your experience has porting and or big bore kits added to the engine's potential? big improvement or not worth the money? has your engine puked a little oil out of the head breather tube after running the engine? all the time, sometimes, never?
i finally enjoy my hybrid. i guess putting some time on it really paid off. now i am wondering if i should have some work done to the engine next season....

[ss440ex]

Yes the small dia out of the top of the rocker box will seep a little oil.
It should be routed back to the tank if you have a dry sump system...
Do not plug it!!!
Stock comp is 12.1-12.5 i believe,upping the compression with a big bore and porting will only make it run that much better!!

Markvette has a ported 444 big bore yz 426,ask him how he like it.

You also should look at the reliability of the yz426 compared to some of these production quads!!!!

[800screws]

i PM some people who i know have had this work done, but i didn't get a response....

[400exrider707]

Originally posted by 800screws
i PM some people who i know have had this work done, but i didn't get a response....


You race D3 correct? Wasn't there a guy running a cannondale frame with a 426 motor a couple years ago... I remember him having nothing but problems with it, though I dont really know the history behind it, but it certainly was fast.

[figair]

HI I know this has nothing to do w/a 426..But 2 of my buddies and I have the yz450 motor in our quads,and knock on wood no problems..They do ride alot more than I do..Though yz motors ripps ***..But like anything,you have to take care of it..good luck

[800screws]

i'm in district 34, i've had no problems with the engine except for the oil out of the breather tube after it's run hard. i've heard this is also contributed by the high compression piston.

what i'm wondering is how does the engine feel, performance wise with porting and or a big bore kit. also how it stacks against the crf and production engines...

[tx450racer]

I just picked up a crf last weekend its alot faster than my yfz450 and my yfz has motor work done to it. but, im not sure how fast the 426's are.

[bow]

Originally posted by 800screws
i'm in district 34, i've had no problems with the engine except for the oil out of the breather tube after it's run hard. i've heard this is also contributed by the high compression piston.

what i'm wondering is how does the engine feel, performance wise with porting and or a big bore kit. also how it stacks against the crf and production engines...

i have a 426 bored to a 450 with head work and stock compressor piston. it was smoother when i got the motor back. easier to ride . it didn't have that yfz hit to it,but much faster. it would take a yfz in a flat out drag, and close to a built 450r. yes, oil comes out my breather all the time too.

[markvette]

we have the 426 in a ex frame. it is bored to 446, ported and polished with 13 to 1 wiseco piston and a auto decompression hot cams exhaust cam. my son says it is stronger than any quad he has rode. he use to race a cannondale and has rode all the rest. we have a large aluminum radiator with no cooling problems. the only time it ever over heated is when he decided to sit on the side of the track for 10 minutes watching other people ride with the quad ideling. with no electric fan you cant do this, you must have air moving through the radiator.. the quad has one race on it since a ground up rebuild, also it is for sale as my son has a new baby and has decided to give up racing for a few years.

Mark