yz 450 head porting

hello all,i have recently bought an atv powered by a yz450 engine....i am looking to up the power and i'm thinking about doing some head porting....i was looking for some advice on good companys or other ideas to gain power....i have heard to stay away from high compresion piston and cams...thank you for any help in advance

jack cucci

Don't want to come off as a jerk, but why do you need more power? The YZ already makes a crap load of power. I can see if you want the power in a different area of the powerband, but I don't know why you would need more "raw" power. The best thing you can do to your bike to make it faster is get your suspension done. Oh and looots of practice.:thumbsup:

hey man,your not coming off as a jerk at all,i understand what your saying but belive it or not my 426 was pushing more power and i kind of got used to it....my quad is built theres nothing left to do just looking to get alittle more power.....also don't forget the engine is in a quad frame.....

Alright, well if you really want more power, then yes, porting will add more power. Unless you want to run Race gas, i wouldn't get a hi-comp piston. I would probably try to find cams that add bottom to mid power, because on a ATV, you will use bottom to Mid more than top and most cams are designed for top end.

A pipe will help, a DRD will help the bottom, and I know the Yoshi's are screamers, not so sure on the others. If I ever get a pipe, I know I will be getting the DRD.

Well hope this helps a bit.

BBOYCE

hello all,i have recently bought an atv powered by a yz450 engine....i am looking to up the power and i'm thinking about doing some head porting....i was looking for some advice on good companys or other ideas to gain power....i have heard to stay away from high compresion piston and cams...thank you for any help in advance

jack cucci

Why would you want to stay away from aftermarket cams and a high compression piston?

the only company that i spoke to in regurds to work has been Doug Dubach racing and they said that they don't reccommed running cams in that engine,and from reading different posts across the internet i have read many times that the stock yamaha piston is the best that you can run in that engine....the main reason that i asked for help finding different companys that do head porting is to get different opinions and make a choice for myself based on the information that i recive....thanks again jack

I don't see anything wrong with wanting to up the power since you're dealing with the extra weight of an ATV versus, a YZF MX bike. If you were asking about increasing the power of a YZ450f MX bike, I'd say save you're money for upgrading the suspension, and ride more......

Anyway, back on topic....... I don't think you'd have any problems with going to a high compression piston. AS LONG as you're willing to pay the added cost of using the higher octane fuel that's NECESSARY to prevent pre-ignition. I've also heard nothing but good things about Hotcams aftermarket cams.

The only negative things I've seen about aftermarket Piston's are those by Wiseco, and that's generally due to improper use. Even my local MX shop doesn't like Wiseco....evidently Wiseco got a bad rap, when some people were firing up their Cold engines, and with no warmup, were blasting off full throttle. Some of these guy's were then experiencing piston seizure when the Piston expanded at a different rate than the cylinder (wiseco's are forged, rather than cast). I spoke to a local mechanic, and he stated that as long as you give them a normal warmup time, you won't have any problems. I hope this helps.

The only negative things I've seen about aftermarket Piston's are those by Wiseco, and that's generally due to improper use. Even my local MX shop doesn't like Wiseco....evidently Wiseco got a bad rap, when some people were firing up their Cold engines, and with no warmup, were blasting off full throttle. Some of these guy's were then experiencing piston seizure when the Piston expanded at a different rate than the cylinder (wiseco's are forged, rather than cast). I spoke to a local mechanic, and he stated that as long as you give them a normal warmup time, you won't have any problems. I hope this helps.

For that most part, the "cold seizure" phenomena is history. Modern forging techniques allow more silicon and other expansion controlling metals to be added to the alloy, which means the piston can be fit with less clearance, like a cast one, and the problem no longer occurs anywhere near as often as it once did. But, as you say, the stigma lives on.

I used Williams Motowerx on our 250f for the head porting. Dipple valves also. NO CAMS. Just stock ones. Bike HAULS ASSSSSSSSS. Son loves it.

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