2004 yz250f rebuilt

[Grensjos]

I have a 2004 yz250f. I rode a friends 2008 crf250r and found it to be much easier to ride than my own bike because of the power. I feel that my bike should have way more low end, compared to the 08 honda i rode. i am looking to spend about $1500 on the motor. I would like to do a high compresion piston, porting, fresh valves, and hot cams. i know that every one has their own opinion on what is best. any suggestions. i am planning on pairing my motor work with a new full exhaust.

I have owned the bike for 1 1/2 years and have probably put about 30 hours on it...i dont know if the bike has ever been rebuilt.

 

[sick 96 250]

I heard the Athena big bore kits are the way to go and can be had for very cheap on the auction site. I just sold my 04 250f to bump up to a 450. Check out the Athena kit and see if you can find some reviews on it.

 

[whenfoxforks-ruled]

All you have to do is keep up with your maintenance schedules. Let your friends 08 go 30 hours and see what a dog it has become. Look in your book, how long ago should you have checked/replaced the rings? Personally, and pathetically, I thought the yz's came out of corners better. An 04, no telling the hours or work that has and has not been done.

 

[Blink-182]

http://www.eric-gorr.com/


and like fox said i would expect it to be a dog too with 30 hours
have the valves ever been adjusted to spec?

 

[Grensjos]

i have checked the valves a number of times, i have had to shim them but they are done within spec.

 

[whenfoxforks-ruled]

How many shim sizes from stock are they?

 

[Grensjos]

that i dont remember. i have the service manuel and i remember that it was within the allowed amount

 

[whenfoxforks-ruled]

How many hours does the book say on the rings? That or a poor carb/ap circuit will kill the bike out of the hole.

 

[Grensjos]

i dont belive that it is the carb---i know that i need rings, but what i am interested in is what to rebuild with. I want to go with a high compresion piston, cams, port and polish, and valves. I have never done anything like this and was wondering what to expect when i dig in. I guess my main concern is the valves and what will need to be done there. i am leaning twords a cp high compression piston, stage 1 hot cams, and a port and polish job. when is comes to the valves i have no clue??? i know nothing about valve seats or valves. if any one can led me in the right direction it would be appreciated.

Thanks in advance
Grensjos

 

[bonitz]

Kibblewhite black diamond valves,springs, and retainers seems to be the top choice of the guys making big power. :cool:

 

[oldguy]

Kibblewhite black diamond valves,springs, and retainers seems to be the top choice of the guys making big power. :cool:

We just parted out an 04 YZ250F and you hit a great combination . Spider raced that bike for 2 seasons with that set up of valves and they stayed dead on with no adjustments being needed during the 2 seasons. We stayed with a stock exhaust and never really needed anything else. The suspension was the biggest boost to its racing and Jeremy at MX tech set it up so just perfect.

Just be sure to use the matching springs and retainers for the kibblewhites and you should be good to go.

 

[Ol'89r]

I also agree with the Kibblewhite valve and spring combo. Excellent, durable, choice.

If you install new valves you will have to have your valve seats cut. This is something a shop with the correct equipment has to do. Eric Gore can do it and he's not too far from you.

Don't waste your time and money on an expensive port and polish job. The ports in these heads are very good from the factory and only need a little clean-up and a proper valve job. Having someone port your head that doesn't know what they are doing can cost you horsepower.

A high compression piston and a stage 1 cam is a good combination and works well with the stock exhaust and even better with a FMF PowerBomb header.

Just my $ .02

 

[Grensjos]

thanks so much for the great information...you guys are so helpful on this site

i have heard really good things about the Kibblewhite valves and springs combo. i have also heard that there were some issues with some of these valves wearing quickly??

as far as a valve seat job goes what am i up against for cost? where is eric located?

once again---thanks for all the input everyone...i am new to the sport and every bit of knowledge you all have shared is great

grensjos

 

[oldguy]

Eric's shop is on the East side of Madison, Wis just off the interstate. Go to his website http://www.eric-gorr.com/ and you should be able to get all the info you need. Better yet buy the 2004 YZ250F engine he has listed (I know for a fact it is a great motor :nod: ;) ) for sale.

 

[Grensjos]

Great thats only about an hour ride from my house. i will call him to see about the motor that he has there.....and to see what he could do with mine. according to his web site it should only be about $1000 for every thing that i want