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Doug_Caldwell

Engine Builder Wanted

14 posts in this topic

I have been looking into sending out one of my motors for modification. I want to have the cases matched, crank trued, head done (possibly bigger valves), etc. But I have only found a couple of places. I was wondering if anyone has had a good experience with anyone. Also I am looking for other internal engine parts to look into.

I am also looking for a Big Bore Kit (475cc - 500cc). But that is not as high on my list of things to do. I want to be able to have a Big Bore cylinder and a Standard cylinder.

Any help would be great.

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Motocross. I race the Open A and +25A Classes. I would like to have the complete motor done for around $800 -$1000.

I am trying to get a little more reliability and a little more power across the board. I like to have plenty of low-end power, so I can just role it on. But I really like to rev it rather than shift it.

I have a really good set-up right now I think (without motor work). I am running a Big Gun Signature Series Pipe, 50-tooth rear sprocket, and Hinson Clutch. Other than that the drive tran is stock (or stock equivalent).

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you might get a big bore kit and have it installed for around $1000 but that would be about it

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I have seen ?470? big bore kits for $300 w/piston and gaskets on ebay. But you have to send them your own cylinder. I believe it comes w/ a wiseco piston.

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I should have been a little clearer with my question. I am a full-time mechanic, and used to work as a tech at a local dealership. I can disassemble and reassemble the engine with little difficulty. I am mostly looking for suggestions on internal parts to upgrade and someone with the experience to perform the machine work modifications.

For example, I would like to have the head ported/flowed. I would take the head off and send it in. If I need new valves/seats/seals, I would send them along with the head. If I were upgrading cams, I would just install them myself.

As far as the big bore goes, I would either buy another brand new Yamaha cylinder and have it bored/plated, or I would buy a cylinder off the internet already bored/plated. I am not worried about the Big Bore Kit. I just wanted some input on where is the best place to talk to. (I have looked at Max Power’s and Eric Gorr’s websites)

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Eric Gorr will definitely give you your moneys worth.

Give him a call or post on DRN.

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My suggestion would be to stay away from the bigbores...reliability has been a problem. We are getting more HP from a good running 450 than the 500 bigbores anyway, and reliability has been really good.

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My suggestion would be to stay away from the bigbores...reliability has been a problem. We are getting more HP from a good running 450 than the 500 bigbores anyway, and reliability has been really good.

I'm bored to 450 with 13.5.1 and reliability has never been beter. There perfectly fine if you do it right and take care of it. Hot cam's will run you about $300. Porting will be about $300. Good complete pipe about $800. Airfilter $25. Bigbore and high compression will be more. Then you have to factor in the race gass you will need.

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My suggestion would be to stay away from the bigbores...reliability has been a problem. We are getting more HP from a good running 450 than the 500 bigbores anyway, and reliability has been really good.

I'm bored to 450 with 13.5.1 and reliability has never been beter. There perfectly fine if you do it right and take care of it. Hot cam's will run you about $300. Porting will be about $300. Good complete pipe about $800. Airfilter $25. Bigbore and high compression will be more. Then you have to factor in the race gass you will need.

Hmmm...60 plus HP from a stock bore 450...been running the same lower end for 2 years...you get what from your BigBore?

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Never dynode. I have had the same low end for 5 years. Run’s on race gas. It was done right. No major failures. I ride it hard! I have a whole list of mod's:

-13.5.1

-450 bore

-ported and polished

-full exhaust (header and slip on)

-air filter

-hotcams

-air box mods

-carburetor mods

Soon to come:

-larger bore

-stroker

-larger valves

-alcohol

-NOS

-all the good ol micro polishing and matching too.

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