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Discussion Starter #1
Ok i got a stock 2003 Raptor 660 for dirt cheap. The compression is low and i will need to rebuild the top end. I am new to atv rebuilding. I have rebuilt many car motors over the years.
So I wanted to weigh out my options i can get a hot rod crank +4 with the 102mm piston plus all gaskets for like 550. Do i need to get a new cam or can i use the stock one with the bike. I just wanted to see if my 550 kit will end up being 1000 dollars in the end. If so I am debating on just getting a .20 oversized piston and just using stock crank and going about my riding. Just wanted to see anyone elses thoughts. I figured if i have to take top end apart why not make it into a litter meaner quad.

I understand either way i will have machined costs to bore out cylindar

Any Suggestions????? thanks
 

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Well the biggest thing is the stock rod. You $550 kit will be more like $2000 because you won't be able to stop lol. With just the crank and piston it won't make much of a difference until you port it and cam it. you will also have to bore it with the stroker kit to a 102mm anyway. It isn't much more to get the stroker kit and when funds allow go in to it again with some headwork-cam. But like I said the Stock ROD is weak and is a ticking bomb as most say. I have never broke one but before I got my raptor it must have broke a rod as you can see damage in the case and it had a hot rod crank in it.
 

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Cam is not required. It will run fine on a stock cam or stage 1 cam. You will notice a lot more grunt down low. The 4mill crank makes more torque and you will notice a difference. And you will get an upgraded rod in the process.
 

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Discussion Starter #4
What about the stock springs and valves are they ok to keep. I am leaning towards getting a std hot rod crank with a 102mm piston and a stage 1 cam. That way I will have a basic 686 kit. Any problems I may run into along the way thanks
 

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Upgraded valves are always good. The stock ones are soft and the heads cup / streatch. Dont get Kibble White valves get Ferrea Stainless valves. They have a much better track record with reliability. Kibble White had a string of valves where the heads would break off the stems. You have to do a valve job when you replace the valves. They will grind the valve seats and faces so they match up and seal tightly. A valve job is part of any builders port job. So if you would get a port job then it doesnt really cost any more to uprade the valves other than their costs. A good port job will really wake the raptor up regardless of what engine build you do.

If your going to upgrade the valve springs you might as well get a stage 2 cam as well.
 

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:eek:Or you could just buy my head with HD valve springs and port job already complete with valves with 1 year on them and matching cover with rockers for $300. ;) and sell yours for about what you paid for mine then I can buy more parts...
 
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