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Discussion Starter · #1 ·
Okay so I have 14-40 gearing on my raptor. Is that pretty good? I was thinking about getting a 15 tooth front but would it be worth it or not? It's bored .020 over or to 100.5mm with a 11:1 high comp piston. I will be puttin in the stage 1 hotcam in it within the next week. I run 20 inch turf tamer tires.

Okay and to the engine question. Can you safely bore a stock cylinder to 102mm? I was thinking about getting it bored this summer. I'd like a 12.5:1 piston. Who makes one this size with this compression? Would it be worth it. All i ride is trails, some roads. No track. This summer I'd like to run a few harescrambles if I can find some near me. And I understand there are alot of topics about the engine and stuff, but what's your thoughts with my setup?
 

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if you do harescrambles, i would go with either a 686 kit or 720/727 kit. You will keep reliability and increase your power a lot. I would also stay with a 11:1 piston so you can run pump gas.
 

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Discussion Starter · #3 ·
Erm.. I completely forgot about having to run higher fuel lol. Stupid me. Anyways so yes I will stick with an 11:1 piston. Would I be able to rune stock sleeve with a 720/727?
 

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I agree. Race gas is anywhere from $6-$12 a gallon and not readily available in our area. I checked when I was considering a 12:1 setup and found I would have to drive 30minutes one way to the nearest VP retailer for gas. :unsure:

As for the gearing, you're going to have to just try the 14 tooth and see if you like it or not. I've got 12, 13, and 14 tooth gears so I can change it depending on what I need. My quad is close to stock so I will probably keep the 12 for now, then go up as I build the motor.

Yes, you can bore the stock cylinder to 102mm, that the biggest you can go. The 686 has great bang for the buck. You can do a 719 on a stock sleeve, but not a 727. A 727 is a 105mm piston a a stock stroke. It'll cost you about $450 for machine work and sleeve for the 727, plus a rod and piston (~$300). So you're looking at about $750 for the macine work and rotating assembly for thr 727. On the other hand, the 719 require a bore job ($75), a stroker crank/rod ($420) and a piston ($120)... equating to a little over $600.
 

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Discussion Starter · #5 ·
So far I like my 14-40 gearing setup. So I think I'll just stick with that. I will be sticking with an 11:1 piston. It's looking like the 686 would be my best bet so far. I am on a cheap budget however so I don't really want to be getting a different crank or rod. Anymore opinions?
 

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If you're broke then a 686 is going to be your best best if you demand more displacement, but honestly you're not going to gain enough power by the 1.5mm jump in bore to even bother with it. You are already at 11:1 compression and compression is where you get the power.

My suggestion is to just leave it like it is. Install the cam you have, and then spend your money on suspension, because judging by your sig you don't have any suspension work done yet.

I would recommend getting some ASR a-arms off ebay, some rear spacers, and yfz shocks. That'll be a huge improvement over the stock suspension and probably get you there for less than $800 total.
 

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Discussion Starter · #7 ·
Well the only bad thing about the ASR arms that I see is that they have heim(SP?) joints. If I was looking more at a-arms I would want ones with ball and socket joints on the end. They last longer because they are covered in grease in a rubber boot. I was looking at the Wicked products arms on ebay and the only difference with those and the ASR are the ends. I am looking at some rear spacers though and found that the durablue ones look nice and sturdy.

One reason I am looking at doing the bigger bore is because when I pulled my head off it looked like there was a small ammount of wear on the cylinder walls. I know normal right? Well there's more than normal. Not enough to kill my compression. I've still got a good ammount more than stock. Just wanted to know so when I do blow it or decide to rebuild.
 

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I thought you had just redone your cylinder? And there's nothing wrong with heim joints unless you light to mud bog all the time. Even then just keeping them well lubed will keep them lasting.

And if you go bigger, just take enough to get the cylinder true. I suggest a +1 piston that way you still have one more step (+2) the next time you have to rebuild.
 

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I'm a fan of the heims, stronger and simpler. Doesn't take much to keep them in good working order either, I don't work on them any more often than I did the stockers.
 
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