88cc kit for an xr70

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Correct me if im wrong but the crf70 and the crf50 both share the same motor but the 70 obviously has a larger barrel and piston hence you can just buy a regular bore kit for a crf50 for your 70cc. Kaos50s have a great range of bore kits and will set you up with one no worries.
 
takegawa for sure is better brand and quality but the trail bikes gear is grea for the money you pay for them and the AMERICANS rate TB parts...they think they are great

so id get the cheaper TB kit
 
Thanks most adds say to get a high flow oil pump (I think)
would you say its compulsery?
 
crf70 engines have a different cylinder head, with a bigger combustion chamber. If you use a bore-up kit for a crf50 you'll end up with a serious lack of compression. It'll run but it'll be lazy. Make sure you get a kit specifically for a 70!
 
Thanks Tormentandglory, so what i should get is a tb 88cc big bore kit, complete with carbie and air filter specifically for a 70....
should i get the recommended oil pump as well? or doesn't it really matter.

thanks for all your help.
 
tormentandglory said:
crf70 engines have a different cylinder head, with a bigger combustion chamber. If you use a bore-up kit for a crf50 you'll end up with a serious lack of compression. It'll run but it'll be lazy. Make sure you get a kit specifically for a 70!
Click to expand...

Legend. Thanks for clarrifying that. Does that mean if you get an R stage head and cylinder kit for a crf50 motor it would still work the same as the crf70 motor? Cheers
 
I've never run a big oil pump on any of my motors, but it probably wouldn't be a bad idea if you're prepared to spend the extra few bucks. Remember to drill out the oil hole in your cases that feeds the top of the engine! Kitaco/takegawa kits have details about doing this in the instructions. I don't think the TB.com kits come with any instructions at all but I might be wrong, I haven't bought any of their stuff for a while.

If you buy a crf50 kit with a new cylinder head you'll be fine. I think the 50/70 bottom ends are exactly the same. Early 70's, like the old dax and sl70 had a big hole drilled through the crank for balancing. I'm not sure if late ones have that to, but it makes no difference anyway. Just rev it :)
 
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all you need to do is replace the old pump and drill out the hole to widen it with a 2mm drill bit
 
The tb kits on faster minis.com look alright, do you know if they post to australia? or have you bought anything from them..

Also is it worth getting a clutch?
 
I got my TB stuff from 50caliberracing.com a long time ago. I have the TB manual clutch on my bike to and its good. Much better than centrifugal. Won't start in gear though. If you're gonna spend that much money, think about getting the kit with the crank. I ran mine as an 88 for a while, but when I put the TB 51mm crank in (108cc), it came to life big time.
 
hey torment

how would the 108 and 117cc kits compare to say a 125-140cc china...???

would the china 125-140c be much quicker??
 
My 108 makes as much top end power as a chinese 125 but its a bit down on torque. The yx140 is fast. A 108 or 117 will get spanked, for sure. Yx140 comp is only 8:1, not the claimed 10:1. I know because I measured it. If you're prepared to pull the head off, you can up the comp to 9.7:1 without to much trouble. Any more than that and you'll have to make the valve reliefs in the piston deeper.

And my 108 is only 3 speed :( If you're drag racing you're gonna lose when the china snicks 4th
 
Is it worth spending the extra money and getting the stage 2 one that includes the carbi and air filter?

I see what you mean about getting the one with the crank, prolly a little too expensive if im also going to get a manual clutch.
 
ok mate thanks for the info...im lookng at getting a crf50 to maybe have abit of a play around on but not to sure yet i would like one to uno ride around the back yard and that but id like to keep my 140 for out trails and that

and i was thinking maybe one of those kits on a crf if i get one would go alright
 
You'll need a decent carb either way. Buy it off them or buy it off someone else. Whichever is cheaper I suppose. I had a keihin 20mm on my 88cc and it was pretty good. Paid f@%ing heaps for it to, it came in a kitaco kit with a manifold and stuff. I've still got it actually. Wanna buy mine?
 
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