So I have a modded 6.5hp clone pushing about 14 horses...If I get a shorty frame for a 6.5, the guy said they only ran them up to 4400RPM's. I can rev my little engine to 7400. Will this work? Any ideas?

i'm gessing it will run like a bat outta hell and then the uncontrollable
boom!!!

i hope it wont do that but at 7400 rpms damn, i would probably put it on a copperhead frame if you could get one

x2 on the copperhead. and im no gear head by any means, but i feel like that would be like puttin a hand grenade on the transom. probably have to rebuild it...a lot.

Go for it. Those little 6.5's on Go carts haul ass.

sounds great but I think you will be at the upper limit of your shaft bearings and may shorten there life if you are continously at that high of an rpm, but i say go for it and let us know how it works out.

In order to get to 7400 rpm you HAVE to build it...We have the compression at 6.5-7:1. The head has been milled...26lb valve springs. Governor of course is MIA. 32mm mikuni carb and uni filter. This motor can take all the punishment because it is done right.
Why the copperhead frame? I have been in contact with Dixie Mud motors but they have only gotten up to 4400 rpm. I need something dang near bulletproof to get to 7400.
Next project is a 13hp build...That one should be interesting

we at copperhead did a custom build for a customer wanting the lightwieght of a 6.5 but the power of our 12hp. The biggest problem we encounterd was propellers, a mud prop is made to work at 3-4000 rpm and your not going to make any power till 6-7000 rpm. Pushing a boat to plane requires alot of torque and horsepower down low. once the boat got going, hit 6000 it did take off but running those kind of rpm for long periods of time results in a bad day. customer ran alot of shallow rocky conditions and open water so it worked but only after we sent the motor back out to detune. Best bet would be your 13.

Hey puddle jumper...pm sent several times

Ur gonna run a 6.5 clone at 7000+ rpms for an extended period of time? Are you running alky or racing fuel? I've had rat motors on my race carts in the past and I have yet to find one that can wind a constant 7000+ rpm for an extended period of time with out lifting once in a while. And believe me when I say I've had some of the best motors available. It should haul ass that much I know but for how long is the question. Good luck with it.
Smoke

I have ran karts for a while and the motor will hold up if its built right. Now a honda would hold up better than a clone but not near as cheap. I have ran 50 lap races on these motors at 7000 never lifting unless somebody crashed. I would imagine if he was goin a real long way on his boat ride he wouldnt be wasting his time with this so the motor shouldnt be the problem. I would say your problem would be the bearings in the frame holding up to that rpm?? Also you would probably need a custom prop. I have wondered if anybody has ever done this with the kart motors because as far as the 6.5 briggs animals and clones the can really haul ass!!! Keep us posted and good luck

Well...put the 6.5 to bed...Building my 13 clone matching with a copperhead frame...Should be interesting with a big mikuni, candy cane pipe, and springs...LOL

I am working a build as we speak. I'm doing a longtail though.... I pushing for around 10-11hp. I plan on only pushing around 4500rpm. Russell at NR racing gave me a cam built for more torque on the low end..... These motors on a shorty frame should do well if prop'd right..... Here's my toy

What size carb is that you are running??? If you want 10-11 hp and you have cammed it, you better make sure you put HD springs in it and upgrade the rod or BOOM!

If that...it will have more torque due to the cam...You need more fuel! Go 22mm mikuni and you wont be sorry

You would be amazed at how much better a 14x36 would plane a load vs a 12' boat.

I ran my homemade 6.5 cvt shorttail on a 1436. It would plane easy with myself, 195, wife 97, 2 kids 100, icechest ,gas, swimming floats etc... Only mods on engine were exhaust header, larger jet. The expeimental cvt drive lasted 2 years, finally broke a belt and I have not took apart to evaluate it as of yet.