How far can I push/modify a 12hp on stock internals?

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  • / How far can I push/modify a 12hp on stock internals?
Anything over 5000 rpm for any length of time and valve float will get eclipsed by piston low earth orbit.

Too funny Bert LOL... I don't know about his club rules on stock engines and about the washers he's adding for more spring strength but, when I was into Sprint Kart racing stock was stock and if you got challenged your engine was tore down by race tech's and checked......... If you were caught you lost the race.... Happened to us a few times.........

Never got caught we were in spec....

Plus Tard Mon Ami ~!~!
 

bertsmobile1

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  • / How far can I push/modify a 12hp on stock internals?
The local club kicked off a few years back and way too many thought you could just remove the governor and make the engine run faster.
We all know what happened next.
Sold a lot of old crankcases that year.
I am not the worlds best tuner but I am the cheapest supply of parts so I get all the sob stories.
We have done a few engines and without going for a forged steel cap rod you have a bomb sitting in front of you.
Modifing the head made a massive difference, but as soon as you win a few race you go up a class and that means an OHV engine.
 

reddman

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  • / How far can I push/modify a 12hp on stock internals?
Anything over 5000 rpm for any length of time and valve float will get eclipsed by piston low earth orbit.

I honestly have no clue what RPM these things spin at. I'm not getting inside the motor at all at this point, and I don't plan on yanking the gov override often, maybe to help with a pass here or there. What kind of RPM do you think these guys run at governed, and do you know how much higher they may go when the gov is overrode? I really don't want to blow her up. This winter I might be able to get inside and see what I can do to up my redline safely, but for today the goal is to finish the race. Can't win if you don't survive to the finish, and this course will certainly eat a few mowers.

I should also mention that this mower is unlikely to ever join sanctioned races. These are informal races put together by friends, so the rule book is only a dozen lines long. No pulley changes, until we have a modified class no piston/crank/cam changes, fire extinguisher, DOT helmet, and whoever picks up the most trash on the trail (this is in an OHV area of the desert) wins a bottle of whiskey. Not much more rules than that. As with all forms of racing, the rules define the lines not to cross, and the racers walk as close to that line as they can get away with. We are all friends, so I don't think we'll have any cheats.
 

sgkent

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  • / How far can I push/modify a 12hp on stock internals?
good job. I smiled because there were a couple formula races we were involved in where the rule book was quite clear that you can't weld metal onto an intake manifold to improve the flow - bu it said nothing about using non-metallic epoxy.
 
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  • / How far can I push/modify a 12hp on stock internals?
I honestly have no clue what RPM these things spin at. I'm not getting inside the motor at all at this point, and I don't plan on yanking the gov override often, maybe to help with a pass here or there. What kind of RPM do you think these guys run at governed, and do you know how much higher they may go when the gov is overrode? I really don't want to blow her up. This winter I might be able to get inside and see what I can do to up my redline safely, but for today the goal is to finish the race. Can't win if you don't survive to the finish, and this course will certainly eat a few mowers.

I should also mention that this mower is unlikely to ever join sanctioned races. These are informal races put together by friends, so the rule book is only a dozen lines long. No pulley changes, until we have a modified class no piston/crank/cam changes, fire extinguisher, DOT helmet, and whoever picks up the most trash on the trail (this is in an OHV area of the desert) wins a bottle of whiskey. Not much more rules than that. As with all forms of racing, the rules define the lines not to cross, and the racers walk as close to that line as they can get away with. We are all friends, so I don't think we'll have any cheats.

I had to leave before I could reply earlier... I had to go do my regular Thursday evening radio show On KBON 101.1 FM...

Get a tach and see what you are turning....... Those are usually turning at 3400 to 3600...... Bert did say anything over 4000 for a long period the counter balance will come out of place.........

Plus Tard Mon Ami ~!~!
 
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