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Discussion Starter · #1 ·
Here ya go fastkid:

This is a 392cc cub we just built. Specs are:

68mm bore

54mm stroke

110mm rod

ex 196

tr 130

custom domes(don't ask I won't tell)

16-1 compression

"drag port"

V-2 reeds

upp intakes

41mm kehins

stock ignition +10

This engine still has stock basket and stock primarys

and SHEARER small bore INFRAMES

can't wait to see how fast it is at Dumont

JL392 CUB.jpg

forgot to mention its on alcohol also

And I guess I need to make clear that this engine was ported and built by me.
 

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Wow, a 15 HP increase just from cubs. For comparison sake this is the same dyno right? Awesome build! Should have no problems getting near the 80mph mark up Dumont, or surpass it even. Still testing things, or did you guys max out with this run?
 

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Discussion Starter · #5 ·
Wow, a 15 HP increase just from cubs. For comparison sake this is the same dyno right? Awesome build! Should have no problems getting near the 80mph mark up Dumont, or surpass it even. Still testing things, or did you guys max out with this run?
Same dyno but remember the cub is 68mm bore. I'm finished for now
 

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Sounds good, ill be checking back for the results. If you can, try and get some good video like your other 350, good resolution and radar in the cam was awesome. Maybe some 392 vs 611 vids too
 

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Another awesome job Matt! Kudos! You obviously have something figured out with these motors.



What do you think the curve and output would be with shelf domes?



Are your ports really wide to increase flow? I am just wondering about ring and piston life.
 

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Discussion Starter · #11 ·
Another awesome job Matt! Kudos! You obviously have something figured out with these motors.



What do you think the curve and output would be with shelf domes?



Are your ports really wide to increase flow? I am just wondering about ring and piston life.
Thanks

ex is at 67% it will run al season.
 

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Had you went with hand coned out of frames and built the motor for those, what would you predict for a power increase?
 

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Discussion Starter · #13 ·
Had you went with hand coned out of frames and built the motor for those, what would you predict for a power increase?
No need for a new pipe. To me the point of sharing all this info is to show what you could or should have out of what we already make. Sadly most cubs (421-465) wont break 100hp on my dyno thats why I post this info so people can see what they should be looking for.
 

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Yeah that makes sense. So, say you had all the same parts as this build (inframes), could you tweak anything in the motor to make more power then this bike with just changing to your out of frames?
 

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That's a killer set up, the front side power, peak and most important the over rev power is outstanding

I noticed 79 dyno runs from the chart info, and some people think dyno time means nothing..... I hope they keep thinking that
 

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Discussion Starter · #16 ·
Yeah that makes sense. So, say you had all the same parts as this build (inframes), could you tweak anything in the motor to make more power then this bike with just changing to your out of frames?
yes this engine with our drags a different dome and a different shape ex would pick up 4-5 hp. This engine was built for inframes
 
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