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Modding a K&B 40 marine

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Modding a K&B 40 marine

Old 04-14-2006, 10:31 PM
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Default Modding a K&B 40 marine

Any engine guru's tell me what else can be done on a K&B 40 - 75 series model 8011 , marine ( not that marine vs plane engine matters ... LOL )

Gots a tuned pipe ( yes , it did have the carb to exhaust flapper , but has been removed by me ) , using a Perry 60 carb for it .... and not sure if any internal work can be done to increase the R's .... ( BHP is fine )
So ... any of you guru's want to give a few pointers/hints how I can get this thing to do a bit better ?
Old 04-14-2006, 11:06 PM
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Default RE: Modding a K&B 40 marine

For all my RC engines I tear drop the side ports and chamfer the boost port(s). Just remember to keep the schnuerle effect, air/fuel mixture is directed away from the exhaust. I do take away a lot of material off the sleeve and find a huge low end boost as well as some top end torque. I do hear some difference in RPM, but when I throw on a larger prop it seems to keep similar RPM's with a few mph gains on top of that.

I also do some rod work and crank work.

Old 04-15-2006, 01:29 AM
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Default RE: Modding a K&B 40 marine

When I asked that same question about the engine around 15 years ago, I was told to look for the "full circle cranks", as they were the most durable for the 40. I'm not sure if those were stock K&B, or actually made by McCoy for the K&B 40.

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