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Old 08-12-2019, 06:13 AM
PaulK PaulK is offline
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Quite a while back, I got a Black Mamba Jr (Predator non-Hemi) as part of a yard kart build with my kids. I'm not terribly mechanical so it's been a long timeline. I finally got the engine running but it seems like when the revs get too high the compression release gets stuck, forcing me to open the engine back up to fix it.

Does anyone have a suggestion as to how to address the problem? Maybe a better choice of cam or some kind of trick?

The engine has a billet connecting rod and flywheel, slightly upgraded piston, I think 22lb valve springs, removed governor, and a Mikuni carb. I tried to emphasize low-end torque over HP.

Thanks,
-Paul
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Old 08-13-2019, 10:12 PM
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I have two identical engines with that camshaft and have not encountered any such problem... I do know the BMjr cam recommends 26lb springs. Isky cams are of high quality and I would call or right Tim 1st to see if he could help. But it almost sounds like there may be a problem at the compression relief if self... Maybe spring is too weak or tight? Maybe it doesn't slid smooth IDK. But good luck.
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Old 08-13-2019, 11:18 PM
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I’ve use the Black Mamba Jr as well. I also used 26lb springs. I have never had any problems with the compression release mechanism. I’ve had a hard time getting hold of Tim. He called me back once. And that was months after trying to get ahold of him.

Did you inspect the compression release mechanism? Does it move smoothly? Does it spring back? Any noticeable stretch or deformation in the spring? Is it clean?
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Old 08-16-2019, 05:10 AM
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Thanks guys. I only get out there every few weeks but I'll pull it and take a look next time.
(love your tag line Bob)
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Old 08-28-2019, 08:19 AM
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Posted another thread with more of the story, but figured I'd get back to you guys about the cam.

I put it back together and the problem has not reoccurred yet.

I would guess that by applying a load it's keeping the RPMs down to where it's not getting stuck.
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