loss of power

foreverfaster

Premium User
fresh oil change, 16 oz.. running my animal on an open track 3/8 paved oval. rpms at the top end wide open... lost power all of the sudden.. took my foot out of it and drove it off the track .. ya think i twisted it to far? short on fuel? motor was still running at idle when i pulled it in sounded ok, but parked it.. before i tear it open,,, thought i would get some suggest
 
If it shut off at end of straight, I would first check fuel flow.
The animal has a bend in the fuel line right where it goes into the carb. This bend will sometimes restrict flow enough to run out of fuel at the end of the straight. But will pick back up as soon as you let off the fuel and hit it again.
Trash in the fuel, Bad fuel pump, Air leaking into fuel line before pump.
It is doubtful that you just twisted it too far. They will easily go over 8,000 without any damage.
 

flattop1

Dawg 89
High spped wide open without any attending sound .
Your probably ok . With sound not so good .
 

sundog

Member
If it sagged off it could be the rod bearing. I've had them tighten up on track then run fine in the pits. Once on track again it slowed down in one lap. If it was like flipping the off switch probably not the rod.
 

Jimbo

If you talk the talk you should walk the walk
The most dangerous issue as far as engine longevity is concerned is that the rod could be seizing to the crank.
For safety sake (preserving the engine) I would check that first.
What rod r u using? What oil?
Look for material transfer from the rod to the crank or discoloration from excessive friction and heat.
If you run for long periods of time at high rpms or on hi "G" force tracks you should have a breather bypass system.
 
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CarlsonMotorsports

Premium User
fresh oil change, 16 oz.. running my animal on an open track 3/8 paved oval. rpms at the top end wide open... lost power all of the sudden.. took my foot out of it and drove it off the track .. ya think i twisted it to far? short on fuel? motor was still running at idle when i pulled it in sounded ok, but parked it.. before i tear it open,,, thought i would get some suggest
Are you sure you didn't just run the bowl dry, or even have the inlet needle hang open (ie run overly rich)?
 

foreverfaster

Premium User
up date, haven't pulled either motor yet, yes had it happen to two different karts. i pulled one kart out of the trailer today and took it to an open lot (paved) opened it up and no issues.. didn't feel sluggish.. if the busy weeks ahead allow i'll test the other motor.. i'm going to guess i had a fuel starvage issue, but the second motor has a reworked bored out stock appearing carb on it.. it should never run short unless the pumps not keeping up... more to com
 

foreverfaster

Premium User
well, should have pulled it completely apart,.. now that it's parts, i'll HAVE to pull it apart now.
What is the bolt size (thread) that holds the plastic fan to the flywheel. can't seem to find one that fits it. need to pull the fly wheel.
 

flattop1

Dawg 89
I'm just guessing , it was the Rod ?
 

foreverfaster

Premium User
I'm just guessing , it was the Rod ?
Yep, stock assembly lower end.. from the parts, it appears one of the bolts backed out.. looks a lot like one of the other motors i puked. no hot spots on the rod or the crank. Of the rod bolts, one was still intact holding both parts together.. just for fun i took the torque wrench and pinched the remaining parts in the vice and started at 50in# and worked my way up through the clicks.. still had the appropriate torque on it, (far as i could tell) the other one looked like new laying in the bottom of the block. the last couple threads had some alum still embedded in it.. the threaded area for that bolt was no longer recognizable.
 
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