99cc Preditor Rod Knock?

GoldenMotor.com

Big Bill

New Member
Jun 3, 2011
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arizona
Hi Guys

I am new to the form and I will be starting a build when I pick up a frame.

I just picked up a new 99cc Pred. motor. I put oil and gas in it , mounted it to a bench and started it, it sounds like it has a rod knock to me, is this normal for these motors? I do have other brigs motors that donot sound like this.

Thanks for the help Bill
 

wayne z

Active Member
Dec 5, 2010
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Are you sure it isn't the valve train? My first Preddy sounded liks a threshing machine. The valves were set way too loose. I adjusted them, and all's normal now.
My second Preddy was very quiet right out the box.
 

Big Bill

New Member
Jun 3, 2011
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arizona
It did not sound like loose vales, it had a knocking sound ( rod knock)
but I will check the valve train in the morning.If that does not work I will
pick up anouther engine. Then I will start on the frame and a build thead.

I will let you know how it turns out.


Thanks Bill
 

rustycase

Gutter Rider
May 26, 2011
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Left coast
Well if it sounds like a rod knock, it very well could be!
Pay close attention and be ready to shut r down, if you don't want to tear it down for inspection.
Good luck with that,
rc
 

azbill

Active Member
May 18, 2008
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Fountain Hills, Arizona
what should the valves be adjusted to ???
I have been pretty sick and haven't even mounted my new engine yet :(
hopefully she will be on the road soon (I miss riding)
 

The_Aleman

Active Member
Jul 31, 2008
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el People's Republik de Kalifornistan
That's a good question Bill, it's not in the HF 99CC manual. I've read quite a few Honda manuals for similar engines and can offer a guess:

My reckoning, you can set the intake at .004-.006 and the exhaust at .005-.007 and it should be fine.
You can set them a little looser than that too, but no more than .010 on exhaust, IMO.
Check em cold, they might be way out of those specs. Probably loose.
 

wayne z

Active Member
Dec 5, 2010
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Setting the exhaust valve is just a little tricky. The built in compression release is activated when the engine is not running. When yoy rotate the engine with the valve cover off, you will notice that you can feel the "bump" or suddenly tighter spot in the valve lash.
Make sure and adjust the lash at a place where this "bump" is not interfering.

My first preddy had the lash adjusted from the factory, over this bump and it caused very excessive lash and clattering rockers.
 

Skarrd

Member
Oct 13, 2010
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currently i have both the intake and exhaust set to .004"

curious though if some of the parts from the gxh160 will fit out preds, since agk sells better rocker arms for it.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
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Ridin' inSane Diego, CA.
I seriously doubt that the rod is knocking on a brand new engine. In order for it to be knocking, the bolts holding the rod cap on would have to be less than finger tight. I'd be looking at the valve train and checking (adjusting) the valve lash as others have suggested.

I also seriously doubt any parts from a Honda GX160 would interchange on this engine.
 

Big Bill

New Member
Jun 3, 2011
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arizona
Much better now after setting the valves at .006 I may go alittle tighter
later. I will be stripping the motor down after it cools down today to see if my frame can be modified to work if not I will start looking for new frame.
Thanks for the help Bill

PS I will start a build thead soon.
 

wayne z

Active Member
Dec 5, 2010
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louisiana
Take an oil sample while the oil is hot and freshly agitated.

Drain it into a glass container and look at it in good daylight.

It will be normal to see fine aluminum particles in the oil of a fresh engine at first. If you see many larger flakes, you could have a knocking rod

Change your oil every couple hours at first. You will be suprised how much aluminum that you will see first few time you drain it.