Cub engine queston?

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While you have the head off, pull the valve springs, and check the play in your valve guides. Those guides are a wear item, and fairly simple to replace.
 
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Found the problem..........Any last guess?
 
Don't keep us waiting, j! What was it?
 
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Choke stuck.
 
Well...at least it was easy. That should have affected all range of rpm. No fair. Bad clues.::P
 
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It ran at idle fine. It was stuck have open. I HAD the same clues to work with. I will have a milled head and gasket going back on to.
 
A stuck choke has nothing to do with leaking oil. Did you ever get a chance to chase that down?
 
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Best I can tell it was surging hard under a load with possaible a litter to much oil. Motor seems way to tight to have bad rings. New gasket sealer on everything I touch. We shall see in a couple days.
 
What's the best way to clean the piston and vaulve carbon deposits?
 
Ok written on the top of the piston std 205 04 13a this mean anything to anybody?
 
Ok written on the top of the piston std 205 04 13a this mean anything to anybody?
It's a standard size piston, otherwise it would be stamped . 010 , .020, etc , if it had been bored oversize at anytime.... Seafoam sprayed on carbon and left to sit overnight will loosen things up..try not to gouge anything .. soft wire brush.. I was good with a razor blade, hold it very flat and go easy... Watch you don't dig the gasket surface as well.
 
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Thanks best I could find 400 grit and some keroseen.
 
That would make since. Everything was fine when I put it up. Change the oil and problems started. The governor is just pop over and over.
Mabey it was the oil,modern oil is different than the old stuff,mabey it dosn't like some of the additives.
 
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What's the best way to clean the piston and vaulve carbon deposits?
Scrape away what you can, sea foam des work to loosen the stubborn stuff. It's not critical to get it perfectly clean. Only the gasket surface has to be spotless.
Mabey it was the oil,modern oil is different than the old stuff,mabey it dosn't like some of the additives.
I run state of the art synthetic oil in some 50 year old equipment. If its been taken care of to this point, it will not create issues now.


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Brake fluid also can work wonders for loosening stuff up.


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Like your nice paint job?

I don't recall that, but then again, I don't recall spilling it on paint.;lol



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Brake fluid also can work wonders for loosening stuff up.


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Works the best on all that pesky paint they have on cars nowadays. :p


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I missed the part where we moved from K series cast iron Kohlers to cars.;lol


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How about cleaning the valves seats? Any good tips here? There is a carbon build up on that lip.
 
How about cleaning the valves seats? Any good tips here? There is a carbon build up on that lip.

Yikes... tread carefully, there!

If solvent and a rag doesn't work, I guess I'd be trying lapping compounds, testing with the least aggressive first.
 
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Yikes... tread carefully, there!

If solvent and a rag doesn't work, I guess I'd be trying lapping compounds, testing with the least aggressive first.

Applying by hand?
 
u sure do have a lot of "i" stuff jags
 
Applying by hand?


I'd wait for MasterMech answer this, since I'm just a hobbyist, but I'd worry about the actual valve seat being clean, not the area around it. So, if there's crap actually on the valve seat, preventing the valve from sealing, and assuming you don't need to re-cut the seats, I'd be lapping the valve in place. That means applying some lapping compound, and using the little suction cup tool to lap (doesn't take much!). You can clean the flat tops of the valves with a razor blade, and clean the stems the same way (very carefully!), but keep the razor away from the seats.
 
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I'd wait for MasterMech answer this, since I'm just a hobbyist, but I'd worry about the actual valve seat being clean, not the area around it. So, if there's crap actually on the valve seat, preventing the valve from sealing, and assuming you don't need to re-cut the seats, I'd be lapping the valve in place. That means applying some lapping compound, and using the little suction cup tool to lap (doesn't take much!). You can clean the flat tops of the valves with a razor blade, and clean the stems the same way (very carefully!), but keep the razor away from the seats.

Yea I don't want the crap in the block. Theres not much and I had a kerosene rag on it since last nigh. Maybe a piece of cake or its going to be a pain in the butt. Valves have a nice crisp angle on them so there good.
 
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