K321 Trouble
 

I have a model 149 with the K321A engine.

The engine was running fine, then suddenly started giving me problems. It is runs pretty smooth at low idle, but when I give it throttle it bogs down. It keeps running, but will not reach max RPM.

My air filter was pretty dirty, so I replaced it. No luck. I reset the carb, following the instructions in the manual. No luck.

My points are fairly new; installed about a year and a half ago. I took off the cover, and they still look like new.

Any ideas what the problem might be?

Going to have to do a little more testing.

Could be:
Plugged; carb, fuel line, tank fitting, filter
Stuck valve
Bad condenser
Bad coil
Blown head gasket
Plugged exhaust


I'd start by taking the carb bowl off and seeing if it has dirt/crap in it. More than likely a fuel problem. If there is no gas in the bowl, work your way back to the tank. If it is full, and everything looks good. Go to checking the ignition.

K321
 

I'm starting to think it's a stuck valve. How do I go about fixing this problem?

What makes you think it's a stuck valve?

K321
 

I fixed it! It was a valve issue, but not a stuck valve. I removed the head, carb, and valve cover. Turning the engine, I could see the valves moving freely. However, I gave each of them a few squirts of PB Blaster down into the valve guides for good measure.

Next I checked the valve tappet clearances with the piston at TDC on the compression stroke. For some reason, the exhaust valve was out of spec. The gap was too small. I reset it to .018; the intake valve was okay at .009.

I put it all back together and she fired up and ran strong. I let it run for 20 minutes at low idle. I will re-torque the head bolts in the morning.

I believe it is repaired. Any other advice?

Well..... if it was a valve it will probably do it again. You need to pull the valves all the way out and clean them and the guides. Did you install a new head gasket?

I don't mean to ask silly questions, but you did make sure that the engine was in the correct spot to set the valves correct? If it was on TDC of the compression stroke, you were probably still sitting on the compression release.

The book says, "Position the crank shaft so piston is at the top of the compression stroke (cam has no effect on tappets)."

Yes, I know that....

What the book means by "cam has no effect on valve tappets" is that they want you to position the engine in a position where the cam has no effect on tappets. TDC would seem to be safe, but you really need to go past that just a little. It's a common mistake. If it starts easy, it's probably ok, but you can get the gap too far, and the compression release won't work right.

You didn't answer the other question. Did you install a new head gasket?
My other answer still holds true. If it was a valve, your going to have to take it apart again and clean it good. You might get lucky, but I doubt it.

Yes on the new head gasket question. I keep a few on hand for situations like this. I also flattened the head; following the technical advice posted here by Matt G.

Regarding the valves: Everything seems to be working correctly. Remember, I had the head off when I set the valves. I could see both valves closed.

The reason I suspected a valve issue is that pretty much everything else is new or recently repaired. New Carb, new points and condenser, new plug and wire, coil tested good, new air filter, etc.

The only thing I never addressed was the valves. The book says to check the valve tappet gaps every 500 hours. This would be about once every ten years for me. The engine is 42 years old with a standard bore piston in there. I have no idea how many hours it has on it. I bought it five years ago.

I will double check everything today (off for election day). I noticed last night that I put the valve cover on upside down :bash2:, so I might have to take it all apart again anyway.

Thanks for your input and advice!!!!