[aaronw]

I have a rectangular headlight 6x4 gas gator, it seems to be running good but when riding it about a mile when I stop and look inside the exhaust pipe the muffler is glowing red inside and it's spitting flames out the tailpipe. I'm thinking it's running slightly lean, how would I richen the mixture on the high speed side? I have been told that the little brass plug on top the carb is an adjustment but I've turned that 1/2 turn with no difference and isn't that a fixed jet?
Thanks in advance

 

[200mph]

Curious what you spark plugs look like.

Not familiar with the carb to offer advice.

Can you post a photo of the carb and brass plug?

 

[aaronw]

I'll get a picture of the carb and plugs the ceramic on the plug is white and the outer part is black.

 

[Cheapsnake]

Usually a super hot exhaust is an indication of a severely retarded engine. However, since these engines offer no means of adjusting timing this doesn't seem to be your case. Another cause I've heard of is old gas.
As for the carb, the mixture adjustment screw is factory limited and, as you've already learned, has little effect on the engine's performance. Speaking of performance, how does the engine run, aside from the obvious?
A couple suggestions: First, check the valve lash, especially on the exhaust side. If memory serves me, I believe it should be .010" on a cold engine. If the exhaust valve lash is too tight or non-existent the valve may never close completely and allow hot gases to escape and eventually warp the heads. Second, drop the bowl on the carb and take the main jet out and inspect for any blockage that could result in a lean mixture. Good luck and keep us posted.

 

[aaronw]

Besides the glowing exhaust the engine seems to run good. I drained the fuel tank and sucked a bunch of water out before I made the inital post, adjusted the valves and put a new air filter in. Occasionally after driving it at full throttle for a while it will bog down and will need full choke to stay running with it floored yet and the engine wont rev above idle hardly. Shut it off for a couple minuets and it runs fine again. I would pull the main jet out but someone has been there before me and stripped the screwdriver slot out on the jet. The needle was leaking a while back put I put an ebay carb on it but ended up going back to the original with new gaskets and needle because it didn't seem to run much better but I didn't check for a glowing exhaust then.

 

[Cheapsnake]

Hmmmm, bogging down and not revving above idle, starts and runs fine after sitting. Off hand sounds like an overheating condition where the engine is bordering on seizing. But you should have gotten an overheat idiot light if that was the case unless it was disabled or somehow defective. If you have access to a laser thermometer check the head temp next time you have a bogging down incident.

 

[aaronw]

I have a laser thermometer I will take it with me on a ride and see what the head temp is. The overheating light bulb is good but I don't know about the temperature sensor.

 

[Cheapsnake]

My mistake, no sense in risking a seized engine in order to confirm an overheat condition. Rather, I would run it for a couple minutes and keep checking the return radiator hose for any indication that coolant is actually circulating. These things are notorious for overheating if an air pocket is introduced in the engine. If that should be the case, it's a simple matter of "burping" the air out and topping off the radiator.

 

[aaronw]

Okay, do you think theres a possibility of a restricted fuel line causing this since it would use more fuel at full throttle and can't supply enough because of a restriction.

 

[aaronw]

I took it for a drive and the radiator hose going into the thermostat housing is warmer than the one going into the waterpump. I topped off the radiator but it took less than 1/4 cup before it was running over.

 

[Cheapsnake]

OK, so it sounds like you've got a working cooling system. Doubtful a restricted fuel line would cause an overly lean condition, more likely it would just quit sporadically. I'm going back to the bogging condition and the possibility of a borderline seizing. Pull the dipstick and check for anything that doesn't look or smell right. Open the oil filler cap and check for signs of oil. I've never heard of an oil pump going bad in these things, but there's always a first time.
One last thought...are you using E85 or other low octane fuel?

 

[aaronw]

I am using regular 87 ethanol free gas. I doubt the oil pump is going bad, when I adjusted the valves there was oil in the valve covers but I'll give it a check.

 

[aaronw]

I checked under the oil fill cap when it was running and an oil mist was coming out but I didn't see a steady flow over the valves. The oil is 5 hours away from needing changed so besides being dark it looks and smells normal. I found another thread that talked about the coolant system bleeder screw on the intake manifold, I removed that and as soon as I hit the starter antifreeze came shooting out so there must not be an airlock in the cooling system.

 

[Cheapsnake]

When you set valve lash did you confirm cyl #1 was on the compression stroke?

 

[aaronw]

I pulled the spark plugs out of both cylinders and did made sure each was at TDC on the compression stroke. I did one cylinder and turned the engine until the other cylinder was at TDC with both valves closed and adjusted that cylinder.

 

[Cheapsnake]

I'm tapped out, but still curious as to the source of the problem. Keep us posted.

 

[aaronw]

Okay, I'm in the same boat kinda been putting up with it. I wonder if it's flat worn out it has 2100 hours on it and smokes kinda blue when idling like its burning some oil.

 

[Cheapsnake]

2100 hours is not a big deal on these engines, assuming it's had good maintenance. Check compression, it should be 170psi.

 

[aaronw]

I'll have to check the compression, I have no idea what kind of maintenance it's had the oil and antifreeze were both clean when I got it but it doesn't take much to change them once.

 

[200mph]

Curious why the new carb was replaced with the original when the original was known to have a suspect jet.

I’d spend the time to do a thorough rebuild scrutinizing every passage to ensure they are clean and functional. Once fuel system can be ruled out perhaps recheck the valve settings to be certain they have proper lash.

Compression and leak down test will confirm power cylinder integrity.

Also verify no vacuum leaks exist.

Old school testing with a vacuum gauge can be valuable along with using a timing light to verify timing stability and if the spark is being triggered consistently. (Assuming they can be performed in this application)