Rebuilt Engine won't Run at Low RPM

[Redneck_Hippie]

I've been reading and lurking on this great site for the past 6 months and now I need some help.

We move to Texas hill country and brought with us a worn out Yamaha G14. When we got here the cart would only climb the shallowest hills in our neighborhood. Thanks to all of your recommendations we got a kit from Plowmans carts. What a great company!! Great knowledge and awesome customer service. That solved the hill problem but it smoked and stunk.

I rebuilt the engine. Block bored over .25 and valve job done by a machine shop. The engine now won't idle or run any slower than about 2500 RPM without dying. It will also backfire through the carb.

I've run a gravity feed fuel line to make sure it wasn't a fuel issue.

I've checked and rechecked the valves (.004)

I've cleaned the carb

The engine runs the same with or without the airbox hooked up

[Redneck_Hippie]

Heres some of my concerns:

The tappets seemed sticky when I installed them. Do they have a plastic bushing?

Is that what this part is?



There was another part that ended up on the work bench. Don't know if it was part of the engine or part of a puller tool.

cart4.jpg

[85.G3]

I would first verify your fuel mixture in the problem RPM range. I would check for air leaks between the carb and engine, you can use a smoke stick to check. If no leaks maybe try a pilot jet change to see if that helps, see what sizes are stock and make notes of where you started and all changes. Will it run at lower RPM with choke on or off, if on you may need to go richer, if off you may need to go leaner. You could also put in a new spark plug and run it for a while at the lowest RPM possible then check the plug color, white would indicate a lean condition and dark would be rich. A very hot exhaust pipe wqould also indicate a lean conditionOptimum would be tan. Good luck

[smallblock450sl]

Can't open up the pictures to enlarge. Yamaha lifters are one peice. Almost looks like a Club Car "flat head" tappets. Last picture looks like the centering end for a puller.

[Redneck_Hippie]

Thanks so much.

I thought the chrome part also looked like part of a puller tool. I used a couple of pullers and didn't use that particular piece. When I cleaned up the tools and work bench it just looked so out of place. One puller is black and the other was just the long bolt clutch tool. No chrome so it became a mystery.

The little melted plastic parts showed up on the workbench by magic or someone broke into the garage and put them on the work bench.

The carb had been rejetted with the Plowman kit. I just went throught the carb again after the engine rebuild just because it was off and I thought I'd just double clean it. I rechecked the carb again after it would not idle.

The choke only has an all or nothing effect. It will either choke it out or has no effect.

Could the counterbalance or cam shaft be off a tooth causing the problem?