89 3pg low power in forward

[Ranger50]

So I have a 89 marathon that I just rebuilt. Cart had a bad crank seal and cylinder base gasket when I got it. It has new crank bearings and seals fresh bore and piston. Starts but runs rough and low power in forward, switch to reverse runs smooth and has great power. My head is sore from beating it on the side of the cart. Any suggestions of where else to look? I have cleaned the carb and am confident it is good, compression is 145 in both directions and the plug is new. Running 100:1 premix. Thinking there may be an issue with timing, I did not remove the pulsar mounting plate when I tore it down. Is there a mark on the flywheel to check timing and what should it be? Thanks for any help.

[redcloud]

First thought, did you install the piston so the large opening in it are facing the intake?
Second thought, Did you do a jacked up rear end test to watch what happens with the carb when you run it? Governor linkage may be the culprit keeping the throttle from opening properly.
Some have did a rebuild also and found they switched a wire that may be causing a spark issue when switch is in forward. Worth looking at after checking the prior thoughts.

[Ranger50]

Piston orientation is correct, governor and carb linkage look to operate correctly. I have the rear cover off which allows me to see what the carb linkage is doing while operating and it does go full open. What wire are you referring to? I’m 99% sure the wiring is correct but willing to look into that if I have an idea of what circuit. Hope to get back out in the next couple days to check the timing in both directions.

[cdeck714]

My 82 was like that. turned out to be a clogged muffler, even after I had BBQ'ed the muffler. I was out of ideas and took it to a shop. they unhooked the muffler to test it and it ran fine. I don't know how they unclogged it, but it's worked ever since.

[Ranger50]

Worth a look, easy enough to unhook it and try. However airflow through the engine and exhaust should be the same no matter the crank rotation. With that said weirder stuff has happened.

Thanks cdeck

[redcloud]

Seems that if the engine runs in reverse and uses the same pulsar to do it that would not be the prob. Wondering on the reverse/forward switch? Check that all wires and connectors are tight and properly located.
That is what I would do at this point.
You say you just rebuilt. Have you made a check on engine grounds and frame grounds? Have heard that a bad ground was a problem on a couple links in the past. Just a thought.
My guess would be wiring at some point not getting full voltage out to get good forward running.

[racin161]

Ranger answer to your question !!! Yes there is a timing mark on the flywheel. There will be a round pin molded in the plastic fan look for it then on the cover there will be a scribe line at the bottom or close to the bottom side. That's the timing marks. With a timing light you should see 18 deg. + or - 3 deg. forward and 21 deg. + or - 3 deg. in reverse at 1500 rpm BTDC if the timing is correct in forward then the reverse will be correct therefore timing will be only required in the forward.

LOU

[cdeck714]

Mine has higher compression in reverse than forward. about 140 in reverse and 130 forward. Before unclogging the muffler it would go up hill great in Reverse, but it would barely crawl and not rev up going uphill in forward.

[Ranger50]

So I finally got a chance to get back to the cart. Tried disconnecting the muffler, no change. Checked timing in forward the dowel is one window below the mark in reverse it is dead on the timing mark. Set the pulsar to .016, no change. Then adjusted the pulsar mounting ring to max advance, that did change it but very minimal. I have traced every wire and they are all in the correct locations. The pulsar does check out high on resistance. Any suggestions?

[Ranger50]

I got it fixed. The igniter was bad, did the hei conversion and she runs like a champ.