1st last week, engine fell on its face this week??????

S

ShaneRedline

New member
Hello guys. Question. We are running a Moon Power flathead engine (11 races on it) and this is our first season. Last week my son got smoked in the first 2 heats as the kart just had no power. A guy came over and asked if I had changed the diaphragm. I said no. We changed it and he lapped up to 3rd place! Sprayed a shot of WD after races while running to be ready for next week.

This week before the races, new plug (indexed correctly) fuel to the seam, new diaphragm (again) clean air filter, and we couldn't get over 4500 RPM, last week 5500 all day long and bad fast.


In the 2nd heat they were pulling away good, then a caution, restart, he was able to start passing like the week before, then it would fall on its face again. It was like a light switch, good then bad. He came in and said "Dad I am wide open and it's bogging and just won't go, then every once in a while, it runs fast like it did last week."

You guys have any ideas what I am doing wrong or need to do?

I pulled the fuel tank off drained it, sprayed card off inside and out with carb cleaner. Put back on and we got rained out. Not sure if that would have made a difference as it all looked cleaned, screens all good.

Thank you for any advice.
 
Is it misfiring or bogging likes fuel related. I'd check the valve lash because its free and maybe swap coils.
 
You may have dirt in the tank clogging the pickup or the pickup is real close to the bottom of the tank. If I remember back, two tank gaskets should be run to keep the pickup a little farther away from the bottom of the tank.

... too old to remember everything but I think there should be some sort of thing in the tank where fuel is last taken from the tank to keep it from sloshing around causing fuel starving or ? in turns.

... I think the long pickup with the screen grabs fuel and dumps it into a small tank in the tank and then the small pickup takes it from there. the thing or what ever is in the small cup part of the tank. You may have dirt in there too sometimes causing fuel to not be picked up by the small pickup. and lots of ???? on if I'm remembering ok.


... clean yer tank and make sure the pickups ain't clogged or kind of clogged. and make sure your using two gaskets... I hope it's legal, I remember it not only being legal... but a must thing to do.
 
I bought a new Turk bros. flathead in 1994. Won first night out, 2nd next time out, then 4th. Someone suggested I lap the valves. I did and won again, started doing it as part of maintenance. Be sure and get lash right after lapping.
 
Ok, tank and screens were clean. I'll ck the fuel cap. I have rebuilt 2 stroke engines before so I feel comfortable doing it. But where do I learn how to lap valves? (read about, Internet link??)
 
u tube.
need a lapping stick and lapping compound . put some on valve install in guide both hands on stick spin like your starting a fire lift a bit now and then spin some more.
clean well. you will see and hear when its right. after clean install spray some wd/40 on top blow in port to check for leakage. clean again, its an abrasive.
 
How many gaskets were between the tank and carb when you first took it apart ? How many did you put back on ? The pick up tube may be touching the bottom of the tank.

Best, WP
 
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