gy6 timing help

[Larry33]

As some of you know, I have been working on this yerfdog cuv for about 2months now and still have the same problem. This is the 3rd carb and electric choke. I don't believe it is the carb as much as it is the timing.
TDC and the cam lined up but still bogs at 1/4 pedel.

It is either carb jets, or timing. I am using it in the TN mountains at 1600' high.

What advances the spark on these things? I have tried moving the chain a couple teeth forward on the cam and will not start easy. Put it back to normal and it starts and idles.

Has all new piston, rings, gaskets, 6 pole stater, regulator, coil,manifold
and new ebay 29.00 carb with electric choke. I bought a resistor for the choke and seems to work like it should.

1. Could the jets be the wrong size. It is running rich as it always did.

2. Could the chain be moved back a tooth or 2 and what would that do?

3. I have no air filter on it yet since I am still working on trying to get it running and have to take the carb on and off all the time.
I took the old big black air filter unit off and am going to use more of a uni type filter on it.

4. Would a timing lite be of any help and how do you hook it up to test?

Thanks again

[chuckorlando]

Raise the pistone all the way up, set the cam with the big hole pointing in the same direction. A tooth can cause many issues. As can wrong valve lash, electric issues and many other things. Are you sure the chain aint tretched? Had tha happen. Hell to find out the issue. Changing everything over and over again

[Johnny 5]

I had the same problem and it was the intake manifold had a air leak. replaced the intake manifold and problem gone.
I had to hit the gas pedal full throttle or it would sputter and die.
When I found the problem I was moving the carb and noticed the idle would go up and down. Hope this will help you.

[Larry33]

No it is not the intake manifold. This is the 3rd new one on there. I even sprayed the wd40 test all around it and no leaks. I took the original carb apart and the main jet on it seems to be a wider hole than the new carbs I have been trying

** Is bogging above 1/2 peddle caused by to rich or to lean????****

I tried to see the numbers on the old jet and can not make them out. I wonder if it is a fuel issue of not getting enough fuel? It idles and revs to 1/4-1/2 peddle and just bogs.

All the hoses, clamps and gaskets have been replaced

[chuckorlando]

a bog is usually rich while a hollow miss is usually lean. Your main jet dont kick in till 3/4 so it's gonna be in the pilot jet or needle jet circuit

[Johnny 5]

I would try the jet for sure. The jet on our stock dune 150 was a 114, and we were using a 120 with the uni filter 58.5 srp piston and the the stock muffler with a larger 3/4 inch inside diameter tail pipe.
When we replaced the engine back in 2009 the motor came complete with a carb and the main jet was a 103. I think that is okay for a scooter, and I did not use it I used the 114 main before I modifyed the engine.
I also tried to run my red buggie without the air filter when I was trying to fix the off idle bog that was a air leak on the intake manifold. The motor would not run properly without the intake tube that I made out of a radiator hose and 1.5 inch sink drain pipe.
I also found out the length of the tube between the carb and uni filter was best at 5 inches for my application.
I also remeber my red dune 150 that we bought used for $400.00 that had the intake leak took me two weeks to get running and our first trip to the desert it ran like junk.
I had to really use the pedal to keep it running, tried float adjustment, swapped out coils and the carb off the blue dune 150 that ran perfect.
I could not find the problem. I removed the cylinder head to port the head and found the intake valve was bent and the exhaust valve had a nick in it. I took the valve out of another head and used lapping compound on the seats and it ran awesome.
I hope this helps and I know how dissapointing it can get when you have tried almost everything. The bent intake valve was blowing back to the carb causing my full throttle power loss. I remeber it ran at light throttle but at full it sputtered so I would back off the gas a bit to keep it running. The bent valves was not visable, I found the problem when I was lapping the valves and it would spin out of round.

Johnny 5

[xlint89]

Have you tried another coil?

When mine was bad (nearly new A/M from Ebay), it would run fine until WOT, then it would cut out. Swapped it out for the stock coil, and it took off again.

Often electrical issues seems like carb problems.

[roysheepdog]

I had one that ran fine up to half throttle then bogged.On mine it was the choke.this is what I did to fix it.
http://buggymasters.com/forum/showthread.php?t=3061

[chuckorlando]

First thing you need to address is what kinda issue do you have. Like I said, and repsponces show, many things can cause this issue. Start tha machine and have someone shoot a bit of carb cleaner in it when it's bogging. If it revs out you have to much air or to little fuel. If it gets worse you have to much fuel all together or a possible lack of proper spark. You can also check the electrics with a meter make sure they are working

[Larry33]

Thanks for all the responses.

I think I have found the issue. It has to be the carb. It finally starts better. I think it is the new Chinese carbs I have been using. The original was a mikuni with manual choke. I broke the choke cable and decided to convert to a primer on it but did not do the trick. Bought a 26mm and then a 24mm with elec. choke/enricher and still have same issue. Runs real rich....black wet pug.

I looked at the Pilot Jet in the original carb, and it was 0.22 and the new ones are 0.35 so I think that is why I am running rich and bogging at 1/2 peddle. Now I am trying to find someone who sells smaller jets for this ebay carb.

There is no adjustment for the pilot jet. I drilled out the plug and there is only about 3 tiny holes under the plug and no adjustment screw.

The only thing I have not changed is the cdi because I can not find one that works on this yerfdog scout cuv. and yes I have a dc cdi and the new one would not start it. Also tried ac cdi and wont start so put the old one back on and it works.

I wonder if a performace coil might help? It only has a 6pole stator on it which is new and a new stock coil.


does anyone else have issues with these ebay carbs??

Thanks


It was alway very hard to start but ran great when it did.

[skiingco]

Mechanic rebuilt carb with carb kit....has spark, turns over with a pop, but just won't start up and run...looking at the rocker arms as it turns over.....would timing cause it to not start?