Coolster MOUNTOPZ 3050C

[porky133]

Bought this as a project, new battery, installed new harness with all the associated parts and it won't keep running after starting. Spray starting fluid and it will run till that burns off. OK, maybe its a carb problem. Ordered a new carb kit, installed. No idea if it's set correctly or not. Starts and runs only with gas or starter fluid applied. It seems the carb isn't feeding gas through to the engine. Float bowl is full, but how do I check any further?

[JerryHawk250]

Even with a new carb you will have to do some adjustment. You may need to do a valve adjustment. Valves may not be fully closed causing low compression. DO a compression check and/or valve adjustment before driving yourself nuts trying to tune the carb.

[J4Fun]

And another thing, make sure you have fresh gas and it’s flowing to the carb!

[porky133]

Don't know any values for the valves. Can't find a maintence manual. Not sure what to look at. Fuel is fresh (was empty when I got it) and bowl does fill up.

[porky133]

After the above suggestions I found a Haynes Manual that covers Honda 110cc engines. The theory is that the Chinese models copied the Honda models close enough for me to get the specs from the book (for valves). I also think I need to adjust the mixture screw, it is only out 1 1/2 turns. And I need to check for vacuum leaks on the carb itself and where it attaches to the engine. Will update as I make progress.

[dirtbkr188]

You have a 110cc engine that is a clone of the Honda 50 engine, the valves should be set at .003" for the intake and .004" for the exhaust.


Post up a few pics of the carb so we can see what you're working with, and be able to determine whether you have an air or fuel screw for fine tuning the carb.

[porky133]

Got it running. Based on the suggestions, I found a port on the carb that was open to air. Checked the old one and it had a brass plug in this hole. So I put a vacuum cap on. Now starts and runs only on choke. More searching, found that we had over enriched it. Changed mixture setting and now it starts and idles like it should. A bit rough after the air filter was installed but I think we are good to go now. Just some fine tuning.

Thanks for the suggestions.

[porky133]

So a bit more to this story: It idles fine, but dies when any throttle is applied. Searched around and found that it is not getting enough fuel. So, opened the mixture screw a quarter turn, start it up, let it warm up a bit and she goes! Yay! but doesn't stop. Back on the lift, no brake fluid at all in the rear disc system. Go to town to get DOT 4 fluid, come back, flush the sytem and finally get the calipers to close and seems brakes are working, another yay! Try to start it and it turns over but won't start.

It appears there is no spark. What/how to troubleshoot this?

[Thumper]

Originally Posted by dirtbkr188

You have a 110cc engine that is a clone of the Honda 50 engine, the valves should be set at .003" for the intake and .004" for the exhaust.
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...

These clearance values work for cg clone 167FMM pushrod engines too.

On the potential carb jetting/setting issue, If enrichment circuit is working (choke) and it starts but won't idle, does it last longer choked, or unchoked???

I ask this because you need to get a baseline on rich/lean behavior to make jetting choices. If you can solve the pilot circuit issue, then you can move onto airscrew/needle and main jet situation. If you have access to the airscrew on your new carb (should), set the airmix screw to maybe 1 and a half, and start there.

[porky133]

Thumper, the ATV was idling and running good when I went to lunch. Came back from lunch, bled the rear brake and it would not start again. It turns over, just no fire. Plug/spark tester indicates that there is no spark going to the plug. I'm wondering if my coil fried at some point, only two wires go to it but I don't know what they carry. One should be current other one ground?

[dirtbkr188]

Usually, a black/yellow wire is power from the CDI to the ignition coil, the other wire is usually green, and is the ground.

[porky133]

Thanks! I'll check those and see what I get. Question: is the power always on the black/yellow or does it pulse with the spark timing?

[porky133]

Putting a test light in line from the CDI to the coil, I got no power when trying to start. When I first went back today, I had spark at the plug for about 20 seconds, then it quit sparking. Checked the green wire, gound seems good. Put test light on yellow/black from CDI, nothing. Swapped in an old CDI that I had and still nothing.

What next? Stator? Regulator?

[dirtbkr188]

Did you try the test light on the black/red wire coming from the stator into the CDI box? That wire comes for the source coil side of the stator and provides the power to run the bike. If there is power going into the CDI from that wire, I'd suspect the CDI to be bad if there is no power going from the CDI to the ignition coil.

[porky133]

Didn't know which wire to check for that, now I do! I'll do it tomorrow.