Coolster MOUNTOPZ 3050C
 

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?

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.

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

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.

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.

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.

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.

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?

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.

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?

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

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?

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?

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.

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

dont know if it will help or not but ive seen some unscrew the spark plug cap and cut a 1/4" off the wire for a fresh connection.

Triprop, the entire harness and all components are new. I don't have spark coming out of the CDI at this point. Going to check from the stator later today and also check the rectifier plug as I've read that they can pull loose and break the ground that the CDI requires. May need to reroute my harness to put less stress on some connections.

The easiest way to check for spark from the stator is to:
1. Turn the key OFF
2. Unplug the stator plug from the harness
3. Remove the spark plug
4. Attach the test light clip to the black/red wire connector coming out of the engine
5. "jump" the big starter solenoid terminals with a screwdriver to turn the engine over briefly. Hold the test light probe to an engine bolt at the same time. If the test light lights up, the source coil of the stator is working fine.

Well, today was frustrating. I have been following some other threads about this type of problem and it was suggested that I may have a kill switch/safety switch issue. I checked the Kill Switch pin from the harness side, and sure enough, it's grounded. But I don't have any safety switches. I shorted the only one (front brake) so it's always there. The only other one is the kill switch on the handlebar (new, by the way). I also checked voltage coming in to the CDI from the stator and it reads a measly 12 volts!

How did I go from running good to not sparking on the next run? I'm going to do a detailed check of the stator as per dirtbkr188's suggustion sometime tomorrow.

There should be a safety switch at the rear brake also. It's tied into the brake light. I had trouble starting my smaller 125cc Taotao and found that it was a pinched wire at the rear brake light switch.

I'll look at that also today.

So, reconnected everything, and the start button does not do anything. I hate that the wiring harness and the throttle controls don't match up in wire color, but they worked before! But I didn't need that for the test I was doing. Connect everything, test light tested and put on stator red/black wire, short out the solenoid: engine turns over, no light. I'm going to order another harness kit and change the stator.

So, using info from here I hit it again today. Discovered that because of the mismatched wire colors, I did not connect the start button! I decided to make a drawing of the left hand controls and map it all out. Once that was done I rechecked the stator voltage and was getting 50VAC. Put a plug into the boot and good strong spark. Installed plug and she fired right up! I have an entire new harness on it's way and it's now working! May need another ATV to install it on.

Anyway, putting harness back in and ran out of zip ties. Will try to finish it tomorrow.

Update: wiring harness is in and it runs. Smokes like heck, but it runs. Now to get some lights working. I think I got the brake light figured out, but the head light is killing me. The headlight has four wires, and the harness has two three wire plugs. I searched Amazon, and don't see any three wire headlights. Suggestions?

The headlight usually uses a white, blue and green wire. White being low beam (I think) blue being high beam (I think) and green for ground.

Yeah, those wires are there, but the headlight has a four pin plug and the new harness has two three pin plugs. I've ordered a new bulb for the headlight as the second filiment doesn't work, then it will be time to redo the plug I think. The plug also has two wires that go off to a small side bulb. It runs off a brown and a green wire that comes out of the same plug. I'm also stopping by Autozone to see if they have the three pin plugs. If not, I'll probably switch it over to barrel connectors and call it a day.

Got the brake lights working with brakes applied, but they don't come on any other time like I think they should. Got my headlight bulbs in and broke the ground connection. Will continue tomorrow. I want to get the lights working if I can, but not gonna keep messing around with it much more.

How many wires coming out of the taillight? One should be power for the brake lights (only when applied), one for a taillight (if there is a dual filament bulb), and a ground wire for both.
If you stop and think about it, the brake lights on your car only come on when you use the brakes, right? The taillights are separate units from the brake lights nowadays, but some motorcycles and trailers still use 1157 dual filament bulbs.

Three wires in the tail light itself. One is Green (GRND) one is a bright all light up (with power applied) the last one starts a sequence of inside out strobing when power is applied. I've connected the ground wire, got the brake switches on the strobing light, was wanting to use the last light as an "always on" tail light.

I've got some connectors arriving today, so I should be able to finish the head light and then I just need to find an "ignition switch on" power source for the tail light and this phase will be done.

My final challenge is to stop it from smokeing so bad when it runs. I'm thinking piston rings, my buddy thinks valve seals.

Got the head light working, had the brakes working like I wanted them to, turns out the battery I just got for it was already down to 6v and would not charge any higher. Anyway, at least the brake light still comes on when brakes are applied. Put the body back on and I'm going to work on something else for a while before deciding what to do about the smoking.

Thanks to all who helped me through this, especially DIRKBKR188!