I have a China Quad the uses the GY6 150cc engine. I got it from someone who left it sitting in a shed for a couple of years. I replaced all the electronics on it, including the battery. I got it running a week ago after I did a valve adjustment on it. When I tried to start it last night, the starter motor had a hard time cranking the engine. It would spin once, stop for a second, then do one rotation, and stop. It does this in that pattern. I took off the spark plug to see if it would help, it did. It spun like it's supposed to do, FAST! I then put the spark plug back in and took off the exhaust, to see if it was clogged. It wouldn't crank that easy, with the same pattern. The only way I could start it was to push the starter button and use the kickstart at the same time. Any help would be greatly appreciated.

Thanks,
-Quad nerd

p.s. could it be the piston, camshaft, or crankshaft that's bad?

Also, when I first ran the engine, I did not run into this problem. The starter motor spun fast, cranked over and started the engine. When I tried to start it last night (about a week of sitting), the hard cranking problem just showed up out of nowhere. That's when I removed the spark plug and it cranks then.

 

charge your battery... does not take much for those little batteries to loose charge after sitting for even a week... i always keep em on maintainers

 

I was able to get the ATV runnings a week ago off of a lawnmower battery. A few days ago, I couldn't even get the starter motor to crank much with a battery charger hooked up to it. This showed out of the blue. Should I just put a higher torque starter motor onto the engine?

Thanks.

 

if you just starting it and letting it idle its not getting enough time to charge the battery. I still think its a battery issue with the battery not being fully charged... You can also pop the starter out and give it a good cleaning.. if you could find a higher torque starter i dont think it would fix the issue... If i do not leave mine on the maintainer it will barley start after a week of sitting

 

Tank you for your reply! I cleaned out the starter motor yesterday, the contacts looked a little rough. I was able to get it going again using just the starter and no kick start, I killed the engine after a few minutes, and tired again. It would barely crank now. I charged the battery until it was fully charged, and tried again, same issue, it barley cranks. Does "over compression" exist?

When the engine is running, it sounds beautiful. There is no rattling, thumping, or knowing sounds of any kind. That's why I don't think somethings bent on the crankshaft. Could a bad piston be my problem maybe?

Thanks,
Quad nerd

 

I'm going to check for carbon buildup in the combustion chamber tomorrow. I've heard that can cause my over compression/ hard to crank problem.

 

It is either a bad starter, bad battery or bad connection between battery and starter, this includes earths. The wires the Chinese use are of barely adequate size and any resistance due to a bad connection makes this worse. You can get a problem with the one way clutch slipping just before it gets to TDC, this can mimic a "lazy starter" but my guess would be wires or starter motor.

 

I would check the valves again... if the valves adjustments slipped at all after you adjusted them, that can cause high compression also...

 

these Chinese quads have a tendency to get bad valves and the guides no longer function properly. I have one currently that had the same issue. Very hard to crank over with spark plug in. On a full charge battery had a very hard time cranking over. Pull the plug and no problem. Tried adjusting valve didn’t help. I ended up pulling the cylinder head off and found it was no good. Guides were worn out and wore out valves. I’ve done a couple cylinder heads on the 110 and 125 cc’s but not a 150. The heads are avail all over just have to get someone to install for you.

 

It's been a while since I posted on this thread, sorry about that. Anyway, about a month ago, I took my top end apart to see if it was carbon buildup in the chamber, there wasn't much but I cleaned it up anyway. As I was putting the rocker arm assembly back on, I over-torqued the bolt and broke the casting. I bought a new one on eBay for $12 and put it on. The engine started up real easy and it's been running great for the past 4 weeks. I don't know what was causing my engine to barley crank, but it got fixed. I think it may have been the rocker arm assembly that needed to be replaced.