What is the compression for a 70CC chinese motor?

Thanks in advance.

Jay

 

Not sure what the optimum level is, but if it's below 90-95 I'd say it's due for a rebuild.

 

95-130 psig. not a thumb trick. use a gauge. anything below the 95 psig, rebuild is required.

 

Thanks guys. I will get a compression gauge on it this weekend.

Hopefully it's not rebuild time.


Picked up a 72CC Buyang BMX Mini Quad for my son pretty cheap.

The previous owner said it only needed the valves adjusted.

So I ended up tearing it apart, adjusted the valves to .004”, replaced the fuel filter and line, spark plug, cleaned the carb and put some fresh gas in it.
The quad would only stay running if I had the idle turned all the way up. By doing so it would creep forward without my hand on the brake. It also had a horrible bog without feathering the throttle.
After many carb adjustments trying all the all 5 clip positions, turning the air screw anywhere from ½ turn out to 2 ½ turns out.
I ended up buying a new carb online.
Now after putting the new carb it idles great but still has a bad bog when hitting the throttle or putting a load on the motor. It won’t go up any sort of incline without stalling out.
I noticed the new carb air screw setting is ½ turn out. If I turn it out any farther it will stall on the stand. Seems the bog gets worse as the motor gets warmed.
I’m starting to pull my hair out with this little thing.
Any advice would be much appreciated.

 

I thought the valve clearnece was .002 on them motors also check your timming

 

Also if it is rebuild time just go online and buy a brand new cylinder and piston they are wry cheap

 

Stapleton 1184 I read on here the clearance is .004

I set them it at .004. If infact the valves need to be set at .002 could this be my Bog and lack of power issue? Seems like my issue is fuel related.

How would I check my timing?

So for all the questions but you kind enough to answer my post.

Thanks Jay

 

I wanna say your within spec let me look up the timing there is a video in you tube I pulled these clearance #s from a trx90 pretty much the same engine