150 carbide don't start
 

Just signed up and wan't to say this is a great site. The information is very helpful.

Ok, my problem is with my sons 150 carbide. a few weeks ago he was riding it and ran out of gas. I put gas in it and it wouldn't start. kept on trying until the batt was dead. when i finally got a chance to look at it i can't find anything. I checked to make sure it was getting gas, it was. i checked spark nice blue spark. tried a small shot of ether, didn't help. cleaned the carb twice. so if i crank the motor for sometimes as long as minute and fiddle just right with the throttle it will start. when it's running it revs fine and sounds good no popping or anything and has normal power. but it will not idle down low and if you try to start it back up it's the same as when it's cold lots of cranking and fiddling with the throttle. I say a minute of cranking but sometimes you just can't get it at all. i've checked all the wiring, valve lash, new plug, fuel pump/petcock. and finally just put a new carb on with no change. I did a compression check and came up with 75 lbs. I'm thinking this is not enough and that possibly the lean condition when it ran out of gas may have hurt something. Also the breather hose off the valve cover really huffs alot of smoke during the cranking but when it starts it seems to stop.

What should compression be?
Can you do a leakdown on these engines? procedure?

Any other ideas?

I believe i bought this in fall of 2008, my son does run it pretty hard but from what i'm reading on here nothing abusive he's 12. And if there is any credibility to the speedos on these things it only has like 203 miles.

Thanks in advance for any ideas or help and again for the great site.

sounds like you need rings
mine produces 160+ compression
with only 203 ish miles are you sure you set
the valves correctly

forgot to say welcome to the group

valves
 

didn't reset valves just checked them and they were pretty much dead on. I think I was using .005 on both.

Rings...thanks for the bad news

It's an easy fix. I've done with the pistin still on. But it's much easier to remove it

your welcome
remove the passenger seat
will give you more room

tore it down
 

ok so I tore it apart today. wht i found was a crack between the two comp rings and another one between the 2nd comp ring and the oil ring. so now i'm looking for parts. are the parts available on this site? i figure i need piston, rings, and gasket set.

should i do something better than stock at this time?

i have a couple reassembly questions.

do you guys orient the ring gaps a certain way
what line and what pointer on the crank do i use as tdc for chain installation
i'm thinking tdc for cam position lines up two small holes on cam sprocket with the top of the head, is this correct?
torque specs for head/cylinder?

under the phillips screw on the tensioner there is a flat blade screw, i can turn this and collapse the tensioner. is this what you do to assemble and if so must you hold the flat screw until you get it back in?

thanks alot!

Contact Tom at SYCPowersports and see if he has the parts you need. Alternatively, these are a standard GY6 engine and any local parts providor for even a scooter shop should have what you are looking for.

For the rings, I typically stagger them making sure none of them are lined up with a ring right next to them.

You are correct in your thinking on the cam lineup. Seems to me I did a vid on cam replacement or something but at any rate, that is correct.

What I do for the cam tensioner is have my sone turn it in to relieve the tension while I put the chain on then let it snap in place.

crank position
 

does anyone have a close up picture of the mark and pointer for tdc on the flywheel. i have read to use the t line but what do you line it up with? there is a casting part that sticks out at about 10 oclock, is this the pointer? a picture would be great. thanks

I dont use the marks. They have been known to be off. I use a screw driver in the plug hole. Bring the piston up to the top. Make sure your valves are loose.

The rings, I stager them like this... One oil ring on the left side of the relief, the other on the other side, the squigly oil rin I place in the center of he other relief,Top ring to the right side of the piston and the finale to the other side. It will make a 5 point star.

I would replace the jug as well and make sure to check end ring gap

I actually manually put it to TDC as well. You'll find that that is easier than it sounds.

I have attached a pic of the cam in the correct position.

thanks for the info. i'm pretty sure i understand the cam positioning. i also understand using a screw driver through the plug hole. what i'm a little worried about is with the small throw of the crank and the fine tooth gears, is getting that crankshaft in the right position first. with it apart right now i was holding the connecting rod and trying to find tdc and it seems i can turn the crank a few degrees without the rod moving. i know it's not much but i just want to be sure i have the crank in tdc before hooking up the chain. maybe i'm just over thinking this, but it seems like it would be pretty easy to get this a tooth or 2 off.

still need to order parts

Thanks guys

Never had a problem and I've done 3 motors. Raise it up with the screw driver and rock it back and forth. It should be easy enough to tell. If you turn the crank the rod should move

chuck is right i have done many motors
no problems
just seems hard till your 1st time

new piston,rings and gaskets installed. runs like a champ! kids says he thinks its stronger than ever. I really thank all of you for your help.

we told you it was easy
glad it went your way

And your the kids hero