help, scooter acting up By seanstr (Read 3,410 times)

[sprocket]

Take the carb apart and clean it completely, run wires through the main jet, check you fuel flow, petcock etc...

[seanstr]

I did, it didn't help, no petcock. , new fuel lines, & vac hoses. I have new carb coming

[sprocket]

Do you have a fuel pump? It could be the problem if the fuel tank is below the carb.

If you have a gravity feed system you want to have a manual shut-off so your tank doesn't drain. That is what the petcock is for.

[seanstr]

Just gravity, I have an electric cut off, it all works, but still no starting, I'm sorry, no running.

[sprocket]

Well if it isn't fuel it could be electrical...what is the spark like.. I have seen scooters idle all day and when you give them gas the RPMs cause the spark to die or advance...usually a bad pick-up coil on the stator.

2008 models are notorious for flakey pick-up coils... they work OK until they are made to run faster and then they loose it and just fire when they want to...

BUT

you replaced the head... much more likely out a cam chain link

[roketafan]

possibly fuel need to check them all air, fuel, compression

[seanstr]

I lost house for compression tool, next step, cuz spark is same as before

[seanstr]

Ok, found hose, compression is shot, down to only 45 now, I had intake valve set to .006 & exhaust native at .004. That is what you guys said was correct. But it made noise it never did ticking noise, asked of that was normal, oh yeah, now it's broke & get to fix it by myself. This sucks. I don't know how to do a seal replacement for piston.

[seanstr]

Ok, I've calmed down. This means a big bore kit would fix compression issues & speed issues. I have 150cc with emissions on head. I need help figuring out what to get. I'd like to get above 55mph & with lots of extra rpms left afterward. Do I get the new engine, then do the big bore, or keep current engine that has clutch pads possibly glazed over & leaking oil most of the time.

[sprocket]

Intake .004inch and exhaust .005inch .. or less by .001inch if it chatters

If the CAM CHAIN is out a link you will get poor compression just like that...

I still think that is the problem

[seanstr]

Really? 40Psi from 185 psi, cuz that is what I had

[bcgreatness]

the compression should range from a low of 90 to a high of 120 its ok to be higher, but i dont see how you got a 185psi reading that is pretty high for a 150cc

[seanstr]

It was, now it's not, I'll take head off & check timing

[jct842]

mine runs 150 which should be just about a 10 to one compression ratio. It drops to 90-100 when the valves need adjusting. I use the gauge to make sure it is valves because it is a pain to get to mine. depending on the gauge it could be off some to read that high. Its just good measure to get a reading when engine is new so that you can tell if some thing is off or you start getting wear. 40 would have to indicate a valve is partially open. as sprocket said the cam chain might be off a link.

[sprocket]

I have never seen a GY6 with a compression below 80psi that was due to ring wear...cracked piston or jacked valves sure...

Also you may want to test that compression gauge.. a new GY6 is usually 148 psi to 155 psi...I have seen one that was 161 psi...

185...no way...

If it is out 30+ pounds then your engine could have no compression and still read 40psi

Do you get any compression holding your finger over the plug hole?