um gp1 150cc not starting By ric812 (Read 3,591 times)

[ric812]

The base setting for the idle screw is two full turns out from bottom. And thanks for the advise on the valves , I will do that before I get to adjusting the carb

[ric812]

I have it running now it is just very hard to start when cold (have to use carb cleaner sprayed in the carb to get it to fire off), when it is warmed up I can crack the throttle and get it to crank. When it is running it runs really well (road tested ot to over 40 mph), it is just when the rear brake is held for longer than 30 seconds to a minute it dies. it is still idling high and spinning the rear tire, it idles around 5 miles an hour. What am I doing wrong. I set the idle mixture 2 turns out and then turned it counterclockwise 1/4 turn at a time until it raised the idle then tried setting the idle down and still having the problem with the rear wheel braking causing the engine to die. Have not had a chance to reset the valves yet, maybe that is affecting the starting problem.

[cyborg]

Adjust the valves then you probably won't have to set the idle so high to keep it running,,, then the bike will not have the trans engaged because of the high idle

[Alleyoop]

The high rpms is the cause of your problems, 1 the hard starts and 2 the dieing when holding the break.
So if we can get it to idle lower around 1500-1800 all will be peachy keen.
Now several things can create a high idle:
1. To much gas is being let in
2. The throttle is adjusted wrong and already pulling on the cable inside the sheave.
3. Valves not closing and because of that the Idle has to be set high to keep the motor running.
4. A bad CDI.

Alleyoop

[ric812]

The tachometer is not working but I do have a dwell tachometer, can I connect this to check rpms?

[Alleyoop]

Yes you can if it is an inductive one Also if you can a video I can tell by the sound of the motor if the rpms are high.
If the rear wheel is spinning pretty good Odds are the rpms are to high. The rear wheel should not be spinning, maybe just wanting to turn is all.
Alleyoop

[Alleyoop]

Get yourself a tach you can always put it on another scoot if you get something else.
These are very good little tachs although my instrument panel already has a built in tach I bought one myself.
Alleyoop

www.trailtech.net/digital-gauges/tto?cat=117

[ric812]

Thank you alleyoop. Also on adjusting the valves can turn the engine until one valve is open and set the opposite valve? Or do I need to be at tdc?

[Alleyoop]

You can do it either way I like to align the CAM like in this picture and you can Adjust both of them without having to rotate the motor over anymore. But also do this AFTER you have adjusted both valves to .004 inchs Rotate the motor over several times and again align the cam and RE-CHECK your gaps Try to put in the .005 feeler and it should not slide in only the .004 feeler. Then you can button it up knowing all is good.
Alleyoop
When you align the CAM like this it is at TDC and both valves are closed and off the LOBES of the cam.

[wile]

Listen to him he's my Bro, I taught him everything he knows
Wile

[Lefty]

Nah, those are my two Bro's and I taught both of them everything they know. So we three know each other and we are all techy mechs.

Don't worry one of us will get you going
Lefty