Won't start without throttle

[aspired]

Fixing a 2004 TGB Laser 150 for a friend with little over 5k on it.

One issue still remaining is that it will not start without giving it some gas. Then it will not idle once running till it is warm. I thought it was the auto chock but not sure. Works and runs great once warm but seem to take a long time to warm up. My zuma fast idles for maybe a minute, calms down then is ready but a totally different scooter.

- Cleaned the whole carb completely = as dirt now spotless
- Checked connection to auto choke = good
- Seems no different with choke plugged in or not
- Can't find a temp sensor or anything so not sure how choke works exactly to tell it when to choke and not
- Tested resistance to auto choke = like 5ohms but hard to get good reading
- Tried to test voltage to auto choke = had mixed numbers 140vDC to start with and changes with rpms = need more hands!

I just found this and will try this test this week: http://tgbforum.com/forum/index.php?topic=173.0

Just wondering if anyone else has had a similar issue so I can get this out of my garage.

FYI original issues to fix were breaking throttle cables, brakes and when shut off would leak gas out the airbox.

- Cory

[harry]

here's a better one with pictures
http://tgbforum.com/forum/index.php?topic=220.msg864#msg864
 however you have a different motor and carb/choke  on that 150.

the chokes are about the same just that the measurement might be different
both have thermal wax that heats up and allows a spring to work causing a hole to
 close off in the carb.

 oilyhans

[aspired]

Thanks Harry I will give it a go here this week.

Regards,

Cory

[aspired]

Well I tested the auto choke off the scooter and it starts moving pretty so and fully out in under 2 minutes so seems to work fine.

Need to make sure it is getting voltage to it again I guess. Can't imagine what else would cause it but will check all the venuties again the carb too.

- Cory

[aspired]

OK my list of things to check/adjust/replace:

-Check 12v to the automatic choke
-Adjust valves (intake .003 - exhaust .004)
-Check fuel flow and fuel filter
-Check the petcock to make sure its vacuum function is running
-Check or replace all vacuum lines

[aspired]

update:

Recleaned carb, checked all hoses, check fuel flow, reset float bowl height, reverified auto choke not stuck, adjusted valves (.004 Exhaust and .003 Intake), checked plug again, readjusted and lubricate throttle cable and tube.

Started up without need for throttle once popped off, ran a bit, adjusted idle, ran about 10 miles. Stopped and started a bunch of times and popped right off.

Then let sit for 5-10 minutes and darn thing doesn't want to start with out throttle.

So it's all good if you start it when it's just been shut off or leave over night.

- Cory

[harry]

most scooters should start without any operating of the throttle.

 there should be about 1-2mm of free play in the throttle cable.
this allows the carb to close to the idle position

 oilyhans

[aspired]

most scooters should start without any operating of the throttle.

 there should be about 1-2mm of free play in the throttle cable.
this allows the carb to close to the idle position

 oilyhans

I couldn't agree more on a 4 stroke, you should never have to touch the throttle and normally it hinders starting. Long live 2 strokes!

There is way more play in the throttle cable and tube than the cable adjustments could even take up and the cable he said is new and looks to be. There is more wear than I would like to see on the slide itself which of course I have no manual so I can't actually measure and know what it should be or see how much wear is on the body itself. Do they make service manuals for these things with tolerances and torques specs and what not?

Also there seems to be no stopping mechanism from rolling the throttle the opposite way? I took at all apart and nothing is missing or worns off, just seem they never engineered a backwards prevention stopping into the throttle tube? I think the bending of the cable both way is what is causing the issue and not lubing the cable at least once a year. He said it breaks the ball on the cable.

Anyways I'll see what a slide, autochoke and maybe a new throttle tube costs.

- Cory

- Cory

[harry]

parts and service manuals are linked at the
bottom of the forum home page...

stock/generic  cables are really stiff and one size does not fit all.
you might think about shorting up the cable by heating up the
 ball with a soldering iron and sliding it up the cable
use some flux and more solder , clip off the excess cable.

many times i make custom cables when i do a mod
so i buy the parts and usually get the slinky cable in bulk.

it might be easiest/cheapest to buy a new carb , many times
i do that for customers because a auto choke can cost as much as a carb
and cleaning the carb can put over the cost of a replacement.

and yes get the kinks out of the cable that will keep the slide from closing on its own. as for the slide wear i wouldn't worry too much about it.

oilyhans