Pulling on carb solved engine die issue at throttle

[vipchamp969]

Ok so I had a working scoot and all of a sudden I went to start it to take for a ride. Started fine. Idled fine for warm up then as I pulled from driveway and gave it throttle it would die. I would start it again and as soon as I give it throttle it revs and dies. After reading everything, it could be the valve clearance in need of adjustment. Maybe even a petcock. Perhaps a bad ignition cable, spark plug, CDI or even some other stuff with the carb. All those things except carb are new and have been replaced prior to issue. While I was ready to pull the carb out I notice the engine sounding better as I tugged on the carb between the two rubber intake and exhaust tubes. Then I said let me try giving it throttle as I pull a little up on the whole carb assembly. Sure enough it did not stall. I let go of the carb and checked the hose clamps and all and all seems tight. Once again fired up and gave throttle and it died. The I did same while slightly tugging up on carb or perhaps the airbox attached to the carb and it revs and spins wheel fine. It does not die at throttle when I tug a little on carb. Any idea what I'm dealing with here? Does position of carb or angle have effect on how things run?

[skyrider]

While I'm no Bull, Blueboy, CapeCodScooter, my thoughts are that you have an air leak. Have you tried removing then reinstalling the carb?? Perhaps check all the air connections from the carb out thru the hoses to their origin. Wish those fellows above would respond!!

[Irish]

Originally Posted by skyrider

While I'm no Bull, Blueboy, CapeCodScooter, my thoughts are that you have an air leak. Have you tried removing then reinstalling the carb?? Perhaps check all the air connections from the carb out thru the hoses to their origin. Wish those fellows above would respond!!

Ditto! Irish

[kz1000st]

You have a cracked intake manifold. You are probably pulling the crack closed when you tug up on the carb. Been there.

[vipchamp969]

Would I see this crack on the outside ? What is that little flexible air hose line that goes to the air filter box? If I pull it or press tighter where it's clamped on that helps engine stay on at revs as well. Maybe just coincidence.

[Shadowfire]

You will probably see it once you take the manifold off. To test it, spray a little starter fluid at the manifold while the engine is idling. If idle speed changes, you have a leak and need a new manifold as previously suggested.

[vipchamp969]

Thank you guys. I will check when I have some time. Just in case I ordered a new manifold for like $8. I got one with single outlet since mine was single. Would I have benefited getting a dual outlet instead?

[blueboy5000]

Agreed KZ, sounds like a cracked manifold.

[vipchamp969]

Yup wish it was easy as that. I pulled the manifold off and looked at it could not find any cracks or anything out of ordinary. Put it back on same thing. I put it on center stand. Give it throttle and it starts going but as soon as I get to full throttle or close to it then it just dies. Same thing if I rev it to full throttle just dies. I even did the painful procedure of adjusting valves just in Case (lots of plastic and screws to remove). No dice there. Yet as I said if I twist it little side ways (the carb) it works better. Got new carb coming in. Too much hassle not to spend another $25 just to eliminate a faulty carb. Are they hot swappable or do I have to prep it some how?

[skyrider]

So I googled "scooter dies" and got this:
http://scootdawg.proboards.com/threa...er-starts-dies

So it could be the carb. Perhaps you should explore solutions given to similar described problems!! And yes, could be a stuck carb so a new one or cleaning the old one is a possible solution. What do they say, "Gas, spark, battery???" or something like that, LOL!

[vipchamp969]

Thanks for the link. Funny when I searched using "dies at throttle " I got different results. Any way since I already have a new carb I might throw that in and then repair the old one when I have time to fiddle.
Do I need to do anything special before or after I mout the brand new carb between the intake hose and the filter ? Will it work right away or does it need priming or something? Also I got one of those uni performance filters with the new carb is that better to use then stock air box? The new carb has 85jet I think.

[blueboy5000]

Uni-style filter and #85 main jet should do fine. You should apply vacuum to ( or suck on the vacuum line) the fuel switch/petcock for about 10sec to "prime" the new carb, or just crank it over a bunch.

Make sure you start with the mixture screw at 2 &1/2 turns OUT.