air blowing out of the intake | Scooter Doc Forum

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air blowing out of the intake by: wizardaeon - Nov 25, 2011 17:28:44 GMT -6

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Post by wizardaeon on Nov 25, 2011 17:28:44 GMT -6

on my 50 cc gy6 139qmb scooter, I just recently had installed a big bore kit from scrappy dog scooters. I did it for 2 reasons= to eliminate any compression issue by replacing the piston and rings, and also to upgrade it to carry my 300 lbs.

The scooter still will not start. I have good spark. I checked today and made a discovery- I have air blowing out of the intake! Im not a guru but shoudnt that be sucking air instead?

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air blowing out of the intake by: Alleyoop - Nov 25, 2011 19:35:23 GMT -6

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Post by Alleyoop on Nov 25, 2011 19:35:23 GMT -6

Well since it top was taken apart are you sure the Valves are CLOSEING. If they stay a little open on the compression stroke it will blow out.

Have you tested for Compression, if you do not have a gauge take the Spark Plug out and Stick your finger in the hole, HOLD THE THROTTLE WIDE OPEN and crank it, IT SHOULD BLOW your finger off the hole. If you just feel some pressure it is leaking.

Also are you sure it was timed correctly it could also be on the compression stroke the valves are open.
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air blowing out of the intake by: sprocket - Nov 26, 2011 14:16:35 GMT -6

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Post by sprocket on Nov 26, 2011 14:16:35 GMT -6

Dollars to donuts you have the cam timing chain wrong...the piston must be EXACTLY top dead center and the cam sprocket marks aligned with the top surface of the head...

Then you put on the cam chain, making certain the chain is on the crank correctly... then release the cam chain tensioner...

Last Edit: Nov 26, 2011 14:17:11 GMT -6 by sprocket

Have you checked your valve gaps?

sprocket PM sprocket sprocket's Posts sprocket's Threads Scooter Doc Currently Offline Posts: 1,936 Likes: 7 Joined: Jun 18, 2010 22:25:14 GMT -6	air blowing out of the intake by: sprocket - Nov 26, 2011 14:19:48 GMT -6 Reply Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by sprocket on Nov 26, 2011 14:19:48 GMT -6 Cam sprocket alignment.. doing it from the flywheel T.. it will be out at least one or two links...the piston must be TDC Attachments:
	Have you checked your valve gaps?

wizardaeon PM wizardaeon wizardaeon's Posts wizardaeon's Threads Clinician Currently Offline Posts: 8 Likes: 0 Joined: Mar 20, 2011 17:51:43 GMT -6	air blowing out of the intake by: wizardaeon - Nov 26, 2011 23:33:51 GMT -6 Reply Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by wizardaeon on Nov 26, 2011 23:33:51 GMT -6 thanks for the advice guys, I usually go on another forum but I wanted more opinions. fortunately everybody says about the same thing. It sounds like this was my problem from the start.

Bashan PM Bashan Bashan's Posts Bashan's Threads Forum Admin Currently Offline In Memory Rich Carman 1953 to 2015 RIP ScooterDoc Posts: 9,389 Likes: 301 Joined: Mar 29, 2010 18:33:42 GMT -6	air blowing out of the intake by: Bashan - Nov 28, 2011 8:22:39 GMT -6 Reply Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Bashan on Nov 28, 2011 8:22:39 GMT -6 Nov 26, 2011 23:33:51 GMT -6 wizardaeon said: I usually go on another forum. [/b][/quote] There's another forum?!