chemi
Scoot Member
Posts: 34 
|
Post by chemi on Oct 19, 2015 15:45:55 GMT -5
|
|
|
|
Post by jkeney on Oct 19, 2015 19:26:17 GMT -5
Do you mean it will only idle, cuts off while idling, or cuts off while riding?
|
|
chemi
Scoot Member
Posts: 34
|
Post by chemi on Oct 19, 2015 19:37:14 GMT -5
it cuts off while idling especially when you pull on the throttle
|
|
|
|
Post by strgazr27 on Oct 19, 2015 21:17:58 GMT -5
So compression is currently 120psi? When you say you upped the jet, what size are you currently running? Have you adjusted the idle mixture screw? Get the scooter started and back out the idle mixture screw till the RPM's no longer climb. Than use the idle speed screw to bring the idle down. If you back out the idle Mixture screw with no change in RPM than go the other way finding the point of highest idle. Are you running the stock air box or open element filter? When you say you checked the valves what is the lash set at right now? .003-.004 is a good value. The timing marks all line up correct? Lots of info below.... 49ccscoot.proboards.com/thread/428/valve-adjustment-pics-video-139qmb49ccscoot.proboards.com/thread/429/idle-mixture-adjustment |
|
|
|
Post by 90GTVert on Oct 20, 2015 5:17:28 GMT -5
120psi is not exactly high compression, but it sounds somewhat normal based on what others have said about their 50mm kits with that big bore head. I'm guessing the combustion chamber cc is a bit much. It shouldn't die out because of this though. Check your vacuum hoses. Make sure you have no leaks. At least check the idle settings, but you may want to go through a thorough tuning process if you haven't already : www.49ccscoot.com/faq/carbtune.html |
|
|
|
Post by strgazr27 on Oct 20, 2015 7:14:38 GMT -5
120psi is not exactly high compression, but it sounds somewhat normal based on what others have said about their 50mm kits with that big bore head. I'm guessing the combustion chamber cc is a bit much. It shouldn't die out because of this though. Check your vacuum hoses. Make sure you have no leaks. At least check the idle settings, but you may want to go through a thorough tuning process if you haven't already : www.49ccscoot.com/faq/carbtune.htmlBrent that's why my first question was about the compression. I bought almost the same kit from the same gentleman and my compression after about 100 miles of riding is right around 170 psi. 120 seemed low based on my results. Hearing it got very hot makes me wonder about possibly a burnt valve? But you're right about vacuum leaks. Always check the easy stuff first. I would also check the plug to see its condition. Is it burned, melted etc. And that carb tuning link is worth it's weight in gold! |
|
|
|
Post by 90GTVert on Oct 20, 2015 7:37:43 GMT -5
I haven't tried that kit and maybe I'm mistaken. There are discussions here about 50mm kits with big bore and big valve heads running low on compression. Nobody posts deck height, combustion chamber volume, etc... to really know what's up when they're low on comp.
Could be a valve sealing issue in this case. Could be a tester not sealing.
|
|
chemi
Scoot Member
Posts: 34
|
Post by chemi on Oct 20, 2015 8:29:08 GMT -5
okay ill try all these when i can
|
|
chemi
Scoot Member
Posts: 34
|
Post by chemi on Oct 20, 2015 9:07:53 GMT -5
i have an open air fliter and also my spark plug is black
|
|
|
|
Post by strgazr27 on Oct 20, 2015 13:54:14 GMT -5
i have an open air fliter and also my spark plug is black Black plug is a sign it is/was running rich. The plug could be fouled from running real rich. I would pull the plug, clean it and see if there is any difference. If it's older than a year just replaced the plug with a correctly gapped new NGK. Open filter will require an upjet as will the BBK kit. That being said you need to start from scratch with the carb. Idle is controlled by the Idle mixture screw and Idle speed screw. The IMS works till about 1/4 throttle at which point it really has no effect. I would start there IIWY. |
|
tvnacman
Scoot Enthusiast
Posts: 408
Location: NYC
|
Post by tvnacman on Oct 20, 2015 20:28:03 GMT -5
Lets fill in some missing info here. Chemi did this rebuild and ran it without the shroud. This engine made a noise. Then Chemi brought this to me we worked on this together. We agreed that the first step was to install the shroud and put the "bigger jet" that came with the kit in the carb. Well The shroud is installed with the jet (not marked) It fires off and will not run long enough to take throttle. It was like 40 degrees outside. We checked the valves the intake jam nut vanished, perhaps its in the oil screen. After the valve adjustment same symptom. Then we did a compression test we got 120psi. There is barley any run time on this top end and is has been over heated.
I suggested at the very least to hone the cylinder and install a fresh set of rings. Perhaps lap the valves or even buy another kit and start over.
Now with some more background as to what has transpired what do you guys think?
I did suggest that chemi start a thread in regards to this.
John
|
|
|
|
Post by niz76 on Oct 20, 2015 21:50:01 GMT -5
Thanks for the extra info. Problems might be related to the carb tune with that open filter. With the jet size not being known you're just stabbing in the dark here. Try installing the stock airbox and/or restrict that open filter and see if it'll throttle up. Always good to have a few fresh spark plugs on hand when trying to tune.
|
|
tvnacman
Scoot Enthusiast
Posts: 408
Location: NYC
|
Post by tvnacman on Oct 21, 2015 5:50:40 GMT -5
Thanks for the extra info. Problems might be related to the carb tune with that open filter. With the jet size not being known you're just stabbing in the dark here. Try installing the stock airbox and/or restrict that open filter and see if it'll throttle up. Always good to have a few fresh spark plugs on hand when trying to tune. Great tuning advice and I agree 100%!!!!! Lets look at the engine stalling out without the shroud installed and the jam nut that vanished. John |
|
|
|
Post by 90GTVert on Oct 21, 2015 7:36:36 GMT -5
Knowing a more complete history, I'd start with an inspection of the head and cylinder kit and I'd want to try and figure out where that nut went.
|
|
tvnacman
Scoot Enthusiast
Posts: 408
Location: NYC
|
Post by tvnacman on Oct 21, 2015 14:43:52 GMT -5
Knowing a more complete history, I'd start with an inspection of the head and cylinder kit and I'd want to try and figure out where that nut went. I was thinking in the oil filter strainer or next to it. John |
|
