help Chinese cy150A starving? By scooterg (Read 1,901 times)

[scooterg]

Hi thanks for the great forum <--------Newb

I had recently bought this scooter for my wife, seems to be doing really well in the short trips for her at cruising speeds 35-45mph, but sometimes she goes on highway and after a few miles the scoot seems to bog down around 50-55mph,but when she got it, it would do 55 no problem.
So i checked to see why the engine was leaning out and discovered the the dealer had taken 2 vacuum lines loose from the charcoal filter on the emissions. One was plugged with a bolt (still connected to filter) and the other goes to the fuel air vent for the gas tank which is lower not in or high in the seat.
I also found the the fuel tank air vent was clogged do to factory defect(a well placed brazing >.< sealed it shut). (Fixed)

But now the scoot still only runs and drive well at 45mph any ideas for the loss of power or engine dying and coming to a halt?

I noticed that the fuel pump is also a vacuum actuated valve, could the pump be faulty or unable to keep enough fuel going to carb in the higher rpms?

[sprocket]

ENGINE VALVES.. check your valve gaps .004inch intake and .005inch exhaust..need to check this every 800-1000 miles and adjust

No feeler gauge?... cut a strip out of the side a Coke can and set the gap with that.. works well...

Utube..Video.. but use these gaps NOT the gaps on the video

[scooterg]

okay ill try that i know its coming up on its first adjustment we are at 300 miles now. also i am looking at installing a motorcycle electric fuel pump to ensure that she is not loosing to the the actuated vacuum pump in top end.

[jct842]

I do not like a electric pump, it runs all the time depending on what little extra current that's available to a 150. A way better bet is a mikuni vacuum pump. Rebuild-able, used in ultra light aircraft, snowmobiles, and other quality vehicles. about 21 bucks, and not likely to cause a fire due to unforeseen events. john

[Alleyoop]

You really do not need a electric pump if the TANK is below the carb it has a VACUUM PUMP, if the tank is above the carb it has a PETCOCK gravity fed. Sounds like the exhaust valve has tighten up and looseing power. Also that hose that was plugged is it comeing from the VALVE cover, if it is that is a VENT for the crankcase put a fuel filter on the end of it and tie up high on the frame it has to VENT. Then plug the hold in the AIR BOX it came out of. The Tank vent hose should also be vented and not plugged as well otherwise it will stop the fuel from flowing to the carb.
Alleyoop

[beachbum]

My 150 cc did the same thing. A minuki high flow fuel pump fixed it. Does it happen all the time or just when you are at the top end? And does it bog for a bit and then run fine after a bit? If it does that sounds like the fuel pump

One other thing you mentioned is the gas tank vent being plugged. That can cause a fuel flow problem.

[scooterg]

yea it bogs a little then runs or if i catch it early i can keep the bike from stalling out by letting off the throttle some. i did fix the gas tank and it is open and clear now.
And no alleyopp the crankcase vent is nice and open but does have a lil oil seepage wich i think is fine.
Thanks for the info on the minuki high flow pump that might makes things a little less complicated

post when found time for repairs. thanks all.

[beachbum]

Its a Mikuni...I typed it wrong.

[sprocket]

Electric pumps suck.. literally not gas... but power...you would be marginal charging on an 8 pole stator probably have to go to a 3 phase 11 pole to be certain...waste of time...

Loosing at top end..could be the float is improperly adjusted..fairly common...or you are loosing vacuum in the carb also common especially with foam filters etc...

Just replace the diaphragm all Mikuni pumps are repairable...

[kz1000st]

Where have I heard this before? I would take off the exhaust and see if the pipe is plugged anywhere. Mine was welded wrong at the end attaching to the head and 1/3 blocked.



I replaced the pipe and-Voila-no more bogging at top end.

[scooterg]

Well here's the update guys had the bike valve timing fixed all vacuum lines reconnected no electric fuel pump am looking into the Mikuni pump. Ill have to order it i suppose because after all the valve check an lines re hooked it actually stalled out more often until i removed the fuel tank vent hose from the charcoal filter to let it breath better now its back to doing same thing again.

Ill check blockage in the exhaust and get that pump ordered. Will i have to readjust the carb or anything for the new pump out-put?

One thing i did notice is when it starts to stall out if i quickly go to 1/4th to 1/8th throttle the bike will stay running then it will work fine for another mile or less and do it again till i shut off bike and let it set for minute, almost as if restarting is refilling the float bowl on carb when i turn it over.

[Bashan]

Mar 29, 2012 18:46:11 GMT -6 scooterg said:

almost as if restarting is refilling the float bowl on carb when i turn it over.

It is, that's exactly what's happening. You're using gas faster than you're supplying it and the bowl empties. When you shut it off whatever is in the fuel line above the carb dribbles down, it doesn't take much. Also, when it is running and you have the throttle closed you actually have more vacuum for the pump since the butterfly is shut. Vacuum pumps at high RPM lose efficiency because the diaphragm stars to flutter and the vacuum is low. Having said that, vacuum pumps work just fine if they're not defective. They're simpler than electric and don't put a strain on the charging system. I have a 250 Fashion with a vacuum pump and it works great. I think you have a bad vacuum pump and you might consider putting a new one on rather than trying to wire in an electric. BTW, what gap did you set your valves at? Rich

[scooterg]

Rich, what i ended up with was .006 on intake and exhaust was closing fine so i didn't mess with that. and since this is 2012 bike not a month old ill see if the dealer will throw in for the pump ^.^

[imnts2]

You might check the PAIR system. They are tricky and will screw up running badly. Particularly at near WOt.

[scooterg]

issue solved guys. I replaced the vacuum pump, cleaned float bowl and valve was kinda gummy in there for a new scoot. and i replaced the cdi just incase the rev limiter was faulty. thanks for all your help guys.

Scooter on! Woot.