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Post by hookahman5000 on Apr 7, 2011 15:02:06 GMT -5
My scooter is a 150 cc Rocketa MC-17-150 with about 1,500 miles on it.
A while back, my scooter was starting to sputter at high rpms. Upon researching this problem, I figured it was most likely build up in the carburetor so I took apart the carb and cleaned it. However, at the time, I knew nothing about carbs and screwed everything back in all the way, including the air/fuel ratio screw. I have recently readjusted the screw but I can't seem to get it right.
Currently, the engine will start, but the engine wants to cut off when I give it throttle. After riding for a little while, this problem stops. Also, while the scooter reached 50-55 mph when I got it, now it goes 40 mph (sometimes 45 after Ive been riding a while). There is also a smell of gasoline coming from the engine while running.
Can anyone tell me if I'm running rich or lean? I've looked up information about carb adjustment and the symptoms of rich vs. lean, but I can't tell.
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Post by edfr on Apr 7, 2011 15:09:11 GMT -5
Follow this method of adjusting your Air/Fuel mixture. Also when you smell gas pull over and check around your carb for gas leaking out from someplace.
Lefty
ADJUSTING YOUR AIR/FUEL MIXTURE:
YOU WANT THE HIGHEST RPMS OUT OF THE AIR/FUEL MIXTURE SCREW:
Before you start it Turn the Air/Fuel Mixture Screw CLOCKWISE UNTIL IT STOPS do not tighten it just until it stops BUT COUNT how many TURNS IT TOOK TO CLOSE it. Then Turn it COUNTER CLOCKWISE the same amount of turns back to where it was.
Start your scoot and Get The Engine Nice and Hot about 10 minutes so that the Enricher is no longer Allowing Extra Fuel to come in. Then do the following to fine tune the Air/Fuel Ratio:
RICHEN THE AIR/FUEL MIXTURE:
1. Turn the Air/Fuel Mixture COUNTER CLOCKWISE 1/4 turn and wait 10-15 seconds to let the engine catch up with the new setting.
a. If the RPMS go up REPEAT 1 UNTIL the RPMS GO DOWN OR NO CHANGE.
b. Then TURN the Air/Fuel Mixture 1/8 CLOCKWISE and that should be your highest Air/Fuel Mixture setting , GO TO 3.
*****If on the FIRST 1/4 TURN from the STARTING Position IN #1 ABOVE the RPMS GO DOWN OR NO CHANGE , turn the Air/Fuel Mixture Back the 1/4 turn to the Starting position and wait 10-15 seconds until the engine catchs up and go to #2*****
LEAN THE AIR/FUEL MIXTURE:
2. Turn the Air/Fuel Mixture CLOCKWISE 1/4 turn and wait 10-15 seconds to let the engine catch up with the new setting.
a. If the RPMS go up REPEAT 2 UNTIL the RPMS GO DOWN OR NO CHANGE.
b. Then TURN the Air/Fuel Mixture 1/8 COUNTER CLOCKWISE and that should be your highest Air/Fuel Mixture setting, GO TO 3.
IDLE SPEED SCREW:
3. If after adjusting your Air/Fuel Mixture your idle is to fast Turn the IDLE SPEED SCREW COUNTER CLOCKWISE until your Rear Wheel JUST Barely wants to Turn or around 1500-1800 rpms.
4. If 1 or 2 above DOES NOT produce any RPM Change you most likely have a CLOGGED PILOT JET "OR" you did not get the ENGINE HOT ENOUGH and you were working against the ENRICHER which has not yet closed off the extra fuel. If the engine was nice and hot running for about 10 minutes and the Enricher was off then its time to take off the Carb and Clean out the Jets and all the Carb Passages.
If adjusted correctly you should be able to give the Throttle a QUICK half turn and the Engine should REV UP with no bogging hesitation and get a nice VROOOOOOOOOOOM. The Rpms should come down nice and settle at the Rpms you set your Idle to.
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Post by hookahman5000 on Apr 7, 2011 17:36:38 GMT -5
thanks, I will try this over the weekend
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Post by sprocket on Apr 7, 2011 18:02:21 GMT -5
If you haven't yet adjusted the valve gaps.. you are overdue.. .004" intake .005" exhaust
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Post by hookahman5000 on Apr 14, 2011 19:11:51 GMT -5
Its still not working right. When I turn the throttle, it revvs smoothly up until about 1/2 throttle, then starts sputtering and loses RPMs.
Could this be a fuel flow problem? I have read that many of these chinese scooters have cheap fuel lines and filters so is there a chance that maybe replacing these would fix the problem?
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Post by edfr on Apr 14, 2011 19:25:14 GMT -5
If you smell gas you are leaking gas from the carb or it is flooding. Start it up and rev it on the center stand and while your doing this check for any gas leaking someplace. Check your Air Filter box see if there is gas in it. Since you do not know about carbs you could have put it back together wrong.
Lefty
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n48
New Puppy Dawg
Posts: 4
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Post by n48 on Apr 30, 2011 18:52:23 GMT -5
If you haven't yet adjusted the valve gaps.. you are overdue.. .004" intake .005" exhaust How different are all of these engines? I found a booklet that "looks like" my scooter on the front cover picture, and it simply says "Valve Clearance: 0.08 - 0.12mm" |
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Post by sprocket on May 1, 2011 11:01:57 GMT -5
.08 millimeters = 0.0032 INCHES ( round up to .004)
.12 mm = 0.0047 INCHES (round up to .005)
Same thing that you were advised ...do the math
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n48
New Puppy Dawg
Posts: 4
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Post by n48 on May 1, 2011 21:31:38 GMT -5
ah. you're right. to note, I found a plate on the scooter that says 0.05 mm In/0.07 mm Ex.
Anyone seen a cam sprocket with no markings on it on these? I see no holes or marks on it.
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Post by edfr on May 1, 2011 21:55:01 GMT -5
Have you turn the engine with your hands, either turn the Flywheel or take the CVT cover off and turn the Variator Counter Clockwise with your hands. The crank may be on the downstroke and exhaust stroke in which case you will not see any holes in the cam sprocket.
Lefty
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n48
New Puppy Dawg
Posts: 4
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Post by n48 on May 20, 2011 21:58:02 GMT -5
I have turned the engine by hand - I see nothing. :-(
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Post by edfr on May 20, 2011 22:08:27 GMT -5
You do have the Valve cover off correct? If so do you see a Chain and Sprocket that is your CAM? Do you see anyholes in the CAM SPROCKET like this: Lefty  |
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n48
New Puppy Dawg
Posts: 4
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Post by n48 on May 21, 2011 11:44:04 GMT -5
LOL. Yes, I do. Exactly what I'm looking at, but no markings/holes.
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Post by sprocket on May 21, 2011 11:59:31 GMT -5
Turn the engine 180 degrees, you aren't on the compression stroke...
But there is a far simpler way to adjust the valves and it doesn't use the top dead center...
1. remove the spark plug or loosen it right back so the compressed air escapes...
2. remove the valve cover
3. remove the fan cover
4. turn the fan clockwise at all times!
5. turn the fan and watch the valves move
6. when you see the top rocker arm press the top valve (intake) all the way down, stop turning the engine.
7. set the valve gap on the bottom valve (exhaust) to .005 INCH
8. turn the engine again, now watch the bottom rocker arm
9. when the bottom rocker arm fully presses down on the exhaust valve, stop rotating the engine
10. now adjust the top valve to .004 INCH.
11. put the valve cover back on and tighten the plug... you are done!
With this method you don't need to align anything, and it also takes into account cam wear etc.
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