Post by lostforawhile on Jan 22, 2018 18:49:17 GMT -6
you have the weights backward, these engines are supposed to run at high rpm, heavier rollers will keep it from going into the highest ratio, and it will basically stay in low gear, the variator doesn't "engage the belt" the belt is always engaged, the clutch engages at a certain RPM. Also your main jet is too big, why won't the air box fit? they run best with the stock airbox, heavier rollers will work with an engine that has more torque, such as a BBK, but not stock
Well my scooter was running OK but the plug said LEAN. I up'ed the main jet and the plug now has a little color, but TOP SPEED was still about 52 MPH (hoping it would help). It is like the ignition is cutting off. It continues to accelerate to 42 mph. Any TIPS to trouble shoot. I had the plug back out and checked the gap an color.
The scooter starts easy, idles nice. has good low speed acceleration, but right at 37 mph like clock work it misses.
I have done some work that was unrelated to fixing this issue, but just FYI:
Removed the emission system
Removed the vacuum fuel petcock and put a manual one on
The problem was before doing this work and the scooters runs the same or better (at low speed).
are you looking at kph or mph, most speedos have the numbers reversed, mph is on the bottom, no stock 49cc will hit 50 plus without a lot of work, the best ones hit 45,plus the speedos are usually off
Post by lostforawhile on Jan 11, 2018 12:52:25 GMT -6
Always non ethenol ethenol gas will destroy your carburator parts, fuel petcock diaphram, and fuel lines, since it dies off idle I suspect the gas has eaten a hole in the needle diaphram in the carb, so it kills it at mid throttle,
Post by lostforawhile on Jan 11, 2018 12:46:14 GMT -6
It doesn't take much more then a basic set of sockets a screwdriver a variator lock tool and a flywheel tool. Take it apart,learn,then sell the remains for scrap, a 38000 mile chinese engine has no value, I've seen entire running chinese scoots go for 100 bucks. Honda and Italian engines are designed to last and repair, chinese engines are disposable with high mileage
Post by lostforawhile on Jan 10, 2018 21:39:50 GMT -6
if it was a honda engine, or one of the Italian engines, I would say rebuild, but for under 300 bucks you can get a brand new engine/transmission assembly for a 139QMB, why rebuid a 38,000 mile one, the big ruckus I'm trying to buy has that many miles, but for a Honda water cooled engine, that's barely broken in.
Post by lostforawhile on Jan 8, 2018 18:11:41 GMT -6
it takes less then a quart to change the oil on a 139 QMB, add a couple of partial quarts together, and you've got an oil change, with synthetic you could probably extend your oil changes to once a month, using cheaper oil is poor economy in the long run, the most critical thing to an air cooled high RPM engine, is the oil .
I went ahead and ordered the engine. I'm trying to find out what else I should consider on ordering.
Doesn't say anything about the varistor being there, would be nice if there is a stock ready to go one on it with fresh variator spacers/slides on it. I have a fairly brand ned stock clutch on mine so if that's not on this scooter that's no big deal. I see I need a carb, just replaced mine six months ago so that's a plus. My main worries is the variator.
Something about my gear puck, speedo cable, or actual speedomotor is off. 50 mph on the gauge is actually 30 mph >.<. I did not see my gauge on parts for sccoter, if this is a gauge issue it would be nice to replace it due to miles that are on it with putting a new engine on.
About synthetic oil, I put synthetic oil in mine a year ago, first time it ever had it, it liked it at first. but in 2010 I had a guy tell me "If you run synthetic in it, you will cause the bands to fly apart, to much worse". Dunno what he was talking about. But I think my problem with this scooter is related to that. So I think I want to stay away from synthetic.
Most engine re builders of all types of engines use Castro Gtx, I thing I will run 10w 30 in the engine once she's broken in.
My first scooter I drove 15 - 20 mph for 100 miles. 20 - 35 for 250 miles. 30 to 40 for 500 miles. And at that point I just started driving it like it was an average scooter. Over time I opened the throttle and hit 60 on a stock scooter, seller said it and I should not go that fast on a stock engine, not sure if it were related to the break in lol..
Would it be safe to mainly run it once she fires for about 7 minutes, turn it off, check the oil levels, re start it, let it run for 20 minutes, check the oil levels. let the engine cool down, and run it again for another 20 minutes or so before I even consider on turning the throttle?
what bands is he talking about? there is no wet clutch in a 139 QMB, they normally take 15W40 which is heavy duty diesel oil, don't run lighter oil in it, these air cooled engines are really tough on oil, run regular dino oil for about a 1000 miles to allow proper break in, avoid constant wide open throttle, then switch to synthetic, there is nothing in the engine that will be hurt by it, all it will do is protect your engine better. It needs the dino oil at first, because it needs some friction to allow proper break in, synthetic is so slippery the engine will never break in, you want this AFTER the first 1000 miles. Nothing is going to beat synthetic in a high revving high heat air cooled engine like this, it's a little pricey, but it takes less then a quart per change, by the time you do several changes, you have enough left over to do another.
Post by lostforawhile on Jan 4, 2018 1:47:12 GMT -6
if you have a regular single phase stator, you will have five wires, yellow,white, blue-white, red-white, and green, the yellow and white go to your regulator/rectifier and are AC for the lights and battery charging, these should go into the regulator, the regulator should have two outputs, one for your lights, one for the battery, and a ground, this ground is very important, the light output wire usually runs your taillight as well as the headlight, it goes to the high low beam switch, where two wires go to the headlight, the headlight socket also has a ground, check this very carefully. These grounds corrode and fail, somewhere in that front harness is a ground wire, or ground wires,heading back to the frame, check these very carefully.
Post by lostforawhile on Jan 4, 2018 1:27:35 GMT -6
the CDI has nothing to do with the headlight, this is a classic ground issue, you have a ground wire broken right in front of a pin or something. you dont need to look at the wires, you need to test. you could even have a wire with a break in it. can someone post a wiring diagram for this bike here,so I can look at it? you need to look at a diagram then you can tell how current is traveling backwards through the other lights and where the biggest probability of a break is