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Post by katt on Aug 13, 2018 19:16:25 GMT -5
Purchased ignition off ebay its say 150cc in description, but i've seen same one rated 50cc 125, 150cc and there's no markings on the ignition so i think it can run on QMB139.
After installing new ignition started hearing misfires like 5 in a raw or in very beginning of acceleration with WOT, on slow acceleration there's no misfires, then after going up the 6000+ RPM i hear no misfires.
From what i remember reading somewhere on this forum there's two types of spark plugs for this motor one with resistor one without resistor and apparently if you got ignition wire with resistance you should use non resistor plug, or if you have ignition wire with without resistance you should spark plug with resistor.
I used both types with my old ignition NGK 4549 CR7HSA - (with resistor) and later NGK 4629 C7HSA - (no resistor) i had no misfires, right now i still have old no resistor plug installed, could it be the issue? |
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Post by scooterpimp on Aug 13, 2018 19:49:47 GMT -5
If the problem wasn't there before the new coil swap....wait for it.......put the old coil back on.
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Post by katt on Aug 13, 2018 20:18:40 GMT -5
If the problem wasn't there before the new coil swap....wait for it.......put the old coil back on. Which ignition would you recomend to use for 139qmb that k own to work? Heres more detailed problem description my normal rpm no less thab 6000 when accelerating now when i go to 6000 it starts misfiring and drops to 5000 after tgis it gains speed okay no more misfires |
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Post by katt on Aug 13, 2018 21:17:01 GMT -5
Okay here's the update i installed new spark plug NGK 4549 CR7HSA (with resistor) and now picture looks totally different. Goes instantly to 7000rpm with a twist of an wrist then drops to 6000 (without misfire) and climbs really fast. How can you explain this, did old spark pug got sort of "broken in" by old ignition?
My old spark plug.
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Post by greginisn on Aug 14, 2018 1:33:12 GMT -5
Resistor spark plug wires & plugs were created to reduce RFI in a car's radio and possibly to help prevent untimely explosions at roadside construction sites. But they aren't really necessary for a engine to run correctly. Think, you would go out of your way to buy a coil / wire combo that promised the biggest fattest spark then you add resistors to it all. It makes little sense. There seems to be loads of crap pieces & parts out there for all types of GY6 engines so try to buy from more reputable sources and maybe you'll have better luck. Your problems sound like crap construction of the coil assy or a bad wire or bad wire connection.
Good luck
Greg
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Post by scooterpimp on Aug 14, 2018 19:23:34 GMT -5
Stock coils with upgraded ngk spark plug boots seem to work pretty well for me , but your results may vary.
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Post by GrumpyUnk on Aug 15, 2018 8:07:38 GMT -5
Out of the box vanilla stock CDI & coil work fine. The orange are touted as 'race' or 'performance', but I have serious doubts. Reports are that they advance the spark timing a bit more than the OEM black CDIs, which could cause harder starting as you work a bit against the spark firing off the mixture as you kick/crank.
Stock will work to more rpm than you need. Resistor plugs cause less RFI - radio frequency interference - the buzz you hear in an AM radio with the engine running nearby. The tend to limit the amount of electricity flowing when the spark jumps. The do not limit spark, and have no effect on the voltage developed.
A plug CAN come apart internally, and make the spark jump more gaps than the one you can see at the electrode end of the plug.
tom
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Post by katt on Aug 15, 2018 16:02:12 GMT -5
Out of the box vanilla stock CDI & coil work fine. The orange are touted as 'race' or 'performance', but I have serious doubts. Reports are that they advance the spark timing a bit more than the OEM black CDIs, which could cause harder starting as you work a bit against the spark firing off the mixture as you kick/crank. What i can tell is before i installed this ignition coil my acceleration from full stop was,
on WOT i get instant 6000 RPM for 5 seconds up to about (20mph) then they slowly grow to 7000-8000 as speed increased.
With this ignition i get on WOT instant 7000 RPM that does slowly drop to 6000 RPM (no misfires) and in 5 seconds goes to 7000-8000 as i speed up. I belive the drop from 7000->6000 is because of variator, overall i feel more power.
Can ignition coil advance timing i thought its CDI job.
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Post by GrumpyUnk on Aug 16, 2018 10:59:53 GMT -5
Given that the coil is fired by the CDI, is seems there is no way it could 'change' spark timing.
Have you tried an OEM (black) CDI along with the elongation of the ignition pickup mounting holes? Elongating the holes will allow spark advance increase over the full rpm range. 90GT has a video or post on the process.
In effect, elongating the holes allows moving the pickup relative to the crankcase CCW. Given the rotor rotates CW, the spark will happen sooner in the cycle as the pickup is 'sooner' in the rotation.
If you look on the web at the comparison of OEM vs 'performance', the spark curve is different. Better? Dunno.
I guess I am not going to push these little beasts more as the BBK adds enough stress by its lonesome. Maybe.
tom
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 17, 2018 15:15:09 GMT -5
Well I guess I’m a little dense, but if I made a change, like say a coil, and then my bike ran bad, I think I would put the old coil back it! Also, based on your old plug pic, I would suggest you go to a bigger main jet. In that pic, the plug looks like it’s running lean. My picture sucks compared to yours, but this is more like I would like to see the engine running. Btw, the pic is a little dark because the camera darkened it because of the white background.  |
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 17, 2018 15:26:16 GMT -5
 Maybe a little easier to see the coil can NOT advance the timing. It could be made to retard timing I guess, but there is no way it can say “well the cdi is about to fire, so I’ll fire first”. I have only tested 3 aftermarket CDIs none where “upgrades”. All three did the same thing. They simply advanced the timing over the whole rpm range. The odd part is they all had the same max advance as the stock unit. When you put a timing light on the units, the stock starts with a small advance then moves more advance as the rpms increase. The after market CDIs simply stay at max advance the whole time! The only change I found was that the after market CDIs made the bike hard to start. My advice is don’t waste your money |
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Post by gsx600racer on Sept 3, 2018 1:26:44 GMT -5
The coil might be self aware or have esp.  |
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Sept 3, 2018 17:49:10 GMT -5
I see nothing wrong with your orginal plug ( well a little lean). There is no reason I can think of th at you would be having problems. Now.
, if the after market coil is a real weak ass POS, the plug GAP could be an issue. If you really want to find out if the new coil is of any value mere is an experiment to run.
Take your old plug, and open the gap really wide. Much wider then you would to run the bike.
Take the plug out of the bike
Go somewhere that is at least a little dark
Now this part may require some extra hands(g) most of these scoots require you to squeeze the break while you crank the engine, but you also have to hold the plug up against some clean metal. I actuly made a little coil like holder out of copper wire, bu I do this stuff a lot.
So crank the bike over to see the spark. You may find it sparks sometimes and not others. If it truly were a “HOT” coil, you would see a fat blue spark every time.
So now put the orginal oil back in
Do the crank/ spark test again. If your results are anything like mine, the spark from the orginal coil will look more healthy and will be easier to hear.
Of course your results may vary.
If it were me, I would use the coil with better spark, even though it was the old stock coil
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Post by SMALL CC TEK on Sept 3, 2018 22:58:43 GMT -5
So make sure your green and black are on the correct terminals first and they are tight as in they don't wiggle at all when connected or you can get a misfire easy. Put the stock coil on and just remove the wire and cap and install the orange wire and cap and see how it goes just a process of elimination with the stock parts and new it should only take 20 min or so even if you change out all the parts twice lol
Probably a cap and wire , on the orange one if you tighten the gap on the plug it might work Welcome to the world of Chinese parts 50/50 chance of them working or not ! Get a Kymco, Sym, PGO, stock coil and they are hotter than any Chinese one just a suggestion..
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Post by katt on Sept 4, 2018 3:38:00 GMT -5
AFAIK for proper plug reading you need to use new plug every time, and have engine warmed up using old plug.
Jtherwise if you been run too reach and then adjusted carb too lean you will not see it as it will be dark.
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