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Post by 90GTVert on Nov 25, 2013 15:28:39 GMT -5
Wet enough. It's washing the plug.
Have you tried checking the spark with an HEI tester or by opening up the gap on an old plug. May help to determine if it's a strong spark.
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Post by 90GTVert on Nov 25, 2013 15:29:47 GMT -5
Yeah, if it's running as bad as it sounds it shouldn't take you long with the exhaust off to figure out if it improves.
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Post by tansen on Nov 25, 2013 15:30:44 GMT -5
Does this look like a 2 stroke exhaust?
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Post by 90GTVert on Nov 25, 2013 15:34:45 GMT -5
I suppose. The fact that it fits pretty much says it's a 2T pipe. I don't think the common 4T stuff would even bolt up. 2Ts don't have to have any special exhaust. They can function with a standard muffler as long as it's not clogged.
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Post by tansen on Nov 25, 2013 16:09:28 GMT -5
Just ran it without exhaust. Same but louder Idles. Pull the throttle and at about 1/4 it misses/bogs then dies unless I release the throttle in which case it settles back to idling fine.
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vaporz
Scoot Enthusiast
IF YA AINT FIRST..... YOUR LAST SUCKA!!!!!!!!
Posts: 117
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Post by vaporz on Nov 25, 2013 17:17:08 GMT -5
Just checking in on ya....
First off those plug pics mean nothing!!!! How many times have you cleaned em and put it back in? The only thing I will say is that the second pic.....look at the insulator, That light coffee/tan color is what you want BUT those pics mean nothing. Look up and read the proper method for doing PLUG CHOPS!!!! It will only help you.
Also, like I said earlier...
Pick up 34, 36, 38, 40 Pilot Jets Pick up 74,76,78,80 Main Jets
Also make sure your air filter (in the AIRBOX which is INSTALLED) is clean!!!!
My money is on a complete incorrect jetting. 47.5 main is completely wrong. 15 pilot is completely wrong. After doing some resarch the only bikes that come close to this awkward jetting are those little japanese or chinese pocket bikes which you do not have.
Lastly as long as the needle is not set to full lean...leave it where it is. This is the last of carb adjustments once you know 100% you have the correct main and pilot installed.
Gotta bounce dude.....Talk Later.
Vaporz
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Post by tansen on Nov 25, 2013 17:42:20 GMT -5
Yup! Jetting is the next step. Here's a little update: with the airbox off I noticed something that may or may not mean anything. Bike's idling and when I pull the throttle I can see a small puff of mixture coming out of the carb on the airbox side. Putting my hand in front confirms that it's fuel and air due to the smell. Maybe it's normal especially given the rich condition. I does make me think of an intake backfire on a 4 stroke that isn't timed right, except it's not violent at all. Just a little puff coming out.
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Post by stepthrutuner on Nov 25, 2013 18:52:15 GMT -5
Other ideas might be...
check strength of spark
try a hotter plug
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Post by tansen on Nov 25, 2013 19:37:19 GMT -5
Thanks step. Another thing I could try. The plug is NGK BR7ES, comes stock with these bikes. Spark is fat and blue but not sure of gap. I noticed 2 things when manually spinning the rotor: no timing marks on the plastic cover or anywhere on the aluminum motor side and a little bit of free play as I turned it quickly left to right. I bit of slack accompanied by a small "clack" noise. Wondering if rod to crank clearance could be offsetting timing a little? I don't know. I'm at the point of throwing any crazy idea out there. So far it's between the jetting and something physical. Well, at least it's a pretty interesting case... Calling it a day. Thanks to everyone for your input.
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vaporz
Scoot Enthusiast
IF YA AINT FIRST..... YOUR LAST SUCKA!!!!!!!!
Posts: 117
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Post by vaporz on Nov 25, 2013 20:01:45 GMT -5
Hotter plug is a good suggestion but your already using a 7 and an "es" plug that extends approx a 1/4" into the head in my experiences.
But hold on....you have me second guessing things now.....
What size carb is it? 14mm? Smaller.
You say you have a 15 pilot in there and it idles perfectly. Rpms don't run away on you cause that's super lean. A/F screw between 1 and 2 turns out? It just doesn't make sense to me....
What cylinder? Stock? The whole bike is stock?
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vaporz
Scoot Enthusiast
IF YA AINT FIRST..... YOUR LAST SUCKA!!!!!!!!
Posts: 117
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Post by vaporz on Nov 25, 2013 20:42:17 GMT -5
I also went back and was looking at your carb. Your running oil injection and auto-choke. Are you sure your autochoke aka enrichner is turning off? This in my eyes is and would be the only reason you would be able to idle with a 15 pilot jet. Also explaining that your 47.5 main jet is way to small so when you twist the throttle due to lack of fuel....
And also backs my statement of why trying to read a plug of an idling bike is completely WORTHLESSS!!!!
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Post by 90GTVert on Nov 26, 2013 10:52:02 GMT -5
15 pilot isn't all that far from what I'm used to. All of my stock carbs have 17.5 to 22.5 pilots.
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Post by 2strokd on Nov 26, 2013 11:31:13 GMT -5
Gotta air filter in the airbox? Sounds like a silly question but ive seen them dry up and get sucked in.. I havent read this thread post for post so it might have been mentioned?
Best of luck!
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Post by tansen on Nov 26, 2013 14:14:42 GMT -5
The inner bore of the carb on the intake side is 18.8mm and fits snugly into the intake rubber boot. Pilot jet says 15 on it. Thing is, I can kill the bike rich if I turn the screw passed 1/2 turn in. It idles ok anywhere from 3/4 to 1/4 out. I can turn the screw out to 4 without killing the bike but I do hear a little bit of lean popping at this point. The 2 unmarked jets in the other carbs both have bigger holes than the 47.5. One a bit bigger than the other. But neither change the way the bike behaves when replacing the 47.5. It does exactly the same thing. Air filter is clean and the foam is in good shape. I gave it a light film of filter oil spray. Very light. Bike looks all stock. The cylinder says 3XY00, 49cm3 Choke replaced with the newer one on newer carb. Passes bench test and revs go up for bit after bike starts then go back down. Compression 120psi I agree vaporz. Seems like highest idle is probably the best way to tune but in this case with so many question marks it's interesting to see what's going on in that cylinder physically. I'm guessing the black we're seeing on the plug comes from when that needles rises a little and the bike chokes on fuel, as affirmed by the smoke out of the exhaust right when the missing/bogging starts. There are a lot of motorcycles that will let you idle with your side stand down, but if the cdi doesn't find ground on the side stand switch it will kill the bike as soon as you pull the throttle. Do you guys know of any such wiring on these 2 strokers? Although I would imagine it to just kill spark and not show all the rich symptoms like smoky pipe and black plug.
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Post by 90GTVert on Nov 26, 2013 15:02:51 GMT -5
There are some scoots that have kick stand safeties. None of the ones I own have it and the only scoot I worked on with it I wasn't concerned about it so never paid much attention. I know it wasn't rev or throttle position dependent. Can't honestly remember even if it was a starter or ignition disable. AFAIK there isn't a safety system of any kind on the Chinese scoots that should disable or modify spark properties under load, revs, or TPS.
CDIs and other ignition components have been known to fail and cause only poor running under load. Most commonly they give up and don't spark at all, but it does happen.
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