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Post by domindart on Jul 7, 2013 4:00:00 GMT -5
Never done that before , doesn't bother me but every now and then I think when I'm engine breaking it will pop real quick. Just sometimes. I thought it was me running over a stick at first. Is it cause the engine is really breaking in now? Just wondering. Have about 3,300 miles now.  |
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Post by prodigit on Jul 7, 2013 4:17:52 GMT -5
probably running a bit on the lean side, nothing to worry about. In deceleration it is normal.
It could also be because of a gasket leak, however if that be the case the bike would sound really sharp.
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Post by wilds on Jul 7, 2013 4:49:57 GMT -5
Could also be the exhaust gasket that needs replacement. It tends to backfire when there is a leak...
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Post by scootnwinn on Jul 7, 2013 8:49:48 GMT -5
You could look for obvious winds of gasket leaks or check your plug but an occasional pop on deceleration might be normalish
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Post by tvnacman on Jul 7, 2013 8:59:48 GMT -5
your vac hoses could be dry rotted or porous creating a vac leak that will cause it to go lean . is it intake pop or exaust pop ?
John
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Post by tvnacman on Jul 7, 2013 9:03:10 GMT -5
Sorry guys leanish is not good with the ethenal in the gas it makes for hotter combustion chamber . I rather see a black plug and no backfire then a coffee colored when using fuel with ethenal .
John
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Post by domindart on Jul 7, 2013 9:20:34 GMT -5
your vac hoses could be dry rotted or porous creating a vac leak that will cause it to go lean . is it intake pop or exaust pop ? John not sure, I think exhaust? |
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Post by tvnacman on Jul 7, 2013 9:32:25 GMT -5
have you replaced your vac hoses ? Are they factory hoses ?
John
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Post by domindart on Jul 7, 2013 11:02:21 GMT -5
have you replaced your vac hoses ? Are they factory hoses ? John ya |
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Post by gitsum on Jul 7, 2013 11:08:23 GMT -5
probably running a bit on the lean side, nothing to worry about. In deceleration it is normal. It could also be because of a gasket leak, however if that be the case the bike would sound really sharp. No it isn't normal. It didn't backfire for 3000 miles. First thing you need is a valve adjustment. you are way overdue and if the exhaust valve gets down to zero clearance, you're gonna burn it. Put a new air filter in it, might as well throw in a new spark plug. Check your exhaust system for a leak. Check the crappy PAIR valve system. Or you could just rip it out and fabricate a block off plate for the exhaust port (like I did). You've only got one vacuum line from the intake manifold to the fuel pump (it should be that simple on all scooters with a carb), check it. Check your fuel pump by removing the fuel line from the carb and hitting the starter. Gas should squirt out in a healthy stream. Your carb my need adjusting, maybe the fuel mixture screw. Unfortunately, all of the adjustments are sealed off to make the EPA happy. You would need to remove the carb and unseal the fuel mixture screw, float bowl screws, and the diaphragm cover screws. Like most scooters and motorcycles, it was tuned lean for the EPA. I had to richen the fuel mixture screw 1/4 - 1/2 a turn and change the main jet from a #108 to a #110. It ran fine stock, but it ran smoother, cooler and stronger after tuning the carb and fuel consumption stayed the same at  mpg. Check the intake hose on the carb all the way to the air box for any leaks. Check the intake manifold and make sure it seals properly on both sides with no cracks or splits. I know you don't like to wrench on your scooter, but your only other choice would be to pay someone too much money to take way too long and do a half @ss job at best. There are lots of "how to" videos to learn from, and several knowledgeable people here that can answer any question you have if you get "stuck". Most of this stuff is very easy and basic, and after doing it once or twice you will wonder why you didn't learn before. Just be careful on who's advice you follow. There are a lot of wanna be mechanics here that don't know what they are talking about... |
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Post by gitsum on Jul 7, 2013 11:18:20 GMT -5
have you replaced your vac hoses ? Are they factory hoses ? He's had the scooter for a while, it wouldn't be a bad idea. But the Tomos Nitro 150 is made by SYM, the hoses were quality rubber from the factory. Somehow they got away with almost no smog equipment, only a PAIR valve system that wasn't even routed into the airbox or intake. Only one vacuum hose from the intake manifold to the fuel pump, simple just like it should be. The only downside is that everything on the carb is blocked off. You have to remove it to break all of the seals, then have you have access to the fuel mixture screw, float bowl and diaphragm. |
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Post by domindart on Jul 7, 2013 15:36:29 GMT -5
I'll do some maintenance like gitsum says asap.
Everything is stock on this bike including the hoses, as far as I know. I bought this from a dealer with 700 miles.
I did a short ride today and it poped once on the same downhill.
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Post by larrball on Jul 7, 2013 15:51:45 GMT -5
Hey gitsum he has a 2009, he might be lucky in that the A/F mix is not one that's sealed off.
My jonway is a 2009 and only had a cap on the A/F and came off with no problems.
Hope yours was like mine Dom.
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Post by gitsum on Jul 7, 2013 22:50:55 GMT -5
[replyingto=larrball]larrball[/replyingto]That would be nice. My carb had epoxy on the fuel mixture screw and on all of the screws on the float bowl and diagram cap. I had to remove the entire carb to break everything free. Took a while and a lot of profanity to get it done  |
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Post by alleyoop on Jul 7, 2013 23:43:23 GMT -5
Big Difference between Popping and Backfire. A POP is just that POP sound, a Backfire is like POW, Which is it? And NONE OR NORMAL so something is wrong. Popping on Decel is also a Lean condition but that happens because the throttle is suddenly closed and not enough fuel is being fed and it runs lean. It could be caused by to low of an IDLE and or running a little lean on the Fuel Ratio which you can just richen it up a little.
Backfiring on Decel is caused by bad air leak usually by the Header Pipe Flange, a nut came off or loose and most of the time blows out the exhaust gasket to one side. Backfires are not good it can damage your exhaust valve that is a lot of backpressure on the valve and it will burn it.
Alleyoop
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mpg.
..BAD TO THE BONE..