Bike won't idle with the muffler on

Hello all,

So I have been working on my second build and though everything is going pretty well I have run into one stubborn issue.

After I got the bike together I went on my first 2.5 mile run and the bike got going ok but all of the sudden I noticed that the muffler started to swing under my feet. I was in the middle of traffic when it fell off and saw a car or two give it a good one two with the tires. the reason it fell off was due to one of the screws coming off and therefore loosening the second until the whole thing gave up.

Now I know that obviously this is no good but the bike ran just fine for a day or two without the muffler except for the noise of course.

Now I have the muffler back on but the bike will not idle with the muffler on. I could tell that there is a little bit of an air leak where the muffler connects to the engine... could this be the reason it won't idle or is the issue that I need to trash this muffler and purchase another?

I can also see that the carb is leaking gas from the bowl screw if anyone wants to help a playa out with with that issue as well .

Thank you guys so much. Ive gotten a lot of help from this forum and always attempt everything before coming here begging for help. I appreciate the patience the experienced folks have with us noobs

leaky exhaust gasket...who cares? all the burnings been done. all it does is create a black mess over everything use locknuts ordecent washers, and tighten them... and use the mounting bracket(my kits always had some thin steel for wrapping round it?) or make something to support the weight of the can!

whereas...not idling...does it run with the exhaust on?

if so, its not blocked. or is it? it got ran over! pulled it apart at all?

tweaked the idle screw?

lowered the needle a notch to pop the idle up a bit?


carby leak...use the search button

RollingStones said:

I was in the middle of traffic when it fell off [the...] bike ran just fine for a day or two without the muffler except for the noise of course.

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My lord, the noise would have been horrendous, and you will now have permanent hearing damage, not to mention the rest of the neighbourhood complaining to police about your bike.

RollingStones said:

Now I know that obviously this is no good but the bike ran just fine for a day or two without the muffler

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By the sound of it, your bike most definitely didn't run "fine", otherwise it would still be running "fine".
Why on earth did you run the bike for 2 days without a muffler, when you could have either bolted on a new muffler staight away, or, just not used the bike till you received a new muffler.
Crikey, common sense logic will tell you that the front wheel is throwing dirt and debris at the front of the engine, so it's quite likely that some of it got in there and has now abraded the piston rings and potentially the chrome lining on the cylinder bore, which is likely to reduce compression and make it more difficult for the engine to idle.

RollingStones said:

Now I have the muffler back on but the bike will not idle with the muffler on. I could tell that there is a little bit of an air leak where the muffler connects to the engine... could this be the reason it won't idle or is the issue that I need to trash this muffler and purchase another?

Click to expand...

I refuse to believe that you have reinstalled the muffler that was run over by a car; i just simply refuse to believe it.

first, fix the carb in case all is due to just being too rich - then blow thru the muffler to see if it flows easily

Muffler is not blocked at all after I picked it up all that was wrong was a small dent on the body. Blows through just fine. I used washers and cush washers to lock it back in, might have to use some liquid gasket material to fill the small gap that still exists. Im going to mess with the carb today after work to see how the engine reacts differently to adjustments.

Actually fabian I loved the noise!! Not sure why you'd be so bothered by it. We must be from different genetations haha

No it ran "fine" what i mean by this is that put the muffler on bike does not idle unless I keep the throttle a bit engaged but runs with perfect power. Take it off and it idles fine and runs the same but louder.

I ran it for 2 days without the muffler because I liked the sound and by this I mean I took it on a mile or two ride around the block. Opened the engine and piston is fine and so is the cylinder. Common sense would've told you that Im looking for help troubleshooting my issue and not some grumpy condescending response.

Believe it or not I put on the same muffler!!!

Thanks for nothing

Gave the carb a look over and I used zip ties where the gas connects to the tank top/bottom of fuel filter but completely forgot to zip tie where it connects with the carb. Zip tied it and now bike idles perfectly.

Thanks to all of those that helped and also to all that doubted my common sense.