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Banshee backfiring on left side and feels like a loss of power.


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Hi I just bought a brand new 2001 Yamaha banshee took it out on the trails over the weekend and when I got home to wash it off I noticed that the left cylinder was backfiring. The bike ran perfect all weekend until I washed it off I swapped the plugs to the left side and still the same thing I also swapped the coils and still left side backfires and pops carbs are in sync no recent work, my next step is a compression test next. Any info would be a great help as this is my first banshee but I am very mechanically inclined I own a auto shop so the work I can do but this is just uncharted territory! Thanks

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Hi I just bought a brand new 2001 Yamaha banshee took it out on the trails over the weekend and when I got home to wash it off I noticed that the left cylinder was backfiring. The bike ran perfect all weekend until I washed it off I swapped the plugs to the left side and still the same thing I also swapped the coils and still left side backfires and pops carbs are in sync no recent work, my next step is a compression test next. Any info would be a great help as this is my first banshee but I am very mechanically inclined I own a auto shop so the work I can do but this is just uncharted territory! Thanks
Good, means you've got all the tools needed. Do the compression test, just to give you rough idea in what state the bike is.
Leave it to dry, maybe water got in somewhere where it shouldn't be, than try to run it.

Sent from my VOG-L29 using Tapatalk

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2 hours ago, the boris said:

Good, means you've got all the tools needed. Do the compression test, just to give you rough idea in what state the bike is.
Leave it to dry, maybe water got in somewhere where it shouldn't be, than try to run it.

Sent from my VOG-L29 using Tapatalk
 

I’m getting 30 psi on the bad side and 90 psi on the side that runs .. from what I have read the psi should be between 100-140 psi correct?

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3 hours ago, 375hp banshees said:

More than likely a lean pop one of your jets is probably clogged, i' d start there...if it doesn't fix it's self when dry?

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I’m gonna put new heads, pistons and rings the carbs I haven’t touched , but I’m curious if this can cause the cylinder to go bad and should I clean the carbs out just for shits and giggles??

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I’m gonna put new heads, pistons and rings the carbs I haven’t touched , but I’m curious if this can cause the cylinder to go bad and should I clean the carbs out just for shits and giggles??
Bad mixture can cause all kinds of nightmares in 2 stroke engines. God air/fuel ratio is paramount.
Once you rebuild it make sure you have no air leaks whatsoever and have proper carburettor tune up.

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^ clean carbs 1st
& leakdown before teardown( if you do) along with fixing any thing you can before.
There's a lot of horror stories that people rebuild because of the Leak and the new Rebuild blew up quickly, due to same leak!

If it ran Perfectly on last ride you might wanna get a GOOD psi tester. It's possible it blew up at the end of the ride but...
The plug in the 30 psi hole should have told you alot ( If indeed it was 30PSi)
If and when you do rebuild , do a search on Chinese parts, do not waste your time no matter how good the deal sounds. Rebuild the carburetors one at a time ( i'd do this now & try), as not to mix parts up, that is another very common mistake, when you're done and can't get it running, Along of forgetting to put that cross over tube back on

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Ok so I just finished installing the new heads started it up to do the heat cycles and it took me some time to get it started.. once I started it up it ran fine but I could still hear it popping some so I gave it some gas and it’s definitely still backfiring but it seems to be both cylinders this time. Could it be reeds?  Beginning to get fed up with this bike😡🤬

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On 5/9/2020 at 7:54 AM, 375hp banshees said:

^ clean carbs 1st
& leakdown before teardown( if you do) along with fixing any thing you can before.
There's a lot of horror stories that people rebuild because of the Leak and the new Rebuild blew up quickly, due to same leak!

If it ran Perfectly on last ride you might wanna get a GOOD psi tester. It's possible it blew up at the end of the ride but...
The plug in the 30 psi hole should have told you alot ( If indeed it was 30PSi)
If and when you do rebuild , do a search on Chinese parts, do not waste your time no matter how good the deal sounds. Rebuild the carburetors one at a time ( i'd do this now & try), as not to mix parts up, that is another very common mistake, when you're done and can't get it running, Along of forgetting to put that cross over tube back on

Sent from my SM-A505U using Tapatalk
 

Ok so I just finished installing the new heads started it up to do the heat cycles and it took me some time to get it started.. once I started it up it ran fine but I could still hear it popping some so I gave it some gas and it’s definitely still backfiring but it seems to be both cylinders this time. Could it be reeds?  Beginning to get fed up with this bike😡🤬

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1 hour ago, 375hp banshees said:

So you didnt clean your carbs 1st...did you after?

Define new heads & if you mean cylinders & brand new. post pics of side view @ intake area & pistons

Whats your compression now?

You didn't check the reeds when you had them out?

I put new pistons 68mm with new 68mm juggs compression is 120-130 both cylinders I cleaned carbs but I’m not sure on how to check the reeds. They looked fine when I looked at them. I Also did plugs , I got a guy coming to look at it tomorrow but he suggested maybe a cracked flywheel 

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21 hours ago, 375hp banshees said:

So you didnt clean your carbs 1st...did you after?

Define new heads & if you mean cylinders & brand new. post pics of side view @ intake area & pistons

Whats your compression now?

You didn't check the reeds when you had them out?

Hey just wanted to let you know I got the bike all set I was missing the hose that connects to both carbs to sync them put that on and tuned the carbs now it’s all set

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