Author Topic: fl350 backfire through exhaust  (Read 2641 times)

navy350r

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fl350 backfire through exhaust
« on: February 13, 2007, 11:56:08 AM »
I recently purchased a 350 and I got it started finally yesterday. It has a water cooled head, 38mm carb with 186 main,aftermarket snorkel and a K&N filter, br9es plug, DG pipe and silencer and has 125psi of compression. Once I got all the water out of the case from the last owner leaving it out in the weather!! I did get it running. It Idles with a little spitting but if you give it any gas at all it picks up some RPM then bogs and shoots flames out of the pipe. Any ideas? Is it just too lean? I have wrenched allot of 2 strokes and never had one backfire this violently!
Thanx in advance!

nuke em

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fl350 backfire through exhaust
« Reply #1 on: February 13, 2007, 01:03:53 PM »
First off, "Welcome to the board!" Where are you located?

Sounds to me like you are still  burning out some moisture. Everytime i have had backfires over the years, it has envolved water. The only other possibility that comes to mind would be a bad reed petal.

There is alot of good info to read on the board. Feel free to ask questions, lots of knowledge here.

Gary

Weed

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fl350 backfire through exhaust
« Reply #2 on: February 13, 2007, 02:18:04 PM »
I agree with Nuke Em........the water issue has been the culprit when I had that problem.  Or a possiblilty is that the flywheel key had sheared and the timing is off.   I would put a bet on the water.  

I added alittle alcohol to get rid of the water(not the stuff you drink) in the carb and crankcase.  Not much, too much will wash the cylinder walls of the oil that protects it.  And it is not compatable with most two-cycle oils so use with caution...... Products like Heet, fuel de-icers, or even grain alcohol will work.

lee1969gb

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fl350 backfire through exhaust
« Reply #3 on: February 14, 2007, 12:31:47 AM »
My pilot has a backfire problem but not the same, When you turn off the engine then wait a few seconds there is a loud explosion, sounds like a shot gun going off.
It seems the more you have thrashed it the louder the bang, then last week my second pilot started doing the same.

FL670R

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fl350 backfire through exhaust
« Reply #4 on: February 14, 2007, 12:44:03 PM »
Sounds like you have a possible air leak or bad carbon build up....
Have you had the top end apart lately ???

Backfires are bad and can easily damage the reeds...

I'd pressure test the engine first and if that checks out
I'd most likely pull the head and de-carbon the top end and exhaust

navy350r

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IT quit backfiring!
« Reply #5 on: February 14, 2007, 05:55:07 PM »
I got the moisture out I guess, It did quit backfiring. I now have a power problem. It doesn't want to rev up. It does just a hair better with the  with the choke on. I cleaned this carb so that it looks new! I may adjustments up and down on the needle. I even changed the mains between a 186 and a 180 just to try it. I believe it may have an electrical issue. I notice that when the light are on. They are bright at idle and then they go dim when the engine gains a little RPM. SO I am taking all of the connectors apart and cleaning them up. I may have a faulty ground or just a plain bad connection. It doesn't REV on it's own like it has an air leak. I will let you know. I sure appreciate the help!!!!   BTW I am in Jacksonville Florida.
Thanx!
Joe

nuke em

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fl350 backfire through exhaust
« Reply #6 on: February 14, 2007, 09:19:04 PM »
Hi Joe,

  I had the exact same problem with my lights. It turned out to be the dead battery. I had been pull starting it and never give it a second thought. Something in the electronics/charging system doesn't like a dead battery. If you have a good battery in it, post back and we will try to help.

 gary