I'm stumped !!!!!!!! 93 Panther - Snowmobile Forum: Your #1 Snowmobile Forum

seppi · 01-29-2006, 06:33 PM

Please help me somebody !!!!!
440 F/C Single CARB... Backfiring through the carb constantly...Here's what I've done
1: Cleaned all fuel system(carb,fuel pump rebuilt,new jets)fresh gas and checked pickup
2:New CDI and Ignition coil
3: Changed stator (used One)
4:New crank seals and top end (pistons and rings)
5:Complete gasket set and carb flange
6:Checked static timing, even tried advancing a couple of degrees...... The only hints I can give you is that when I choke it while its running and backfiring it picks up momentarialy(stops backfiring) but then it starts to over fuel!!!
7: Checked Exhaust,not plugged.....I'm at Whits end and stumped
8:New,spark plugs(2 new sets)
Sorry for the long post,but I wanted to let you know what I've done so far....I also unplugged the main harness and jumpered the brown and black wires ???Has electric start but the battery is not connected???

Thanks SEPPI

**smallengineguy** · 01-29-2006, 06:34 PM

Does it have reeds? Sounds like a broken reed.

seppi · 01-29-2006, 06:44 PM

No it doesn't have reeds,but thanks for the quick reply....I'm hopeing someone will have the answer ,it's probably something I'm overseeing and simple (LOL)
Thanks Again SEPPI

**smallengineguy** · 01-29-2006, 08:09 PM

Did you put an inline spark tester on it and run it. That will tell you if your spark is intermittant.

**RJ Gleason** · 01-30-2006, 11:26 AM

"6:Checked static timing, even tried advancing a couple of degrees...... The only hints I can give you is that when I choke it while its running and backfiring it picks up momentarialy(stops backfiring) but then it starts to over fuel!!! "

It sounds as if you are not getting enough fuel. what jet is in the carb and where is the air screw set to? Should be from 3/4 to 1 full turn out to start. The slide needle should be in the middle clip.

seppi · 01-31-2006, 08:11 AM

I'm running stock jetting 300M ,30P and .5 to2.0 turns on the air screw.....middle clip position

Seppi

seppi · 01-31-2006, 11:19 AM

The electric start is still wired in the the harness could this be shorting out or causing a problem to the ignition circuit somehow......Just a thought!!!!!!!

Seppi

**RJ Gleason** · 01-31-2006, 11:36 AM

Are the float arms parallel to or slightly down when you have the carb upside down and the bowl off. If they are sticking of set too low, you will get the fuel starve that seems to be happening here.

seppi · 01-31-2006, 04:06 PM

Just tried a carburetor off a 94 Panther 44o F/C (exactly)the same with the same results.Backfiring through the carb with a odd time through the exhaust?????? Unplugged harness at or near the recoil (4 pins)and jumpered the black and brown wire or else it wouldn't start ?fully advanced the stator just to try it(turned stator fullyccw)Stopped the backfiring,but no power at all ??????

What happens when the center crank seal is going or gone ????? I have a wierd problem,but I'm not going to give up!!!!!

Seppi

**RJ Gleason** · 02-01-2006, 02:54 PM

Try moving the stator about 1 degree at a time back towards 12 degrees retarded. Somewhere in there you may get lucky.

If the center seal was gone, It would keep switching sides that run and foul the plug. Eventually it would burn down a piston and quit because one cyl. is running lean and the other is too rich.

seppi · 02-01-2006, 10:09 PM

Ok guys and gals,I tried a complete exhaust off a 95 Panther 440 F/C,same result,but upon your ideas I did notice, that it is changing cyls(mag side very hot and dry,pto side warm but very wet)Stop engine and restart and guess what,pto side hot& dry and wet on the mag side!!!! Gathering all the info together and I would say the center seal is kaput ,right ?????

Seppi

seppi · 02-01-2006, 10:12 PM

Would I be able to change the center seal myself ???

Seppi

**smallengineguy** · 02-01-2006, 10:16 PM

No, the crank needs to be pressed apart to change it. But you CAN strip the motor down and remove the crank yourself.

seppi · 02-01-2006, 10:20 PM

Do you agree it's the center seal ?????

Seppi

**RJ Gleason** · 02-02-2006, 03:36 PM

Most definately!!!!!!!! it is the center seal.

seppi · 02-02-2006, 04:13 PM

Guys we found the problem!!!!! I took it apart and guess what,the connecting rods aren't 180' degrees apart. When the mag side rod is at TDC the PTO side is at 5:00 or about 165 degrees. Hense, I would think it is out of time on the one cylinder for sure,right???? Again thanks for all your expertise and pointing me in the right direction !!!!!

Seppi

**RJ Gleason** · 02-02-2006, 04:23 PM

With the swapping or sides when running, I still reccomend that you replace the bearings and seals since you have to have it pressed apart to get it realigned correctly. Best thing here is that you will have a nearly new engine when done.

seppi · 02-03-2006, 08:49 PM

10 - 4 RJ ,it's at the engine shop as we speak,and he recommended the same thing ! Thanks again people for the quick responses, I'll be on the road er trail in about a week !!!!

Seppi

BskidooC · 02-03-2006, 09:09 PM

always good to hear some good news

**RJ Gleason** · 02-05-2006, 10:56 AM

Another happy customer helped by good information(note: I sprained my shoulder patting myself on the back here)