Polaris XLT backfiring through the carburetors - Snowmobile Forum: Your #1 Snowmobile Forum

lmassy · 01-31-2012, 06:39 AM

Need some help on a 1997 Polaris XLT Limited.
I just purchased it this year.
At first it was hard starting and flooded the entire motor.
I read up on this site on how to adjust the carbs, drain the fuel from the block (and to shut off the gas when not in use).
I pulled the carbs off, cleaned them with a thin wire and put them back on.
It starts perfect now and seems to run great when on the jack stand.

Took it out for a ride last weekend for the first time and it backfired through the airbox until it hit about 5K RPM.
It is a dog on take-off, but pulls like crazy once it hits 5K RPM.

Sorry for the long story, but wanted to give you the background.
So, since this winter looks like a short one, I want to fix this ASAP.
Someone suggested just buying new jets and reed valves and simply replacing everything and setting back to factory specs.

Anyone have any suggestion on what parts are best and where to get them?
Would like to just order some type of jet kit and reed valve kit on line if possible.

Open to any other suggestions also.
This is my teenage son’s first snowmobiling experience and want to get some good riding in this year.

northeastnate · 01-31-2012, 10:05 AM

have you pulled the plugs and looked at the pistons ?

TwinsofMLB · 01-31-2012, 11:32 AM

Check the float levels.

robhill1965 · 01-31-2012, 12:15 PM

Backfiring points to timing. Even if it's got too much fuel, it shouldn't spark while the intake port is open and blow it out the carbs unless it's too far advanced. This would also explain why it runs great at higher rpm.

guitarman69 · 01-31-2012, 12:23 PM

Check your reed,s I bet the peddels are worn out or broken, My sled was doing the same thing, it took a while to figure it out, but my v-force reeds were thundered

lmassy · 01-31-2012, 12:27 PM

I am pretty sure i got the carbs as clean as I could. The plugs were brand new and looked good after I ran the sled. I looked at the piston tops and all 3 looked good and clean (no marks at all).
How can I check the timing?

Indy92 · 01-31-2012, 01:05 PM

If there is no carbon on the pistons at all that means your running too rich

ppolaris1010 · 01-31-2012, 03:26 PM

put new needle and seats in the carbs common problem with the xlts to flood the case.only issue with that is they also twist cranks fairly easy and with the bottom end full of gas it doesn't take much to hydro lock it and knock the crank out of phase which would mess your timing up and cause backfire but thats a last resort check everything else recomended on here first and if nothing works then you have to get the crank specs and check it with a degree wheel and dial indicator to see if its out of phase

lmassy · 01-31-2012, 06:40 PM

Quote:

Originally Posted by ppolaris1010

put new needle and seats in the carbs common problem with the xlts to flood the case.only issue with that is they also twist cranks fairly easy and with the bottom end full of gas it doesn't take much to hydro lock it and knock the crank out of phase which would mess your timing up and cause backfire but thats a last resort check everything else recomended on here first and if nothing works then you have to get the crank specs and check it with a degree wheel and dial indicator to see if its out of phase

Does this year even have Reed Valves?

TwinsofMLB · 01-31-2012, 07:20 PM

Quote:

Originally Posted by lmassy

Does this year even have Reed Valves?

Not hard to check. Just pull off the carbs and intake boots.

I wouldn't think timing would cause this issue. Sounds a lot more like it's running rich to me. Does it smoke too? If so, I'd check the oil injector too. Most likely scenario, though, would be that the floats are sticking, set incorrectly, or the needles may be slightly bent. Oh, and make sure you didn't put the slides in backwards

ken3296 · 01-31-2012, 07:31 PM

Good luck. The best day I had with my XLT was the day it left my driveway on someone elses trailer.

lmassy · 08-06-2012, 08:02 PM

I made the move and got another SkiDoo.
I picked up a 1999 SKI-DOO MX Z 670 H.O Toni Haikonen 06.
It is all stock with studded track and only has 2,400 miles on it.
I runs great.
I still need to get rid of the Polaris, but looking forward to the new Skidoo.
I do not know much about the 670 H.O Toni Haikonen edition, but I am guessing it will hold it's value.

white lightning · 08-08-2012, 12:26 PM

twisted crank? Theres no reeds in XLTs. WL