Gas In Air Box?? Tech Challenge

Another thing I've noticed lately, since these things are getting older, I've been replacing the orings around the needle and seat. I've taken acouple carbs apart and the seats just fall out, there's no tension from the oring, they shrink up. So now it's just standard procedure.

I had a customer with a piped Viper that ran OK for 2 years and then just started fouling plugs on one hole, we chased that one, that carb, the seat fell out when I turned the carbs over, the oring was flat, 3 orings later it was back to normal.

FYI
 

I have not pulled the orings - but what i have done is i turned the carbs upside down and i blew into the fuel line intake and the needle seems to hold the pressure from me blowing into it - would this test show that the needle is seating good with the orings
 
Run it with the can off or try another can and see if your problem is gone. If you run it lean with a plugged exhaust it will show rich on the plugs, use more fuel and could cause the spitting back through the carbs.
 
You know what that is starting to make absolute sense.

two years back I heated the exhaust so much on the rail line that the y pipe cracked. once i stopped the sled the fuel that was blowing back to the air box and pooling down on the bottom of the machine caught on fire where the exhause exits the machine. Luckily I was able to put it out quick and all that was damaged was a little bit of moulding around the exhaust.

Anyway a little bit after that I was out on the trail and pulled into the garage of a yamaha dealer to change out a bogey wheel. When I pulled into the garage the two machanics both said that my machine sounded different and they couldn't really pinpoint why. This may be my trouble all along. Maybe the can is allowing just enough flow for the machine to function but is too restricted and causing to much back pressure.

I also just rebuilt the top end of the machine. The piston wash indicated that I was running lean and I couldn't understand why cause thats not how my plugs looked so I have a can that I am going to switch out this afternoon and I will let you know.

If thats not it I got another carb that I will switch out but I really don't think its my carbs.
 
152.5's are pretty rich....and raising your needle???that is going to make it richer....if your float levels are stock they are off by a mile, i would certainly adjust those....i believe they should b 15.3mm but that is off the top of my head.... sounds like plugged exhaust and/or worn cap and sheave bushings and combination of things to mee....i would try a different silencer first.....
 
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Hey Guys,

Well I don't think its the can....... I threw everything back together...needles and mains are stock again and I am still getting tons of blow back especially when I hit the throttle. I have a line on some carbs and a fuelpump from my buddy Viperken that I will switch out and give a try when I get the chance.

Damn this sucks....All this snow and it is costing me tons of $$$$ in gas and oil to ride...i need to figure this out soon cause the line of credit is going to take a beating. lol
 
Interesting post. My Viper also got in the 9-10MPG range. I had hopes of figuring it out before modifying mine and never did. Replacing all of the secondary bushings on mine made no difference. Mine was also rejetted and the float levels fixed, no change. Mine would do fine if it was babied but normal riding it was a pig. I put pipes on mine so I don't have to feel so bad when it eats gas like it did.
 
I do not know the specs on the reed stoppers....I guess it could be.

Does anyone know the specs on the reed stoppers
 
I switched out my reed stoppers and cages but they look to be in the same shape as mine so I am not counting on any miracles when I try them out.

Any more suggestions guys???
 
I think your beating a dead horse here, triples will have spit back!!!! that's just how it is!!!,,put her back together and focus your attentions on another area.

My SRX does the same thing, and i get killer mileage outa it..
 
I am with Daman on this....my SRX always has oil/gas residue in the air box, always. I clean it every year and good to go. It is normal.
 
hey guys I realize this but if you actually saw the amount of spit back you would see that this is not normal. I have been thru everything else.

I ride with other stock vipers....they do not have the same amount of spit back as me....not even close
 
I'd check ignition timing. You have done soooo much. What else??? Ignition , compression, spark. 2 strokes are fairly simple. You should update a list of all the things that have been done to the sled and all the things you have checked over....all the cylinders spit???? What kinda mileage do you actually get????
 
if you ride with sooo many vipers I'd start swapping parts!!!! reeds, carbs, exhaust, air box etc....anything that is mounted externally. IF they don't work maybe it is time to tear into the engine.
 
does anybody know if the expansion chamber has an inner lining? My old sx600 does and I have found some loose pieces of metal [perforated like the inner tube from old stingers] from time to time.Again maybe a partial blockage.
 
100 miles to a tank on a Viper is terrible milage.On a warm sticky snow day I can get at least 125 before the low fuel light comes on.And it will go a long way after that.
 
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