Now before I get 20 replies telling me to clean the carbs let me say that they were cleaned when we did the jetting for the pipes. Yes we took the jets out and sprayed carb cleaner through each, etc... Could there still be dirt in there? Yes of couse and I will probley clean them again anyway, but I've got a questions I want answered regardless.
-- rant over, down to business --
Like the title says. Only riding I've really had a chance to do so far has been on warm days. Sled is jetted for 0-20F and both times I've had the problems it's been approx 32F. I think it drops the PTO cyl which run the richest due to lower compression and the fact the pipes run close to the other two. Seems to be worst from idle to 1/4 throttle. If I put it to the bar it takes off on all three and climbs right to peak RPM. Anyway, I think the pilot is so rich it's fouling the plug? Once you crack it open it clean it's self off and starts firing again.
One more thing to add here. When it starts running bad (i.e. one cyl not firing), if you let it idle it will backfire lightly now and them (mostly after a long WOT pull). Is that just cause the plug finally decided to fire and there was a tone of fuel to burn?
Help....
-- rant over, down to business --
Like the title says. Only riding I've really had a chance to do so far has been on warm days. Sled is jetted for 0-20F and both times I've had the problems it's been approx 32F. I think it drops the PTO cyl which run the richest due to lower compression and the fact the pipes run close to the other two. Seems to be worst from idle to 1/4 throttle. If I put it to the bar it takes off on all three and climbs right to peak RPM. Anyway, I think the pilot is so rich it's fouling the plug? Once you crack it open it clean it's self off and starts firing again.
One more thing to add here. When it starts running bad (i.e. one cyl not firing), if you let it idle it will backfire lightly now and them (mostly after a long WOT pull). Is that just cause the plug finally decided to fire and there was a tone of fuel to burn?
Help....
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SRX7
New member
did you just blow this thing up ?
stock jetting is good for a wide temp range, i rode mine on the very last day i could last year and I think it was like 50* out and the sled ran fine all be it not much pep but it pulled fine,check your carbs again and make sure you can see light through all the little holes in the jets etc.ater you clean them throw in new plugs, there no reason if the carbs are done correctly it shouldn't run like normal.look at your pilots again.
i can't remember when i had pi pipes on my sx700 if i changed pilots or just jets.
also hows your plug boots? clean and tight fitting?could be a weak coil?
stock jetting is good for a wide temp range, i rode mine on the very last day i could last year and I think it was like 50* out and the sled ran fine all be it not much pep but it pulled fine,check your carbs again and make sure you can see light through all the little holes in the jets etc.ater you clean them throw in new plugs, there no reason if the carbs are done correctly it shouldn't run like normal.look at your pilots again.
i can't remember when i had pi pipes on my sx700 if i changed pilots or just jets.
also hows your plug boots? clean and tight fitting?could be a weak coil?
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SRX7
New member
also oil pump set ok?
SRX7 said:
No she's not blown up. When I say drop I mean it stops firing. Jetting is not stock as I have SLP pipes on it. Plug boots are fine. Could be weak spark, but it runs fine at higher RPM. Oil pump is set to stock.
I'm going to redo this same plug reading test tonight as its supposed to be 0f which is the low end of my jetting setup. If it runs fine, then its just because it's pig rich. If the problem continue, I'll know I have a carb problem. Glad the wether is helping me out, lol.
SRX7
New member
what is slp calling for in jetting and pilots?
daman
New member
You need to clean carbs for one!!!! 
like srx7 said what pilots you using and where's your f screw's???
like srx7 said what pilots you using and where's your f screw's???
For 0-3000' running between 0-20F, SLP calls for 47.5 pilot and screw at 1 3/4, which is what I'm running.
daman
New member
If electrical system if fine?, i'd check into jetting,,,float hight etc...
how's the rest of the range??? rich too??
how's the rest of the range??? rich too??
Electrical should be fine, check the wire harness etc when I had the motor out. Jetting is fine in the rest of the ranges. Just seems to affect 0-1/4 throttle, right where pilot and needle over lap. I'm still leaning towards rich pilots. Guess I'll find out tonight when the temps from to 0F like I said.
daman
New member
what temp was it out when you fould????
viperino
New member
plug caps, wires, coils ok?
just close the pilot screw some and try it back...this is the best way ...
SRX7
New member
relax yamer ,daman just trying to help..............YamerDown said:see post #1.
SRX7
New member
why don't you try putting the stock pilots back in and see what it does. i know for pi pipes they give you that option but not necessary for a 47.5 pilot and jets where pto 143.8, cent 145, 145 mag
good idea after that u will see if its still missing... make sure you didnt change the float levels
SRX7
New member
you may know the stages already,
http://www.lafishmag.com/CarbTuning.html
http://www.lafishmag.com/CarbTuning.html
daman
New member
K missed that part..YamerDown said:
Ummm i wouldn't do a thing till you test on a cold day,,32deg is warm!!!!!!
SRX7 said:
I know, I appreciate the help.
Just the whole point of the post was to find out if running outside the jetting specs is what's causing the two symptoms I described. The post is basically asking two questions.
1. Is it more likely I have a dirty carb, or am I just fouling cause the pilot is too rich?
2. Can a rich condition cause a backfire?
No offense intended daman.
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