99' SRX 700 Poor Acceleration

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Fleury_XLT

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Nov 29, 2010
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Quebec,Canada
Hi, i've got a '99 SRX 700

When I put it wide open throttle when the engine idle, it want to die. When I unplug once at a time the spark plug cap, when the engine idling, the 2 two first cylinder work but not the last one. I've just cleaned all of my carburator without any changements. When it rev over 3000 rpm, everything is correct, it give me good performance. I forgot to say that the engine backfire when I decelerate (probably the last cylinder). I've changed the sparks plugs too

What could it be? Thanks
 
Sounds like a plugged pilot jet, try cleaning the carbs again and look at the jets. Blow everything out with air too.
 
No, nothing changed when I've switched spark plug cap.

I observed that the engine rev when I give throttle, and the rpm down slowly
 
A few things to check:
-clean the carbs again, paying close attention to the pilot jets and the air jet[at the front of carb], ensure you blow out all the passages with compressed air,and check the filter under the float needle and seat
-check the carb float levels
-check that start valves[choke] is working properly
-check coils, if your sled is a 1998/99[can't do this on 2000+] you can just move the spark plug wires from cylinder to cylinder, see if the problem moves with the plug wire
-check your reed cages,a broken reed can cause this

Just some ideas to check...

Bob
 
Fleury_XLT said:
Hi, i've got a '99 SRX 700

When I put it wide open throttle when the engine idle, it want to die. When I unplug once at a time the spark plug cap, when the engine idling, the 2 two first cylinder work but not the last one. I've just cleaned all of my carburator without any changements. When it rev over 3000 rpm, everything is correct, it give me good performance. I forgot to say that the engine backfire when I decelerate (probably the last cylinder). I've changed the sparks plugs too

What could it be? Thanks
Click to expand...

First determine if there is spark to that cyl, also you could compression test that cyl as well. If you have compression and spark then its a fuel issue!!
 
Hi guys, today i've checked a lots of things, but nothing worked.

- I've cleaned carburator ( ajusted fuel screw to 1 7/8 turn each and cleaned air jet, pilot and main )

- I've changed spark plug cap

- I've taken compression, not sure my gauge is precise, but there 110 Psi to each cylinders

- I've checked spark plugs, can you remind me the good one, I'll go buy some new, is NGK BR9...??

Now, I have great power after 4000 RPM, could it be reliated with powervalves or anythings elses ??

I've just bought this snowmobile 3 weeks ago and i'm really confused, I want to fix it because I like the power !
 
Just forget to say that, there still a ''lag'' when the engine running at idle and I put it full throttle, but after 3000-4000, everything is ok. When I decelerate, there some back fire. Worn plug ? Powervalves ? ? ?
 
hate to say it..but check your pilot jets again.Next time you have your carbs open,check that little umbrella type of screen where the float pin is.There is a small philips screw to remove and then caefully remove each one and inspect for clogged screens.
 
Today, changed all three spark plugs for brand new NGK BR9 ECS, nothing have changed....

- Later, i'm gonna re-open my carb, and check my jet again...

The cylinder that didn't work at idle is the one beside exhaust pipe. At idle, the manifold stay cold, until I give some throttle. That cylinder give me the highest compression number !!
 
Hi guys, I've just found the issue today. Since I was checking for reed valves, I saw a worn intake gasket. This is why the engine speed up when deceleration and back firering. So I want to say thanks to everybody who helped me !

Thanks.
 
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