2000 sxR 700 Gargling sound mid range.

2

24vtd

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Feb 18, 2025
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Hi, i am having a time trying to figure out this gargling sound out the exhaust is. Its fine at WOT but around a quarter to half its a weird sound out the exhaust like its fluttering until i open it up. i have cleaned the carbs and adjusted the float height and mixture screws, also the Oring's in the seats. All three plugs are tan color. I live in Indiana so there is hardly any snow to test it out and when it does snow i would like to be prepared. I've read on here about reed spacers? and shims for the needles. I'm not sure what im looking for so any help would be awesome.
 
See if the main nozzles are still available and replace them. The hole where the metering needle slides through enlarges over time causing a rich mid-range condition.
 
Im looking at them online and it shows 3 different ones. i can't read the original number on my jets to determine size.
 
Cool, they are showing main nozzle 2 and 3, 8ch-14141-54-00. Then a nozzle main for a 600 but no 700.
 

8CH-14141-54-00		NOZZLE, MAIN | 2, 3
8CH-14141-54-00NOZZLE, MAIN | 1 SX600
 
PTO is a series 798 size Q-8
Middle and mag are series 798 size Q-4

I think the Q-4's are still available.
 
74Nitro said:
PTO is a series 798 size Q-8
Middle and mag are series 798 size Q-4

I think the Q-4's are still available.
Click to expand...
I just went out and rode it, the PTO carb is running rich the other two are kinda wet. it doesnt pop or backfire just acts like the choke is slightly on. its fine if its pinned all the way across the field. I really appreciate your help on this thing. I had a brand new one in 2000 and it didnt do this at all. this one has right at 4000 miles on it.
 
74Nitro said:
PTO is a series 798 size Q-8
Middle and mag are series 798 size Q-4

I think the Q-4's are still available.
Click to expand...
What would it hurt if i run the q4 and the needle in the PTO side? I can find those new.
 
24vtd said:
What would it hurt if i run the q4 and the needle in the PTO side? I can find those new.
Click to expand...
At your own risk, anytime I ever tried going down a size, the engine burned down. Did that on an indy 500 and a doo 550.
If you do try it, raise that needle all the way up.(lower clip)
The Viper 700 had the same size across the board, but the PTO cylinder head had slightly lower compression.
 
74Nitro said:
At your own risk, anytime I ever tried going down a size, the engine burned down. Did that on an indy 500 and a doo 550.
If you do try it, raise that needle all the way up.(lower clip)
The Viper 700 had the same size across the board, but the PTO cylinder head had slightly lower compression.
Click to expand...
Are the tubes straight thru on the i.d? If so i could have a shop ream the smaller new one out to size. If they are tapered i wouldnt think i could go that route.
 
74Nitro said:
At your own risk, anytime I ever tried going down a size, the engine burned down. Did that on an indy 500 and a doo 550.
If you do try it, raise that needle all the way up.(lower clip)
The Viper 700 had the same size across the board, but the PTO cylinder head had slightly lower compression.
Click to expand...
I think i have it figured out. It only has 80 psi in each cylinder.
 
74Nitro said:
That doesn't explain it idling good and revving out good. Try another tester.
Click to expand...
The neighbor has a compression gauge i can use. Hopefully my gauge is wrong. I have never ran into problems like this before with any Yamaha sled except the 83 vmax.
 
The fact that all three cylinders are reading the same compression would indicate to me it may just be the gauge reading low. Don't forget to do the test with all three plugs removed, throttle wide open, and 5 or so real good pulls on the recoil.
 
sideshowBob said:
The fact that all three cylinders are reading the same compression would indicate to me it may just be the gauge reading low. Don't forget to do the test with all three plugs removed, throttle wide open, and 5 or so real good pulls on the recoil.
Click to expand...
Can i use the electric start when doing this test? Or should i pull it? Thanks
 
sideshowBob said:
The fact that all three cylinders are reading the same compression would indicate to me it may just be the gauge reading low. Don't forget to do the test with all three plugs removed, throttle wide open, and 5 or so real good pulls on the recoil.
Click to expand...
Used a Snap On tester and it is around 138 per cylinder. Good old Harbor Junk gauges said 80.
 
When they say number 1 2 or 3 cylinder which one are they referring to when sitting on the sled? 1 being the PTO side? Or 3 being the PTO side?
 
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