97 Vmax 700sx Mystery Bogging Issue

rudim_86

New member
Joined
Nov 24, 2020
Messages
6
Location
Houghton, MI
Hello,

I am experiencing very weird issues with my vmax. I'll preface this with saying that I have new spark plugs, clean carburetors, properly synced fuel screws/carbs, and 120 psi of compression in three cylinders. My sled idles on three cylinders, seems to be fine there, when it gets warmed up it will bog around 4000 rpm and won't even engage the track because it won't exceed this engine speed. I have a video attached hopefully depicting exactly what I'm talking about. Out of frustration the other day, I took it to a shop and they are saying this could be a stator issue. I have no idea what the indicators of a bad stator are, hopefully someone could offer some insight there.

Another suspicion I have is that my needle valve assemblies may be bad in my carburetors. I rebuilt the carbs last fall and used a cheap rebuild kit. I suspect the seat may be bad as these are rubber, maybe my floats need to be tuned, I don't know. The sled ran perfect last year and now it doesn't. I took the carburetors off a few weeks ago and cleaned them out, this did nothing, it still bogged. I don't want to buy a stator if I don't need it, I'm a broke college student.

Any help would be so incredibly appreciated. Thank you.

The video is here: Video Link

PS: I've already looked into a potentially faulty throttle safety switch. It's not that.
 
Last edited:

sideshowBob

VIP Member
Joined
Jan 7, 2009
Messages
2,224
Age
65
Location
Northwestern Ontario
That sure looks like a TORS issue[Throttle Over Ride System]
Try loosening your throttle cable and maybe unplug the THORS on the throttle rack then plug the two wires from the sleds wiring harness together to bypass it. If its the TORS fix it and for safety sake don't ride it with its bypassed.
 

rudim_86

New member
Joined
Nov 24, 2020
Messages
6
Location
Houghton, MI
That sure looks like a TORS issue[Throttle Over Ride System]
Try loosening your throttle cable and maybe unplug the THORS on the throttle rack then plug the two wires from the sleds wiring harness together to bypass it. If its the TORS fix it and for safety sake don't ride it with its bypassed.
I have in fact tested the TORS and it isn't that. The engine limits itself at a higher rpm than the TORS does.
 

sideshowBob

VIP Member
Joined
Jan 7, 2009
Messages
2,224
Age
65
Location
Northwestern Ontario
It seems to run at low RPM too well to be fuel related and acts like a rev limiter cuts in so maybe it is the stator or CDI

-try draining the fuel and adding fresh premium fuel a long shot but who knows
-check for badly rusted flywheel
-check the reed valves
-check/replace the float needles
-check the O rings under the brass needle seats as they can dry out and leak
-while you have the needle seats out remove the little top hat filters that are under them...they plug up at times

Keep us posted
 

mod-it

Member
Joined
Nov 15, 2006
Messages
907
Age
48
Location
Lewiston, ID
So, you're 100% positive it isn't the TORS? Pardon my asking (it sure sounds like TORS engaging), but what testing was done to ensure it isn't the TORS engaging? I do think a shop would certainly be able to easily dismiss a TORS issue properly, but...

With the above being said, the very next thing would be the "cheap rebuild kit" that was put in. It worked perfectly fine last year, but now doesn't. The carb components are what is different this year. But while sitting, gas can go bad, flywheels get rusty, mice block exhaust pipes by building a nest...all good things to check.
Sometimes a stator getting weak can be diagnosed by unplugging the headlight, unplugging the taillight, making sure the hand warmers are off, and then seeing if the problem is better. By reducing the load on a weak stator you will sometimes see the engine bogging go away.
 

74Nitro

VIP Member
Joined
Feb 4, 2020
Messages
266
Location
Dublin, On
Do another video, and instead of feathering the throttle, stay right in it, as in keep it squeezed.

It does sound like TORS, but hard to tell because you're dicking around with the throttle.
 


Top