it has a new belt installed
A couple of bucks
VIP Member
Keep in mind that I'm just trying to brainstorm here. What do the plugs look like after a good long pull on top where it is falling on its face. Hitting the kill switch at WOT.
spark plug caps should ohm out at 5000k each, thats a good place to look.
I would also see if you put the sled up on a stand and remove the powervalve servo cover. rev up the snowmobile beyond 6000rpm with a few big throttle hits and observe the servo wheel. When the powervalves open does the servo hold the wheel steady or is it a jerky back and forth motion???(you might need someone to help you do this test so you can watch it since its on thewrong side from the throttle)
I would also see if you put the sled up on a stand and remove the powervalve servo cover. rev up the snowmobile beyond 6000rpm with a few big throttle hits and observe the servo wheel. When the powervalves open does the servo hold the wheel steady or is it a jerky back and forth motion???(you might need someone to help you do this test so you can watch it since its on thewrong side from the throttle)
plug caps are at 5600
I put the machine on the jack stand, and took a video of the servo motor. It is opening full under full throttle, and also cycles when letting off the throttle.
I put the machine on the jack stand, and took a video of the servo motor. It is opening full under full throttle, and also cycles when letting off the throttle.
well.... then theres nothing wrong with it then.....lol
when you ride this sled, what happens if you just barely reach down and touch the choke lever, not up to the first notch but just barely lifting on it, this will richen it up. Does it gain rpm back or drop even more? obviously you need a nice flat field or road to try this.
when you ride this sled, what happens if you just barely reach down and touch the choke lever, not up to the first notch but just barely lifting on it, this will richen it up. Does it gain rpm back or drop even more? obviously you need a nice flat field or road to try this.
This morning I re-jetted to 152.5 mains, as I felt it was a little too lean on the 150's.
I went to the near by lake and did a few passes at -5 C. the machine still fell down towards 7800 rpm. I lightly lifted the choke plunger and the rpms fell even more.
I think I would like to try changing the ECU next. I am hoping to borrow one from a friend.
I went to the near by lake and did a few passes at -5 C. the machine still fell down towards 7800 rpm. I lightly lifted the choke plunger and the rpms fell even more.
I think I would like to try changing the ECU next. I am hoping to borrow one from a friend.
A couple of bucks
VIP Member
Have you taken a SHARPIE to both clutches? Just to see if the belt is going through the full range of both clutches.
well if it wont take more fuel its either too rich to begin with or... you could possibly have a timing issue which would be handled thru the cdi box however i have never in 15yrs had to change one out because of that but its an electrical device so theres no for sure rule about it. I dont think that will be the problem but if you can swap it out and test it will remove one more item from the list. after that we will need to look at exactly what engine mods you did...
Is there a chance the TPS is not working properly? It seemed to be in spec when I tested with the Ohm meter by the manual. I think I did this correctly?
I am not ruling out the mods, but this machine was not pulling RPM in stock form last year either.
I am not ruling out the mods, but this machine was not pulling RPM in stock form last year either.
joejammer
New member
- Joined
- Mar 19, 2014
- Messages
- 71
Could it be a tors switch? Are clutches cleaned?
the clutches are clean and tors is disconnected
shaggyzr2
Active member
My sleds was doing about the same thing last year, I went leaner on the jetting and it made a huge difference!
rechecked the tps and found it to be out of adjustment. it was at .56 volts and I adjusted to .64 volts.
I went to the races this weekend and switched the cdi with a buddies. this made no difference, the machine still fell off. I switched to my cdi and adjusted he clutching by adding a shallower helix and silver spring. the machine pulled a steady 8500 after this adjustment. Trouble is, this is just a band aid to raise the rpm.
Surprisingly, all the planets lined up and I took 2nd in 700 imp. 2 machines red lighted in the final and I was left with 2nd. LOL
Has anyone ever found issues with the stock silencer plugging off, or loose baffles etc.? When I bought this machine, it had a silencer on it that I sold, because it was too loud and I felt the stock silencer worked better. I wish I had kept this so I could try it again.
I went to the races this weekend and switched the cdi with a buddies. this made no difference, the machine still fell off. I switched to my cdi and adjusted he clutching by adding a shallower helix and silver spring. the machine pulled a steady 8500 after this adjustment. Trouble is, this is just a band aid to raise the rpm.
Surprisingly, all the planets lined up and I took 2nd in 700 imp. 2 machines red lighted in the final and I was left with 2nd. LOL
Has anyone ever found issues with the stock silencer plugging off, or loose baffles etc.? When I bought this machine, it had a silencer on it that I sold, because it was too loud and I felt the stock silencer worked better. I wish I had kept this so I could try it again.
yamalars
Member
Did you ever find the problem?
viperhauck
Member
Maybe the choke cable is slightly out of adjustment. I don't see how it could be running lean with brown/black plugs. Or is has wrong belt but he said he watched it shift.
Did you ever find the problem?
No, I have never found the problem. I have installed an updated TORS. Haven't had time to check this yet.
No, I have never found the problem. I have installed an updated TORS. Haven't had time to check this yet.
Way too cold to ride today and waiting for the shop to warm up so I can work on my Apex...-33c!!!
I just reread your initial post and saw you have bored your carbs to 35.5. You are obyiously rotating your TPS further at full throttle with the added throttle movement to fully retract the slides.
When I was dealing with TPS issues on my 2002 SRX I found that the full throttle TPS value had a huge effect on full throttle performance. Too high of full throttle TPS voltage would cause the sled to lay down on top. acting like it was rich and loosing RPM.
I found the optimum full throttle TPS voltage for my sled was @ 3.0 volts or slightly less....worth a try.
I just reread your initial post and saw you have bored your carbs to 35.5. You are obyiously rotating your TPS further at full throttle with the added throttle movement to fully retract the slides.
When I was dealing with TPS issues on my 2002 SRX I found that the full throttle TPS value had a huge effect on full throttle performance. Too high of full throttle TPS voltage would cause the sled to lay down on top. acting like it was rich and loosing RPM.
I found the optimum full throttle TPS voltage for my sled was @ 3.0 volts or slightly less....worth a try.
I hooked a leak down detector on my SRX today. I am getting 10% leak down on all 3 cylinders. Is this too much and could this be causing the machine to not hold the revs @ 8500?
10% isnt great by any means but that wouldnt be enough to do the rpm drop, thats somewhere else.
are the buttons on the secondary clutch worn flat?
when you say your using a straight 45 helix is it a stock yamaha helix or an aftermarket helix thats maybe coded?
are the buttons on the secondary clutch worn flat?
when you say your using a straight 45 helix is it a stock yamaha helix or an aftermarket helix thats maybe coded?