85 & 86 SRV same issue - Snowmobile Forum: Your #1 Snowmobile Forum

Ant · 12-19-2011, 05:42 AM

Both sleds were bought from the same owner after sitting a couple years indoors.
They start up great and idle really nicely but when you give them throttle they pop take off and rev up but immediately automatically drop back off to a bit above idle, moving at around 25mph and won't go above that rpm.

One sled is more sever then the other. If you let it sit there for a little bit and punch it, it responds and get to around 6000 rpm for a second only to drop off again. This sled doesn't always backfire. This sled is stock and still has the autolube system.

The other sled has been rebuilt and is supposedly of higher performance and has had the autolube system removed. It doesn't come even close to making it to as high of an rpm before falling off and staying at a steady ~2000 rpm like the other sled (i can't recall, it's been a year since i was on them)

They both respond to choke when at an idle but idle doesn't affect the machines while they have throttle.
When they pop there is a bolt that goes up the pulse line to the fuel pump.

What has been done:
New fuel lines
New fuel
New fuel filter
Rebuilt carb
Rebuilt fuel pump and tested for pressure
Replaced all rubber lines
New sparkplugs
New ignition coil

My dad has been a mechanic for 30+ years and can fix just about anything. This has stumped him and the places he was going to bring it to were just going to do the same things that have already been done to them. So we'd rather not waste the money.

Thanks for your time I hope I'm not forgetting anything and am portraying accurate information.

**RJ Gleason** · 12-19-2011, 08:16 AM

Is the TORS bypassed on these?

yamadad4 · 12-19-2011, 06:51 PM

sure sounds like a tors issue. yes, they both are equipped with an early variation of tors.

check the how to sticky for a tors explanation and then check how the wires from the carb are connected, or not connected. the carbs dont care, but the rest of the wiring system does.

Ant · 12-19-2011, 08:30 PM

Both have the TORS bypassed on the top of the carb (If I recall correctly)
Guess I'll have till I'm in front of them tomorrow, unfortunately no snow is on the ground yet.

yamadad4 · 12-19-2011, 08:56 PM

the wires leading to the carbs, not the wires at the carbs, need to be connected to each other. your looking for a black wire and a black wire with a yellow stripe, each should have a bullet connector, one male, one female.

Ant · 12-24-2011, 07:33 AM

Never mind what I said, there isn't any provisions for wires to go to the carb.
I don't see any wire like what you are talking about. I've looked over the wiring diagram too, i don't see anything to do with tors.

Ant · 12-25-2011, 03:57 AM

Nevermind I do see carb provisions currently both have plugs though.
Still unable to see Amy wires floating around. Let me know if I should post the wiring diagram.

yamadad4 · 12-26-2011, 06:53 PM

go ahead and post the diagram for the wiring, may be able to lead you in the right direction. sometimes wires dangling under or behind oil tanks and stuff are hard to locate.

Ant · 12-27-2011, 12:16 PM

Appreciate the help.
It is snowing outside!

yamadad4 · 12-27-2011, 07:14 PM

didnt see what i was looking for in the diagram. it looks more pre-83ish.

couple of questions. is there a tether and where the throttle flipper pin goes into the perch is there an elongated slot? the slot may not be visible without removing the flipper, but it may move side to side,(or at least to the left) indicating an elongation.

Ant · 12-29-2011, 12:23 PM

Yes it has a tether
One is disabled the other still has it
I don't think it has the slot, you tell me

yamadad4 · 12-29-2011, 07:47 PM

well you can rule out the throttle switch, it doesnt have one. i will do some more research.

you say the carb has a pair of wires attached, but lead nowhere?

have you tried to run the sleds with the track in the air(no load on the engine)?
at the least, if you cant get the track up, remove the belt for testing purposes only, and see if the problem exists without load on the engine.

i am leaning towards a grounding problem or corrosion on the magneto. your the eyes and ears here, be patient, keyboard troubleshooting can be trying.

Ant · 12-30-2011, 01:51 AM

Oops ignore this post

Ant · 12-30-2011, 01:55 AM

Rode them today they fling up to 6-7 thousand the. Die off to 4-5 and struggle to contInue to stay at that rpm going Around 40mph
After letting up for a few seconds u can reapply throttle to repeat
Fuel problem?
I'll try the suggestions in a few hrs
Thanks
Ps there is plugs were the diagrams show the tors switch on the carb

**RJ Gleason** · 12-30-2011, 11:34 AM

This is the performance under load, correct?
Have you tried running them on a stand to see if they do it without any load?

I'm beginning to suspect that the problem is in the drive line (clutching).

yamadad4 · 12-30-2011, 07:50 PM

Quote:

Originally Posted by RJ Gleason

This is the performance under load, correct?
Have you tried running them on a stand to see if they do it without any load?

I'm beginning to suspect that the problem is in the drive line (clutching).

good read rj, sounds like a sticking secondary or one lacking twist. not a quick enough backshift.

Ant · 12-31-2011, 04:58 AM

I don't understand how that could explain the popping and bogging but I'll try running it without a belt today. I think the problem is fuel related.

yamadad4 · 12-31-2011, 09:24 AM

wouldnt involve the popping issue, but may be contributing to the bogging.

not much to the fuel delivery system. pulse line, supply line, tank filter and line and the vent lines. easy to rule out.

**RJ Gleason** · 01-01-2012, 08:11 AM

Do not run it without the belt on.
Find a way to prop the back end up so that there is no load on the track and try running it up. This will tell you for sure if the problem is related to the drive line.

yamadad4 · 01-01-2012, 07:39 PM

^^^exactly. cant tell what the clutches are doing without a belt and the primary really hates slamming into itself.