ski
New member
I just finished a bunch of work on my wife's 94 Vmax 600 and it works really good... up to about 1/2 throttle.... 
It is pretty odd, it starts and runs perfect choke and all works exactly as expected, but under full or near full throttle it kinda "breaks up" and sounds like crap, almost as if it lost a cylinder, but revs to 7500 still. Has lots of power lower down, especially around 1/4 throttle.
I have gone through the carbs twice no issues found all jetting is stock
I tried a different exhaust pipe - No change
CDI box - No change
Coil - NO change
Spark plugs - No change
Inspected reeds - seem fine
I don't have a compression guage but it seems to pull over evenly and has great low end and Idle so I think it must be within reason
My friend said he thinks it is getting to much fuel above 1/2 throttle but it doesn't blow black smoke or foul the plugs, but I agree that it doesn't seem like a lean Bog.
I am going to try a completely different set of carbs tomorrow but any other thoughts would be helpful.
P.S. New bushings\shims in Primary clutch, weights were very good, new secondary spring (green) 60deg wrap, stock 39 deg helix with new buttons.
It is pretty odd, it starts and runs perfect choke and all works exactly as expected, but under full or near full throttle it kinda "breaks up" and sounds like crap, almost as if it lost a cylinder, but revs to 7500 still. Has lots of power lower down, especially around 1/4 throttle.
I have gone through the carbs twice no issues found all jetting is stock
I tried a different exhaust pipe - No change
CDI box - No change
Coil - NO change
Spark plugs - No change
Inspected reeds - seem fine
I don't have a compression guage but it seems to pull over evenly and has great low end and Idle so I think it must be within reason
My friend said he thinks it is getting to much fuel above 1/2 throttle but it doesn't blow black smoke or foul the plugs, but I agree that it doesn't seem like a lean Bog.
I am going to try a completely different set of carbs tomorrow but any other thoughts would be helpful.
P.S. New bushings\shims in Primary clutch, weights were very good, new secondary spring (green) 60deg wrap, stock 39 deg helix with new buttons.
mulderdad
New member
Just a shot in the dark, crank seal maybe?
ski
New member
Well I suppose it could be, but wouldn't it run poorly at all speeds?
are your main jets clogged?
ski
New member
nope, I have been through the carbs twice and all passages appear to be open and jets are clean.
Check your slides....give it throttle and make sure they are all going up and down.
I had a screw come loose once. Luckly it cant get into the engine.
Second..when does it engage? I wonder if the clutch needs work.
I had a screw come loose once. Luckly it cant get into the engine.
Second..when does it engage? I wonder if the clutch needs work.
OZ
yes but...
Sounds like a carb problem (mains, slider adjustment) ...what "bunch of work" did you perform?
sleddheadd
New member
when you did the carbs where you able to get to the pilot jets? sometimes they are overlooked and that really sounds like what happens when they are clogged. the thing will idle great but give it throttle and it really bogs down!
sandmanmike1
New member
When you slowly pull the pull start do you feel good compression on both cylinders. You could have lost a ring.
ski
New member
Update:
I replaced the carbs altogether with a different set which I pulled both bowls and removed both main and pilot jets and cleaned with carb cleaner (also did that to the other set) carb slides are working in sync as well on both sets .... NO CHANGE
Swapped fuel pump - NO CHANGE
Tested compression with a crappy tester I found here, not sure how accurate but it shows 112 psi both cylinders, so it is at least balanced, feels like more to pull over
checked resistance on the pickup 213ohms same as another one I checked today (208 ohms)
As far as clutching, I had the primary apart and found the weights and bushings in very good condition, so I cleaned them up and reinstalled them with new shims, pins were also in excellent condition showing almost no wear.
Secondary was in pretty nice shape as well but I put new buttons on it and a new green spring (calls for red I had a new green) and set it at 60deg wrap I did try A few different settings as well 70deg and 50deg seems fine at 50 or 60. The sled will go about 40 mph at 1/4 throttle.
As for what "bunch of work" I did:
campolast track, swapped drive axle (splines worn), seat recovered, cleaned carbs, pulled engine and cleaned belly pan inspected wiring, high temp coating on Y-pipe and muffler, New exhaust gaskets, all new bearings in skid, new sliders, replaced all bushings in skid, 4th wheel install on axle, coolant change, synthetic chain case fluid, and new spark plugs BR9EYA
I should mention I bought the sled not having heard it run before and it sat for an unknown amount of time, I pulled the air box cleaned the carbs, flushed the oil reservoir drained fuel and changed plugs, put it together to see if it would start, once there was fuel in the bowls I put the plugs in and it fired up in 2 pulls, seemed to run ok so I proceeded to pull it apart again and do the rest of the work.
I am going to try swapping the Stator tomorrow, if that doesn't work I will probably shoot myself so If I don't post again you know why....
BTW thanks for all the input so far....
I replaced the carbs altogether with a different set which I pulled both bowls and removed both main and pilot jets and cleaned with carb cleaner (also did that to the other set) carb slides are working in sync as well on both sets .... NO CHANGE
Swapped fuel pump - NO CHANGE
Tested compression with a crappy tester I found here, not sure how accurate but it shows 112 psi both cylinders, so it is at least balanced, feels like more to pull over
checked resistance on the pickup 213ohms same as another one I checked today (208 ohms)
As far as clutching, I had the primary apart and found the weights and bushings in very good condition, so I cleaned them up and reinstalled them with new shims, pins were also in excellent condition showing almost no wear.
Secondary was in pretty nice shape as well but I put new buttons on it and a new green spring (calls for red I had a new green) and set it at 60deg wrap I did try A few different settings as well 70deg and 50deg seems fine at 50 or 60. The sled will go about 40 mph at 1/4 throttle.
As for what "bunch of work" I did:
campolast track, swapped drive axle (splines worn), seat recovered, cleaned carbs, pulled engine and cleaned belly pan inspected wiring, high temp coating on Y-pipe and muffler, New exhaust gaskets, all new bearings in skid, new sliders, replaced all bushings in skid, 4th wheel install on axle, coolant change, synthetic chain case fluid, and new spark plugs BR9EYA
I should mention I bought the sled not having heard it run before and it sat for an unknown amount of time, I pulled the air box cleaned the carbs, flushed the oil reservoir drained fuel and changed plugs, put it together to see if it would start, once there was fuel in the bowls I put the plugs in and it fired up in 2 pulls, seemed to run ok so I proceeded to pull it apart again and do the rest of the work.
I am going to try swapping the Stator tomorrow, if that doesn't work I will probably shoot myself so If I don't post again you know why....
BTW thanks for all the input so far....
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sandmanmike1
New member
If it has a broken piston ring it may have good compression some of the times. When my piston ring broke in my 94 it was still pulling strong then would cut out and make no power then take off again like a bat out of hell. Did you do the simple test I recommended?
ski
New member
sandmanmike1 said:
I did do that and it seems fine, the problem is very consistent. I wouldn't be surprised to find out this is a clutching problem when all is said and done, it seems to run so well down low and idles perfectly, but I just don't see anything wrong with the clutches.
I just double checked and the clutches seem to shift smoothly when sled is running on a stand. I thought that if the primary was not shifting open fully it may cause the type of problem I am having but it seems to shift out all the way on a stand.
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woolyviper
New member
my first guess was main jets, but i would check the position of the jet needles before anything else. sounds like it's gurgling in the high end of the midrange (when the Jet needles come completely out of the needle jets.tomseal6 said:
sandmanmike1
New member
How many miles are on her?
ski
New member
6300 miles on it
as far as the carbs go, 2 sets of carbs having the exact same problem is pretty unlikely but who knows... I am a little confused by this one
as far as the carbs go, 2 sets of carbs having the exact same problem is pretty unlikely but who knows... I am a little confused by this one
bluemonster1
LIFE MEMBER ONLY ONCE!!!
Hey Ski how are u doing besides ready to shoot yourself.It may be something so simple.Does it back-fire when you accelerate?Floats are adjusted properly.I am thinking carbs to,but if that change doesnt work,I guess your a dead man.LOL.
sleddheadd
New member
one other thing.... you mentioned the air box.....and it has been sitting for a while.....air box might be full of mice nests? one year mice got into one of my buddies machines and filled the exhaust with soy beans!!! lol... couldn't believe that one but it was true!
ski
New member
bluemonster1 said:
Well so far I am alive, but it is getting close, between crappy snow conditions and this issue with the Vmax I am a bit dismayed... LOL
Again, with the carbs float levels looked ok on both sets of carbs. I have 2 racks here and I swapped them and it is exactly the same, not backfiring but runs poorly at anything over 1/2 throttle, come out for a beer and I'll show you ...lol
Air box was a bit dirty mostly sprider webs, but I cleaned it completely before the sled was even turned over. I am wondering if there was somehow something in the crankcase I didn't see and the transfer ports are plugged in the engine... that is what it feels like to me, but seems pretty unlikely I know...