chadzeilenga
New member
Hi All,
Just got back from a bummer of a weekend, luckily my friend had a spare sled and I was able to get some riding in so it wasn't a total waste. I am re-writing my original post now that I'm home and have more information:
The issue started when we got up to Northern WI and unloaded the sled. Went to do a quick lap on the lake and it was severly low on power and max speed was 30RPM. Brought it back and started investigating. The engine did not change RPM when I unhooked the PTO side plug cap, but died when fan plug cap was removed. Below is what I found/did:
1. Siphoned gas tank and installed fresh non-ethanol fuel. Rode for a while on lake to purge through the system.
2. Cleaned the carb. Removed carb and back flushed all passageways etc.
3. Freed the stuck choke plunger in the carb. The cable still feels a little sticky, so I'll need to free that up as well.
4. Installed new BR9ES plugs gapped to 0.030". PTO plug wet with fuel & clean after short ride on lake.
5. Compression checked out at 110PSI both cylinders
6. Sprayed carb cleaner down towards the PTO side crank seal (new ~500mi ago) and there was no change in engine RPM
7. Checked down the intake manifold for any obstructions in the reed cages and didn't see much there, but also hard to see
8. Inspected the exhaust manifold/muffler for any restrictions and none found.
9. Swapped the plug caps and engine will still run on just the fan cyl. Is there a way to check these on the bench? Maybe a resistance or continuity check???
10. Followed the FSM troubleshooting guide and checked the Charge Coil resistance (Brown-Black) wires. Measuring 540ohms but that was at 40F and spec in the book was 350ohm at 68F, so I should re-check that in my warm garage.
11. Pulse Coil checked out at 16ohms, but then was steadily dropping the longer I measured. I figured I'd re-check once I got home since the temp didn't match the 68F as stated in the FSM.
12. Ignition Coil Primary circuit checked out at a higher resistance than specified in the manual, but will re-check tonight.
13. Ignition coil secondary circuit (orange lead wire to either plug wire end was going to 1 so I need to re-check with the proper range selected on my meter at proper temps.
Now that you have read everything above, any suggestions on what else to do/check? The sled ran great last season and I put ~150 trouble free miles on it, but this was the first time I had it out and I wasn't able to test drive around my house due to now snow this year.
Just got back from a bummer of a weekend, luckily my friend had a spare sled and I was able to get some riding in so it wasn't a total waste. I am re-writing my original post now that I'm home and have more information:
The issue started when we got up to Northern WI and unloaded the sled. Went to do a quick lap on the lake and it was severly low on power and max speed was 30RPM. Brought it back and started investigating. The engine did not change RPM when I unhooked the PTO side plug cap, but died when fan plug cap was removed. Below is what I found/did:
1. Siphoned gas tank and installed fresh non-ethanol fuel. Rode for a while on lake to purge through the system.
2. Cleaned the carb. Removed carb and back flushed all passageways etc.
3. Freed the stuck choke plunger in the carb. The cable still feels a little sticky, so I'll need to free that up as well.
4. Installed new BR9ES plugs gapped to 0.030". PTO plug wet with fuel & clean after short ride on lake.
5. Compression checked out at 110PSI both cylinders
6. Sprayed carb cleaner down towards the PTO side crank seal (new ~500mi ago) and there was no change in engine RPM
7. Checked down the intake manifold for any obstructions in the reed cages and didn't see much there, but also hard to see
8. Inspected the exhaust manifold/muffler for any restrictions and none found.
9. Swapped the plug caps and engine will still run on just the fan cyl. Is there a way to check these on the bench? Maybe a resistance or continuity check???
10. Followed the FSM troubleshooting guide and checked the Charge Coil resistance (Brown-Black) wires. Measuring 540ohms but that was at 40F and spec in the book was 350ohm at 68F, so I should re-check that in my warm garage.
11. Pulse Coil checked out at 16ohms, but then was steadily dropping the longer I measured. I figured I'd re-check once I got home since the temp didn't match the 68F as stated in the FSM.
12. Ignition Coil Primary circuit checked out at a higher resistance than specified in the manual, but will re-check tonight.
13. Ignition coil secondary circuit (orange lead wire to either plug wire end was going to 1 so I need to re-check with the proper range selected on my meter at proper temps.
Now that you have read everything above, any suggestions on what else to do/check? The sled ran great last season and I put ~150 trouble free miles on it, but this was the first time I had it out and I wasn't able to test drive around my house due to now snow this year.
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Throttle Junkie35
New member
Answer for you on VS.
Hold the track off of the ground with a block of wood and try getting it up to temperature/speed on the stand. Sometimes you just need to get the crap out on the stand for it to clear up.
chadzeilenga
New member
I updated the info above with what we were able to determined. I think issue is electrical, but I'm not very good with electrical issues.
chadzeilenga
New member
Does anyone know the p/n for the spark plug caps? I see on Dennis Kirk they are listed as NGK LB05EZ, but these don't have the flare out at the bottom that covers the opening on the plastic cover.
that rubber is not nessasary but you can transfer it to the aftermarket caps with some work. i never use them myself.
Throttle Junkie35
New member
If you swapped wires, plugs, caps, etc, I would almost guarrantee its not electrical. You have an air leak. Crankseal, head or base gasket, possibly intake gasket. Since it seems it came on all of the sudden, Im guessing base or head gasket.
caravanman
New member
I don't see it in your write up: Have you checked for spark out of the PTO side plug wire?
The coil fires both cylinders at the same time, so a quick check to see if its mech is to swap the leads side to side.
The coil fires both cylinders at the same time, so a quick check to see if its mech is to swap the leads side to side.
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chadzeilenga
New member
I wasn't able to swap wires as they are both rigid in the coil and the fan side wire is too short to reach the PTO plug. I was only able to put the PTO wire on the fan plug and the engine ran on just that.
The motor probably has <500mi on it since I replaced crank seals, base, head & intake gaskets. I did spray some carb cleaner at the PTO crank seal and didn't notice any change in RPM. Are there any other methods to troubleshoot an air leak?
I did verify that I'm getting spark to both plugs both physically
and visually. I got a little buzz while holding plug cap and verifying spark...I have yet to sit down and go through my component resistances in my garage. I'll plan on that tonight to see if I can figure anything out. I was planning to pick up a new coil and plug caps just as a precautionary measure as both appear to be original.
chadzeilenga
New member
Update
Hi All,
I had some time to mess around with the sled in the garage tonight. Thought I'd post what I had figured out:
1. I removed the choke plunger and cleaned up the brass real well. I also cleaned out the well that it drops down into. While it was out, I verified that turning on the choke pulled the plunger up. I lubricated it with some Yamaha Marine Grease and reassembled. I noticed that when I start the sled with the choke on and then flip it off. At first the lever is laying flat, but then eventually the lever looks raised 1/8"-1/4" which would mean that the choke was on right?
2. I checked the compression on each cylinder on a warm engine. PTO cyl - 130PSI & FAN 140PSI.
3. I started the sled in garage with lights off and pulled each plug cap. PTO cyl had a frequent blue spark going to the plug. When I pulled the FAN cap I couldn't lift it enough to see the spark before the engine died. Does this mean that the spark is weak? I was able to verify that the engine will idle on just the FAN cyl. I can run on only the PTO cylinder but I need to give it throttle as I'm starting it.
4. I checked over the engine for any sources of air leaks. I sprayed down the cylinder with staring fluid and listened for any changes in RPM. I did spray some down by the PTO outlet, but it's hard to reach due to spinning clutch. Is there a better way to approach this?
The resistances were measured in my garage with an ambient temp of 26F. I'm not sure how to convert the measured values to 68F for comparison to the FSM specs.
5. Plug cap resistance. PTO 5540 ohms & FAN 4770 ohms. I thought I had heard that the spec was >5k ohms.
6. Charge Coil Resistance: 586 ohm
7. Pulse Coil Resistance: 17.2 Ohm
8. Primary Ignition Coil circuit: 2.2-3.0 ohm
9. Secondary Ignition Coil Circuit: Displayed 1 while measuring from both plug wires to the orange signal wire on the coil. I believe this tells me that there is no continuity?
Next steps are:
1. Install new coil & plug caps and recheck Ignition Coil circuit
2. Double check exhaust for any blockages
3. Clean carb passages again with spray & compressed air
4. Double check the reed cages for any contamination/blockage
Hi All,
I had some time to mess around with the sled in the garage tonight. Thought I'd post what I had figured out:
1. I removed the choke plunger and cleaned up the brass real well. I also cleaned out the well that it drops down into. While it was out, I verified that turning on the choke pulled the plunger up. I lubricated it with some Yamaha Marine Grease and reassembled. I noticed that when I start the sled with the choke on and then flip it off. At first the lever is laying flat, but then eventually the lever looks raised 1/8"-1/4" which would mean that the choke was on right?
2. I checked the compression on each cylinder on a warm engine. PTO cyl - 130PSI & FAN 140PSI.
3. I started the sled in garage with lights off and pulled each plug cap. PTO cyl had a frequent blue spark going to the plug. When I pulled the FAN cap I couldn't lift it enough to see the spark before the engine died. Does this mean that the spark is weak? I was able to verify that the engine will idle on just the FAN cyl. I can run on only the PTO cylinder but I need to give it throttle as I'm starting it.
4. I checked over the engine for any sources of air leaks. I sprayed down the cylinder with staring fluid and listened for any changes in RPM. I did spray some down by the PTO outlet, but it's hard to reach due to spinning clutch. Is there a better way to approach this?
The resistances were measured in my garage with an ambient temp of 26F. I'm not sure how to convert the measured values to 68F for comparison to the FSM specs.
5. Plug cap resistance. PTO 5540 ohms & FAN 4770 ohms. I thought I had heard that the spec was >5k ohms.
6. Charge Coil Resistance: 586 ohm
7. Pulse Coil Resistance: 17.2 Ohm
8. Primary Ignition Coil circuit: 2.2-3.0 ohm
9. Secondary Ignition Coil Circuit: Displayed 1 while measuring from both plug wires to the orange signal wire on the coil. I believe this tells me that there is no continuity?
Next steps are:
1. Install new coil & plug caps and recheck Ignition Coil circuit
2. Double check exhaust for any blockages
3. Clean carb passages again with spray & compressed air
4. Double check the reed cages for any contamination/blockage
caravanman
New member
Before you go out and buy a coil, try unbolting the coil and move it to were you can swap the wires then re-ground the coil with a jumper wire.
chadzeilenga
New member
Ha!!! Didn't even think of that 
I call this Mechanics Block, kinda like writers block...haha. I'll take a look at that tonight.
I've been trying to think back of what changed since the last winter when the sled ran great. Last spring I summerized the sled by removing the belt and then putting some oil down each cyl and rotating the engine with the plugs out. I can't recall if I had the plugs installed in the caps or not. Would this have any effect of not providing a ground for the spark to go while I was pulling the cord?
I call this Mechanics Block, kinda like writers block...haha. I'll take a look at that tonight. I've been trying to think back of what changed since the last winter when the sled ran great. Last spring I summerized the sled by removing the belt and then putting some oil down each cyl and rotating the engine with the plugs out. I can't recall if I had the plugs installed in the caps or not. Would this have any effect of not providing a ground for the spark to go while I was pulling the cord?
sledtillsed
New member
Not sure if this was mentioned. But did u replace pick up line in tank and have u changed the in line / in tank fuel filter ? Had an issue just like this, Sled would not pull RPM and was a plugged filter
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Sent from my iPhone using Tapatalk
chadzeilenga
New member
Thanks for the idea. I have replaced all fuel and oil lines in the sled with new, and did put a new fuel filter in ~500mi ago when I first got it running.
C. Zeilenga
C. Zeilenga
Bob Vehring
New member
Kind of a stretch here, but happened to my 83 V Max. Went through alot of hard to pin point problems, went through normal check list. I rebuilt the engine that came in the sled, With no luck, I built a new, different everything engine, still had the problem. Finally turned out to be momentary short in the wiring going to the cdi box. Previous owner had moved the box under left foot well and it was in the wiring extension he had made.
chadzeilenga
New member
Yea, I'll have to look over my wires and see how they look. Luckily they are accessible.
I messed around with the sled a little tonight. One item I am noticing is that the sled is smoking quite a bit even with choke off. Also I noticed that there isn't any force on the choke cable when it is in the off position and it sets about 1/4" above the panel. This makes me think that my choke is always on and possibly I'm overfuelling and fouling out plugs?
I've had choke plunger out of carb and it moves freely but spring doesn't seem to be putting much force on it. Do these cables get stretched out or springs get weak?
C. Zeilenga
I messed around with the sled a little tonight. One item I am noticing is that the sled is smoking quite a bit even with choke off. Also I noticed that there isn't any force on the choke cable when it is in the off position and it sets about 1/4" above the panel. This makes me think that my choke is always on and possibly I'm overfuelling and fouling out plugs?
I've had choke plunger out of carb and it moves freely but spring doesn't seem to be putting much force on it. Do these cables get stretched out or springs get weak?
C. Zeilenga
chadzeilenga
New member
Help identifying choke parts
Can anyone help me identify the parts 6, 7 & 8 in the picture below? I know that I have items #4 (Plunger) and #5 (spring), but can't seem to match the others up. Possibly they are the sub components to the choke cable?
After all of this troubleshooting, I'm wondering if my engine is getting too much fuel and fouling out the plugs? I'm going to remove the carb and make sure everything is clean & clear. It was just re-done last season, but there might still be some mouse nest lurking in there.
One item that I don't understand is my choke lever does not sit flush to the panel when the sled is running. I can flip it up freely. I'll get some pictures to illustrate, but I'm wondering if my choke cable got stretched out??? One of the issues I had when I was in WI last weekend, was that my choke plunger was siezed in the bore of the carb and I had to pry it out to free it up. I'm wondering if any of that prying stretched the cable and now my sled is running with choke on 100%?
Can anyone help me identify the parts 6, 7 & 8 in the picture below? I know that I have items #4 (Plunger) and #5 (spring), but can't seem to match the others up. Possibly they are the sub components to the choke cable?
After all of this troubleshooting, I'm wondering if my engine is getting too much fuel and fouling out the plugs? I'm going to remove the carb and make sure everything is clean & clear. It was just re-done last season, but there might still be some mouse nest lurking in there.
One item that I don't understand is my choke lever does not sit flush to the panel when the sled is running. I can flip it up freely. I'll get some pictures to illustrate, but I'm wondering if my choke cable got stretched out??? One of the issues I had when I was in WI last weekend, was that my choke plunger was siezed in the bore of the carb and I had to pry it out to free it up. I'm wondering if any of that prying stretched the cable and now my sled is running with choke on 100%?
sifton
Member
Also check carb boots for leaks.
caravanman
New member
I know that is a Yamaha microfiche pic, but it looks like a generic carb diagram?
#7 is normally up the cable more, not right at the carb. #8 looks like a shaft that an under hood choke lever moves? Like motorcycle or REAL old school sled stuff??
I was just up riding our 440's this weekend. I would have looked at them more closely if I had known.
If you're concerned that the choke is on. Remove the cable from the plunger and drop it into the carb and use the spring and nut to hold it down all the way.
#7 is normally up the cable more, not right at the carb. #8 looks like a shaft that an under hood choke lever moves? Like motorcycle or REAL old school sled stuff??
I was just up riding our 440's this weekend. I would have looked at them more closely if I had known.
If you're concerned that the choke is on. Remove the cable from the plunger and drop it into the carb and use the spring and nut to hold it down all the way.
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chadzeilenga
New member
Update
Spent some more time on the sled tonight. I noticed that when I first start the sled cold it runs real strong and smooth and then as it idles it get's rougher. Not sure if that means anything.
1. Since I have the new coil on and I haven't shortened the FAN cyl wire yet I swapped them to see if there was a difference. No noticeable difference with the general running/acceleration. In this configuration I can get the sled to idle on each cylinder individually and it doesn't die immediately when I unplug the FAN cylinder. I do notice an RPM drop when each plug wire is pulled where as with the opposite, the unplugging the PTO cyl doesn't seem to change anything and the FAN cyl dies immediately. I ran it for a while with the wires swapped and checked my plugs. Both had some oil on them and both had evidence of firing. I did notice that the plug wire that was originally on the PTO cyl had a bunch of spark when I was removing it and this was the same condition when I swapped to FAN cyl. On the other wire that allowed the FAN cyl to kill engine, the spark is barely visible. Much less than the other wire.
2. I must have been reading caravanmans mind when I was messing with the choke tonight. I removed the plunger and fabricated a nail that I could push it all the way down in the well while I ran the sled. It didn't seem to run any smoother or have any better throttle response. I did notice that when the choke cable is out of the carb and the plunger is attached my lever sits flush like below:
As I threaded the choke cable fitting into the carb I noticed that the lever on my panel started to raise
This leads me to believe that my plunger is getting hung up and isn't fully seating in the well when the choke is off? I wish this was the answer, but I would think I would have seen an improvement when I ran with just the plunger installed.
3. I removed my carb again and took the bowl off. Everything looked clean and clear, but I blew out all of the passageways with air to be sure. My float level measured at 14.8mm which is pretty close to nominal.
4. I removed my intake to take a look at my reeds and ensure that they weren't clogged with mouse nest or an acorn. Unfortunately, they were clean and were intact with most of them having a good seat on the cage.
So I'm making great progress in identifying what is NOT the issue, but don't have anything solid to put my finger on just yet. A few ideas though:
1. Timing. Is it possible for the timing to change over time? I had the engine timed by the dealer when I rebuilt it 5yrs ago and it's ran great since. Typically starts on the 1st or 2nd pull.
2. PTO Crank Seal. I know this has been mentioned in previous posts, but is there any good way of checking this. It's hard to get starting fluid down there with the clutch installed, maybe I can run with the clutch removed so I have a clear shot at it? I don't recall what's requried to change this out, but don't I have to split the case to get at this?
3. Choke adjustment. Is the end of the choke cable adjustable and can I increase the pre-load on the plunger spring by adjusting the nut
4. CDI Box. I've seen that these can go out on these older Yamaha's, should I find a used one and swap it out to see if there is a difference? What are the symptoms of a CDI going bad?
Spent some more time on the sled tonight. I noticed that when I first start the sled cold it runs real strong and smooth and then as it idles it get's rougher. Not sure if that means anything.
1. Since I have the new coil on and I haven't shortened the FAN cyl wire yet I swapped them to see if there was a difference. No noticeable difference with the general running/acceleration. In this configuration I can get the sled to idle on each cylinder individually and it doesn't die immediately when I unplug the FAN cylinder. I do notice an RPM drop when each plug wire is pulled where as with the opposite, the unplugging the PTO cyl doesn't seem to change anything and the FAN cyl dies immediately. I ran it for a while with the wires swapped and checked my plugs. Both had some oil on them and both had evidence of firing. I did notice that the plug wire that was originally on the PTO cyl had a bunch of spark when I was removing it and this was the same condition when I swapped to FAN cyl. On the other wire that allowed the FAN cyl to kill engine, the spark is barely visible. Much less than the other wire.
2. I must have been reading caravanmans mind when I was messing with the choke tonight. I removed the plunger and fabricated a nail that I could push it all the way down in the well while I ran the sled. It didn't seem to run any smoother or have any better throttle response. I did notice that when the choke cable is out of the carb and the plunger is attached my lever sits flush like below:
As I threaded the choke cable fitting into the carb I noticed that the lever on my panel started to raise
This leads me to believe that my plunger is getting hung up and isn't fully seating in the well when the choke is off? I wish this was the answer, but I would think I would have seen an improvement when I ran with just the plunger installed.
3. I removed my carb again and took the bowl off. Everything looked clean and clear, but I blew out all of the passageways with air to be sure. My float level measured at 14.8mm which is pretty close to nominal.
4. I removed my intake to take a look at my reeds and ensure that they weren't clogged with mouse nest or an acorn. Unfortunately, they were clean and were intact with most of them having a good seat on the cage.
So I'm making great progress in identifying what is NOT the issue, but don't have anything solid to put my finger on just yet. A few ideas though:
1. Timing. Is it possible for the timing to change over time? I had the engine timed by the dealer when I rebuilt it 5yrs ago and it's ran great since. Typically starts on the 1st or 2nd pull.
2. PTO Crank Seal. I know this has been mentioned in previous posts, but is there any good way of checking this. It's hard to get starting fluid down there with the clutch installed, maybe I can run with the clutch removed so I have a clear shot at it? I don't recall what's requried to change this out, but don't I have to split the case to get at this?
3. Choke adjustment. Is the end of the choke cable adjustable and can I increase the pre-load on the plunger spring by adjusting the nut
4. CDI Box. I've seen that these can go out on these older Yamaha's, should I find a used one and swap it out to see if there is a difference? What are the symptoms of a CDI going bad?
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