Best guess which ignition component is causing trouble?

[Sean M]

I'm a returning member who has been gone for some time. I've been trying to sort out running problems on my higher mile (66000 mile) stock 2001 and I THINK it's ignition related. I'm looking for some sage advice here.

The bike was running reasonably well on a ride though it seemed to run a little rough (partial miss or something else causing a weak cylinder) before it got really rough. Then it got low on power and felt like I'd lost at least one cylinder.

What I've discovered so far.

WITH OR WITHOUT VBOOST CONNECTED: From about 6000 to 6500 the engine sound changes (little louder) but no additional power, if I get up past around 6500 rpm it will suddenly pick up power and smooth out like a cylinder or two fired up. There are occasional brief drop outs but mostly better (but not right) all the way to red line. It seems like something is changing like maybe timing (there is good spark at each plug, see below)??

Carbs were cleaned, float level set and sync'd last summer. I shotgunned them recently during trouble shooting with no change.

Coils ohm out at 3.1 to 3.3 ohms and 21K to 25K plug cap to connector. Plug wires alone on 1 and 3 are around 9K, didn't check the 2 and 4 wires off the coil due to PITA access. Coil cases on 1 and 3 don't show any cracks.

Pick-up ohms out at 103 ohms at running temp.

The ignitor wires leading to the ignition coils (the ones that connect to the yellow connectors on the coils) are isolated from ground and harness still has all wrap tape intact (no abrasions).

If the Vboost controller is connected the wire leading to the number 3 cylinder coil wire (not the plug wire) losses total isolation and shows 37K ohms to ground. This has been traced to the Vboost itself and not the stock gray wire that goes between the Vboost controller and the yellow wire for the #3 ignition coil. NOTE The running issue is unchanged by electrically connnecting or disconnecting the Vboost controller so I don't think the poor isolation from ground is causing the current problem, don't know it it is causing other issues though.

Plugs all look the same and show a clean burning engine (light tan color). All ohm out (top to electrode) at about 4.2K ohm. A spare plug grounded to the frame and connected to any plug wire shows good spark on all 4 cylinders.

If you pull a plug wire while the bike is running at near idle and a bit rough the engine drags down about the same for each cylinder. In other words a weak cylinder or misfiring cylinder is not obvious.

Also I've checked temps on each cylinder with an infared temp gauge aimed at the exhaust pipe right next to the cylinder. All cylinders are pretty even though number 3 sometimes is a little warmer. I've done this during warm up, at idle and right after a test ride.

I'm to the point I THINK my next step is replacing ignition components, but which ones first?? Any ideas on what else to check?

Much thanks in advance to anyone who responds.

 

[Fire-medic]

Ask Sean Morley for his Traveling Kit of Electrical Tricks. He sends you a kit of electrical components, you change one thing at a time until you identify your issue. You pay him for that piece you keep and send back the kit. That may help. Sounds like you've done some quality trouble-shooting.

Suggestions:
What does the inside of the gas tank look like? Shiny-clean, bottom and sides? Or something else? Corrosion/rust can ruin your clear path for fuel to be where it's supposed to be, when it's supposed to be there.

Gas filters are cheap. I'd replace yours, you should be able to match up a replacement at your local parts store.

I would also one at a time, drain your gas bowls, into some clear container, and see what comes-out. You may find a 'lens' of different liquid on the bottom of your container, which is likely water. Look for any particulate material also. If you see any of that, a cleaning of your carbs is probably indicated. The carbs should be operating mostly on the main fuel jet at the RPM's you're describing, of each carburetor. Any particulate material in the float bowl could partially obstruct the main jet, especially if it's not big-enough to pass through the main jet. Draining the float bowls, one at a time, will help you to see if any contaminants are present. Drain screws (arrows):

 

[Sean M]

Thanks Fire for the ideas. I know first hand of old tanks. I replaced my tank and fuel filter last year or the year before. Bottom of the tank was rusty. No ethanol for me unless I have no choice.

I've had rough running in the past and a thorough carb cleaning fixed it. I've never had it run this rough or have it suddenly gain a cylinder back so I'm thinking ignition. I shotgunned to see if it had any effect (it didn't) but draining the bowls to see what I find is next.

Time to reach out to Sean Morley, see if he can fix me up.

 

[MaxMidnight]

Cam we assume that the spark plugs and caps have been replaced within living memory?

I could guess at what is causing the issue but it would be no more than that and just as likely be wrong. Follow Mr Medics advice.

 

[Sean M]

Plugs have been replaced but probably due as the electrode edges are no longer knife sharp.

The caps are original. I've not replaced them since they ohm out in spec, don't have cracks and don't seem to be leaking (no change in how engine runs when they are misted with water).

New ones would eliminate one more problem source, going COPS would eliminate two (coils and caps).

Any recommendations on a good source for COPS?

Thanks for the feedback.

 

[gentsvmax]

Plugs have been replaced but probably due as the electrode edges are no longer knife sharp.

The caps are original. I've not replaced them since they ohm out in spec, don't have cracks and don't seem to be leaking (no change in how engine runs when they are misted with water).

New ones would eliminate one more problem source, going COPS would eliminate two (coils and caps).

Any recommendations on a good source for COPS?

Thanks for the feedback.

Ah the Vmax rabbit hole, and its many tunnels LOL.
Not at all funny is your running issue.
I have experienced a similar symptom that was a result of bad connections at both positive and ground circuits for both charging and ignition.
Some not so deep wabbit hole's to explore though if you take your time, varify components (coils etc.) ,their connections and battery condition to check off the electric side of things as a possible cause.

One thing I have done from day one of my ownership of the Max was and is to keep detailed notes of ANYTHING I have done to maintain, repair or modify the bike, especially anything that alters original design, you mentioned C.O.P.s.
I have recorded the symptom, action taken, milage and its effect and was damn glad I did when I have had to reference this info.
Anyway, good luck to ya!

Gent

 

[Fire-medic]

I have experienced a similar symptom that was a result of bad connections at both positive and ground circuits for both charging and ignition.

gentsvmax has a great point, I normally suggest anyone having electrical problems to make the ground connections shiny-bright and tight. One ground is by the oil filler cap to an engine side case cover (not the ones saying VMax attached to the frame) and the other is on the right side, where the faux gas tank bracket is. It's in front of the seat. Also early bikes have the R/R being grounded by its mounting to the passenger peg left side bracket, where the R/R mounts behind it. Later models have a separate ground wire as part of the R/R leads.

 

[Sean M]

Thanks guys, good points. It's been awhile since I cleaned ground connections. I was aware of the first two Fire- medic called out but don't know what you mean by the R/R by the foot peg (and I'm not near the bike to go look) but I assume I must have dealt with it when I replaced the gas tank (what a PITA).

I think the only positive connections I've not checked (opened and inspected) on the ignition are directly to the ignitor. I'll go through the schematic and check them off to verify.

As for tracking my work, I agree and I do it too but probably not as thorough as you Gent. My bad.

Thanks again guys, it's good to have a place to turn when I run out of ideas.

 

[99YAMAHAVMAX]

Thanks guys, good points. It's been awhile since I cleaned ground connections. I was aware of the first two Fire- medic called out but don't know what you mean by the R/R by the foot peg (and I'm not near the bike to go look) but I assume I must have dealt with it when I replaced the gas tank (what a PITA).

I think the only positive connections I've not checked (opened and inspected) on the ignition are directly to the ignitor. I'll go through the schematic and check them off to verify.

As for tracking my work, I agree and I do it too but probably not as thorough as you Gent. My bad.

Thanks again guys, it's good to have a place to turn when I run out of ideas.

Regulator/Rectifier is mounted inside the left passenger footage bracket--can be tested with a multimeter and plug is under the left side cover--1985-95 are the smaller ones notorious known for melting---I would look at the later model 1996-2007 upgrade or even a Kawasaki or R1 rectifier upgrade.

 

[Sean M]

Hey 99 thanks for the clarification. I've got an 01 so I'm already upgraded but that doesn't mean I don't need to check its ground. I'll identify its ground wire on the schematic and check resistance between it and the frame and battery negative.

 

[Sean M]

Well I finally got my issues (ok my bikes issues) sorted out. I'll not labor through all the things I checked other than to say I checked everything you all suggested. Thanks for your input.

I've learned this lesson before and I had to learn it again, if it's not running right start with the carbs. I'd cleaned them only 3K back which turned out to be the problem. Oh, they were still clean but the brass screw that holds and caps off the main jet in carb 1 had come off, apparently lightly snugging it down isn't enough. It's amazing it ran as well as it did as it had backed itself all the way off.

My second problem is the clutch is giving out and starting to slip/stick. So when I'd get around 6k rpm I was moving enough air thru 1 to overcome all the extra fuel going thru the main jet and cyl 1 would come on line, overwhelm the clutch and cause it to slip then grab making it feel like a second cylinder was kicking in. As Fire-Medic said at those rpms the main jet is doing all the work.

I hate not hearing the solutions people find when they write in so here's my solution for what it's worth. I suspect main jets coming lose isn't real commom.

 

[99YAMAHAVMAX]

Well I finally got my issues (ok my bikes issues) sorted out. I'll not labor through all the things I checked other than to say I checked everything you all suggested. Thanks for your input.

I've learned this lesson before and I had to learn it again, if it's not running right start with the carbs. I'd cleaned them only 3K back which turned out to be the problem. Oh, they were still clean but the brass screw that holds and caps off the main jet in carb 1 had come off, apparently lightly snugging it down isn't enough. It's amazing it ran as well as it did as it had backed itself all the way off.

My second problem is the clutch is giving out and starting to slip/stick. So when I'd get around 6k rpm I was moving enough air thru 1 to overcome all the extra fuel going thru the main jet and cyl 1 would come on line, overwhelm the clutch and cause it to slip then grab making it feel like a second cylinder was kicking in. As Fire-Medic said at those rpms the main jet is doing all the work.

I hate not hearing the solutions people find when they write in so here's my solution for what it's worth. I suspect main jets coming lose isn't real commom.

Main jets rarely come loose but the copper slotted screw with washer that screws to the main nozzle will become a problem when it falls off. I've seen many from photos showing the inside by the butterflies. The reason for this i've noticed is when rebuilding a set the main nozzles are pushed up through the carbs then the o-ring is attached around it and next is the gasket--jetblock sets down over the nozzle then washer and brass screw tightened----the problem with that is now you ad the two jis screws to tighten down the jetblock and that brass slotted screw now loosens. Needs to be retighten after screwing down the jetblock.

 

[99YAMAHAVMAX]

Well I finally got my issues (ok my bikes issues) sorted out. I'll not labor through all the things I checked other than to say I checked everything you all suggested. Thanks for your input.

I've learned this lesson before and I had to learn it again, if it's not running right start with the carbs. I'd cleaned them only 3K back which turned out to be the problem. Oh, they were still clean but the brass screw that holds and caps off the main jet in carb 1 had come off, apparently lightly snugging it down isn't enough. It's amazing it ran as well as it did as it had backed itself all the way off.

My second problem is the clutch is giving out and starting to slip/stick. So when I'd get around 6k rpm I was moving enough air thru 1 to overcome all the extra fuel going thru the main jet and cyl 1 would come on line, overwhelm the clutch and cause it to slip then grab making it feel like a second cylinder was kicking in. As Fire-Medic said at those rpms the main jet is doing all the work.

I hate not hearing the solutions people find when they write in so here's my solution for what it's worth. I suspect main jets coming lose isn't real commom.

There is a brass screw on the float bowl that has access to the main jet and if you had left that loose and then it came off you would have leaked out all the gas in that carb.

 

[Sean M]

There is a brass screw on the float bowl that has access to the main jet and if you had left that loose and then it came off you would have leaked out all the gas in that carb.

Well I feel a little better about the the lose screw as its not unheard of. It is the one holding the main nozzle you mentioned in your first reply. I misspoke calling it the main jet.

I can't vouch for if I tightened it before or after the jet block screws the last time I cleaned them but I certainly did jet block screws then main nozzle screw then check jet block screws this time. Last time I didn't tighten it much as the anti rotation peg in the jet block and the slot in the nozzle looked easy to mess up. I guess I was lucky the main nozzle didn't end up in the carb throat. Lesson learned.

Thanks for the feedback 99.

 

[99YAMAHAVMAX]

Well I feel a little better about the the lose screw as its not unheard of. It is the one holding the main nozzle you mentioned in your first reply. I misspoke calling it the main jet.

I can't vouch for if I tightened it before or after the jet block screws the last time I cleaned them but I certainly did jet block screws then main nozzle screw then check jet block screws this time. Last time I didn't tighten it much as the anti rotation peg in the jet block and the slot in the nozzle looked easy to mess up. I guess I was lucky the main nozzle didn't end up in the carb throat. Lesson learned.

Thanks for the feedback 99.

Good to hear you have it sorted.

 

[brian hicks]

I'm a returning member who has been gone for some time. I've been trying to sort out running problems on my higher mile (66000 mile) stock 2001 and I THINK it's ignition related. I'm looking for some sage advice here.

The bike was running reasonably well on a ride though it seemed to run a little rough (partial miss or something else causing a weak cylinder) before it got really rough. Then it got low on power and felt like I'd lost at least one cylinder.

What I've discovered so far.

WITH OR WITHOUT VBOOST CONNECTED: From about 6000 to 6500 the engine sound changes (little louder) but no additional power, if I get up past around 6500 rpm it will suddenly pick up power and smooth out like a cylinder or two fired up. There are occasional brief drop outs but mostly better (but not right) all the way to red line. It seems like something is changing like maybe timing (there is good spark at each plug, see below)??

Carbs were cleaned, float level set and sync'd last summer. I shotgunned them recently during trouble shooting with no change.

Coils ohm out at 3.1 to 3.3 ohms and 21K to 25K plug cap to connector. Plug wires alone on 1 and 3 are around 9K, didn't check the 2 and 4 wires off the coil due to PITA access. Coil cases on 1 and 3 don't show any cracks.

Pick-up ohms out at 103 ohms at running temp.

The ignitor wires leading to the ignition coils (the ones that connect to the yellow connectors on the coils) are isolated from ground and harness still has all wrap tape intact (no abrasions).

If the Vboost controller is connected the wire leading to the number 3 cylinder coil wire (not the plug wire) losses total isolation and shows 37K ohms to ground. This has been traced to the Vboost itself and not the stock gray wire that goes between the Vboost controller and the yellow wire for the #3 ignition coil. NOTE The running issue is unchanged by electrically connnecting or disconnecting the Vboost controller so I don't think the poor isolation from ground is causing the current problem, don't know it it is causing other issues though.

Plugs all look the same and show a clean burning engine (light tan color). All ohm out (top to electrode) at about 4.2K ohm. A spare plug grounded to the frame and connected to any plug wire shows good spark on all 4 cylinders.

If you pull a plug wire while the bike is running at near idle and a bit rough the engine drags down about the same for each cylinder. In other words a weak cylinder or misfiring cylinder is not obvious.

Also I've checked temps on each cylinder with an infared temp gauge aimed at the exhaust pipe right next to the cylinder. All cylinders are pretty even though number 3 sometimes is a little warmer. I've done this during warm up, at idle and right after a test ride.

I'm to the point I THINK my next step is replacing ignition components, but which ones first?? Any ideas on what else to check?

Much thanks in advance to anyone who responds.

Sometimes electrical components can check ok when cold but during operation they can break down.eg. your spark lead may look great with a 9volt test meter but when it's got several KV. going through it then things can be different. I would change components 1 at a time even if they appear good and see what happens.