Perplexing Problem - Part II

Hi guys,

This is part II of Perplexing Problem (http://www.vmaxforum.net/showthread.php?t=4572).

I'm still trying to figure out why I'm getting some kind of sputtering - some days better, some days worse.....

Took a ride today and the bike wanted to sputter and cough regardless of RPM. This makes me think the problem is not a fuel/carb issue. I have gone through the carbs 2 or 3 times very carefully. I don't have any vacuum leaks that I know of, either, as I've replaced all of the rubber parts.

Anyway, I was just messing around trying various things. Took the DP8REA NGK plugs out and gapped them at 0.033. Checked coil wires and caps, etc. Then I started the bike and ran it up and down the road to fully warm it up. Still had flubs and sputtering.

Brought the bike back, started messing with idle mix screws one at a time. In until the bike wanted to die, out until idle stopped increasing, then back in somewhere in the middle. Did this on all 4. Took the bike out. Still flubbs and sputters but less backfire out the drilled exhaust and more "fuel" smell out the exhaust.

Pulled back into the garage thinking it just has to be some kind of spark issue that has developed since I got the bike. Lifted the plug caps off each plug one at a time to listen to how differently the engine would run when a particular cylinder didn't fire. I discovered that #2, #3, and #4 all seem to drop the engine speed about the same. But #1 hardly drops the engine at all.

In other words, when #2, #3, or #4 are disconnected, the engine really starts laboring just to keep idling. But disconnecting #1 doesn't change it as much.

Started fiddling with the idle screw for that carb and between full in and full out, that cyl pops infrequently and in a mushy sort of fashion. Doesn't seem like the idle mix screw has much effect on that cyl as far as producing a proper combustion on the proper cycle.

Poor compression? Or a problem with that carb's idle circuit? Or, problem with the ignition coil for that cyl?

If #1 isn't pulling it's weight, would that create v-boost issues? I can't tell if this happens at all RPMs on this cyl but it sure isn't working like the others at idle. It might occasionally be firing when I'm out on a ride, which may explain the popping and lurching when I'm trying to cruise. I know it doesn't take much throttle to hold cruising speed in town, so this may be reasonable....

#1 and #3 coils and caps are stock but #1 and #3 coil wires are some non-OEM yellow wires that say "radio supression" on them....

So..... there are a few things I can do, if I have some help.

1. I can do a compression check on that cyl, if someone has the right adapter. I've yet to find one.

2. I can try another set of coils/wires/caps if someone can lend me something to try.

Open to other ideas. Anyone find any clues that stand out in the stuff I've posted?

Shuri, how does the spark look for that cylinder? Same as the rest? I would definitely check compression. I have a 12 mm adapter if you wish to borrow it. I'll take a pic and you can let me know if you think it'll work.

Here's my 2 cents worth - take every single electrical connector on the whole bike apart & clean with contact cleaner. Then pack with di-electric grease before re-assembly. I fixed several problems with my '96 by doing this as well. Ignition switch connector was especially corroded & probably the root of all problems, but corroded connectors will sometimes have changing resistance values depending on temp., humidity. etc. & cleaning everything up may help eliminate hanging on un-necessary parts. If nothing else, this is free (except for your time) so why not give it a try ? I fixed my temp. gauge, charging system & corrected a HUGE ignition mis-fire just by cleaning connectors. To be fair, the PO of my Vmax left her out in the weather for several years - that's a SIN in my book. :biglaugh:

richwrench said:

Here's my 2 cents worth - take every single electrical connector on the whole bike apart & clean with contact cleaner. Then pack with di-electric grease before re-assembly. I fixed several problems with my '96 by doing this as well. Ignition switch connector was especially corroded & probably the root of all problems, but corroded connectors will sometimes have changing resistance values depending on temp., humidity. etc. & cleaning everything up may help eliminate hanging on un-necessary parts. If nothing else, this is free (except for your time) so why not give it a try ? I fixed my temp. gauge, charging system & corrected a HUGE ignition mis-fire just by cleaning connectors. To be fair, the PO of my Vmax left her out in the weather for several years - that's a SIN in my book. :biglaugh:

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I agree with this. And I wish it were that easy. I actually did this already, which I documented in the other thread. I even disassembled the connectors that I could and got them bright and shiney. Hard to get all of them this way but I did it with the ones I could.

On a former XS11, I bought a wiring harness and installed it as a replacement. I'm not against trying that on this bike. Wonder if all the harnesses will swap.....

maleko89 said:

Shuri, how does the spark look for that cylinder? Same as the rest? I would definitely check compression. I have a 12 mm adapter if you wish to borrow it. I'll take a pic and you can let me know if you think it'll work.

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I would gladly pay shipping both ways and return your adapter.

The plug has a black carbon ring around its base with a medium brown insulator. #2 and #4 have the carbon ring but have a white-ish insulator. #3 is also a little darker like #1.

#1 and #3 are the coils with non oem wire.

I guess I could try swapping #2 coil to #1's spot and see what happens. I can see that the spark color is a little different between the stock coil/wires and the others.

I may have missed this in your other thread. I agree with mark. What color is your spark? Have you tried different plug wires? If the PO didn't put them on right or somthing may have come loose.

I had a similar situation on my Venture, and it turned out to be somewhere in the coils or plug wires. I cant tell ya which cause I swapped them both out at the same time. but the problem went away.

I have the same issue with my 90. but it can be intermittent. mostly not though

I did everything you have done. in the process I found some significant carb issues I fixed (so much for my $900 carb work at the local shop) though that did help, the poor spark/no spark kept happening. swapped plugs with no difference and all electrical connections are good. I got new (used 4k) coils and wires to try since 3 of my coils were cracked I thought that might be it.

I put them in and took it for a ride last night. ok around town, still missing power though. I hit the highway to wind it up for a bit. when I got off the highway to eat it was worse/VERY noticeable. got on it after dinner and the damn thing ran like a raped ape- no issues on the way home :confused2:
I am now away for the week, but have a dyna 300 to put in when I get back. not sure what else to replace. :ummm:
I also think my v-boost is not working. the geared motor does not cycle on ignition anyway.

ssnsltd said:

I have the same issue with my 90. but it can be intermittent. mostly not though

I did everything you have done. in the process I found some significant carb issues I fixed (so much for my $900 carb work at the local shop) though that did help, the poor spark/no spark kept happening. swapped plugs with no difference and all electrical connections are good. I got new (used 4k) coils and wires to try since 3 of my coils were cracked I thought that might be it.

I put them in and took it for a ride last night. ok around town, still missing power though. I hit the highway to wind it up for a bit. when I got off the highway to eat it was worse/VERY noticeable. got on it after dinner and the damn thing ran like a raped ape- no issues on the way home :confused2:
I am now away for the week, but have a dyna 300 to put in when I get back. not sure what else to replace. :ummm:
I also think my v-boost is not working. the geared motor does not cycle on ignition anyway.

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Let me know how your Dyna works, as I've been wondering about the ignition module also.

I don't know what coul dbe wrong with the #1 carb - I've been through it at least 3 times. I have tools, compressed air, and cleaner, which I've used.

I had the V-Boost issue as well before taking part the v-boost module and resoldering a bunch of pins.

Shuri, here's the pic I promised you. let me know if you could use the adapter. The top adapter is 12 mm, other is 14 mm. Also pictures is the hose end of the compression gauge.

Shuriken said:

Let me know how your Dyna works, as I've been wondering about the ignition module also.

I don't know what coul dbe wrong with the #1 carb - I've been through it at least 3 times. I have tools, compressed air, and cleaner, which I've used.

I had the V-Boost issue as well before taking part the v-boost module and resoldering a bunch of pins.

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will do, right as the guy said in War games said "i'd piss on a park plug if I thought it would help. . ."

maleko89 said:

Shuri, here's the pic I promised you. let me know if you could use the adapter. The top adapter is 12 mm, other is 14 mm. Also pictures is the hose end of the compression gauge.

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I think that would work. Where did you get the adapter or did it just come in with the guage?

It came with the gauge.

If interested PM me with you name/address information. Thanks.

maleko89 said:

If interested PM me with you name/address information. Thanks.

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Mark, where did you get the guage? I wouldn't mind buying one if I knew it came with the right adapter.

I swapped #3 coil with #1. Still seems to be a problem so I don't think it's the coil. If it were the TCI, wouldn't #1 AND #3 exhibit issues?

Hoping I'll find compression to be good. If compression is not good and it's not just a simple valve shim issue, I'll have to consider buying a newer VMax than perform an engine repair.

Thanks Mark for the adapter. I'll get it back to you next week.

Compression test (cold, no oil added) results
8-28-08, 6pm, 85f, 5700ft elevation:

#2: 141 #4: 150
#1: 153 #3: 141

Per the manual, this seems fine at my elevation, although the difference between pressures is getting close to the 14psi limit. Has to be spark crapping out on me or still some kind of fuel problem.....

When you swapped coil, did that include HT lead & plug ? If not, could be the issue:ummm:

Shuriken said:

Thanks Mark for the adapter. I'll get it back to you next week.

Compression test (cold, no oil added) results
8-28-08, 6pm, 85f, 5700ft elevation:

#2: 141 #4: 150
#1: 153 #3: 141

Per the manual, this seems fine at my elevation, although the difference between pressures is getting close to the 14psi limit. Has to be spark crapping out on me or still some kind of fuel problem.....

Click to expand...

You're welcome. Manual says to test compression when engine is warm. I would re-test...maybe you're not as close to that 14 PSI differential.

One option is to take it to the dyno. They use an ignition pickup which can help in detecting ignition problems. This helped me years ago detect failing Dyna hot coils.

jedi- said:

When you swapped coil, did that include HT lead & plug ? If not, could be the issue:ummm:

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I swapped everything except the plug. But I have tried different plugs too.