Not running on all four!! HELP!

[Semi239]

Hey yall, need some help thinking through this issue.

A week ago I was riding and suddenly the bike sounds different and felt very sluggish. I limp it home and I find the plug wire from cly3 is grounding on the frame. I knew I had some cracked coils and wires. So I replaced all four coils and wires with a COPs setup from Jon Harris. It is still running very poorly. If I unplug the COPs lead to cyl3 or cyl2, no change. I put a fresh plug on each lead and they all spark well to the frame.

I pulled the carb( which was leaking gas also) to take a look. I recently had a shop go through them and supposedly didn't find anything for $700. I found nothing unusual in there, stock jets, and floats are set right per the forum.

What should I be looking for? Fuel problem, electrical? Compression? Does this sound indicative of any other known issue?

 

[Semi239]

cont.

the slides holding the needles aren't fluttering at idle. I have to rev up past 2000 to get them to move, lots of backfire and it's struggling pushing that dead cly

 

[Fire-medic]

Neither #2 nor #3 are firing?

OK, before the COP's, only #3 wasn't firing, but now neither #2 nor #3 is firing? Do they cut-in and run at higher rpm's? I'd try swapping the #1 and #4 COP's into the #2 & #3 cyl's, and see what happens, to start. Then try swapping the same, order, for the sparkplugs. Change 1 thing at a time, to see what works or what doesn't.

 

[MaxMidnight]

I assume when you say 'they all spark well to the frame' this is earthing the plugs to the frame? On that basis I would assume that the ignition is performing as expected. Helpful hint: An in-line spark tester is a good tool to have in your kit.

You also say 'I have to rev up past 2000 to get them (the throttle slides) to move'. That may be normal(?) because at low revs it is the idle circuit that provides the fuel. The slides will only move once the engine needs more fuel and the needles start to control the mixture.

You mention a fresh plug...have you put four new plugs in to see how it runs?

First step will be to establish which cylinder is misfiring or not firing. On a multi cylinder engine this isn't easy. One way is to see if one header is cooler than the others. Helpful hint: Touching with fingers or any other part of you anatomy is a BAD idea; an infrared thermometer is a better way.

Once you have established which cylinder is the culprit then, as Mr Medic suggests, swapping the COP's may move the problem but if not then you are looking at a fuel or compression issue. A compression or better still cylinder leakage test will confirm or rule out the latter.

If it turns out to be a carb issue then you will need to look into the offending carb. As the issue came on suddenly I would rule out float height (although checking is easy enough) so look for some foreign body or something come loose.

 

[wayne billings]

I am having a similar issue. After limping home I shut it off and restarted ,it would idle fine but would not rev past 2k give or take. Later it wouldn't start or even pop I am getting a ignitec to replace the old box. Is there any info on what values I would see if I measured the pins at the 2 plugs that plug into the module with the switch on ?

 

[MaxMidnight]

Never seen any published values but you could work out what some should be by studying the wiring diagram.
Out of curiosity, why are you fitting an Ignitec?

 

[wayne billings]

Never seen any published values but you could work out what some should be by studying the wiring diagram.
Out of curiosity, why are you fitting an Ignitec?

 

[wayne billings]

I believe the orginal icu is the problem.

 

[Semi239]

OK, before the COP's, only #3 wasn't firing, but now neither #2 nor #3 is firing? Do they cut-in and run at higher rpm's? I'd try swapping the #1 and #4 COP's into the #2 & #3 cyl's, and see what happens, to start. Th

Im thinking they both weren't firing before COPs and I just missed cyl2

 

[Semi239]

You mention a fresh plug...have you put four new plugs in to see how it runs?

This thought process from Midnight makes the most sense to me. If I have folded plugs but they are getting spark it would still be misfiring. I need to nail down which cyl is missing before continuing. If I rule out the spark issue then I will look back at the carbs. I had them off last night and nothing is in any of the carbs suggesting there is a blockage. floats all look correctly also

 

[Semi239]

p I am getting a ignitec to replace the old box.

What is this Ignitec system?

 

[Semi239]

I saw on this other thread that a tight exhaust could be causing an issue. I know I have an exhaust leak bc gas was spewing out of it when the 2 cyls were dead. Should I consider this also?


https://www.vmaxforum.net/threads/cannot-rev-past-6500-rpm-under-load.52049/

 

[99YAMAHAVMAX]

The instructions I got with the cop kit said to cross the front wires.

 

[99YAMAHAVMAX]

The manifold on the carb you posted a photo of has a crack in it and the vboost rubber is cracked and out of the clamp also.

 

[99YAMAHAVMAX]

Vboost rubber and manifold cracked.

 

[Semi239]

The instructions I got with the cop kit said to cross the front wires.

Thats correct. I installed them accordingly

The manifold on the carb you posted a photo of has a crack in it and the vboost rubber is cracked and out of the clamp also.

hmm I found a missing clamp on the carb boot also. didn't think much of it, but I guess there could be unregulated air coming in there.

 

[MaxMidnight]

What is this Ignitec system?

It is a programmable ignition control unit. A good replacement if yours goes bad but as it is programmable i.e you can change ignition parameters, you have infinite number of ways to cock things up.

I saw on this other thread that a tight exhaust could be causing an issue. I know I have an exhaust leak bc gas was spewing out of it when the 2 cyls were dead. Should I consider this also?

https://www.vmaxforum.net/threads/cannot-rev-past-6500-rpm-under-load.52049/

Not sure if you are referring to the 'restricted' part of the quote?
If so he was referring to the engine power being restricted - all French Maxii are restricted to 100HP by removing V Boost and limiting carb slide maximum lift.
Nothing to do with the exhaust.
A leaking exhaust is unlikely to cause a misfire but should be fixed.

The manifold on the carb you posted a photo of has a crack in it and the vboost rubber is cracked and out of the clamp also.

IMO the 'crack' in the inlet manifold is a casting mark (never read of a cracked manifold) and is not an issue. Are you referring to the mark at 10 o'clock on the rubber? That looks like it is where the air box has been forced on. Some rubber glue would fix that plus the clamp would tend to close it up.
External cracks on the rubbers are not unusual and provided they don't go right through are not a problem. A gentle probe with a feeler blade or wire will confirm the boots serviceability.

hmm I found a missing clamp on the carb boot also. didn't think much of it, but I guess there could be unregulated air coming in there.

There should be a clamp at the top and bottom of the boots.

 

[Semi239]

External cracks on the rubbers are not unusual and provided they don't go right through are not a problem. A gentle probe with a feeler blade

I think they are all in working order. No cracks all the way thru. Need to replace that missing band clip tho.

Something like this shouldn't be causing my level of issues I wouldn't think. Im putting fresh plugs in it this weekend to determine which are missing. As I said in the first post if they will spark well outside of the engine then I should be getting good spark inside and I should look closer at air/fuel?

 

[99YAMAHAVMAX]

It is a programmable ignition control unit. A good replacement if yours goes bad but as it is programmable i.e you can change ignition parameters, you have infinite number of ways to cock things up.


Not sure if you are referring to the 'restricted' part of the quote?
If so he was referring to the engine power being restricted - all French Maxii are restricted to 100HP by removing V Boost and limiting carb slide maximum lift.
Nothing to do with the exhaust.
A leaking exhaust is unlikely to cause a misfire but should be fixed.


IMO the 'crack' in the inlet manifold is a casting mark (never read of a cracked manifold) and is not an issue. Are you referring to the mark at 10 o'clock on the rubber? That looks like it is where the air box has been forced on. Some rubber glue would fix that plus the clamp would tend to close it up.
External cracks on the rubbers are not unusual and provided they don't go right through are not a problem. A gentle probe with a feeler blade or wire will confirm the boots serviceability.


There should be a clamp at the top and bottom of the boots.

The casting marks are on the sides and Sean posted a box full or repaired ones before-No, not 10:00 o'clock on the rubber manifold, the vboost rubber is certainly torn at 5:00 o'clock -I'm not saying that is the reason he is having this problem just pointing out that I would fix it.

 

[brian hicks]

cont.

the slides holding the needles aren't fluttering at idle. I have to rev up past 2000 to get them to move, lots of backfire and it's struggling pushing that dead cly

Put a pressure meter on the cylinder to check compression just to eliminate that there isn't a problem there.