Problem with 85vmax missing.

[Hemingway506562]

I took my vmax out for a weekend ride and revved it to the limit in third gear and now it's missing. I changed all the spark plugs due to them having dry black carbon on them and it is still missing in first and second gears. I can't really feel it in third on to fifth. It will sometimes quit while idling also. I bought a new ignition box from Morleys muscle and it ran great for a couple months. Can anyone give me an idea what I should check?

 

[Parminio]

I would make sure you're still getting fire to all cylinders first. If you are I'd move on to a compression check.

 

[digin150]

I’d check spark plug caps,probably time for a carb cleaning.

 

[user 16790]

what do you mean by 'revved it to the limit'

 

[Hemingway506562]

what do you mean by 'revved it to the limit'

I revved it till it cut out.

 

[Hemingway506562]

I’d check spark plug caps,probably time for a carb cleaning.

One carb away replaced and all carbs have been recently rebuilt and cleaned.

 

[user 16790]

as far as I'm aware the gen 1 has no rev limiter so you may have caused engine damage

 

[Hemingway506562]

as far as I'm aware the gen 1 has no rev limiter so you may have caused engine damage

I'm not sure but the aftermarket ignition control may have a limiter.

 

[VMAXXIMUM]

The ignitech does have a rev limiter. It may or may not be active. It’s also adjustable so it could be set to high. You need to hook it up to a computer and verify it’s active and set to an appropriate rpm.

 

[Parminio]

as far as I'm aware the gen 1 has no rev limiter so you may have caused engine damage

That's why I suggested the compression check. I think he may have bent a valve or something along those lines.

 

[Hemingway506562]

That's why I suggested the compression check. I think he may have bent a valve or something along those lines.

Do you know what the compression on all cylinders should be between?

 

[Fire-medic]

VMX12- Service-Manual.pdf (vmoa.net)

 

[Parminio]

Do you know what the compression on all cylinders should be between?

10.5 to 1 or 150 lbs. per square inch. Most gauges are labeled both ways with the PSI on the outside and ratio on the inside.

Bear in mind that due to age, condition and the gauge you use it may not be exactly per the manual, but it should be close. What you're looking for is to make sure all your cylinders are pushing roughly the same compression. If you have one that's a lot lower, you have a problem and you're going to need some serious investigative work.

 

[Hemingway506562]

One carb away replaced and all carbs have been recently rebuilt and cleaned.

When I was doing a compression check yesterday I yanked the plug wire free of the cap lol. That was the problem the whole time.