2 cylinders not firing at low rpm

[ctonton]

I am having fits w my 95 vmax not wanting to run at low rpm. At first I thought it was the low rpm circuit in the carbs but it was running perfect only a few days ago and I went through the carbs just to make sure. It seams that the front right and rear left cylinder are not firing at low rpm. It it picks these cylinders up at around 4000 rpm and runs strong. Does any one know if there is something in the ignition system that could cause this?

 

[MaxMidnight]

The earlier bikes had two pick-up coils so if one of those was playing up it could take out a pair of cylinders.

However, as yours is a later machine with a single pick-up coil then I would discount that as a cause.

AS far as I can see the only thing that is common to the ignition coils post ignition modules is the feed (red/ white) wires.

I would be more inclined to investigate for any detritus that has made its way into the carbs.

When was the fuel filter last changed?
If not done so drain the float chambers into a bowl to see what comes out.

 

[ctonton]

I pulled the carbs and sprayed carb cleaner through everything but still no luck. I'm thinking ignition system at this point. But am confused as to why it is acting the way it is. Is there multiple circuits in the ignition control unit that operate at different rpm? I am 90% sure that the carbs are good. There is always that possibility but 2 weeks ago it ran perfect and since then I tried cleaning the carbs. If it were just one cylinder I could see it. But it is 2 cylinders acting the same way. Thanks for the advice.

 

[tugla]

you try switching plugs from the other cylinders or new ones. how about just bad wires or even the wires not quite on the plugs properly?

 

[[email protected]]

I wouldn't rule out the carbs yet. Try the shotgun and/or peashooter then put a little seafoam or something like that in the fuel and ride it for awhile. It might clear right up.

 

[tugla]

I wouldn't rule out the carbs yet. Try the shotgun and/or peashooter then put a little seafoam or something like that in the fuel and ride it for awhile. It might clear right up.

+1 , ive seen a bunch of bikes that totally acted like ignition issues, cyl not firing and it all ended up being clogged pilots or idle circuit etc

 

[Rhoy Carter]

Check your charging system, low voltage can cause this problem. The tci requires good voltage to operate right.

 

[one2dmax]

Voltage is definitely a key but the symptoms he's describing sounds like a failing CDI/TCI box to me.

Sean

 

[maleko89]

Yep, always test ignition, compression and charging voltage before digging into the carbs.

 

[526 turbo]

hey guys who makes after market high out put coils for a 1993 model, also how r the dyna 3000 units? thx:damn angry:

 

[one2dmax]

You don't need high output coils but you can look up the COP conversion (Coil on Plug). The dyna's are not as dependable as the OEM units in general but we do sell them (and they do have the rev limiter which I like).

Sean

 

[satariel666]

hey guys who makes after market high out put coils for a 1993 model, also how r the dyna 3000 units? thx:damn angry:

COP's are good and realible mod with You ignition system.
Most of us are happy with this mod.
Id say try to grab gsxr100 ones as they seems to have the higher primary resistance.
Also You should grab nice harness form our forum member 88vmx12.
Remeber: dont ever ever run the COP's with DYNA3000 without added resistors in series.

But if You want something traditional and You have some serious coin to spend over You may try with nology or dyna coils

 

[Thevmaxrider]

You could do the COP mod that a bunch of us here have done as a replacement for your stock coils. IMHO the Dyna3000 is a POS and I would stay away from it, unless Dyna has done some improvements to the boxes as they had some issues in the past.