Engine Miss Fires at 5000rpm

[ScottG]

Morning, the bike has the above problem. Bike runs perfect up to 5000 rpm, full power, no misfire, still starts first time every time. I have reviewed all the posts on the site that explain similar problems but cannot find a solution, so please allow me to explain the background on our situation and maybe someone can assist.
My wife had a accident with a pedestrian, we had to then change out the following to repair the bike; Front Fairing, Headlight, Clocks and Ignition Key. There was no damage to frame or engine / engine casings. Since the repair, the bike now has a splutter / misfire immediately at 5000 rpm. It will will rev past that but continues to misfire. This happens when standing still and revved or on the move through each gear. I have cleaned carbs, changes plugs, swapped and changed coils. I have also swapped the (small box) Converter Unit that feeds the coils and the problems still exists. It cannot be fuel supply as the fault is there under standing rev's (less fuel demand) and under load (greater fuel demand).
My next step is to swap out the actual ICM (Cdi), however I cannot find one to use unless I buy one... So, I have a few 95' F3's that have a ICM with the same 16 pin plug and an inquiring if anyone would know if that unit would work on the Firestorm. Part # are different between the two bikes, however I find it difficult to believe that Honda would develop multiple units for different bikes. The firestorm has the converter from the ICM to coils as it is a twin!
I had the bike on the Dyno, swapped coils, cleaned all plugs / adapters and still no joy.
Any idea's or suggestion will be welcome - thank you.
Scott.

[VTR Phoenix]

I wouldn't continue to chuck parts at it as you will end up with a new bike.

If it was running fine before and not so fine after then I would be checking fitment of carbs, airbox and pipes, plugs for good constant spark, timing, (manual or auto cct's?) on the tip over could have dislodged some crud in the fuel tank that has partially clogged the filter thus starving engine of fuel when at higher demand.

[ScottG]

Thank You, Spray Guy told me that he cleaned / rust removed tank fully before spray job - maybe a second check could be time well spent.
Thank You.

[tony.mon]

Didn't fit mcct' s at the same time, did you?

[ScottG]

Sorry, but what are Mcct's?
We changed nothing other than Ignition / Key assembly, the clocks and head light plus of course some body work fix and spray..

[macdee]

Sorry, but what are Mcct's?
We changed nothing other than Ignition / Key assembly, the clocks and head light plus of course some body work fix and spray..

Cct = cam chain tensioner
this would be a problem in these bikes there's a spring inside them that tends to break and this lets the chain slip and then there's contact between piston and values
Mcct= manual cam chain tensioner
After market part produced with no spring and using a bolt , when adjusted to the right tension it is then looked off and can't back out like the original cct

When doing a service or changing for mcct sometimes the timing is set wrong giving a similar result to what you are getting

That's what tony was getting at
Did you by any chance renew the ccts at the same time

[8541Hawk]

Make sure the vacuum line to the petcock is in the right location.

[ScottG]

Morning, we did no work on the engine at all! Motor was running sweat all along. Going to re look the fuel supply once more and see if there is not a problem there.

Thank you for the suggestions thus far.

Scott

[ScottG]

Evening - has anyone got any experience on swapping the ICM as noted below;

My next step is to swap out the actual ICM (Cdi), however I cannot find one to use unless I buy one... So, I have a few 95' F3's that have a ICM with the same 16 pin plug and an inquiring if anyone would know if that unit would work on the Firestorm. Part # are different between the two bikes, however I find it difficult to believe that Honda would develop multiple units for different bikes. The firestorm has the converter from the ICM to coils as it is a twin!

[8541Hawk]

The quick answer is no it will not work.
The ECU is bike specific as the ignition map will be different for each model of bike.
There are even differences in the map between early and late VTRs.

So once again you must use the proper ECU for the bike.

[8541Hawk]

I'm a bit too far away but I, like many others, have one sitting in my parts bin.
Ask nice and someone might offer up one for test purposes.

[Cadbury64]

My ST1100 had a similar problem; started and idled fine, ran well below 4000 rpm, but over that it misfired badly, and I spent a lot of time assuming the carbs were at fault, but they weren't. I finally traced the fault to low voltage getting to the ECM, which resulted in a weak spark. The root cause was corrosion in the red connector which feeds power to/from the right bar pod.

I would suggest you grab a multimeter and the wiring diagram, and check that you are getting close to 12v through the ignition circuit. You might also want to find and clean the ground connections and the battery terminals.

I have also read elsewhere that a failing battery can cause the same symptoms on the VTR. Might be worth trying a new one if yours is more than 2 or 3 years old. Best of luck.

[8541Hawk]

I will add I have not heard of a ecu going bad. What your issue is starting to sound like is a bad pulse generator pick up. It is located inside the clutch cover

[ScottG]

Update: So I have tested the Peak Minimum Voltage at the ICM and Pick Up connector. The Honda Manual suggest that anything less than 0.7V relates to a faulty Pick Up Unit. Readings at both points on the multi meter were at 0.6V!
I have also checked wiring continuity from Pick Up Connector to ICM plug and all good with no loss at all.

So next step is back to Ebay to search and find a Pick Up that I need to ship to SA. I am hoping this will solve the problem, I may as well also purchase another ICM for 'just in case' that the Pick Up's are not the only fault. Just amazes me how a small accident, with no mechanical damage to engine casings / frame etc can cause the Pick Up to be faulty.

OI will keep the thread updated once the bits have arrived and been fitted. Thank you to you all for your inputs thus far, really appreciated.

Scott.

[8541Hawk]

The pick ups have been known to go bad on their own from time to time. So the accident might or might not have caused it to fail. I would hold off on the ecu as again I have never heard of one failing so far.