FJ1200 - How to derestrict - aka remove the japanese limiter

[Kenny1098s]

Hi Guys, and girls...
I run a small business here in South Africa, making screens and fairings for bikes. 
On the side I race Yamaha bikes, play on my dyno and fix just about any electrical and electronic issue with almost an bike, and this brings us to where I found this forum:

A repeat customer - fellow racer - and bike repairer, dropped of a FJ1200 and asked me if I could make is go past 6600rpm.

Strange thing is, the bike already has 46000km showing, and only now is his customer thinking of going faster!

I had a look in the speedo cluster, there is no 'bell' on the speedo nor on the rev-counter. 

I read here that there is a black wire to earth on the XJR and FJ, but can from the picture posted not figure out exactly what wire to look for.

Am I on the right track, or missing something somewhere completely?

Cheers.

Kenny.



www.wareagle.co.za

[FJmonkey]

The restricted bikes had smaller intake manifolds I think. Not sure how else they restricted them other than a speedo with less numbers on it.

[Kenny1098s]

Thanks Monkey. 

I read in a very old post here that the rubbers are down to 28mm at the bottom, I will have a look tomorrow.

It sounds like the spark is cutting / retarding on the dyno though in every gear -2nd and up - at the same revs. I will test the coil output tomorrow as well to confirm that it is spark that is affecting the bike.

I could not find it, but a guy called NED had a look here at the de-restiction a while ago.

[FJmonkey]

Thanks Monkey. 

I read in a very old post here that the rubbers are down to 28mm at the bottom, I will have a look tomorrow.

It sounds like the spark is cutting / retarding on the dyno though in every gear -2nd and up - at the same revs. I will test the coil output tomorrow as well to confirm that it is spark that is affecting the bike.

I could not find it, but a guy called NED had a look here at the de-restiction a while ago.

Make sure the bike does not have the dreaded 2nd gear issue. Mine has it and when pulling hard in 2nd gear, somewhere above 6K, it acts like a revlimiter as the gear jumps out and back in. Other gears can be affected. They get worse if you don't short shift and will then happen under lower revs. Eventually 2nd gear will just crap out with a very bent shift fork and badly worn dogs. Randy at RPM sells the parts to fix this on his site www.RPMracingCA.com. 

[Kenny1098s]

Hi.

It does the same in all gears.  On the dyno there is no real load if the drum is not braked, hence the 2nd gear problem does not seem to be here.  It does the same if run up freely with very little throttle.

I sent Ned a PM.....

Thanks for the replies so far.

[Harvy]

Hi.

It does the same in all gears.  On the dyno there is no real load if the drum is not braked, hence the 2nd gear problem does not seem to be here.  It does the same if run up freely with very little throttle.

I sent Ned a PM.....

Thanks for the replies so far.

Kenny - the Japanese import bikes had a hall effect type arrangement on the back of the speedo shaft which cut the spark at ~180kph, but there was no rpm restriction that I am aware of.
My '91 had similar spark problem to what you are describing - cutting out at around 6000 in my case....... after much stuffing around trying to find out where the problem was, I eventually bit the bullet and installed Dyna 2000 ignition, Dyna coils and new Dyna plug leads...... somewhere in that lot was the fix to the problem - but all up the Dyna stuff was cheaper than OEM ignition components for me - but I got a really good deal!

Long story short - I believe you have an ignition problem - but I can't tell you what component is causing the issue.

Yes, intake manifolds on Jap domestic models are 28mm at the head end. Rest of world have 32mm - but that is not the cause of your problem. Even when I had 28mm manifolds and properly working OEM ignition, the engine would still rev to redline.

HTH
Harvy

[SlowOldGuy]

If it's doing it at the same RPM in all gears, I'd bet it's in the ignition box.

Install a box from another country or an aftermarket ignition.

DavidR.

[Kenny1098s]

Thanks guys.

From your advice and experience I am only going to try two more things:

- swapping out the pickup coil - the part fish names it 'pickup coil governor'
- swapping out the ECU - There are a few available on eBay.

This is the link to the part-fish: http://www.partshark.com/fiche_section_detail.asp?section=16656&category=Motorcycles&make=YAMAHA&year=1991&fveh=425

I will post the result.

[Kenny1098s]

 

Unfortunately we will not get to the bottom of this problem, the customer will 'SAVE UP' first 

I am not sure if I will get it back to fix it.

Thanks for all the help, if it arrives back, I will post here what happens.

[SlowOldGuy]

Just for future reference, there's absolutely nothing that the pickup coil can do to limit the RPM.  It is purely passive and simply reports the position of the crank for the ignition to use in timing the spark.

DavidR.

[fj1289]

Just a thought. Sounds like a rev limiter. As I understand, the stick rev limiter is in the gauge cluster and fed off on of the coils. Could both coils be hooked up and trigger the rev limiter at half RPM?

[rktmanfj]

Just a thought. Sounds like a rev limiter. As I understand, the stick rev limiter is in the gauge cluster and fed off on of the coils. Could both coils be hooked up and trigger the rev limiter at half RPM?

Hmmm... didn't someone have an electrical fault a while back that caused the tach to read double speed?     

[Flynt]

didn't someone have an electrical fault a while back that caused the tach to read double speed?     

I had this issue, but changed too many things at once to know what fixed it.  I suspect it was a poor ground at the coils, but changed the tach as part of my winter project that included tearing the whole bike apart and re-assembling...  thus fixing grounds, connectors all clean, new switchgear, etc.

That's one known way to fix it...   

Frank