Yamaha FZR750 Genesis 2LM

[Icanopit]

Hi all from the UK, I am currently rebuiling a FZR750 2lm 1987 which I believe to be a "Japanese import"
I have manged to resolve most problems but have 2 major outstanding ones.
1. the engine seems to be power restricted do I need a replacement "igniter box" or ??? whatever. (won't rev above 4.5k)
2. the forks, as fitted, do not match any of the oil/weight/quantities that I have reference to and are very soft in action although I have stripped cleaned and replaced seals oil etc.

ANY advice to resolve the above problems in particular the power output, as I need to put the wind back across my "receeding" hair line, plus of course a smile on my face.

JOHN

[gammaguy]

the fact that it wont rev out probably has little to do with the ECU

I would suggest you check the carburetors and fuel tap for a start,then check the air intake system.

As for the forks new seals and oil wont drastically affect the springing,but the springs will.eighties and nineties Yamahas were notorious for soft suspension so the best way to go is to get a set of progressive fork springs.

[Icanopit]

Hi GAMMAGUY,
thanks for the reply, the reason I mentioned the ECU/Igniter is I had read elswhere that the 2LM for the "Japanese" market was power restricted and an additional "plug in module" was available to overcome the restriction.
I am currently midway through stripping and cleaning the carbs, which having stood for a number of years are amazingly clear of sediment etc and the fuel flows very freely, proven when I switched the ignition and had a "fountain" of petrol ? god job I no longer smoke, blow myself up one day??
Yes agree over the forks, but when trying to compare the spring length with other varients they are NO where near anything. I am fortunate that very near to me I have one of the better spring suppliers Ktech and will probably end up asking their advice/opinion.

JOHN

[Grumph]

Back in the day I saw the same "won't rev over about 4500" problem on an FZR1000.
It turned out that it had a "get you home" mode in the ignition which when the ignitor failed would still give a limited spark.

I'd suggest trying to borrow an ignition box to at least eliminate this as a source of your problem.

[GrayWolf]

Hi GAMMAGUY,
thanks for the reply, the reason I mentioned the ECU/Igniter is I had read elswhere that the 2LM for the "Japanese" market was power restricted and an additional "plug in module" was available to overcome the restriction.
I am currently midway through stripping and cleaning the carbs, which having stood for a number of years are amazingly clear of sediment etc and the fuel flows very freely, proven when I switched the ignition and had a "fountain" of petrol ? god job I no longer smoke, blow myself up one day??
Yes agree over the forks, but when trying to compare the spring length with other varients they are NO where near anything. I am fortunate that very near to me I have one of the better spring suppliers Ktech and will probably end up asking their advice/opinion.

JOHN

Power 'restriction' is not going to limit you to 4.5k revs... it will likely alter ignition etc in the higher revs to drop the absolute power, Kwaka used a set of carbs with an 'insert' to prevent full opening to restrict the ZZR1100's, didnt stop them revving to 11k rpm through the gears. Modern rodent P (unleaded petrol) leaves a horrible varnish? inside the carbs... they may need a sonic cleaning and/or have blockages due to said 'crap'....
Failing that, are the coils OK,,,, coil breakdown at high loads (rpm)? If the obvious are all ok, guess it could be time to look at the ignition module.
Re soft forks? As above crap Yamaha 80's springs... replace em

[White trash]

My K4 GSXR1000 stopped reving past 4500 at a trackday once. Turned out it'd skipped a tooth on the inlet cam sprocket. Could'a been disasterous.

[Icanopit]

Thanks for all of the observations guys. Went into the workshop early this morning refitted carbs and slave fuel line, checked compressions etc. Bike started very easily 2nd press "no" throttle/choke let it run for 30 seconds, still wont rev above 4500, stopped engine scrathed head drank coffee then for some unkown reason touched number 1 downpipe "just warm" other 3 too hot to handle, the lights came on?? Just of outside again to strip coils out and recheck as they are new, fortunately I have a couple of replacements to try.
Think I need to have a spin out on the Street Triple to clear my head

JOHN

[gammaguy]

Thanks for all of the observations guys. Went into the workshop early this morning refitted carbs and slave fuel line, checked compressions etc. Bike started very easily 2nd press "no" throttle/choke let it run for 30 seconds, still wont rev above 4500, stopped engine scrathed head drank coffee then for some unkown reason touched number 1 downpipe "just warm" other 3 too hot to handle, the lights came on?? Just of outside again to strip coils out and recheck as they are new, fortunately I have a couple of replacements to try.
Think I need to have a spin out on the Street Triple to clear my head

JOHN

coils fire two cylinders per each.

check the spark plug/lead/cap first.

while you are at it,check the compressions.

[ducatilover]

Jap import eh?
Find the speed limiter and plug it back in.