I'm so sorry

i have to start a new 3d about that but im really astumped and i need help.
GPZ900R , bike is running PERFECT. easy start, perfect idle, alot of power in the entire power band of the FIRST FOUR GEARS, but when is in 5th or in 6th gear she wont go over 7000 rpm. just stop climbing rpm, just sitting there and nothing.
i have tried in the last months:
swapped coils
swapped pick up coils
swapped cdi box
different sets of plugs
new plugs caps
a good condition used alternator assembly.
bypassed lockout switches (clutch and kickstand)
tried differetn fuel
tried to use the choke under heavy load in 5 and 6 gear..(no way)
tried to running with opened gas cap
new air filter
cleaned airbox
new intake boots NOS

the engine can redline in 1, 2, 3, 4 very easily and it is FAST! 140 rpm in fourth gear is so easy..
i cleaned the carburetors million times and i ve tried another set of carbs from another bike, still no joy.

compression is a good 150 psi and carbs was synched recently.

the bike is totally stock and is only missing the centre tube between the silencers under the bike (the PO for some reason cut and weld it)

please HELP ME

Unless you're tracking it, performance above 7000rpm in 5th gear shouldn't be a problem.

Compression at 150 sounds pretty low to me - if all the cylinders are the same then it will run fine, but you can't expect the same performance as new. Every compression gauge reads different, but for full power in the top gears I would expect to see above 180psi in a new-condition engine, since it's a fairly high compression ratio. But check your manual for expected values.

I"d be wondering about the lack of a crossover, which seems like that would be a pretty significant modification of the muffler system. Eliminating the crossover reduces the exhaust cross-section by about half or thereabout & I would assume increase the back pressure by quite a bit. There was a topic w a link here on KZR about exhaust system physics, but the last time I checked the link was gone. Unrelated to the mufflers, I would make sure the battery is good >> charge it with a good motorcycle smart charger & do a load test. I don't think this is your problem, but checking the battery is easy & should be done anyway.

....

You didn't mention anything related to fuel flow in your list.
Do you have an inline fuel filter? If yes, make sure it is not a paper element for cars. They restrict flow over time.
Make sure the fuel line pours fuel out fast.

You might be expecting too much from the bike. I'm not sure how much speed you can expect past 140 mph. Anyway, since it's not mentioned I'd be sure to catch up on all the maintenance such as valve clearances.

I hope you have good tires.......

Did he really mean 140 mph? He wrote "140 rpm" so maybe he means 14000 rpm? He seems to be speaking in rpm rather than mph, but I guess 14000 rpm would be awfully over-revved.

Nono, i mean 140 mph and the bike stop at 7000 rpm in 5 and 6 gear. I have valve clerance checked and registered and this problem will make me crazy..
Battery is new and charged but i have swapped the battery also from another bike.
I have a inline fuel filter, no paper element and the fuel flow is good!
I was wondering if the problem can be in the red stop switch button maybe?
I dont think im expecting too much from the bike because other 900r i have tried go past 7000 rpm easily in 5 amd 6 gear

The GPZ900R max. Speed is round about 250 Km/h = 155 mph under optimal conditions with a single driver!!!
You shamal do 140 mph in 4th gear!!! Sound like you drive with the wrong front/rear sprocket setup (secondary gear ratio)???

GPZ900R front/rear sprockets 17/49(50) = 2,88 to 1
GPZ1000R(X) front/rear sprockets 15/40(41) = 2,66 to 1




Just a thought...

No i have a new did set 17/49.. I really dont know what can i do. Its very frustrating on the highway hitting the 7000 rpm limit..

So if you shift from 4th (150 mph) into 5th gear the bike slows/revs down to 7000 rpm???
In 4th (150 mph) how many revs are on the speedo (rev meter)?
Are both wheels Spinning freely???

Yes. The bike is just unable to rev past 7000 rpm in 5 and 6 gear. Is no acting strange, just stop climbing rpm, and the engine should pull at least more + 3000 rpm.. As it does in the other gears