Have purchased 1992 CBR1000f with around 50k on the clock. Bike in sound, original condtion, but performance is poor and in fact my old VF1000f would make it look silly. Barely able to make 140kmh. New plugs, filters, fluids etc. Thought it might be the lower power (100bhp) model, but no restrictors in air intake/carb system. Had the carbs out, cleaned needles etc and checked thatthrottles are opening fully. All okay. Engine oil at change was clean, and no smoke at start up or any odd noises. Starts first time, idles at around 900rpm. Next step is Dyno tune etc, but perhaps someone might have some thoughts on this.

 

I'd go ahead and check your valve clearances and then do a compression check on all your cylinders. If both of those check out, then it probally isn't anything internal, but rather carburation or ignition. and that 50k = 50,000km? that isn't much at all, I bet it's something simple like the ignition getting out of time or something.

Also check your plugs to see if it looks to rich or too lean.

 

I would check the timing and choke as well, there isn’t a blockage in the exhaust.
Also check you brakes and how free your wheels spin

 

Thanks guys. Plug colour near perfect. No friction in drive chain/wheels. You are probably right about the valve timing and a call to a local Honda Dealer has me thinking that possibly the Cam Chain Tensioner has been replaced recently and the valves may be on cog out in timing. Will check and let you know.

 

Does it rev freely?

 

Motor responds to throttle without hesitation with no load on, but through the gears there is no sign of the 130 claimed bhp and it struggles to get to 140kmh. It's like only using half throttle and waiting for the revs to build up. There's no misfiring or popping ont he overun, and the motor sounds mint - The lights are on but nobody's home!!! Had a look at the valve timing last night, and it's obvious from the gasket silicon on the head cover that there's been recent work upstairs (probably the cam CCT). Intake clearances of 1 & 3 revealed that gap adjustment is required (there was not gap on a couple of the valves). Will complete the rest of the clearances in the next day or so and get it back together to see how it goes. After that it'll be ignition timing, then .......F Knows! Probably have to hand her over to the "Experts" and take my wallet out. Am getting very good at removing body panels though!

 

Okay, all valve clearances within limits. No major adjustments required. Next it's on to ignition timing I guess.

 

You could run a compression check while you're at it, although if compression was low enough to really affect power one would think there would be oil out the tail pipe. Synchronizing the carbs might also be in order if you find everything else is okay. Actually, it sounds as if the ignition timing is retarded, or isn't advancing as it should.

 

Unfortunately, you can't adjust the ignition timing on these beasties as they have a fixed CDI controller, so I now have a suspicion that the "Ignition Pulse Generator" is faulty. Will test this with a voltmeter and report back.

 

how about a cloged air filter or

make sure all the clinders are fireing that the headers are equally hot

get your finger wet and make sure ones not cold on you