Engine losing power (hp)

[westie]

I have a zxr 400 1989 h track bike.
Been reved to shit and had lots of fun.

Thing is it has been loosing power. It used to rev out to 16000rpm now it doesn't go over 12000rpm

I have tried tuning the carbs and air box to no avail.

Tried compression test and the readings have gotten better than when I first got the bike.

Old 110 110 135 135 new 130 133 135 138

Plugs are six months old and the very expensive ones. May be getting a bit low on spark. Will have to try new ones.

Any advice would be greatly appreciated.

edit.
Has gauges form a zxr 250. Never had a problem with them before this.

Never had a speedo

Unsure if derestricted but used to go faster than nc 30 derestricted.

[NordieBoy]

Compression is going up?

Gunge in the head?

[westie]

Not really sure. The internals look really clean and oil looks nice. But the oil did have a metalic look when put out in the sunshine.
and yea might be a good idea to take the head off to be sure.

[xwhatsit]

You hear stuff about the ignition system not being able to produce proper spark when you're talking about such astronomical RPMs. Coils failing, in particular.

You didn't do the compression test with a warm engine the second time around or something?

[boostin]

I have a zxr 400 1989 h track bike.
Been reved to shit and had lots of fun.

Thing is it has been loosing power. It used to rev out to 16000rpm now it doesn't go over 12000rpm

I have tried tuning the carbs and air box to no avail.

Tried compression test and the readings have gotten better than when I first got the bike.

Old 110 110 135 135 new 130 133 135 138

Plugs are six months old and the very expensive ones. May be getting a bit low on spark. Will have to try new ones.

Any advice would be greatly appreciated.
12,000 rpm exactly? Does it come in like a rev cut type thing, or it just slowly strugles up to 12000?

I recently had a similar problem, and I finally (after thinking my CDI was blown, only to remember what I had done) remembered that I had unplugged the speedo. Even when not hooked up the CDI still needs the speedo to be plugged into the eletrics for the speed cut.

[YellowDog]

If the spark plugs are good: What about the HT Leads?

[Morcs]

Are you still using those Mega coils?

[montsta56]

I Had similar type thing with my track NC30 an changed to New plug's ($200):shit: Now the bike feels sooo much better pull's harder an cleaner.

[westie]

12,000 rpm exactly? Does it come in like a rev cut type thing, or it just slowly strugles up to 12000?

I recently had a similar problem, and I finally (after thinking my CDI was blown, only to remember what I had done) remembered that I had unplugged the speedo. Even when not hooked up the CDI still needs the speedo to be plugged into the eletrics for the speed cut.

It gets to 12000 there abouts and then spits farts and misbehaves like an old girlfriend of mine. Its no fun being on top of that!

I've never had a speedo. It used to rev out fully and was faster than a few nc 30 bikes.

[westie]

If the spark plugs are good: What about the HT Leads?

Leads are good and the spark plags are ok. But I cant help but think the plugs might be a little thrashed.

[westie]

Are you still using those Mega coils?

Yea mega dyna coils. Dont think it'd be them.

[boostin]

It gets to 12000 there abouts and then spits farts and misbehaves like an old girlfriend of mine. Its no fun being on top of that!

I've never had a speedo. It used to rev out fully and was faster than a few nc 30 bikes.
Does it pull up to 12,000 as well as it used to before you had this problem?

Which CDI do you have in there? I found that if I didn't have a blue 'M' CDI in there I still had to have the electrics out of the speedo plugged in or I would get a rev/speed cut at about 12000. Maybe check to see if there is something come loose around the speedo wiring loom, if it is still there?

[westie]

Does it pull up to 12,000 as well as it used to before you had this problem?

Which CDI do you have in there? I found that if I didn't have a blue 'M' CDI in there I still had to have the electrics out of the speedo plugged in or I would get a rev/speed cut at about 12000. Maybe check to see if there is something come loose around the speedo wiring loom, if it is still there?

The bike used to run real good but I played god with the tuning and it went bad. Got it back to normal now and it is still bad but more defined.
Could have done some engine damage but the compression is better than ever.
The cdi is a red Y? Might take it round to a place that fixes them and get it checked out.
Never had a speedo gauge