1991 ZXR250 hesitating at 14,000 rpm

[Darealsytfromdagheto]

My 1991 zxr250c is hesitating at around 14,000rpm it feels like its popping kind of. Also sometimes it takes a while to start and other times it starts right away. Any ideas?? Thanks

[Akzle]

da real shit? Shyte?
Im uncertain.

[Darealsytfromdagheto]

da real shit? Shyte?
Im uncertain.

Nah im just da realyst from da ghetto

[Darealsytfromdagheto]

da real shit? Shyte?
Im uncertain.

Nah im just da realyst from da ghetto

[caspernz]

My 1991 zxr250c is hesitating at around 14,000rpm it feels like its popping kind of. Also sometimes it takes a while to start and other times it starts right away. Any ideas?? Thanks

Meh, back in the dark ages when I had a teenie weenie rice rocket thingeemajig I had a secret remedy for this problem. Nowadays we calls it changing gear :innocent::shit:

[Akzle]

Nah im just da realyst from da ghetto

ahh. The ghetto. New Zealand.

Sorry sugar, you clearly dont understand some of the words youre trying to spell.
Despite the third world poverty rates in nz, we have no actual 'ghettos' and those who do live in real ghettos would be offended by your twisted panties.

[Rhys]

Put a bottle of carb cleaner and a fresh tank of gas and give it an Italian tune up

If that doesn't work take it to a bike mechanic and get it tuned up

[SNF]

Put a bottle of carb cleaner and a fresh tank of gas and give it an Italian tune up

If that doesn't work take it to a bike mechanic and get it tuned up

Lol "iItalian tune up".

Seriously though, possibly an air leak? My bike did something similar in upper revs 12k + one day I had the tank off and discovered the collars which hold the intake pipes from the engine to the airbox was broken off and it wasn't sealing. Replaced them all with shiny new hose clamps and its better.

Does it back fire alot when downshifting?

[Darealsytfromdagheto]

Haha the name is just a joke btw. And okay cool, ill try that. The ram intake hoses have cracks in it but that wouldn't have anything to do with it?

[husaberg]

The ram air intakes are for show.
if you are getting hesitation and popping as others have said it indicates lean.
This could be blocked jets (varnish) or air leaks in the mainifold or intake boots or even the carb balance screws.
It could also be something else, diagnosis over the internet is pretty hard.

[Darealsytfromdagheto]

The ram air intakes are for show.
if you are getting hesitation and popping as others have said it indicates lean.
This could be blocked jets (varnish) or air leaks in the mainifold or intake boots or even the carb balance screws.
It could also be something else, diagnosis over the internet is pretty hard.

Sweet man, i'm going to clean out the carbs and see what difference that makes, it goes through the rev range perfectly until it gets to about 14,000rpm and then it just feels like its limiting almost.

[husaberg]

Sweet man, i'm going to clean out the carbs and see what difference that makes, it goes through the rev range perfectly until it gets to about 14,000rpm and then it just feels like its limiting almost.

The hard starting also points towards lean, but it could be also ignition faults coils braking down and a million other stuff.

[Darealsytfromdagheto]

Yea i understand what you mean by diagnosing it by the internet, Well i'll clean the carbs and if its still happening i'll take it to a professional. Thanks bro

[Darealsytfromdagheto]

Lol "iItalian tune up".

Seriously though, possibly an air leak? My bike did something similar in upper revs 12k + one day I had the tank off and discovered the collars which hold the intake pipes from the engine to the airbox was broken off and it wasn't sealing. Replaced them all with shiny new hose clamps and its better.

Does it back fire alot when downshifting?

Nope doesn't backfire when downshifting

[Akzle]

Sweet man, i'm going to clean out the carbs and see what difference that makes, it goes through the rev range perfectly until it gets to about 14,000rpm and then it just feels like its limiting almost.

fueling. Set your floats higher.

[husaberg]

Yea i understand what you mean by diagnosing it by the internet, Well i'll clean the carbs and if its still happening i'll take it to a professional. Thanks bro

when you are doing the carbs have a good look for air leaks seal as nes with some silicone if they are cracked

[bungbung]

Look for leaks in the vacuum pipes that feed the vacuum side of each of the slides, it's a common place to fail now the rubber is 20 years old.

[ducatilover]

fueling. Set your floats higher.

Unlikely at 14,000rpm. But you'd have a faggy flatspot at 3-4000

Has it got a standard exhaust and air filter?
Is the filter clean?
Are the plugs in good nick?
All sealing surfaces on the intake sweet? (as already said, the ram tubes are not real on them)
If yes to those, it's time to play carb games

Hard starting hot, or cold? When were the valve clearances done and the last carb sync?
Also, will it actually rev past 14?

[Darealsytfromdagheto]

Unlikely at 14,000rpm. But you'd have a faggy flatspot at 3-4000

Has it got a standard exhaust and air filter?
Is the filter clean?
Are the plugs in good nick?
All sealing surfaces on the intake sweet? (as already said, the ram tubes are not real on them)
If yes to those, it's time to play carb games

Hard starting hot, or cold? When were the valve clearances done and the last carb sync?
Also, will it actually rev past 14?


Hey, it has standard filter and aftermarket tyga tip. I haven't checked the filter. Plugs were replaced recently. I haven't had a chance to look at intakes yet. Its hard to start hot and cold sometimes. I had been riding my bike about a hour and went to restart it straightaway and it wouldn't start for like 5 minutes. It probably would keep reving past 14,000 but really doesn't want too

[ducatilover]

Tyga muffler? First off it'll need a re-jet anyway.
Try get it past 14k in 2nd or 3rd. If it does not go past, check the pink wire on the cdi unit is not cut or has a resistor to ground installed. Then check the 3 wire plug on the back of the speedo is connected.

[Darealsytfromdagheto]

Tyga muffler? First off it'll need a re-jet anyway.
Try get it past 14k in 2nd or 3rd. If it does not go past, check the pink wire on the cdi unit is not cut or has a resistor to ground installed. Then check the 3 wire plug on the back of the speedo is connected.

Okay ill check now bro, is the cdi under the seat? and its in 2nd and 3rd that it wont go past

[ducatilover]

Will it go past in other gears? Yeah under there somewhere man.

[Darealsytfromdagheto]

Will it go past in other gears? Yeah under there somewhere man.

I don't think it will go over in other gears, i havent really tried in higher gears, it gets around the 14,000rpm and it sounds like its hitting limiter or pops real fast

[mossy1200]

Is your speedo connected?

Does it have a low fuel light or fuel level indicators.?

Does it have a fuel pump?

[Darealsytfromdagheto]

Is your speedo connected?

Does it have a low fuel light or fuel level indicators.?

Does it have a fuel pump?

Yes speedo is connected, no fuel light or fuel level indicators, i don't think it has a fuel pump. I checked the pink wire on the cdi and all the wires seem intact

[mossy1200]

Yes speedo is connected, no fuel light or fuel level indicators, i don't think it has a fuel pump. I checked the pink wire on the cdi and all the wires seem intact

Are there any wires coming from the tank base?
Some bikes that age go into limp mode when fuel level is lower or if has a faulty sensor then all the time.
If there is wiring harness coming from tank base trace it to the plug and unplug it.

[Darealsytfromdagheto]

Are there any wires coming from the tank base?
Some bikes that age go into limp mode when fuel level is lower or if has a faulty sensor then all the time.
If there is wiring harness coming from tank base trace it to the plug and unplug it.

Not that i can see bro, there looks to be some sort of a small leak around the reserve switch.

[ducatilover]

They have a 180k limiter and if the pink wire to the cdi gets the wrong resiatance or an open circuit they cut cyl #'s 2/3 at 14,000rpm.
There should be voltage present between the pink wire and ground, and should be lower than battery voltage.

As far as I remember there is no fuel pump on one, or level sender.

[Darealsytfromdagheto]

They have a 180k limiter and if the pink wire to the cdi gets the wrong resiatance or an open circuit they cut cyl #'s 2/3 at 14,000rpm.
There should be voltage present between the pink wire and ground, and should be lower than battery voltage.

As far as I remember there is no fuel pump on one, or level sender.

Okay that sounds like a real possibility, how would i check if it has the wrong resistance?

[ducatilover]

Multimeter. I'd check voltage.
Usually a cheap 12v led will have a resistor on it and is the right resistance to sort the issue, so chop that wire and put the led from the cdi to ground.
Has worked for me several times.

[Darealsytfromdagheto]

Multimeter. I'd check voltage.
Usually a cheap 12v led will have a resistor on it and is the right resistance to sort the issue, so chop that wire and put the led from the cdi to ground.
Has worked for me several times.

Awesome bro i'll try that, thanks for your help

[ducatilover]

All good. Hope it sorts it

[F5 Dave]

Sometimes an engine just won't rev that high on its own accord- so the answer is simple. You'll just have to force it.

Mechanical advantage means you can show it who is boss. It might overlock the gears for a while, but try shifting to 2nd from about 90 (ideally on a wet road, so if it does lock you don't waste too much rear tyre) & that should scare it into submission.

:innocent:

[Grasshopperus]

I used to have a zxr250a and had the same problem. Turned out that a previous owner had installed carb jets one size larger than the factory specifications. I replaced them all with the proper-sized jets and the hesitation went away.