ZXR250C carb help wanted

[Spoonrider]

Hey guys,

I have a 1994 ZXR250C and I am getting hesitation issues between 6-8k rpm, I am also told the bike is running very rich. The hesitation seems to come on as the bike warms up, it could be the richness fouls the plugs... but not sure. The bike has an aftermarket exhaust which I am told could be making the issue worse.

Just wondering if there is anyone in the Auckland area that is clued up on these bikes that doesn't mind giving up some of their time (for a box of beer) to help me remove the carbs and have a look at them to see if they are dirty or there is any other obvious sign as to what could be causing the issue?

Also, has anyone had experience with these http://www.ebay.com.au/itm/91-04-Kawasaki-Ninja-ZXR-250-ZX2R-ZX-2R-ZXRR-Carburetor-Carb-Stage-1-3-Jet-Kit-/230799496111?pt=Motorcycles_Parts_Accessories&hash=item35bcb8d3af&_uhb=1#ht_2524wt_1163 Given the needles aren't adjustable I was thinking of getting one of these to maybe help my issue?...

Any help would be very much appreciated :-)

[Haggis2]

Have you thought about gettign yourself a Haynes type manual? I consider myself reasonably clued up (sometimes) and have found mine invaluable with some things.

[Spoonrider]

Have you thought about gettign yourself a Haynes type manual? I consider myself reasonably clued up (sometimes) and have found mine invaluable with some things.

Yeah, have watched videos and have a service manual but always good having someone there who knows :-)

[FJRider]

A blocked / dirty air filter will make it run rich too ... give it a clean and see if it improves.

No filters (or small ones) will lean the mixture out a little. See if a short run with no filter makes any difference ...

[Spoonrider]

A blocked / dirty air filter will make it run rich too ... give it a clean and see if it improves.

No filters (or small ones) will lean the mixture out a little. See if a short run with no filter makes any difference ...


Thanks for the reply.

Air filter has been cleaned already so not that, o-rings between the airbox and carbs have been replaced too as they were poked. I was told it was running rich cos there was some black soot in the end of the tail pipe, so I am not certain if it is running rich or not...

[FJRider]

Thanks for the reply.

I was told it was running rich cos there was some black soot in the end of the tail pipe, so I am not certain if it is running rich or not...

The black soot is the result of our poor quality petrol. This is evident in most motorcycles since the introduction of unleaded petrol.

[Spoonrider]

The black soot is the result of our poor quality petrol. This is evident in most motorcycles since the introduction of unleaded petrol.

Ah, ok then.

So is there any easy way to tell if it is either running rich or running lean?

A lot of research that I have done points to it running lean and that I should try a couple of shims under the needles... It has a non-standard slip-on muffler as well which people say can play havoc with them too

[FJRider]

Ah, ok then.

So is there any easy way to tell if it is either running rich or running lean?

A lot of research that I have done points to it running lean and that I should try a couple of shims under the needles... It has a non-standard slip-on muffler as well which people say can play havoc with them too

Try the air filter stuff I suggested first. (easily done) Air filters can get dirty quite quickly ... especially in spring with all the pollen in the air. Dirty/dusty roads too ... (also a cheap quick fix you can do ... usually)

An aftermarket exhaust helps the engine breathe out ... what steps were made to help it breathe IN .. ???

What re-jetting has been done after the exhaust was fitted ... ???

[Spoonrider]

Try the air filter stuff I suggested first. (easily done) Air filters can get dirty quite quickly ... especially in spring with all the pollen in the air. Dirty/dusty roads too ... (also a cheap quick fix you can do ... usually)

An aftermarket exhaust helps the engine breathe out ... what steps were made to help it breathe IN .. ???

What re-jetting has been done after the exhaust was fitted ... ???

I am not sure what work was done after the muffler was added as I bought the bike with it already on. Will definitely try the air filter stuff first and see what happens but it was cleaned and oiled less than a month ago.

[FJRider]

I am not sure what work was done after the muffler was added as I bought the bike with it already on. Will definitely try the air filter stuff first and see what happens but it was cleaned and oiled less than a month ago.

Possibly no work done ... may need checked to see .... ???

When I had a 250 ... I cleaned it (air filter) weekly. It doesn't take much to affect small engines. (clean the plugs too)

If the filter is standard ... try an aftermarket one ..

[ducatilover]

It has an aftermarket pipe, it's lean.
Put .5mm washers under the needles and go ride it again, repeat 'till it's done.

Or, if you're near Tauranga, PM me and I'll do it for you :niceone:

[Spoonrider]

It has an aftermarket pipe, it's lean.
Put .5mm washers under the needles and go ride it again, repeat 'till it's done.

Or, if you're near Tauranga, PM me and I'll do it for you :niceone:


Thanks heaps for the advice ducatilover, I wish I was in Tauranga but I am in Auckland. I think if I take it slow I have watched enough videos and read enough manuals \ info to do it. Do you know where is a good place to get the washers from?

[ICE180]

j car have the type you need they are 0.2mm each if you get stuck let me know and i can get some when I go into work next on New years eve

[ducatilover]

j car have the type you need they are 0.2mm


Thanks heaps for the advice ducatilover, I wish I was in Tauranga but I am in Auckland. I think if I take it slow I have watched enough videos and read enough manuals \ info to do it. Do you know where is a good place to get the washers from?
What ICE180 said :niceone:
It's not a very hard job to do.
ZXRworld.co.uk could help, they're mainly ZX400H/L but the process is the same and I think they'll have a few write ups there

Essentially you remove the tank and airbox, un-do the caps on top of the carbs, don't lose the springs
If you have a magnet on a pole you can lift the needles out without taking the slides/diaphragms out, but it's easy enough anyway
Then, put the washer under the needle, re-assemble and be careful not to over tighten the screws on the caps, I've seen a few crack
Also be careful with the diaphragms and make sure they're seated flat
One of the caps will have a little metal mount on the engine side (number 3 from memory) for the choke cable, try not to lose that either.

[Spoonrider]

Nice, thanks guys!

I didn't know you could do it without taking the carbs off the bike... I have taken the tank off heaps of times before and the airbox also so that isn't a problem.

Really appreciate your help.

[ducatilover]

Nice, thanks guys!

I didn't know you could do it without taking the carbs off the bike... I have taken the tank off heaps of times before and the airbox also so that isn't a problem.

Really appreciate your help.
I've always managed on Kwakas of the era to do it on the bike
Holding the slide up a tiny bit with a spanner can help make it easier to get the diaphragms seated again too

[Spoonrider]

Do I need the 3mm or 4mm washers from Jaycar?

http://www.jaycar.co.nz/productView.asp?ID=HP0430&keywords=washer&form=KEYWORD
http://www.jaycar.co.nz/productView.asp?ID=HP0465&keywords=washer&form=KEYWORD

[ducatilover]

Either will do it I think, as long as they're not thick. I generally use .5mm ones with about 4mm diameter hole

[Spoonrider]

So I finally got around to taking the carbs off, they were a pig to get off as one of the screw heads on one of the collars that connect the carbs to the engine was munted. I then opened up one of the carbs and put the washers on only to find they are too wide and the plastic thing on the end of the spring wouldn't sit back over the needle properly... doh. So I had to put it back together as I was at my mechanic mate's workshop and I needed to ride home. Will get some more washers soon.

One thing I did notice is that a previous owner has done the slide mod where you drill a second hole in the bottom of the slide next to the one where the needle goes through. Could this possibly be the cause of my issues?

[ducatilover]

Yeah the slides could be raising too quick

[Spoonrider]

Which would be making it run rich I assume?

Can you get new slides for these bikes anymore?

[ducatilover]

Yeah, will make it stumble.
I'd try adjust the needles down first, if possible

To get around the slide issue, run a harder spring in it. I had a set of D32 springs, but one's gone AWOL.
Or, epoxy the hole up and sand it fairly flat underneath (we like air flow!)

Or... use this as an opportunity to get a uni-foam filter in it?

[Spoonrider]

ok so I was wrong, it doesn't have the carb slide mod done. I mistook the second factory hole on the slide as one that had been drilled.

I remember that when Spectrum looked at my problem and changed the orings between the airbox and carbs that the issue seemed to be fixed. Rode it a few times and there was no problem whatsoever, but then the issue came back after a couple of weeks which has always had me wondering why.

It dawned on me that as part of the work they did they removed the airfilter and re-oiled it. I am wondering if that temporarily fixed my issue by it running a bit richer from the oiled airfilter. I am going to oil the airfilter again and see if it makes any difference, if it does then at least I know that it is running lean for sure...

[ducatilover]

A look at the plugs will tell you it's lean

They will warp the plastic plate betweent he airbox/carbs with the velocity stacks if you do the bolts up too tight.

[Spoonrider]

yeah, would have looked at the plugs but they are hard to get at without removing the radiator. :-(

[ducatilover]

It's not a hard job though and a good excuse to do the coolant and get to know your bike

Plus, when the radiator is off, I can steal it for my bike

[Spoonrider]

I wish you lived in auckland lol :-)

[ducatilover]

I'm glad I don't :bleh:

[Spoonrider]

do you know of any how to's to take the radiator off?

[ducatilover]

Been a while since I've done one, but I'm certain there's two 10mm bolts up top of it and one bolt, or locating pin under it
Take the drain plug out the bottom of the water pump (8mm bolt)
Remove the inner fairing filler piece around the rad (again, hazy memory, easy when I have a ZXR in front of me), un-do the radiator pipes, un-do the temp sensor, remove the bolts for the rad, wriggle it out, un clip the plug on the fan
Put radiator in box, send to me :D

[Spoonrider]

Thanks man, has been an ongoing saga with this bike lol

[ducatilover]

They can be a bit troublesome :shutup:
Another thing I'd do, while playing with carbs, is remove the cam chain tensioner and clean it, they get gummed up occasionally and will cause rattles, and in bad cases they'll fuck out and the chain jumps teeth
It's pretty simple, just on the back of the block below the head, two bolts to un-do, then a central bolt to take out once removed (careful, there's a spring up it) then take it apart, clean, check the teeth on the tensioner arm aren't chipped or work. A ZXR manual will tell you the spring free length to measure
Put it back in, take off the front left engine cover and turn the motor with a spanner about three times so it resets, then it should be as good as gold.

I clean mine every oil change, paranoia!

[Fast Eddie]

I clean mine every oil change, paranoia!

how dirty is the inside of your engine!

mines self cleaning, I add a bit of dishwashing liquid into the oil and run it for 100km then do oil change. Fuck its clean in there

[ducatilover]

how dirty is the inside of your engine!

mines self cleaning, I add a bit of dishwashing liquid into the oil and run it for 100km then do oil change. Fuck its clean in there

It's sparkling bro :D last oil change (500km ago...) I whipped the sump off, did all the o-rings, perved at my crank and annealed the copper washers for the oil cooler
After polishing the sump... :wings:

[Spoonrider]

So, I had a thought... why don't I just get a second hand standard muffler and put that on and problem solved....

The standard ones are just slip on aye?

[ducatilover]

Yeah, pretty sure they bolt on to a flange

Or, get a nice air filter and set the carbs up. It'll sound nice

[Spoonrider]

It's more of a temporary measure to get the bike rideable for the mean time while I get my self organised to work on the carbs and do the airfilter.

What is a good airfilter to get for these and where can you get them from?

[ducatilover]

OEM.
You won't get any gain from a K&N or Unifoam without setting the carbs up