My ZXR250A Project Log

Right so it's been a few months, so much work done (will update with separate post) bike should be back together tomorrow but one things BUGGN the hell out of me.

Already checked with Chris (thanks buddy) but just wanted to check with all. It's the coils to sparks order for the ZXR250A

This is the A Model part Fiche diagram for the ignition coils. Sequence from left to right. 1 to 1, 2 to 4, 3 to 2, 4 to 3

This is not what was on the bike when I got it, it was using the ZXR250C setup (1-2 2-3 3-1 4-4) it may explain some issues however it did run. Perhaps at some point a mechanic etc rewired it off a ZXR25oC I don't know.

Now the thing I can't find on the A model diagrams is the colourcode for the wires running to the respective coils. For the ZXR250C it's Green Lead ignition coils #2, #3 Black leads #1, #4 Red Leads Both coils.

If a forum member could share any knowledge I may be missing in this department it would be greatly appreciated. Also will I risk damaging the engine if I manage to turn it over with the wrong leads. I've just spent a bit of money on the motor so don't want to get this wrong after months of work.

PS- I've rewired the spark leads from the ignition coil so I can't go off "The shorter lead goes to 1 and the longer to 4" thing.

Thanks in advance all.

 

WHOOHOO finally finished and back together!

It's been a massive few months I've lost track of time but I am finally finished. After a final few electrical hassles I put everything back on, primed the bike and vhroom, she started up first time like a beauty!

The bike has basically been totally stripped apart and gone over from the ground up. I can't even remember everything that's been done but here's the basic list.
* - Second hand replacement

Stripped and re-lined fuel tank
New fuel lines
New fuel filters (In-line and inside carby)
Cleaned, rebuilt and re-balanced carbies inc new float needles
Re kit rear brake Master C (Stainless steel sleeve and kit)
Replacement front disks*
Replacement front forks*
Replacement rear shock*
Replacement stand kill switch*
Replacement speedometer cable*
Replacement speedometer unit*
Rebuild- Rear Tie-Rod and Rocker Arm assembly
Rebuild- Rear swingarm assembly
New Sprockets F/R
New Chain (O-Ring)
New Cam Chain
New spark plugs
New vacuum hoses
Rebuild/Modified Cam Chain Tensioner
Valve rework (cleaned and reset to factory specifications)
Some inner engine adjustment stuff by mechanic (Camshaft etc)
Clutch rebuild inc new clutch plates
Custom cooling system gaskets
Oil and Oil filter (twice haha)
New brake fluid and full flush
New Tyres- Pirelli Sports Demons
Replacement regulator*
Charging system overhall, rewired from stator to regulator
New Battery
New fuses
Electrical overhaul (Clean connections and custom loom mounting)

All nuts, bolts, screws and **** back to factory torque (some loctite) and a lot of other adjusting, tinkering, breaking and fixing and swearing etc

It's certainly been a lot of fun, a great learning experience and I now have such a great appreciation for what a truly amazing bit of machinery the ZXR is.

A few more minor fixes over the next few days and then it'll be off to register the bike EXCITED

After that I'll have to figure out what to do with the farings (buy new or get repaired), completely rebuild both the front and rear brakes (for safety), buy some new gear and have fun.

Will post some photo's and perhaps a video soon

 

Thanks guys This bike I swear!

I'm having a final problem though! Should be able to resolve it but I'll post it anyway for others who may be interested.

Anyway I think it's down to a bad fuel tap but would be good to get other opinions. Bike starts fine, idles fine and runs pretty ok for the a few hundred metres. After this is studders when attempting to hold cruising RPM and has a lack of power under throttle and also after pushing it for a K or so it just conks out and wont start without the choke. I removed an in-line filter I had on between the carbies and the tank and this made a slight improvement.

When I stop the bike and leave it for a few mins, wallah, starts first time no choke no throttle!

Now the fuel tap is crap. I have already ordered a brand new one from japan at the cost of a kidney (it needs replacing anyway). I'm hoping it's just that the vacuum tap doesn't work well/at all and the bikes running out of fuel stored in the float bowl.

My only other concern is that this could be a Carby problem, although after clean/rebuild I had new float needles all within the 15mm +/- factory range.

EST DELIVERY next Wednesday guess I'll sit around till then!

 

I may have to have another look at the floats then. 15mm if I remember correctly was wha they were on, that was many months ago now though .

I thought about repairing the tap however it's missing a few non-essential components and the amount of wear on many of the internals from... well years of neglect, is rather bad so I just bought another one.

 

Adjusted float bowls to bang on 13mm, worked a charm the bikes run smooth now and doesn't conk out. Not sure if I'll have to re balance the carbs at all after the adjustment?

Thanks for the pointers guys!

 

Yea one of the first things I did was actually rebuild the Carbies. It's got new needles and the O-rings there are pretty good. Just that I set the original settings at 15mm not 13mm

But you do make a good point.

 

This son of a #!#!@#!@#!@#!@# bike.

On the plus side of things I got one of these pulled out of the back of a storeroom in Japan. brand new parts




ANYWAY on the other side of things. Every dam time I get on this bike for a test ride it changes. I am still having problems with running. Thought the float bowl adjustment would fix it but it changed it's mind today. Still having the same problem as before so I pulled out the spark plugs to see whats going on.
Cylinder 2,3,4 plug fine
Cylinder 1 plug..... It's blacker than the night sky.


It's not oil on the plug it looks to me to be carbon. Does it mean it's running too rich?? Anyway it's only one plug.

This is how I described the engine problem to my mechanic.

"It starts fine, idles fine for the first few minutes. You drive down the driveway (long driveway) and it's fine in first gear get to the end go for a ride. It struggles to hold cruising RPM sometimes. Sometimes it fails to have decent acceleration. Sometimes it bogs down around 8-10k. Very very rarely you get a small backfire/pop on the down-run. Sometimes after a run it just turns off and you need to start it with the choke. Etc Etc"

The issue is all of these problems don't occur all the time, one day there will be one problem, some days all of them, sometimes it seems to be fixed!

My mechanic suggested Grey's theory of blocked tank breather. So I tried a run with low fuel and tank lid held slightly open... no difference. (Plus i also cleaned an already blocked tank breather)

I'm running out of ideas here! Does anyone in brisbane have a spare set or carbies they would be willing to lend me or sell?? This has to be a carby issue as I've legitimately fixed/replaced every other possible candidate!

PS- Forgot to add. It doesn't hold an idle well. Once it warms up the idle does not drop back to 1.5-2k rpm without constantly adjusting the idle adjuster. It does this every time