Help ZXR250 A Model Engine in C Model Frame

To the best of my knowledge, I beleive this is an ignition advance issue,' easiest fix is find a c model engine.

@Frankster

 

The bore and stroke of the A/C models are different, so the the ignition timing will be different also. If the A model loom didn't work, try the A model CDI with the C model loom. I'm not sure on wiring or pinout differences. The carbs are also jetted differently between A/C models, have you got A or C model carbs?

@Frankster has encountered the 16k RPM issue as well with an A model motor and C model everything else.

Your not starting issue could be a few things, but you need to sort out the ignition timing/CDI before anything else.

 

Did you use the a model switch blocks and gauges ? Alas they are different between models

 

Probably fix all the problems you're having. The fact it starts and runs is dumb luck, and because the motors are similar, but not the same.

I'd be looking at getting the A model cdi box wired up to the C model loom.

I've never seen an A model in the flesh but if it's anything like the Yamahas, the earlier CDI's will have wires coming out then a connector to the harness. The wires will be colour coded, as will the wires on the harness. Try and match them up. Take a look at the C model wiring diagram and go from there.

Otherwise, change the loom, cdi, switchblock and gauges to eliminate them as an issue.

EDIT: read this thread: https://2fiftycc.com/index.php?threads/zxr250a-vs-zxr250c.1952/

 

A model switch blocks are different , it has the head light switch , whereas the c model doesn't have it but instead has circuitry so once the engine is running then the headlight comes on

 

My zxr was a full C model originally with the red cdi & the A model light switch block which I think had a C model wiring loom re-wired to fit the switch block & maybe cdi, I can seem to use the A & C motors without issue though, & have the dash or headlights off aswell.

 

Just checked the CDIs on all the bikes, luckily I have a A & C model here aswell as my bike, they all have different CDIs I noticed, mine is wired up similar to the A model & has similar coloured wiring suggesting its a loom off an A model but has a different CDI number. My bike cdi- B 21119-1263 A model cdi- M 21119-1290 C model CDI- J 21119-1322

 

so in the name of science, I decided to sacrifice a set of C model gauges to work out what is in there, here is what I have found.



I removed the gauge from the pod, there are 3 wires running to circuit board in the gauge





After removing the circuit board, I have noted that on the speedo needle, there is a backing plate and at 160kms, the backing plate comes between 2 contacts on the circuit board






the black plate on the speedo needle comes between the black blocks effectively closing \ opening the circuit





here are some close ups of the board.



The easy fix is to trim the black plate off, the only challenge with this is getting your gauges open as its quite invasive to get them apart, mine wont be going back together. The other option is to use a resistor to trick the circuit. The pink wire goes back to the CDI.

@Khaiden Cori , can you go to Dick Smith and buy a 10 k ohm resistor , on the end of wire going to the CDI put a 10K ohm resitor on, then wire that to a nice clean earth or splice it in to a black/yellow wire which is an earth ( don't snip that one)


Hopefully this resolves your issue.

 

there is an after market option too which would plug in

https://japan.webike.net/products/21125979.html

 

I thought that, the brown wire says ignition, I wonder what that does

 

Probably adds power to the circuit when the ignition is on, instead of having it on all the time. Pink wire is probably a signal wire.