Discussion ZXR250A Vs ZXR250C

Chris,

Went and saw Peter at Motorcycle Spares Warehouse this morning. Asked him about the different jets from A to C and if he knew about any other differences. He said he'll hunt down what he can for us and send it through to me. I will post as soon as I have something.

 

Very nice Murdo. Great time for a small capacity naturally aspirated bike. Doesn't look like it weighs more than 80kg plus unsprung weight (wire wheels) would have made it launch hard too.

A man after my own heart...a collector. Is that an XL125 I spy above it?

Frank

 

Chris,

How did you go? Are they the same?

Frank

 

Murdo,

Love to see the rest of the collection. You're a driven man...10.40 @ 97mph is bloody quick for a 250. I'm trying to see how quick I can get a 4-stroke 250 to get down the quarter. As you probably know, most 250 drag bikes are 2-strokes, so I thought I'd go down a different path. I have an RZ250R track bike that I could build up as a drag bike, but I'm focused on the ZXR at this stage. I enjoy learning and the ZXR drag bike project is certainly giving me plenty to digest. I've been around drag racing for over 35 years, so I've seen plenty of changes over the years. Your bike would be perfect in nostalgia racing. PM me if you're ever coming to Melbourne and need somewhere to stay.

Cheers

Frank

 

AJ,

Thanks for your suggestion. You might be onto something, but I'm not sure how to look at fixing it or if it is exactly the same issue.

My drag bike HAS had the speedo removed. Unfortunately, my mechanic has ripped out the standard loom and replaced it with basic wiring to basically start and run the engine. I don't know if I can even wire the speedo back into the bike. Also, my RPM problem is in all gears, not just when I hit 180kph. Actually, because of the RPM issue, I've never come close to 180kph (on the drag strip or otherwise).

I will see if there is anyway to wire the speedo back in. I'm actually waiting for Chris to confirm if the pickup configuration is different between A and C models. Given the RPM issue happens in all gears I like the idea that it may be causing the ignition to retard via an incorrectly configured/used CDI (I have an A CDI with a C engine!).

Cheers

Frank

 

AJ,

That sounds like the problem I'm having. How do I "fix" this on my bike? The tacho on my bike still works, so is there anyway of putting the speedo back into the circuit that controls the RPM/speed scenario? Is there anything in the CDI that might affect the RPM issue?

Thanks

Frank

 

Thanks Chris

 

Murdo et al,

Well, I finally got to get the ZXR street bike to the strip and did a few passes. As some of you may recall, my ZX2R "drag bike" managed to run 15.46 @ 87mph on a hottish day with a 100kg jockey on board. My street bike zxr250 A ran 14.89 @ 91mph also on a hottish day with the same fat bastard jockey on board. To say I'm mega pissed off would be an enormous understatement. I am now 100% focused on getting the drag bike to rev paste 16,000rpm as I am convinced this the major issue restricting it. My street bike revved to 19,000rpm in all gears and never "hit" the limiter. My street bike also has the "8,000rpm hesitation" issue that these things seem to suffer from.

Does anyone have a C model loom and CDI (21119-1322) they don't want? Despite the following image, my drag bike leaves "harder" than my street bike...probably because it weighs 30kg less and has a hopped up clutch.

 

AJ,

I had a look at both the drag bike wiring and the street bike wiring on the weekend. I've included 2 photos with this post. One is the drag bike taken from the LHS of the bike and the other photo is of the street bike from the RHS of the bike. They're so different it's not funny. I will need to pull the drag bike wiring apart to see what goes where. The guy that re-wired the drag bike didn't use any of the original loom, so even the wire colours are different.

I think maybe the quickest and cleanest way for me to resolve my revving problem is to get a new loom and a CDI for the C engine that's in the bike. Hopefully then I can put the speedo back and go from there. My drag bike has also had the alternator removed, which I want to put back. Is this a fairly easy process?

I took the street bike to the strip on the weekend and it was soooo refreshing to watch the tacho climb cleanly all the way to the red line (19,000rpm) in every gear without even the slightest hint of "restriction".

Thanks for your help AJ.

Cheers

Frank

 

Thanks Risky. My only concern with these after market CDI units is they don't have a rev limiter and missing a gear will more than likely be terminal to the engine. I will try and resolve the revving issue by following AJ's post and see how I go.

Cheers

Frank

 

Hi AJ,

Thanks for the guidance. I will try this on my street bike. If it does the same thing then we're nearly home. I will see what happens and then report back.

I really should use the right terminology/name to describe parts...yes, it's the Stator Coil (see B in pic.) I am referring to. I will address putting this back in the engine once the restricted revving issue is resolved.

The bike still has its starter motor. While I have you, does removing the starter motor cause any issues? I know most bike racers remove it and either bump start or use that funny spinning thing. Sorry for the stupid questions, but I'm not a mechanic and I'm learning as I go. I expect removing the starter will save a kilo or two.

Cheers

Frank