Indy's Highway to the Danger Zone - GPZ900R

[yoeddynz]

On 12/07/2026 at 22:45, Indiana_Jones said:

 

 

https://www.repco.co.nz/tools-equipment/safety-protection/disposable-latex-nitrile-gloves/tgc-rocket-black-nitrile-gloves-large-10-pack/p/A6244942

 

This is a fun read.

Looking up Kelly was not so fun.

[felixx]

On 03/07/2026 at 14:31, HighLUX said:

Atleast this has aged better than Kelly McGillis

It was a challenging Fap, but I got there in the end...

 

The bike however.. gorgeous

[Indiana_Jones]

Some progress today (will do a bigger post down the line), but hit a snag when trying to test the spark plugs.

It looks like one of the ignition coils is getting power, but not the other. Now trying to work through where the issue lies, I have a suspicion it's the ignitor box. Have tried following the workshop manual procedure to test, going by the results it looks like the box is poo poo (based on resistance numbers), but I have two and they both seem to be failing in the same way. I have my suspicions the odds of them both failing in the same manner are very slim, so will need to look into it further. You can get replacements, but they're not cheap and don't want to get one, only to find out that I have the same results on my hands.

In other news, I got the carbs back together.

 

 

 

 

 

[Bearded Baldy]

In the oven to cure the paint when the wife goes shopping next?

[Indiana_Jones]

I had high hopes of getting the GPZ fired up this weekend, but alas, it wasn't meant to be, due to the afore mentioned ignition issue, seems that I'm only getting spark on one of the coils (there's 2, one doing cylinders 1 & 4 and the other doing 2 & 3).

Oddly, I seem to get one spark and that's it, you hold down the starter and no more sparks.

I have checked the coil packs themselves, they seem to be ok (based on the resistance testing as per the workshop manual), as previously mentioned, I have tested the 'igniter box', now based on the figures from the manual, it seems that this isn't in spec, but I have a spare and that has the same results, so I have my doubts that both would be poo. 

I also checked the coils again and I think I had misunderstood how the system is meant to operate, I had assumed that both coils were meant to be live all the time (based on one having voltage across it and the other not), but further reading online seems to suggest that the live is always connected to the coils (which testing confirms), but the negative/earth alternates due to the pick up coil / igniter box swapping them over.

Lastly, I tested the pick up coil, one set of wires seems to be in spec for resistance, the other is showing a no go (what does '-1' on a multimeter mean?), so that could be the issue, as it would tie in with only 2 cylinders going (as each pick up fires 1 & 4 and 2 & 3 etc). Might need to bite the bullet and order a new one and see if that helps. While I'm at it, I think I might look to replace the HT leads and plug caps, as they seem to be showing their age (but that can wait for the minute).

At least I'm getting to know the bike better and a better understanding of how the various components interact and work with each other.

As always, any advice / tips are welcome.

 

 

[tortron]

Are your plug caps the type to have a resistor pill built into them?

I had 1 fail and 2 intermittent on my fzx750.

The intermittent one was like you said, 1 spark and then none

[Indiana_Jones]

4 minutes ago, tortron said:

Are your plug caps the type to have a resistor pill built into them?

I had 1 fail and 2 intermittent on my fzx750.

The intermittent one was like you said, 1 spark and then none

Yes, I believe that they are, I took one apart to clean it up and a ww2 German suicide pill looking thing fell out.

Do you reckon that could be the issue? I'm assuming you replaced yours and that resolved the issue?

[tortron]

I had to replace my coils anyway (high performance HARLEY) and made new non resistor leads and caps for them (and use resistor plugs)

You can test the pill itself, or swap them around

[Indiana_Jones]

Well I found the issue with pulse generator.......

 

That said, the wiring was a bit iffy on the part that lives in the engine, so will look to replace the whole thing next pay day.

But we did get spark!

 

 

So got the airbox, carbs and cooling system installed......

and fuel pissed all out of the carbs....

fuck.

 

What I determined was that the issue was that the floats were set at the wrong level, that'll teach me to follow the manual (I looked online and I see other people had had similar issues).

Needed to take the carbs off anyways, as I had a leak from one of the coolant pipes coming from the block.

So out came the carbs, floats adjusted. Essentially this became a trial and error process to figure out (filling the carbs off the bike, checking for leaks, adjusting etc). The manual stated 17mm, I ended up around 20-22mm for them.

Also I believe one of the designers for the cooling system must've had a past career in Unit 731, because only a sick fucker would make the coolant pipe to the water pump live here....I had to drop the exhaust pipes to get it in there, which meant dropping the front brackets and all cooler (not super hard, but still, why.......).

    

 

 

Anyways, got the carbs back on.....shit, No. 1 was leaking again. Now because the carbs are a prick to get on and off (as an aside the 1:3 water green oil to rubbing alcohol solution softened up the airbox rubbers to allow one to role them back to make room for the carbs), I decided to adjust this float in place. 

 

 

Righto, got the coolant system filled up, checked the spark plugs were going to the right place, hooked up the fuel.........hit the button......crank, silence.....tried a couple more times and then it clicked.......I hadn't purged fuel out of the cylinders from last time, so I had hydro-locked the engine........bloody idiot. Took the plugs out and then hit the starter button, fuel came squirting out of the cylinders (and not in the good way)......kicking myself for that, should've been on top of it.

She was spinning freely (you can see the top of the cylinder from the spark plug hole), so hopefully no damage was done (I have heard nightmare stories of the No. 1 cylinder filling up with water if parked in the rain on the side-stand and then rods getting bent etc).

Righto, let it purge out for while and then got reset.

Hit the starter button, she fired into life first pop (video is not the first start)....

 

 

Big milestone, really stoked.

[Indiana_Jones]

So there are some leaks to chase down, as you can imagine for a vehicle of this age.

Also, it looks like No. 1 isn't firing, based on the exhaust temps using the hand-momotor. It is getting spark, so I'm guessing I have over compensated on the float level and perhaps the carb isn't getting enough fuel. Also the choke doesn't style on (looks like it's at the handle end), likewise the throttle is not self-returning (springs etc are on the carb, so assuming a sticky cable / throttle grip). Jobs for another day.  

 

Also......those pipes are loud as hell. Still trying to decide what to do with them......I do have a tidy looking 4 into 1 system on the spares bike........thoughts?

 

[Bearded Baldy]

4-1 all the way. Less weight. Only one muffler to burn ya leg on etc etc

[Indiana_Jones]

2 minutes ago, Bearded Baldy said:

4-1 all the way. Less weight. Only one muffler to burn ya leg on etc etc

Do you need to fuck around with jets to do that?

[Bearded Baldy]

Potentially. I bought a jet kit when i rebuilt the carbs so fitted the ones recommended for a 4 2 1 system and decent filter.

[Indiana_Jones]

uhhhhhhhhh, I don't wanna take the carbs off agaaaaaaaaaaain. 

I'll look into it some more. I do kinda like the idea of a 'cleaner' look of the 4 into 1. Especially as the condition of the 4 into 1 pipe looks a bit tidier than the current 4 into 2.

[Bearded Baldy]

Just think. The weight removed means you can gain weight yourself and not lose any performance.

That is my story anyway.