FZR250 track bike

Following on from what Grey said about building a race bike I thought I’d post some stuff I’ve been up to.

In the UK there is no race series that fits the FZR250 and I’m no racer anyway, but following a wide eyed experience at PB magazine “Frenzy” in 1996 (maybe ’97 – the year the beer tent burnt down), a drunken night on ebay in 2013 and then an early Sunday morning in april, I found myself dragging a trailer out of the mists of Norfolk with a very uncared for 3LN1 strapped to it.

I didn’t know what I intended to do with it, maybe a restoration back to “as sold”, but once I’d got it home it soon became clear that if it a bog stock machine was what I was after then I’d be better off starting from somewhere else.
Looking at it from 20 feet away, the only thing that stopped it being used was a (badly) leaking fork seal. I was desperate to ride it, but there were some paperwork issues that meant I couldn’t ride it on the road for a while, so I pushed it in the garage and went indoors to book a track day.

Full on race bike may have been a bit too much, but from this point the voyage to track bike that could be used on the road started.
Now, I consider myself an innovator, a renegade who isn’t bound by historical uses of materials and process’s.
Hmm - Anyone else would describe me as a bodger, they type of man who would cut a section of the door chassis from a rental van to use as a chain guard to get through scrutinising, a man whose TL1000 has a number of components made from wood, in short a man who should have his tools taken away.

So lets see how far I get and how long it is before I loose interest and like a butterfly, flit to the new more pretty flower…..
Well, here it is, as collected, as always, indoors (squinting) makes it look a lot better that it is. Don't look too close

 

I was going to detail all of the mess I had to repair before I actually ended up using it, (fork chrome/seals/bearings, cracked bodywork, holes in exhaust headers, seized exup valve, “remodelled” subframe and tail piece, lights held on with wood screws, no air-box, individual pod filters wrapped in uct tape, no grease anywhere, only 1/2 coolant!! etc) but it’s too painful, it was too expensive and they’re all in the past now. Having undone the majority of these bodges I set up the standard suspension as much as I could, put some air in the tyres and finally hit the track. There’s no point in me banging out 1000 words on what a great time I had. Needless to say the little fizzer gave a good account of its self, embarrassed a host of bigger / faster/ more expensive stuff.
The only problems were:

• An oil leak from somewhere, which got more and more conspicuous as the day went on.
• What I thought was a seized gear selector when changing down from 6th I met only neutral and the gear lever didn’t return. Back in the pit is transpired that a sprocket cover bolt had wound it’s way out and had jammed the lever – easy fix.
• There were also lots of other fasteners coming undone!
• Foot pegs grounding out too early.

Still it lasted 7 x 20 minutes sessions at flat stick- and nothing blew up.
Back home – into the shed, plans were made for a track bike.

First up was weight loss. Volunteers were:

• Bodywork
• Rear seat and subframe
• Battery, it’s a house brink.
• Lights / redundant electrics
• Exhaust can
• Back brake and torque arm
• Wheels?

Next plan will be to hit handling:

• Forks – as detailed on forum or aprillia/mitor/zxr250 etc
• Shock – R6 as detailed on forum or whatever is cheap.
• Head bearings
• More ground clearance – rearsets, ride height etc.
• Tyres – I’ve got no complaints about the BT45’s it’s on, but what sticky radial options are there?

Last on this list – if I get the rest done – faster

• Pressurised air box
• Were there every any tuning parts made for these little FZR’s. Not turbos or FI, but stuff I can do in my shed like cams, higher comp pistons etc.

 

Lets start with the easy bits - Exhaust
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Top we see std item. 3.50 kg
Middle a DIC can. All aluminium, lovely it is 1.60 kg
Bottom. Cobra Pro, by S.T.Tadeo it says. Cool bent can sleeve in aluminium but the rest of it stainless. 1.80 kg
Had to go for the Cobra Pro as it looks awesome. Weight saving 1.70kg over std.
Not convinced that the DIC can would have ended up lighter as I needed to make an intermediate piece, and that would have been stainless. The parts for it weighed 350 g

 

The tail piece and subframe had been seriously hacked about by the previous owner.
The eagle-eyed amongst you will have noticed something weird in the original photo in this thread.
Whilst I can bash bits of metal back into place repairing plastics is beyond me, and replacement costs for the four parts required were too high to justify.
I got hold of a Honda RS250 fibreglass race item. Here it is after a little cutting around the front to get it to fit the tank.


At only 1.775 kg This should give me a massive saving over the standard which weighed 1.355 kg …what? Bugger.
Factor in that I won’t be using 2 seat pads at 660g and 422g and things start to look a little better.
Weight saving 0.66kg – better than nothing.

 

Need to mod the subframe to fit it the tailpeice., oh and I want to sit about 50mm higher.
Cut the lower triangle rails, shortened an re-welded to support just at the back of where I will sit. The old top rails are in the same place as they always were – they have to be as they have the tank rear mount welded to them.
Chopped everything else off the back – later wishing I hadn’t as this now meant no where to mount the number plate if required. Welded a couple of nuts in the ends so something else could be bolted on here.
Additional 10mm x 1mm wall thickness tubes added to provide a higher base for the seat

Excuse the paint, I had an young assistant that day. To young to trust with a spray can, so I gave them a pot of primer, a brush and the promise of £1 to complete. Looks like I’ll need to rub most of it back if the top cost is going to look presentable.
Here it is compared to the standard item

I chopped off most of the excess lugs, or repositioned. The exup motor for example is now within the framework so if it goes on it’s side it’s more protected.
The solenoid bracket is removable to allow access to the battery which I’m going to push as far don onto the top of back of the motor as I can.
The relays now move to the back of the rear hoop. The plastic inner mudguard has also come up higher. I’ll photograph when assembled.
f the worst should happen then it wont
Rear footpeg mounts remain – although in a different position now as I need to mount the exhaust can somewhere, and I may use them to to bolt D-rings to make strapping it to a trailer easier.
Std item: 4.06 kg
Modified: 2.94 kg
Weight saving 1.12kg. Poor effort, I think I can get more here, it’s still way to way stronger than required for one.

 

I just had a look at your thread Boydie - looks like you're having a wail of a time! - great stuff.
I don't intend to cut my wiring loom in case I every want to go back, I don't understand electrotrikery anyway, but I agree with your suggestion on batteries. The FZR battery is huge anyway, and 3.58kg, so I intend to use one I had lying around off a CBR 400 gullarm. It's still a lead acid job, but is only 2.42kg saving over a kilo, and is smaller so I can move it forwards and downwards if you see what I mean.
I say it's 2.42 kg, but it is flat at the moment. When charged it may be heavier......(joke)

A Lipo item would proably net me another kilo, so it's a compelling arguement. Like you though, I spent very little on the initial purchase, spending half of what I paid for the whole thing on a new battery is going to hurt me!
The change in size meant I needed to make another battery box - I daren't weigh it but I bet it's not lighter than the std part!

 

Has anyone got any 3LN1 wheels without tyres on them that they could weigh for me. I don't really want to pull my tyres off just to weigh the wheels.
Looking at the YZF125R wheels as they are the same sizes. They look ultra light, although I don't like the shape as much as the FZR.
Not sure I could put up with only having one front disk however well it performed.
The YZF swingarm looks good as well. 25 years of development mean it must be lighter.

 

Come one then, make me feel bad - get it on the kitchen scale....

 

Hell - better get my wallet out!

 

You may well be right mboddy, the more bits I weight the more I realise how much effort they put into making it skinny at the start.
But yes, if you do get a chance to weight the swingarm and wheels that would be great. Thanks

 

No worries - I've got more immeadiate issues at the moment as I checked valve clearences this weekend.
Exhausts all fine, but the majority of inlets too tight - one as low as 0.04, eek! What was even more of a shock was my local yamaha dealer quoting £7.50 plus VAT (20%) for each shim! Fortunately I had an old yzf 750 head floating about which I had intended to put into a coffee table - don't ask.
Anyway, much to my joy they are the same 7.48 diameter shims, there were 20 of them, and as I don't as YZF750 I was perfectly happy to use all I could, meaning I only needed 2 new. The dealer only had one of them, not the other, and then charged me only £2.40 including tax. I was tempted to buy some I didn't need just for the deal. Fortunately there was a moto-X independant local, and the same shims are used in some honda crf, so I got all I needed, and a very late night later it was all running again.
But, questions:

I only managed to get about 1 litre of coolant back in. True the motor may have had a little in it but I drained it from the pump when it came out - I was expecting to get about 1.5 litres back in. Have I got a huge bubble somewhere? I've run it a few miles -it still looks full.

I slackened off the cam chain before releasing the cam caps. I'd heard the cams are hollow and can crack if not well supported, so it's a half turn at a time on those cap bolts. I see the advice on the forum it to leave the chain tight whilst taking the caps off? Anyone got any experience of the mythical cracking camshafts?

 

Thanks mboddy. They're both more than I expected. Just to be clear, these are both weights without tyres, but with bearings and internal spacer right?