Project My '90 FZR250 3LN3

I picked up a cheap set of used Flow gauge's, some stainless pipe's, and about 15ft of Tygon tubing today.
Thinking i should be able to make myself a carby synchroniser
The Gauge's are made by Fisher and Porter of Workington, England, these flow up to 800cc p/min and have a specific gravity of 1 @ 70°F (same SG as water)
Each of them is adjustable and able to be set to flow between 0% and 100%
I have already cut and fitted the Tygon hose, and a balance tube between 2 meter's, just need to make up some adapter's to connect the hose to the vacuum port's of the carby's.
I'll see how this goes, and will make up a 4 meter set if it work's ok.

 

Thank's, yeah i have a few idea's for mounting them

 

I'm sort of basing my design on what i have seen with the genuine Suzuki Manometer.
From what i can work out, the Suzuki Manometer has a tiny jet in the bottom, to allow the ball to rise in the tube.

So i might have to have the bottom port's open to atmospheric pressure and then turn the adjuster valve in to restrict flow to get the ball to sit at one set point on the gauge, then swap meter's and set it up to have the ball sitting at the same point while running off the same cylinder to calibrate them

I found some suitable M6 threaded, 3/16 barb's for the manifold's too, in a china fuel tap

 

Think i've found why my bike has been running cool for the last few week's, it hasn't been



Bit of a scrub with a brass wire brush and a coat of dielectric grease has solved that problem

 

They were plugged in together when i spotted the corrosion

 

I'm making up some intake manifold vacuum hose adapter's.
The thread's for the manifold screw's is a little hard to access as it's 35mm deeper than the bottom of the fuel bowl's, so i am making some extended screw in tube's for the vacuum hose

4x M6 x 16mm high tensile bolt's drilled out to 2.5mm,
4x M6 x 32mm female thread socket head bolt's (M5 internal thread), drilled out to 2.5mm,
and 4x M6 nut's drilled out to 6mm

At the bottom of the pic below, i will weld the head's of the 2x bolt's together, and weld the drilled out nut's to the outer end's to make doing them up easy.
Not sure if i'll be able to stretch the 1/8 Tygon hose over the end of the bolt shank yet, but if not i'll just screw in some M5 stud's (drilled through with a 1mm drill bit) and loctite them in there, that'll let me screw the hose onto the end's

 

Got the manifold tube's done, now just need to fit them

 

It has 2mm Nitrile O'Ring's fitted on each one now, the thread's are the same length as the oem screw's that came out of there,
and the original screw's had nothing between the screw head's and the threaded alloy part of the manifold, not even any sealant on the thread's

You would have trouble doing up those brass tube's ^ especially on the 2x centre manifold's the heater hose metal pipe is in the way

 

Just got back from a ride, temp gauge still doesn't go over 1/8 so engine is still running too cool?
Might have to swap in my digital temp gauge and see what temp it's getting to

 

I received my new Litetek FZR250 sprocket today, many thank's to @maelstrom
Now i had better get down to the bike shop and pick up a new chain to go with it

 

Bought a new cheap DID 428HD 136L chain ($49) yesterday to fit along with my new sprocket.
I want to go for a ride later today/tonight so thought i'd swap them over now
Got the bike up on the rear stand and noticed the rear sprocket was a little loose, so undone them and used a bit of loctite on the thread's and re tightened them.
Also saw that there was a bit of movement between the hub and wheel through the cush rubber's so i have made up some 1.2mm shim's out of gasket paper to take up some of the play.
The hub sit's in the wheel nice now, only needed a slight wiggle to get it in




Next i cleaned up the old grease and grime around the front sprocket area




And fitted the correct thick bossed Litetek FZR250, 17T front sprocket (raised boss to the engine side)
I measured from the face of the sprocket to the lip at the end of the shaft where the sprocket spline's are, and where the thread's begin, it's 3mm
And also measured the recess inside the sprocket retaining nut, it's 3mm also, plus the 1mm thick locking washer
Then fitted the splined locking washer and nut after cleaning and giving them a quick coat of Black Zinc













After i cool down for a while i'll put the back wheel on and shorten and fit the chain

 

With the 3LN3 front sprocket orientation, i believe that the raised section need's to go on the inside toward's the engine.
If it was supposed to go on the outside it would be a lot cheaper for Yamaha to have made a retainer nut with a deeper recess than to make a custom raised boss sprocket which only suited the FZR250's 3LN3 and on
Also if you look at the chain slider that goes on the front of the swingarm, it actually sit's over to the left, it hang's off the side of the swingarm by about 10mm
And another thing, there is only about 10mm clearance from the O'Ring chain to the tyre, so spacing the sprocket out and having the rear sprocket set toward's the outer side would give the chain more clearance to the tyre
The earlier model's ran a skinnier rear tyre to so that may come into thing's why there was a sprocket change?





It's pretty hard to get pic's of the sprocket alignment, the chain slider on the swingarm might need to come off to get a straight edge or string line across the sprocket's
When i line up the front edge and the back edge of the rear sprocket, i can just see the outer edge of the front sprocket.

In the pic's below the rear suspension is compressed so that the centre of the front sprocket, the centre of the swingarm front pivot bolt. and the centre of the rear axle are all parrallel, i used my $3 Sonitax laser level
This is the proper way to set the chain adjustment for any motorcycle,
Yamaha recommend's 20mm to 25mm up and down movement when the front and rear sprocket's centre's and swingarm front bolt's centre line are all aligned

 

I have adjusted all my bike chain's like that for year's.
It make's sense, with all the centre's lined up, that's the longest point in the full suspension travel so the chain need's to have a little bit of movement there