Project Yamaha SRX 250 3WP

I might have to go to Supercheap and have a good look at that kit.
It looks to be a much better quality kit than the one I killed today.


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Well that puller worked a treat... didnt have the correct bolts but lucky I did.. the ones in the kit just weren't long enough.
I put my long breaker bar on a 14mm socket and couldnt budge it.. so out came the little 3/8" Ryobi Impact driver... still wouldnt move so next was the 1/2" Ryobi impact driver with a fully charged 5 amp/hr battery... 10 seconds and she came off...
it really was on that taper nice and tight.
Now all I am waiting on is my JIS screwdrivers so I can undo 2 screws that havent been replaced with capscrews and then I can split the cases.. next weekend I think.
In the meantime I will read up on removing the gear-set... hopefully as a cassette.

 

So... managed to get the crankcases separated today, just hope I can get all the gearbox back together again later on...lol
One small issue is that I need to get s slightly larger puller to be able to use it to press the crankshaft out of the bearing. My new puller is 5 mm too short in the 2 hole slots.. Supercheap didnt have anything.. hoping Bursons might when I have a loook tomorrow.
I found the degreasing concentrate that I am trying to use in my parts washer is rubbish.. what does everyone else use.. more specifically in a parts washer.. I dont want to be emptying it all the time so the solvent doesnt all evaporate...lol

 

I have to be careful with what I use as the Bike Garage is attached to the "granny flat" my son lives in... and it is just a lined garage so I am not sure he would like a mix of Kero and diesel wafting in all the time... not that any other cleaning solvent will have less odour... that is just something I need to take into account. The parts washer is at the front door of the Garage so it is as good as it can be for that side of it.

 

Hmm seems I have a reasonable amount to catch up in in this thread..
So.. engine cases are apart and bearings are all out, I ended up using my BBQ (Weber Q series) to heat them up to a point where the blind bearings fell out. I will use it again when installing new bearings.. just control the heat a bit better and I will freeze the bearings so it should all work well.
The cases are out being machined as well as the clutch cover is having some plugs made for the kick start lever and de-compression lever. I have to use the TT350 clutch cover as the Oil feed for the cams is done via an external line but the 250 has an internal line. I will also need to plug the oil feed in the crankcase... no big deal.
Front forks are all back together and have been painted (again) and will be Clear coated over the weekend, as long as it is not raining..
I have the top triple clamp in with the guy doing my engine cases to be able to use the 3WP instruments, so when that comes back I will need to figure out what colour to paint it.. Maybe the same as the frame.. satin metallic charcoal....

Frame is painted and waiting on clear coat.. I am going Satin finish on this.. just for something different.
Hopefully I will get my tank back this week from having it dipped to remove all paint and any rust spots. I dont think there was any pin holes but we will see. The pain on it was super hard, Diggers paint stripper did very little in getting it off so rather than sanding it I opted to have it stripped.
Next on the agenda (other than clearing the frame and forks) I need to remove the tyres so I can strip the paint off the rims and refurbish them with new bearings etc. As well as stripping, cleaning and putting kits through the front and rear brakes.
Plenty more to do.. I will try to update this on a weekly basis from now on.
A few pics below.

 

OK... I have an interesting problem to sort through.. With the SRX250 I have been planning all along to use the FZR250 3LN1 front end.. forks, triple trees etc apart from the Instrument cluster as the SRX 250 3WP, SRX4 and SRX6 all had more of a Cafe type instrument setup and hence the top triple was entirely different.
I had planned on trying to have a new top triple designed and CNC machined to suit the FZR geometry as well as the SRX 3WP Instruments.. but... the cost of 3D design is a bit over the top for a One Off item so I have been looking at alternatives.

The best alternative I can find is to use the full steering arrangement from an SR4 / SR6 3VN model (lower triple, stem and top triple) which uses 38mm forks (tick), Instruments bolt straight up as does the headlight bracket (tick) with the differences being as follows.
FZR250 3LN1 has Pitch of 185mm and offset of 40mm where the SRX4 / 6 is 190mm pitch and 35 Offset.
I would require a new stem to be machined to suit the bearing size and spacing of the SRX250 / FZR250 as well as a total of 5mm spacing on the discs (2.5mm each side) as well as new wheel spacers and possibly a new 5mm longer front axle.

Given that these mods would be far less complicated and easier to machine than a new top triple etc what do the Brains Trust in here think of my solution?
I cant find any info on pitch or offset for the SRX250 but it should be around the mark..

Happy to listen to both sides of the coin..

 

That is the other option.. and viable.. I have been talking with my machinist / bike shop about that that exact strategy..
I was kind of inspired my @maelstrom changing the stem which got me thinking about going that way... I already have an SRX4/6 top triple and the lower is around another $80 plus all machining etc.. I was kind of thinking it would be closer to Factory specs (sort of) than a hacked up, welded and smoothed top triple... sort of

 

No, I didn’t keep the SRX front end. My aim was always to use the FZR with dual discs and 38mm forks. The SRX was a single piston single disc wit 33mm forks.
As you can see from the title I was originally going to do my version of a Cafe Racer but came to my senses when I saw the 1991 3WP model which was still 1 disc on the front but had a rear disc and for me a better overall shape / look. I also will use the FZR250 front and rear wheels so easier to get decent tires than for the SRX wheels.

The cut and shut method isn’t quite as simple as it seems due to the extensions to mount the instrument binnacle and relocating the ignition from the Centre to around the 55 degree mark.
I will grab a picture in the morning of the 2 top triples to show the difference.
It’s not impossible at all and should be easier (cheaper) possibly than what I proposed above.

The FZR swap is apparently a very popular swap in Japan fro racing. A relatively easy way to get dual discs as the stem bearings and spacing on the stem make it a straight (relatively) swap.
I am just being fussy in wanting to use the 3WP gauge set.

My TIG isn’t suitable for Alloy so I can’t even set it all up and tack it for someone else to fully weld it.

Like most things there are a number of ways to achieve an end result. Picking the best one is the hard part.

I should also talk with the guy who is doing my machining etc to which method is better suited to him as well.
For a motorbike repair / service / custom builder he has a very good machine shop and a 250 amp Miller TIG. He is a great machinist, welder etc.
He actually has been talking me out of the CNC route to the cut and shut.
I guess my thinking was the more simple machining ( stem, spacers and axle) would be easier to achieve the factory look, hence the post earlier on.
Jeez, I dragged that out lol.


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OK.. some pictures to add to the above....
First is the 3WP Top triple from above and underneath



and now is the FZR Top Triple.. same as above





While there is plenty of meat in the FZR (or looks like there is) the ears that hold the instruments need to be positioned accurately and the cut out for the ignition isnt easy to manage from the mounting bolts underneath either.. Not quote as straight forward as it seems.

 

Yes, a 3D printer for high strength Alloy would be wonderful.

Talking late today with my machinist and he thinks changing the stem will make a better job and make it look like a factory job.
So long as I can get the complete lower plus stem it will be the way to go.
If I can’t get the bits then we will revert to the clamp it, cut it, weld it course of action.
He will machine a new stem ( looks like the SR6 item is pressed into the bottom bridge) and spacers for the wheel and calipers to get the alignment right.
Another twist to my SRX250


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Thanks for the offer but Pattern making is well outside my skill level. I will stick to the direction I am heading for now.


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A bit more investigation today and the SRX4 and 6 use the same wheel bearings as the FZR250 so there is a good chance the Axle from an SRX4 will work so really all that changes is the stem and some caliper or disc spacers.
Yep, this is the right way to do it I think.


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