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Project Yamaha SRX 250 Cafe Racer

Discussion in 'Your 250cc Projects' started by Andych, Oct 9, 2016.

  1. Andych

    Andych Well-Known Member Premium Member

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    One day my better half was going through the local FB Buy & Sell Groups looking for furniture she could refresh and sell on (her hobby...sort of) when she mentioned to me there was a Motor bike that looked OK going cheap and that it would give me something to tinker with...

    Well... I bought said bike, an SRX 250 in questionable condition. The seller told me the engine was seized... then changed it to the cam chain had broken so I was under no illusions as to the engine condition but the failure surprised me a little.

    I started to look into the bike and found there were not many around and even less spares available but I had it (paid $80 for it) and figured I would build it up slowly and see how it developed.

    I also found out that FZR 250 front end had exactly the same bearings and steam height and that would give me dual front discs... plus the swing arm was adaptable... so I sourced a donor (it was rubbish) and I have been moving on from there...

    Lots of little wins along the way and a few more since joining here so it is progressing, plus now the weather is warmer it is easier to get out in the garage and play..

    Lots of pics and will keep it better documented from now...

    Just picked it up..... What have I let myself in for???

    thumb_IMG_1937_1024.jpg


    Starting to look at what I actually bought...

    Oil drained and starting to look at what is wrong with the engine...oh dear...

    thumb_IMG_1943_1024.jpg

    thumb_IMG_1945_1024.jpg

    From what I can tell... the exhaust cam gear had come lost one retaining bolt (or it hadn't been tightened correctly) and it came adrift, breaking the end of the cam and locking up the engine.
    It had managed to destroy one of the chain guides, the oil tube (internal oil feed for the top end), the exhaust cam and bent 2 valves. there was very little inertia on the engine when it failed as the damage was relatively minor.
    I think someone had tried changing the cam chain (as the chain was brand new with no damage thankfully) and hadnt done a good job.
    I found out later during re-assembly that there was a pin missing from the primary drive (there are 6 springs and 3 pins to help dampen the vibrations) which would have caused a lot of vibration and that wouldn't have helped matters.


    thumb_IMG_1949_1024.jpg
    After weeks of looking I managed to source the Oil tube, a spare exhaust cam (in good condition) an almost new chain guide and a cracked TT350 head with good valves... (new valves are made from gold I think).
    A new set of standard rings and a good hone... ring end gaps were adjusted and assembly began.

    Some gaskets are hard to find... so it was time to make a new one...this also shows the damping springs on the primary drive. One pin missing from here and it would have been shaking itself to pieces....lucky they are still available from Yamaha.

    thumb_IMG_2190_1024.jpg





    Final Assembly
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    Engine painted
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    thumb_IMG_2199_1024.jpg

    With a couple of coats of HT clear....

    thumb_IMG_2215_1024.jpg

    thumb_IMG_2214_1024.jpg

    This might give you an idea of the colour scheme... The Red is from a 2016 Mustang... it is called Ruby Red.... It was quickly sprayed onto a half prepped tank to see what it looked like... and I liked it :)

    thumb_IMG_2211_1024.jpg

    thumb_IMG_2213_1024.jpg

    Tank prep... lots of work to do on this one.
    thumb_IMG_2217_1024.jpg

    thumb_IMG_2218_1024.jpg

    thumb_IMG_2224_1024.jpg
    Swingarm is a perfect fit... Rear shock needs some spacers etc to make it work though, including revised links.... around 25mm shorter to get the right stance and to ensure the tyre doesn't hit the rear guard at full travel.

    thumb_IMG_2202_1024.jpg

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    thumb_IMG_2204_1024.jpg

    thumb_IMG_2205_1024.jpg
     
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    Last edited: Jul 31, 2017
  2. Andych

    Andych Well-Known Member Premium Member

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    My Bike:
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    After having some spacers machined for the dogleg and top shock mount I did a trial fit...

    UNADJUSTEDNONRAW_thumb_db8.jpg

    UNADJUSTEDNONRAW_thumb_db9.jpg UNADJUSTEDNONRAW_thumb_dba.jpg


    And these turned up.... new Gauge faces made up... all the way from Poland.

    UNADJUSTEDNONRAW_thumb_dbb.jpg
     
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    Last edited: Jul 31, 2017
  3. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Nice work.
    Just watch out when you shorten or lengthen the linkage dog bone's, length will affect the stiffness of the rear end.
    Eg shorter rod's mean's less leverage and will stiffen the feel of the rear shock
    I know on bike's with shorter dog bone's standard, 4mm shorter can make the rear shock feel like it's a solid rod
     
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  4. Andych

    Andych Well-Known Member Premium Member

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    Thanks for the info... I am also contemplating moving the top mount as the angle isn't real flash either... I might have to dummy up a new mount to see how it works out.
     
  5. Mclaren

    Mclaren Well-Known Member Contributing Member

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    Nice stuff I'm trying to source a cb/sr400 for a flat track project
    Will be following
     
  6. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Andy,

    I believe the 1983 Yamaha TT250 had basically the same engine (many parts interchangeable).

    Also, if you need to bore the bike at any stage, I have an oversized piston for it.

    Good luck. It looks to be coming along nicely.

    Cheers
     
  7. Andych

    Andych Well-Known Member Premium Member

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    Good luck with that...they are both popular and pricey but do come out nice.
     
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  8. Andych

    Andych Well-Known Member Premium Member

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    Yes... there are a number of common items... I am pretty sure my new (2nd hand) oil tube came from a TT250.
    Damn... wish I had known about the oversize piston before... every little bit of displacement helps when it is a Thumper...lol.
    I will make a note of it though... if anything goes wrong and I need to pull it down.. then that will be part of the plan.
     
  9. Andych

    Andych Well-Known Member Premium Member

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    My Bike:
    1987 Yamaha SRX250, Honda 1975 CB400F
    So... while researching on Japanese Yahoo Auctions for bits I might need I tapped across a later version of the SRX250.. Mine is a 51Y model but there is a Japan only (by the looks of it) a 3WP model from around 1991 which changed a little in terms of bodywork and tank.. Engine has been tickled a touch but gearbox remained the same with the other changes being a 210mm rear disc and 17 inch rims... it looks like the rims are straight from the FZR250 as is the disc and caliper. The swing arm is a little different to accomodate the disc with the Cush drive being the same (so it looks) as the FZR.

    So... based on that info and some feedback from another person (outside of here) who built an SRX250 with the FZR swing arm (chain issues at full travel) I am revising my plans...

    I was going to go the full Cafe style and cut the frame.. weld in a hoop.. modified seat etc but now I am thinking to keep it almost stock.. well 3WP stock anyway... I can source the swingers and rear shock which means I don't need to modify the shock top mount.. the geometry remains as per factory. I already have the FZR rims and I will keep the FZR front end in it (dual discs).

    I will need to source a new seat and the rear fairing but they seem cheap enough though Jauce.

    It should look something like this example

    SRX 3WP.jpg

    So now all I need to do is sell the FZR swing arm and monoshock :)

    This way there will be less hassles getting Rego and no Engineering needed (I won't say anything about the front brakes). Plus the FZR front end should work nicely with the lighter weight of the SRX (123kg vs 141kg dry weight).
     
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  10. Andych

    Andych Well-Known Member Premium Member

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    After much more googling... google translating (and me laughing uncontrollably at the translations) it appears that a common modification with the Road Racing guys (yes they race these in Japan) is to use FZR front end (dual discs etc) and the FZR250 Monoshock, which it looks is a bolt on with the 3WP swing arm, dogleg arrangement.
    Saves me the hassle of trying to import a specific shock as the freight alone is expensive..
    Now I am just waiting for all my new (old) bits to arrive from Japan... might have to finish off the frame mods this weekend and get it blasted...
    Time to head North for work... Tamworth tonight and tomorrow Night... so no more Japanese Yahoo Auctions for now..:)
     
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  11. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    I think you are going the right way with this project, that 3WP looks good. Do you have a link for the Polish instrument faces?
    Cheers
    Blair
     
  12. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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  13. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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  14. Andych

    Andych Well-Known Member Premium Member

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    Hi Blair, I am glad I found the 3WP because I wasn't happy with the options out there for the look I sort of had in my head... and the 3WP fitted it... almost to a tee... I might still makes some changes around the tail light etc... just to tidy it up but in general I am happy with the direction.
    I do have their details but they are at home.. I am away for work in Tamworth / Gunnedah till Friday night but I will get it for you when I get back.
    They were pretty good... I sent them a full size scan of the gauge faces and he did the rest... $40 if I remember correctly.
    Ahh found his email address..
    info@venoxy.com His name is Bartlomiej Kaszac
    They also have an ebay store as venoxy-com

    Cheers
     
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  15. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Hi Andy, That SRX250 3WP looks great! I might have to see if someone can import one into Australia. It looks very much like the SRX400 of around the same vintage. Looks like some of the parts are identical.

    SRX400.jpg
     
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  16. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    That whole front end looks exactly like the zeal ( fzx250) except for the guages.
     
  17. Andych

    Andych Well-Known Member Premium Member

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    All built from the big parts bin I guess...
    I know the FZR250 front end goes straight into the SRX frame... same head bearings.
    Main difference is the SRX has 33mm forks.
    I like the instruments on the 3WP and the SRX400... both are the same, cable drive Tach.
     
  18. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Yep. Andy's right...all built from the same big parts bin. I like the zeal. Good looking bike.
     
    Last edited: Oct 13, 2016
  19. Andych

    Andych Well-Known Member Premium Member

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    More work done over the weekend...
    I finished up what I needed to do on the frame so now it is to be stripped and de-rusted... thinking of using Red-Strip at Blacktown for an alkaline dip... $150 + GST for the frame... plus $80 each for the wheels... I haven't priced up Blasting yet but I guess it would be similar... at least the alkaline dip is non destructive.

    I then moved onto the tank... time to finish the surface prep, rub it back and hit it up with Etch primer and then Spray Putty.
    Etch Primer done...
    UNADJUSTEDNONRAW_thumb_de8.jpg

    First coat of Spray putty...

    UNADJUSTEDNONRAW_thumb_dea.jpg
    While it was all drying I decided it was time to repair my inlet manifolds as the rubber had completely let go from the Alloy...
    All cleaned up and ready for the Sikaflex..
    UNADJUSTEDNONRAW_thumb_de7.jpg

    UNADJUSTEDNONRAW_thumb_de9.jpg

    Last item for the weekend was to clean up some of the plastics and brighten them up... this was finished with a product called "Black Wow".. I have used it plenty of times before but it is a bit too oily for my liking.. I am thinking of getting some Solution Finish and seeing how that goes... Still... this is much better than it was when I stripped the bike.

    UNADJUSTEDNONRAW_thumb_dec.jpg
     
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  20. sharky

    sharky Well-Known Member Premium Member

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    For the black plastics I tried VHTs hood, bumper & trim, seems to be working well so far, surface prep is the key
     

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