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Project GT250 Fun and games!!!!!!!!!!

Discussion in 'Your 250cc Projects' started by Damian_74, Oct 20, 2019.

  1. Damian_74

    Damian_74 Member

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    G'day all, new here in 2fiftycc.com.

    I've posted most if the following over on ADVRider but thought it would be more appropriate readership over here.
     
  2. Damian_74

    Damian_74 Member

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    Had a mid life crisis. The first bike I owned was a GT250 and was born in 1974 so w hen I saw a 1974 GT250L for sale I had to have it. The bloke that I bought it off has a home resto / repair business for old Jap bikes and put this bike together from bits and pieces.
    It's overall a nice bike but as it was done to a price it has it shortcomings.
    I originally had intentions of taking the angle grinder to the 74L but it was too nice a bike to hack up. After I finish this project I might attack it and do a proper job.

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    So in the mean time I went and bought this!!!!!!!!!!!!1976 GT250B
    What the hell was I thinking??????

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    It needs everything.

    Not entirely which way this project will end up - definitely leaning to the Cafe style but not committed as yet.

    This is going to take a while!
     
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  3. Damian_74

    Damian_74 Member

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    Going to start with the engine until I decide what I'm doing with the rest of it - it was locked up and originally suspected the crank - got a surprise when I split the case. The bike had been sitting in the weather with no gearbox filler cap and it had partially filled with water - definitely didn't expect that.

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    There isn't too much to salvage in the gearbox bit the crankshaft is in fairly good condition (obviously needs a rebuild but turns freely).
    Supplied with the bike were a set of barrels and a head that had been Vapour-blasted. The bores were 0.5mm over-size - and almost usable and was seriously considering just throwing a set of pistons in them - more on that later.

    The cases were as expected for a 40 year old 2 stroke - hours spent with de-greaser, phosphoric acid and a petrol powered pressure cleaner and I found the cases.

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  4. Damian_74

    Damian_74 Member

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    Thought that I was on a winner.....found a 74RAM engine in Tassie that had had had been overhauled and partially assembled. Advertiser (who turned out to be a Mate of a Mate) had "rebuilt" the crank, New OEM 1.0mm OS pistons gasket set, all casings vapour blasted. $1000 delivered to Brisbane - how could I go wrong!

    i-rgQJ3jS-L.jpg

    Well..................I had asked specifically about the crank rebuild when we were negotiating the deal and specifically asked about the crank seals but something was lost in the phone call.

    WHY WOULD YOU GO THE THE TROUBLE OF REPLACING THE MAIN BEARINGS, CONRODS AND PINS AND NOT REPLACE THE SEALS!!!!!

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    The seller didn't intentionally miss-lead me, was going off poor advice from others. Emailed the bloke and he agreed to refund $300 towards the crank rebuild.

    Now what to do - re-build the 74 engine or use the parts in the 76 (correct for the frame)?
     
  5. Damian_74

    Damian_74 Member

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    The 74L and the 76B engines have a different crank design - 3 vs 4 bearing - the latter more robust. My biggest unknown was the gearbox and clutch.

    When they went to the 4 bearing crank the gearing was also slightly changed.

    K,L,M 1st 2.333, 2nd 1.50, 3rd 1.105, 4th 0.905, 5th 0.782 and 6th 0.708:1.
    A,B,C 1st 2.333, 2nd 1.32, 3rd 1.050, 4th 0.905, 5th 0.782 and 6th 0.708:1.

    Had a fit up of all the gearbox and clutch internals of the 74L to the 76B's cases, it all appears to fit - so it is the 76 engine it will be!

    The bearings for the 76 are now obsolete. There are NOS on eBay for silly prices, and then there is the concern of how well the bearings have been stored for the last 30 years and how long an ancient rubber seal will last????

    The other option is the eBay seller "cruzinimage". Complete crank and bearing seal kits for under $200 AUD shipped to Australia and about the same for the rod kit. Obviously Chinese pattern parts.....quality unknown!

    Has anyone had any dealings with cruzinimage?
     
  6. Damian_74

    Damian_74 Member

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    Just got the cases back from the Vapour Blaster - they look like they just came out of the die! Couldn't be happier!

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  7. Damian_74

    Damian_74 Member

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    I didn't expect the hurdles to jump up at this early stage. I work away month at a time hence ordered the crankshaft parts so that they would be sitting ready for when I get home - thought it was all sorted.......... :cry:

    Ordered form Cruzinimage via eBay.

    It appears that they have sent me the parts for a GT250 X7.......not really the same engine!
    Different mains (they completely failed to send any seals) and different length big end pins (need 57mm pins rather than the 50mm).

    At least they are talking to me on eBay and trying to sort the problem.....see how this works out!


    From what I have researched.........can anyone in the know please confirm that these are the correct crank parts for a GT250A (4 bearing) crank.

    2 pc. Suzuki # 09262-25009, Koyo # 83197-9, Size 25x65 x17
    2 pc. Suzuki # 09269-25005, Koyo # 83190-9TC3 NR, Size 25x65x17/14

    1 pc. Suzuki # 09283-25019 crankshaft oil seal 25x65 x12
    2 pc. Suzuki # 09289-33006 crankshaft oil seal 32.3x65x10

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  8. Damian_74

    Damian_74 Member

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    It seems that my engine overhaul has stalled for a bit till I sort the bearing and seal issue - so in an effort to push the project along I have started on all the components. Hadn't intended to strip the rest of the bike at this stage but with all the delays I wanted to at least feel like I was making some progress.

    Have a selection of different cutting and polishing wheels and started with the side cases and wheel hubs.
    WHAT A PIG OF A JOB but at least the effort pays off.

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    But makes a hell of a mess.

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  9. Damian_74

    Damian_74 Member

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    New Hyd Press - 150mm between the rails - easily big enough to fit a 2 stroke crank!

    I need to make up a few special tools but at 30 ton this will be more than sufficient for a little 250 crank!

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    It is typical Chinese quality - **** welds, sharp edges but when I priced the material and jacks to make my own it was cheaper to buy this one (and a hell of a lot quicker/ easier).

    https://www.machineryhouse.com.au/P1475" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

    Also a press brake attachment - will bend 4mm x 450mm or 6mm x 300mm

    https://www.machineryhouse.com.au/P450" onclick="window.open(this.href);return false;

    Man can never have too many toys - but he can have a lack of space!
     
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  10. Damian_74

    Damian_74 Member

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    Had a little trip the the local Zinc Platers.

    In anticipation of getting a start on the engine I want all the cylinder studs and bolts plated, took a few other bits along too.

    They turned out well - I had given them all a buff and run a file over all the burrs before hand.

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  11. Damian_74

    Damian_74 Member

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    Finally finished the wheel hubs - then spent a couple of hours cleaning the workshop (aluminium polishing isn't my favourite part of any restoration).

    But was more than happy with the result!

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  12. Damian_74

    Damian_74 Member

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    Some progress - have been searching through eBay after my parts failure with Cruzinimage.

    Most of the parts I need are on eBay but when the freight is added, it starts to get expensive due to the multiple sellers (hence multiple postage).
    For a laugh I took my list to my local Suzuki dealer and was pleasantly surprised - kicking myself for not going there first.

    For the engine rebuild all but the conrods and one gearbox bearing were available - and at reasonable prices.
    New rims - Front $67, Rear $88.
    Spoke sets - Front $37 Rear $52.
    Complete clutch lever and mount - $40

    Now if I can find the time we might be able to get somewhere soon!!!!!

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  13. Damian_74

    Damian_74 Member

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    Special day - on leave and everyone out of the house!!!!!
    Time to tinker in the shed.



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    There is a oil dam under the bearing on one end and a seal on the other that prevents me from getting the knife edges under the bearing.

    Had a scrap of 6061 25x60mm left over form another job.



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    Milled flat and bolted them together to make a split pair.



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    Machined to a 64.8mm (0.20 interference) with a lip in the inside to pick up the bearing above the oil dam.


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    On the primary gear end bearing, as the puller was flipped over and the lip wasn't in use and it allowed the bearing to slip in the puller. I threw one side of the puller in the mill and machined off about 1mm on the bolt up faces to provide a bit more crush....worked a treat!


    Now just have to make a few more tools to get the rest or it apart!


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  14. Damian_74

    Damian_74 Member

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    Public holiday here so not much going on - didn't want to compete with the crowds at every slightly public place today so locked my self in the shed for the arvo - little Miss 4 was helping me so everything took that little bit longer but well worth it so that she may one day appreciate all the old bikes that Dad will leave to her!

    Was going to get all pedantic and machine up a plate to hold the crank webs but didn't have any material and noting open due to the public holiday - thought I would give it a crack with a some offcuts of 6mm angle. It actually did it fairly easy - I don't have the pressure gauge fitted to the hydraulic press but it didn't take a silly amount of effort to press it apart. The bearing tool that I had made was again used for the center bearings - making that was time well spent!

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    Crank apart and all cleaned up - the only parts that I couldn't get from Suzuki Australia was the conrods - have the ones that Cruzinimage sent me in that package with the incorrect pins and bearings - will use them with Suzuki small and bigend bearings.

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    On the primary gear end seal there is some damage to the seal face - SKF makes a speedie sleeve that size, will have a think about that one - I can still throw the rest of the crank together in the meantime

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  15. Damian_74

    Damian_74 Member

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    Things moving along nicely now that I have some parts - crank back together and pressed.

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    Set the beg-end side clearance at 0.4mm. Can't find any information at what the factory clearance so if any one has the specifications I would be grateful if you could post them (closest that I could find was.......... T200 is 0.185--0.575mm and the T20 is 0.14--0.445mm)

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    I bought a $50 induction form Kmart - told the Mrs it was so we could have Korean BBQ's at home - she saw through my lies when she walked in the shed to see me heating bearings on it.
    Using a cheap thermocouple, heated the bearings to 80 Deg C - they slipped straight on!

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    Bit of work with a large copper hammer has the crank runout less than 0.05mm.

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  16. Damian_74

    Damian_74 Member

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    Rolling on to the wheels :ricky

    The new rims supplied from Suzuki have a sticker on them "Made in Thailand" but are still stamped RK EXCEL. I've laced plenty of aluminium dirt bike rims over the years but never a steel rim.
    I'm not sure if it was just poorly made rims or the fact that they are steel but I had a bugger if a time tuning the wheels - it took an extra couple of stubbies :drinkbut ended up getting them all below 0.2mm in each axis.

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    NICE AND SHINY!!!!!
     
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  17. Damian_74

    Damian_74 Member

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    Supercheap had a sale on the other day - picked up a smallish sandblasting cabinet for $190.

    Filled it with 0.85mm Crushed Glass - works well on steel, bit more aggressive than I had wanted but will give a good etch for paint to stick.
    Was thinking about trying walnut shell down the track for alloy and softer materials.

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  18. Damian_74

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    For the 74 GT250L that I am currently riding am having nothing but trouble with the front brakes squealing. Have cleaned everything, tried different pads, scuffed up the disc - even tried another 2nd hand disc that I had.

    In desperation I decided to get the disc ground.

    Tried a few different brake places and none of there machines would take the Suzuki disc. Found one friendly workshop that let me measure up their machine so that I could turn up an arbor.

    http://www.a1brakes.com.au/

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    Even tested the new sand blaster on the hub. Like new!

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    He had a bit of trouble with the disc chattering but the finish should be OK - and at least I now know its flat and true! When I fix the other issues on the bike I will report on the success.
     
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  19. Damian_74

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    Circumstances are forcing me into a change of direction for this project.

    My GT250L 1974 bike that I’ve been riding around looks like it’s done a crank seal.

    Some time ago, was walking through the shed and noticed the smell of petrol, was in a rush so quickly forgot about it. A few days later I was cleaning up to go back to work (go to sea for 4 weeks at a time) and found petrol dripping from the exhaust.

    DAM – I forgot to turn off the petcock!

    Early GT250’s don’t have an overflow on the carburetors – fills the pots when the needle and seat leak. Short of time I pulled the plugs, slowly turned it over on the kick starter, blew it out with compressed air and squirted some oil down the bore. Got home the other week and fired it up.

    Bit of smoke out the left pipe…………….”it will clear when it gets hot” I said to myself.

    Rode to the local shops – still plenty of smoke from the left pipe – white smoke!

    Had another grand thought – “take it out on the highway and get it properly hot – that will clear the exhaust!”

    Well……….……there isn’t an exit for about 5km’s. I attempted to disappear inside my helmet from embarrassment due to the now epic smoke trail that followed me……..and then I had to do it again for another 5km’s to get home.

    I suspect that the residual petrol that was sitting in the crank for the month damaged the crank seal. The center crank bearing is lubricated from the gearbox, oil level in the gearbox dropped on the small but hazy test run.

    So with the rego due and the fact that I was never really happy with the restoration that was done by the previous owner, it is now parked.

    So the Suzuki GT250B 1976 that I’ve been playing is now going to be a nut and bolt restoration to appease the rivet counters and the GT250L 1974 will be the Café Racer.
    Another contributing factor in this decision is that as ADR’s (Australian Design Rules) didn’t come into affect on motorcycles until 1975, so there might afford a few more liberties 74 that I couldn’t on the 76.

    So the café project will take a little longer than originally intended – will do the resto first.
     
  20. Damian_74

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    So with the demise of the road going bike and this now turning into a two bike resto/Cake project, I didn't want have my bike lift permanently filled up with 70's 2 Strokes, so an alternate work bench is needed - getting to old to be working off the floor.

    Left over from some house reno's (new stairs and landing) I had a length of 75x75x4mm RHS. For a bike work bench it is absolute overkill but I can't see myself having another use for it in the foreseeable future - best use it rather than constantly tripping over it.

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    Bunnings (local hardware warehouse for those not in Australia) had sheets of 2150x600x30mm Soft wood pine ply for $65, add some Heavy duty 100mm Casters and 20mm leveling feet from eBay, I will be all finished for under $200.

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    Since the new bench is of such heavy construction I may in the future turn it into a welding/fabrication bench - will just need to find a suitable top.
    My current welding bench that I made several years ago (DIY Stronghand tools copy), although extremely useful is limited to smaller jobs as its only 1050x600mm.

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