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750 Katana Resurrection

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  • KiwiAlfa156
    replied
    Originally posted by dweller View Post
    Very nice rebuild. Good work. Any updates?
    Hi there, yes an update coming soon. Been away on our 3 week NZ summer vacation down in the South Island.


    Back home now and will be completing the build shortly.

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  • dweller
    replied
    Very nice rebuild. Good work. Any updates?

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  • Suzukian
    replied
    Sweet! You've got to be chomping at the bit!

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  • KiwiAlfa156
    replied
    Engine pretty much finished. Cam end covers, complete the wiring and exhaust and it's start time.

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  • Suzukian
    replied
    It's looking really good. Nice and tight.

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  • KiwiAlfa156
    replied
    A Suzuki parts guy I knew back in the early 80s gave the tappet adjuster to me. I've had it for 40 years.

    Fitted the new aftermarket coils. They're a little larger and have a wider bolt spacing than the OEMs. Had a short length of aluminum flat, so made a pair of brackets.



    Found the best position for the coils and made a pattern out of a gasket paper offcut transferred the pattern to the mounting holes to the alloy flat and then bent to suit. Cut to shape and drilled some decorative 'weight saving' holes



    Cut 7mm copper core leads and screwed on new NGK resistor caps.

    Last edited by KiwiAlfa156; 11-27-2022, 08:56 AM.

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  • Suzukian
    replied
    I was very surprised to the find the valve adjusting tool for your bike, and my GS750ESD is the exact same as my 1975 CB400F (which I also purchased new). I love when you don't need to buy a specialized tool. I think the cam follower, is , for people who work on their own bikes the only way to go. You can literally tune these bikes up in a parking lot, or the side of the road, if need be.

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  • Big Block
    replied
    Super interesting tutorial. Thanks for posting your progress.

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  • Suzukian
    replied
    That gasket looks great! They are a PIA to make, but well worth the effort. Great outcome your taking time paid off. I wouldn't use it on a Top Cover gasket, but on other gaskets that aren't coming apart, or to seal cases, Yamabond#4 is incredible. I used it on my M.G Midget (1973) as the stock oil pa gasket would always leak. I had to remove the oil pan, and the gasket came apart, split in halves right down the center. I brushed a little Yamabond#4 on the halves, put it back together, hasn't leaked in 8000 miles. A little scary because if your British car doesn't leak oil, you have to make sure there's oil in it.
    Last edited by Suzukian; 11-21-2022, 02:27 PM.

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  • KiwiAlfa156
    replied
    Yes, having replaced the ATU drive dowel with a section of shank from an appropriate diameter drill bit, I thought it wise to index the timing marks.

    Pulled out the cam cover gasket and it was the earlier bolt pattern... Poos!

    So I have gasket paper and time on my hands, and I don't want to wait for a gasket to turn up.



    I used the cover for the basic outline and assembled the pieces of the old gasket and the wrong gasket to get an detailed outline and internal pattern. Bolts were placed punch punched in the gasket and aligned with the cover



    The finished article. The gasket sheet was 10mm too narrow, so I distorted one of long sides into a shallow vee, thinking that there's enough flex for it to sit flat when pulled into position. It worked. Well pleased. Only took 2 and a half hours.


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  • Suzukian
    replied
    Great to see someone doing this kind of work with the care it deserves.

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  • KiwiAlfa156
    replied
    Camshafts in and valve clearance set


    Indexed TDC with a dial gauge, and the reference mark was out, so made a new mark to indicate true TDC




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  • KiwiAlfa156
    replied
    The results of the journey into the squish zone ended up being a bit of a mixed bag. They clearance in all cylinders are closer to what I was aiming for, but not exactly there. What I have learnt, is that gasket compression is much less that what I expected due to the comparatively low stud/nut torques and thus clamping forces applied to the gasket. There is significant thickness differences between brands of gasket, and that finding appropriate base gasket or material to cut base gaskets of the various thicknesses to adjust squish clearance is difficult because you are wanting to make adjustments in the 100th of a mm.

    So in the case of this build, the squish clearance has a variation from cylinder 1 through to 4 of 0.05mm. With the tightest clearance (cylinder1) being 0.82 mm and the widest at cylinder 4 being 0.87 mm. I was aiming for 0.75 - 0.80 mm.

    So why the variation?

    A couple of options: the barrels may not have been planed perfectly square, or there is some distortion from the PO running the engine with a broken stud and ridiculously high torque on the remaining cylinder studs. So if it had been planed with reference to the head/barrel mating face, which is highly probably, then any variation in the deck height of alloy barrels wouldn't be machined out. What ever the reason, it is what it is. And in a road bike, I don't think it will make a huge difference. Having received it as a non-runner, I have no previous data or experience to compare it with.

    Will it improve performance?

    Skimming the head and taking 0.15mm off the barrels will have a positive effect on compression ratio. Re-torquing after a few heat cycles may also nip up the squish clearance a nanometer or two. Looking forward to running her, and that isn't too far away.
    Last edited by KiwiAlfa156; 11-16-2022, 05:47 PM.

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  • KiwiAlfa156
    replied
    OK, next update. Had to do some repairs. The first road block was swapping camshaft sprockets to my good spare inlet. Apparently there was a camshaft material change in later GS/GSX with a higher bolt torque.... This I didn't know and used the figures from a later torque table and... Bugger... Cracked both bolt holes on the cam. A bit of ringing around and found a specialist machine part welder. They work with cast materials and did a fantastic job.



    Next repair was also welding, this time by me building up the drive lugs on the ATU that got sheared off. MIG-ed up suitably sized beads and then ground and filed to shape



    Now I can rotate the crank the normal way rather than by using the rotor bolt. So stator/cover back on. Have put in the oil filter, neutral switch, and the final drive sprocket. Just the camshafts to fit, valve lash, ignition timing, pipes, carbs and airbox to be fitted.




    Last piece of the puzzle will be a new Rec/Reg. After finding the rec/reg to be the cause of a vicious parasitic drain on the battery in my 650, I tested the part fitted to the 750 with less than stellar results. So a replacement has been ordered.
    Last edited by KiwiAlfa156; 11-15-2022, 09:19 PM.

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  • Suzukian
    replied
    It's cheap insurance, and a lot of factory manuals don't mention it, but it should be done. However, you haven't touched them so you're good to go. I shot peened the Rods on the last bike engine I built, so I purchased new nuts and bolts to not have to worry about it.

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