1977 400F2 first restore project

[smoothoperator]

Thanks so much for the help guys, Tim has me sorted with a matching crank and cases which is fantastic.

[sprinta]

Drilled out the engine mounting bolt which was mostly something like body filler until well down to just above the nut. Drilling the actual bolt wasn't too bad as I used a new 11 mm HSS Cobalt bit. 10 mm bit wasn't long enough to give clearance between the drill chuck and the crankcase. I drilled away a good part of the nut also. Anyhow it was all going fine until the bolt was relieved when the end of the nut was reached. I could see cracks open up slowly in front of my eyes, almost in slow motion. Bummer. The end of the bolt was pressed up hard against the crankcase which must have been causing stress. The pictures tell it better than words. First image shows most of the bolt removed before any cracks. 3rd image shows the indentation in the crankcase made by the end of the bolt. Anyhow this leaves me needing replacement crankcases or possibly a welding job? I haven't split them yet as I'm waiting on a clutch nut tool at the moment. Can't wait to see what's inside!

https://photos.app.goo.gl/sHrq2Xko7tHU2FuE7

Are you sure they are cracks and not just casting flaws as they all seem to have slightly raised ridges? Pity you did not clean the cases in the area first as if they were they present before drilling you would have seen them?

[Laverda Dave]

I found the link to someone who had a similar problem and how they cured it.

http://www.sohc.co.uk/index.php/topic,21245.0.html

[smoothoperator]

Crank cases split with some difficulty, the top bolt near the drive sprocket sheared leaving an inch of bolt in the bottom half, this one is exposed and had badly rusted. However once the cases were split the remainder came out OK with mole grips. Inside very grimy but the gears all look good. Crank shells are excellent. Horseshoe completely seized and very worn. Bit more disassembly then cleaning and assessment.

https://photos.app.goo.gl/McKNaChzh5Y7fpNi7

[smoothoperator]

Drilled out the broken bolt tensioner from the cam chain adjuster so that I could remove the cam chain bar. This really didn't want to come out. Left a fairly central 6 mm hole in the case so it could be re-threaded if I end up using this case for any reason. The cam chain bar came out in good nick but it was very tight in the hole so probably just needs deburring with a fine grade of emery.

https://photos.app.goo.gl/tk5am6szGwEf8pez5

[mike the bike]

Burrs caused by a PO overtightrning it.

[smoothoperator]

Having measured piston clearance at 10 thou, decided on a re-bore which has now been done! Dechromed and polished clutch casing now back from Agbrigg looks brilliant. One of my cylinder head bolts had a damaged thread so had to be removed which was a pig of a job. Really had to keep the faith that successive heat cycles in oven and then with my puny blowtorch combined with WD40 would actually work. 4 visits to the oven with the last cooking cycle at 150 did the trick. What surprised me was for how many turns the bolt stayed stiff, only to come out with very little to show for it on the threads which are in perfect nick. Many thanks to my amazing wife who didn't moan once about me using the oven and all she got for Valentines day was a Covid jab, in for mine on Wednesday!

https://photos.app.goo.gl/Q37ysChqBLj1TRyN8

[McCabe-Thiele (Ted)]

Reads that you are making good progress now.

[Bryanj]

Problem with that bar is the dimple from the drill which the end of the lockbolt will always find, it needs to be flat so if you cant get another one it needs weding and flatening

[smoothoperator]

Thanks for the tip Bryan I did wonder about that.

[smoothoperator]

Frame is now fully stripped down and I have stripped 80% of the paint from it. I have got the silencer separated from the headers so they can soon be sent for chroming, the 2 clamps are useless so I'll be looking to source replacements, I'm guessing original ones aren't available any longer. The silencer is pretty rotten on the inside so will also be looking to replace that.

[smoothoperator]

Bought a Gateros plating kit and started plating with some crank case bolts. Happy with the results so far and it's a lightweight job I can be doing since I banjaxed my back, stripping the frame! Back is on the mend now and the frame is completely stripped, just needs a final clean before painting as it has been stood for a while. Engine work still ongoing.

Plating pics.

https://photos.app.goo.gl/vDCvXd5aR91kTgJv7

[Oz350Four]

smoothoperator & Bryan,

What I found when I took my cam chain tensioner bar out the PO applied that much force they actually bent the bar at the flattened section... and they (POs) wonder "how on earth did I strip that thread.." sheesh...

[smoothoperator]

Primed the frame today use the MK I spray booth i.e. Outdoors on a calm sunny day. Also collected some bits that Trigger has fixed so a productive (Birth)day. Fish and chips on the way.

https://photos.app.goo.gl/ZojbH7ZjffVeP2oB8

[McCabe-Thiele (Ted)]

That gey primer looks good mate!