1961 CB72 Project

G-Man · Post by **G-Man** » Sat Feb 03, 2018 9:59 am

HaHa!

Thanks for the vote of support, sir. It's damp and cold outside today. I managed about 40mins in the workshop but couldn't get the place warmed up. Better weather tomorrow, I hope.

G

Seadog wrote:Congratulations on your upcoming retirement. About time you shed that 9-5 drudgery and get down to the real important work of motorcycle restoration.

G-Man wrote:Well, it's been a hectic couple of months with very little 'shed' time. I am just three weeks away from retirement but seem to be busier than ever just trying to extricate myself from various projects. More time for my projects but very few opportunities for trips to the US, the land of cheap Honda parts. I just hope I've got everything covered.....

John Watson · Post by **John Watson** » Sat Feb 03, 2018 10:38 am

I'll second that, Seadog.

G-Man · Post by **G-Man** » Sun Feb 04, 2018 8:26 am

Jon

Thanks for your good wishes. We'll have to sort out those parts you wanted.

G

John Watson wrote:I'll second that, Seadog.

John Watson · Post by **John Watson** » Sun Feb 04, 2018 8:57 am

I'm away for a month from the 24 Feb, Graham, returning 25 March, that will give you some time to get used to retirement after which I'll get back in contact, as I said, I'm in no great rush.

G-Man · Post by **G-Man** » Sun Feb 04, 2018 12:19 pm

John

Sounds good. Work or leisure? I've been putting off some surgery which will now happen at the end of Feb so I'll be be 'relaxing' for most of March...

G

John Watson wrote:I'm away for a month from the 24 Feb, Graham, returning 25 March, that will give you some time to get used to retirement after which I'll get back in contact, as I said, I'm in no great rush.

G-Man · Post by **G-Man** » Sun Feb 04, 2018 2:18 pm

I needed a bit of machining therapy today and promised my good friend Les that I would help repair the crankshaft of his 150 Gilera. To complicate things he wants to bore it to 64mm and for even more complication the engine uses a flat top piston.

The interesting thing here is that the standard engine is 60 x 54. Sound familiar? Exactly the same as a CB77!

It turms out that the closest 'stock' 64mm piston is a +1mm XL185 but, and it's a big but, the position of the wrist pin is way too high. We need a longer rod.

After a lot of head-scratching, it seems the nearest useful con-rod is a CB72/77 rod and even then the piston is 5mm too far up the bore. To solve that, Les is going to make a compression plate to fit under the barrel and I am going to modify a scrap CB72 rod to take a plain bush like the Gilera big end uses. We may even use a Suzuki GS750 rod with roller big end but that would involve using one of my NOS Suzuki rods that I was going to use to reclaim a scrap Honda crank.....

I've spent the best part of the day machining up the fixture that we need to safely press out the big end pin of the Gilera crank.

Apologies for the break in transmission of the Honda CB72 but this is all about therapy isn't it? :-)

G

John Watson · Post by **John Watson** » Sun Feb 04, 2018 2:23 pm

We're touring South Africa for a month. Went a few years ago and promised ourselves we'd go back some day and do it properly this time, self drive for 3000 miles taking in the Zulu battlefields(guide booked), Panorama route, garden route, Kalahari and Sun City together with pretty much everything in between.