Piston pins/gudgeon pins
Hmmmm, just another thought.......
If you made up over-sized pins (easily done by a machine shop with a lathe & cylindrical grinder, be sure to use an appropriate steel), you would run out of depth for the circlips if you went too big..... 15.2 or 15.3 might be the limit to retain good circlip retention......
Buy another good used crank and stop the program ................LM
RIDE IT DON'T HIDE IT!
Good advice, LM, & ultimately cheaper, BUT:
You forget that you have easy access to parts in the US....... Outside of the US, we don't....... Most of my parts I have to get shipped fromthe US & that gets expensive, especially for a crank, which may or may not be useable when it turns up....... I've actually bought NOS rods rather than buy a used crank......
I didn't forget anything. I've sold many parts to fellers near ya and I also know that some parts are just as available there as here but not all. Ya can bet if I sell ya a part it's a good to use part. HONDA didn't supply the rods and big end bearing to the US which cause us to look for another good engine/crank and also now days we can't find a shop to split 2 to make one because shops here won't mess with these old engines. I'm of the opinion that HONDA offered one over size pin because they felt/knew how much to go at that part of their engine. I've seen a feller in NORWAY buy a CB77 crank on eBay and I don't recall he had a problem with the transaction. Where ya get your CB72/77 rods/bearings from?. .............lm
RIDE IT DON'T HIDE IT!
LM, realistically, the US probably got 20-30 times as many of these bikes as we did down under - maybe more. So, whilst new parts from a dealer are not a problem here (if available), 2nd hand parts - like cranks - are not. I got a couple of crank assemblies as part of a bulk deal & they were both useless...... After all, if you have one that is worn out, there is a risk that another 2nd hand one may be worn out, too..........
I have never - repeat never - seen a second hand hawk/dream complete motor for sale on Australian Ebay. I did see a head once & bought it, but 2nd hand parts are rare. Likewise, I have only seen 2-3 complete CB72's, and maybe 7-8 dreams, for sale on Ebay in Australia over the last few years. Compare that to the US, where at any given moment you can turn up a few bikes. LM, I know you're not a fan of modifying things beyond stock - and your reasons are sound - but sometimes you just don't have a choice & solutions to problems have to come from left field. Yes, maybe 15.1mm was all Mr Honda was willing to risk - but I'd give 15.2mm a go if it meant saving an otherwise good crank assembly. After all, people have success using CB350 & Kawasaki 400 pistons, too - something that might make Soichiro turn in his grave, but they can be made to work. When you look at what some of the guys have to adapt/modify/build from scratch to make veteran motorcycles run, I'm sure there is room for home-made parts & creative engineering with these old Hondas........ I have a huge amount of respect for your knowledge & contribution here, but sometimes there is more than one way to skin a cat..... My rods came from Japan, and there are a few guys around that will press up cranks here - we did have alot more 2-strokes than you guys & they mostly have pressed-up cranks, so the knowledge is still here.......
Hey Ed, I take it you've tried (or know of those who have) and failed with this idea of a solution? Please elaborate, as it's always interesting to learn from your experiences. Regards, Steve
|