Primary chain rub on top bolt hole boss of left outer coverLooks like David Silver Spares in the UK has NOS available for about $108. I have ordered from them before and they are reliable. My VISA charged me an international transaction fee of a few bucks as I remember. Not a big deal, but keep it in mind. I wouldn't even try to replace it with something else. The new ones fit so perfectly that you have to slide the crank sprocket and clutch on at the same time. It's an important part and I wouldn't skimp on it. I would also check around your area Honda dealers, I found a dealer near me that had two on the shelf a couple of years ago. Good luck!
Today I had a very nice thing happen to me. I had inquired about a used on that was on ebay for $29 plus shipping. Asked about stretch and guy said he never checked. So I measured how much mine flexed (bends sideways to show play in pins/plates) and then made up a diagram to show him how to make the measurement. He emails me back that he's going to send it to me for free. If it is bad, throw it out. If good, remember him the next time I need parts. I told him if the chain is good, I'm going to pay him for it.
Can't believe he offered to do this. Still some nice folks out there on ebay. I thought I'd share the diagram I made for measuring a chain off the engine. Not sure if we can get a correlation between side deflection off the engine and stretch on the engine, but it is probably worth a try should we come across a chain at a swap meet or similar. That said, as I typed this message, I decided to call another dealer and sure enough, he had one left. I'm a mucho happy boy today. So, now I can use my new chain and my old chain to make a range of side flex others can use should they find a chain in a swap meet or similar. See attached diagram. Here's the instructions so you know how I'm measuring this side flex. All views are looking down at a flat surface, such as a bench. First, take the circle of chain, place it flat on the bench so that one side (link plates) are in contact with the bench. Now collapse it so it forms a double row as in fig 1. Now turn it so the edges of the link plates are now in contact with the bench. The double row is now stacked one on top of the other. Figure 2 is what you will see and a similar row is beneath that. Now bend the chain sideways so it forms an arc. The amount of arc will be determined by how much play exists between the pins, rollers and inner link plates. This is the wear. See fig 3. With the chain tightly arched, place a steel scale or ruler across the bottom end points of the chain and measure the distance D between the outer chain plate on the inside of the arc and the top of the ruler. regards, Rob
Rob
Great story and great diagram, thanks. I have a few NOS primary chains including an original DID one I picked up, in it's original wrapping for £15 (about $20) this summer. The used ones I have are pretty indistinguishable from the new ones using a 'droop' test, where you hold two side by side and check the deflection. The worst one I have has no play in it at all on account of it being inside my waterlogged CB77 motor. It's rusted solid! G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F Thanks G-man. I was not sure if the amount of stretch that makes these unusable would be reflected in side flex. Based on what you found, sounds like it might not be accurate enough to tell you anything. It's probably like trying to measure the change in length to see if it is stretched. I did a quick estimate and for a 10mm sag measurement, the change in circumference would be 0.099 inch. So if you fold the chain in half so it's a double row straight run, it will be half of that or 0.045 inch which is less than 1/16".
Well, when I get my two it will be interesting to see if I can make a correlation between the two. But I suspect I won't. The only reason I went down this road was because of that used on on ebay that was no longer on an engine. regards, Rob Got my NOS chain yesterday along with my ebay freebie. I checked side flex to compare all three chains and as G-man said, it's not indicative of stretch. My NOS chain had as much side flex as my old worn out chain. The ebay freebie had about half the flex and was also a DID versus OCM. But when I mounted it on the engine, the stretch was the same as my old chain at 15mm.
New chain shows 8mm slack. regards, Rob
Hi,
Indeed, side flex isn't an indicator of stretch, it's an indicator of tolerances, and these can vary between one and another chain. However, side flex can me used on one chain, a before and after method, but that isn't the case. The only way to determine the stretch of a chain is to measure it's length, and compare it with a new or NOS chain. The best way to do this is measuring the length dry (no oil, no grease). Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
Depends on what the word "FLEX" means. (Bill Clinton?)
Seems contrary to my teachings for all to many years of riding/racing. Or could it be that if the chain has a lot of side flex the tolerance has warn/stretched and I using common since would replace it in an effort to protect both sprockets?. ...........lm
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