Primary chain k2

[Pauarc]

Honda cb750k2 Can you check the primary chain on the bike (still in the frame)

[K2-K6]

Yes.

Sump pan off and you'll see the "tensioning" wheel from underneath just in front of oil pump.

[Pauarc]

That’s what I was hoping

[Pauarc]

How many miles should a chain and tensioner do approximately

[Bryanj]

How long is a piece of string, it depends on level of thrashing and servicing

[Jan B]

There is a service limit on the primary chain according to the service manual. Just measure the slack and then you can decide on splitting the cases or not.

[archmill]

Pauarc, just re-newed the primary chains and tensioner on a 79 F2. The limit on the F2 is 70mm and mine measured 70mm so new chains and tensioner from CMSNL. after fitting, the measurement was 63mm. I think the limit of 70mm is for all 750 SOHC engines but double check.

[K2-K6]

They are a pretty durable chain and generally don't display premature wear when used with decent service schedule.

There's schematic in the official manual showing where to measure and asses to chain. Described with vernier caliper in depth measurement from face of oil pan mating surface up to a point on the tensioner arm.

[Pauarc]

Thanks for the help will have to drop the pan and see

[Martin6]

Yes, 70mm for the CB750K. I left mine alone at 68.2mm until I next take the engine out, as I had no other reason to go into the engine case. Maybe should have done it, if I had the opportunity again, I would, but I didn't know the top end would go back together so easily at the time and didn't want to get in above my head.

I have 40,000 miles on mine, so 1.3mm wear or 'stretch' per 10k, if it's linear!

[Pauarc]

Just checked tensioner and the reading is 67.8 so I think it’s good to go the tension wheel is good no marks