C95 bearing rumble

[Michael Stoic]

Link works!

That's a lot of play! I am not sure whether locktite sleeve sealer or equivalent can distribute itself so that the shaft stays centered. With so much clearance, the sealer may pool deeper at the bottom.

Hopefully the usuriously priced bearings will help with tighter clearance to the CS.

--
Michael

[Geoff Hastings]

I’ve managed, with a struggle,to remove the crank bearing, it was definitely loose on the crank. The new bearing is a much better fit so I’m confident that a smear of Loctite bearing fit will cure the problem. When I said struggle to remove a loose bearing, what was causing the problem was the cam chain sprocket which I had to remove first.I have a large puller but it slipped off the gear and damaged a tooth so I now need another shrink fit gear. After the new gear arrives I’ll have to find out how to push a very hot gear onto the shaft but more importantly timed in the correct position as this type is not keyed. If anyone out there has any info on this I’d be glad of your help.

https://youtube.com/watch?v=QiARpsT55LU&feature=share

As a follow on, I was a bit puzzled as to why the bearing had spun on the shaft because when I built this engine the bearings seemed fine and so we’re not replaced. I previously stripped the oil spinner which was full of crap but this time after only a couple of thousand miles I expected it to be pretty clean but it was not. It contained quite a significant amount of what looks and feels like blast media. I’d flushed all the galleries with white spirit and was convinced I’d got it all but it would appear not. First and last time I send a head away for cleaning.

[Geoff Hastings]

The little Honda is back together, I did a rough guess as to correctly locating the cam gear. I looked at a few pictures of the type that has the locating key way and the timing mark appeared to go to the bottom position with the crank at tdc. I put the gear in the oven for about fifteen minutes and used some plumbers pipe freezer to chill the crank as much as possible. With some thick gloves on I positioned the gear onto the shaft and gave it a swift clout with a club hammer and a short length of tube slipped over the shaft. After it had all returned to normal temperature I checked the gear for timing and it looked pretty close. I didn’t relish having to try pulling it back off if it had moved. The rest of the engine went back together as normal and I confidently pushed the start button. I must admit to being a bit surprised when it didn’t fire up straight away so rechecked the points and plugs, I had some carb cleaner nearby and being highly flammable it makes an excellent easy start so I gave it a quick squirt into the carb while cranking. It fired up straight away so I knew the cam timing and sparks were ok so that left only the carb. Naturally, as the carb had been removed I’d given it a thorough clean so I was a bit puzzled. I removed the fuel line and petrol flowed freely, I took the carb off again and being careful not to tilt it I took the float chamber off, it was empty! I eventually found that when I’d pushed the fuel line back onto the carb the brass carb tube had neatly shaved off a sliver of rubber that had then blocked the inlet. With that little issue sorted the bike fired up straight away. I’ve given it a short couple of mile test ride and it now runs sweet with no sign of the rumble and more importantly I hadn’t realised just how much vibration the loose bearing was generating, it’s now so smooth.

[Michael Stoic]

Geoff,

Congratulations on your success!!

Such a methodical and disciplined approach and ulimatgely - triumph! Thank you for posting and taking us all along on the journey!

--
Michael

[mrhonda-hawaii]

Looks more like a bad bearing to me. The Benly crankshafts went through at least three changes, plus there are versions with no middle crankshaft bearing, but most of them do have one.

https://www.cmsnl.com/honda-c95-benly-g ... t/E02.html

https://www.cmsnl.com/honda-c95-benly-g ... t/E03.html

At least you can just remove the camchain and then the clutch and shifter mechanisms then split the cases, perhaps to be able to raise the crankshaft up enough to replace the bearing, if that is the case.

[Tim Allman]

In your position I would be a bit concerned about maintaining the shaft alignment. The centre axis of the crankshaft needs to be as close as possible to being co-axial with the centre of the bearing. Otherwise the shaft will wobble and at the very least cause significant vibration but the consequences could be more severe because of the stress and strain caused by the off centre shaft if you go the Loctite route..

[Geoff Hastings]

Hi guys, a couple of replies to Mr Honda Hawaii and Tim Allman. First Mr Honda, I did exactly that, I flipped the engine and removed the bottom end, withdrew the crank partially and rested it on some wood. Getting the cam chain sprocket off was a challenge but eventually it released its grip. I fitted the new bearings and applied the Loctite bearing fit, I then fitted the cam drive sprocket and reassembled the engine. On this engine there is no centre bearing and on the first few rides all seemed well, much quieter and smoother but yesterday I took it out for a buzz and the rumble seemed to have returned. I took the points cover off and sure enough there was lift on the end of the shaft. I’ve currently started another project so the little Honda will have to go on the back burner till spring, I might try to source another crank over winter or perhaps when I strip it again get the crank built up with weld and ground back to size. The bearing fit was worth a try but the clearance was possibly too much or, clouting the cam drive sprocket onto the shaft ruined the bearing fit adhesion.