Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: paulbaker1954 on March 24, 2018, 11:46:18 AM
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Ok I am stumped, rev counter sticks and jumps around above 5k. It seems to be not consistent though sometimes it sticks at 5 then jumps up all the way to 7 or sometimes just plain jumpy.
I have striped the unit and all seems good inside, running it up using a drill on the end of the cable it’s as smooth as anything all the way through the range.
I have tried different cables all to no avail
I am beginning to wonder if it may have something to do with the worm drive off the cam but it looks ok.
Questions
1) anyone any ideas, Iam sure I have isolated the counter and the cable as not being the root cause.?
2) would anyone have a spare worm drive I can borrow for a couple of weeks to try to see if that fixes the problem?Happy to pay postage 2 ways of course.
No urgency as am off road for a few weeks following Inguinal Hernia op so can’t get my leg over so to speak. Julie it is sodding painful by the way!
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Oh dear Paul, it can be painful for a few days. Don't laugh, cough or sneeze without putting pressure on it and as for having a poo, well, just take it easy :o
Hope you have a speedy recovery.
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Try routing the cable differently, not the first time changing the way the cable reaches the tacho can sort the issue, and make sure you use a genuine cable, many pattern parts are cheaper for a reason!
Sent from my X6pro using Tapatalk
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Paul, Well snap on both counts. I'm two weeks after hernia repair...my fourth. But my first was 25 years ago. This one was the least painful and didn't bother with pain killers after day 2. And my 500K1 was suffering the same rev counter jitters.
I also took it off and ran it on a drill and seems fine. I have checked over the rubber mounting and the rubber bushes on the fittings and oiled and checked the cable a few months ago but because of the weather and then op I similarly have not got a run in to check.
I have a spare untried drive, but think it unlikely the problem.
Phil
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Thanks for replies
Julie all I can say is thank god for Lactulose!!!!!
Hairy hit it is am OEM cable and I have tried different routes all to no avail
Phil I may take you up on your drive offer when proper walking returns (my wife says I remind her of the 2 soups sketch)
This problem is driving me nuts I have to say
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Although a gauge functions correctly when 'run up' on a drill it might not necessarily work correctly when fitted as it's not subjected to vibration. These straight drive gauges tend to suffer wear in the drive spindle housing, to check this place a small screwdriver in the square where the cable is connected and see if there is up/down movement of the spindle within the drive housing. Any 'slop' should be barely determinable. Difficult to determine how much wear can exist before if causes a problem.
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Thanks Peter i will check the spindle as you say
If it is sloppy is there any fix or is it a replacement gauge?
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The drive spindle is flared at the cable end and the internal magnet is flared onto it at the other end. The flare would need to be removed and the spindle drawn out after dismantling the gauge. Bush the housing but having done that the spindle would need to be re-flared at the cable end and I doubt that's possible as material was removed to remove it.
The only other possibility is something has been attracted to the internal magnet and stuck between it and the magnet cover and usually it's a flake of rust that's come from the inside of the base.
I have quite few gauges, bought at jumbles and restored there might be a 500f one there or another type that could be tried by substitution to see if it resolves the problem.
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Hi again Peter
Thanks for the advice. I pulled the gauge today and yes there is quite a lot of slop in the drive bush ( at leas a mm I’d say)
I have sourced another counter from fleabay that the PO knows works well so will go for the replacement option and see what happens
Will post results as and when I can get back on the road once this hernia op has eased off some more
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Well a bit further....
Bought another counter that was known to be good and a bit better but not right. Still erratic around same rev range but not as bad
I am beginning to wonder if this is a vibration issue, the soft rubber mounts (the big ones under the gaugesj are pretty worn so have now ordered some new OEM ones.
Anyone agree with my theory?
I hate chasing problems like this!!
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Hello.
The one thing that has not been mentioned here is.
Have you removed the inner cable from the outer & checked its condition?
I have known them to snap. But still work to some degree. As the two frayed ends will mesh together and drive. But will also slip making the needle appear to bounce.
Sean.
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Hello.
The one thing that has not been mentioned here is.
Have you removed the inner cable from the outer & checked its condition?
I have known them to snap. But still work to some degree. As the two frayed ends will mesh together and drive. But will also slip making the needle appear to bounce.
Sean.
It’s a Brand new OEM cable !!!
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I bought new rubbers about a couple of years ago and the speedo is definitely better, but my tacho still erratic at 5000+. I'm going to try removing it a little and balancing it on cotton wool for a trial today if I get out. It's difficult to get above 5000 except in 1st or 2nd round here!
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I bought new rubbers about a couple of years ago and the speedo is definitely better, but my tacho still erratic at 5000+. I'm going to try removing it a little and balancing it on cotton wool for a trial today if I get out. It's difficult to get above 5000 except in 1st or 2nd round here!
Hmmm interesting as I just also ordered a new set of OEM rubbers, existing are well past their best!!! We will see ............
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Well the cotton wool test was a partial success. Unfortunately all we had was those small cotton wool balls, so I stuffed a few round the tacho and taped them in. The cable comes mighty close to the metalwork of the bracket still, so it may have touched during the test. But is was fine up to 7200ish rpm. So more work to go. But as I say I already had new rubber cushions a couple of years ago.
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The gauges need to flexible within their mounting plates so using the correct length distance pieces on the gauge studs and the correct washers under the cap nuts is important. Drawing the gauge too far in the plates compress the foam cushions too much and defeats their purpose. I'll have some of those distance pieces in the spare box, they often drop out when the gauge is removed and roll away into some dark corner never to be seen again.
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Thanks for that info Peter and an update.
I think I have the correct spacers (7.1mm) in there, but I have tried inverting the stepped rubber washers and putting then in the holder from the top. Tried this loose with good results and will try with an additional rubber washer on the outside. But much improve.
Paul, I see you have additional thoughts on your mind (exhausts) and I will be following that with interest as I have been running a set of the repros from DSS for a year.
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That's the correct size spacers and the washers on the top of the should be 2 mm.
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I have the sticky tacho problem on the 400, does anyone offer a gauge refurb service?
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I have the sticky tacho problem on the 400, does anyone offer a gauge refurb service?
Yes, Kent400 (Peter) refurbs them.
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Thanks Julie