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SOHC.co.uk Forums => CB500/550 => Topic started by: SpannerBrat on August 02, 2017, 01:18:43 PM

Title: Blanking off rev counter - to do or not to do?
Post by: SpannerBrat on August 02, 2017, 01:18:43 PM
Hi there everyone,

I recently discovered that the rev counter drive gear casting of my CB550K2 has completely sheered at the point it leaves the rocker cover & one side of the "slot" (that the rev counter cable end locates into) has also snapped off so an alternative solution needs to be sorted out (i.e. either find a replacement part or do without a rev counter on the final build altogether).

Before I finalise the idea I've had for the neatest way of opting for the latter (preferred) option & blanking off the hole that would be left in the rocker cover (ditching the clock would help significantly clean up the cockpit area #cafebuild), is there any reason why I shouldn't do away with the rev counter?

One potential issue I can foresee is setting up the carbs without accurately knowing the revs. Is it essential to know the revs or is there a trick out there means I don't need that particular bit of information? Thinking out loud....I wonder if there's a way I could Heath Robinson the rev counter "off" the bike just for the purposes of the carb setup????

Over to you you amazing people. Is there's any information / advice you can offer :)
Title: Re: Blanking off rev counter - to do or not to do?
Post by: deltarider on August 02, 2017, 02:10:36 PM
It depends of how well you know your bike. An option for you is to have an electrical tacho. It's very simple and wont cost that much. It's connected to the - of the coil and so reads the rpm. Another option is to buy an (automotive) DMM that reads tach as well as dwell, can handle ampères up to 15A, etc.
Title: Re: Blanking off rev counter - to do or not to do?
Post by: SpannerBrat on August 02, 2017, 02:57:54 PM
Thanks Delta,

I don't know my bike at all (it was bought in many many...many bits & pieces  :o) so something like the alternatives you've mentioned will probably be my best option,

Thanks for the starting point. I'll take a look into both!
Title: Re: Blanking off rev counter - to do or not to do?
Post by: Bryanj on August 02, 2017, 04:34:44 PM
You dont really need a tacho to set the carb balance, just an even tickover
Title: Re: Blanking off rev counter - to do or not to do?
Post by: SpannerBrat on August 02, 2017, 04:54:01 PM
If I can manage to get the bike to hold an even tickover, I'll be WELL chuffed :o (it sounds like a challenge in itself & seems a long way off atm but I'm moving the project forward - slowly - so we'll get there in the end)!!!
Title: Re: Blanking off rev counter - to do or not to do?
Post by: Wenman on August 04, 2017, 06:20:12 PM
Hi spannerbrat!!

I had the exact same issue on my Cb550f

I decided to blank mine off and cleaned up the cockpit!!
I've had no trouble with balancing the carbs!
I did have a slight issue getting the jetting right what with the 4-1 and pods but got there in the end!
I did have trouble finding a blanking plug mind!

Alan
Title: Re: Blanking off rev counter - to do or not to do?
Post by: matthewmosse on August 04, 2017, 07:09:26 PM
Get a blanking bit turned up by someone with a lathe, it's not really needed. A £10 digital taco would give a accurate rpm reading for setting up but even that's not really needed.
Title: Re: Blanking off rev counter - to do or not to do?
Post by: SpannerBrat on August 06, 2017, 10:48:42 PM
Thx Wenman & Mosse,

I've seen that plug & may well go down that route but have an idea to fashion a "plate" which would do away with most of the external part of the arrangement (I'll try to post a sketch up to describe the idea).

Good to hear about the carb set up not really needing a rev counter. I'd be interested to hear the results / jetting settings for the 4 into 1 & pods. Sounds like the same as I'm aiming for.

I've also seen a small hub mounted speedo advertised  online which still further cleans the cockpit area & does away with another cable run. I'll look for that link too (but I'm toying with a GPS option too).

Thx again.
Title: Re: Blanking off rev counter - to do or not to do?
Post by: Tomb on August 07, 2017, 04:37:17 PM
Groovy looking plug Wenman, are you planning on using the tacho drive at some time? Just wondered why you didn't remove the drive and make a plate to blank off. I used a flat ali plate, the advantages are less work for the cam, and more plug access.

Is that what you're talking about doing Spannerbrat?
Title: Re: Blanking off rev counter - to do or not to do?
Post by: Seabeowner on August 07, 2017, 05:49:08 PM
If you can blank it with a plate then you could sell the tacho drive gear holder. New ones are £102 from DSS!
Title: Re: Blanking off rev counter - to do or not to do?
Post by: SpannerBrat on August 07, 2017, 07:04:47 PM
Exactly the plan Tomb! Ali plate awaiting shaping & will remove the whole drive assembly.

Thx for the info on the gear holder Seabe. I was looking for an alternative to a pension  :o
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