Author Topic: Blanking off rev counter - to do or not to do?  (Read 1014 times)

Offline SpannerBrat

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Blanking off rev counter - to do or not to do?
« 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 :)

Offline deltarider

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Re: Blanking off rev counter - to do or not to do?
« Reply #1 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.

Offline SpannerBrat

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Re: Blanking off rev counter - to do or not to do?
« Reply #2 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!

Offline Bryanj

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Re: Blanking off rev counter - to do or not to do?
« Reply #3 on: August 02, 2017, 04:34:44 PM »
You dont really need a tacho to set the carb balance, just an even tickover

Offline SpannerBrat

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Re: Blanking off rev counter - to do or not to do?
« Reply #4 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)!!!

Offline Wenman

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Re: Blanking off rev counter - to do or not to do?
« Reply #5 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
If at first you don't succeed.. hit it with something!

Offline matthewmosse

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Re: Blanking off rev counter - to do or not to do?
« Reply #6 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.
Got a 500/4 with rust and a sidecar and loadsa bits. nice and original and been round the clock

Offline SpannerBrat

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Re: Blanking off rev counter - to do or not to do?
« Reply #7 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.

Offline Tomb

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Re: Blanking off rev counter - to do or not to do?
« Reply #8 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?
Tom
'73 CB550 with CB500 engine café racer
'62 CB77 Sprinter
'70 CD175
'78 CB550 with sidecar
'80 Z50R
And a load of old Yamaha 1100's

Offline Seabeowner

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Re: Blanking off rev counter - to do or not to do?
« Reply #9 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!
Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange
1978  CB550K     Excel Black

Offline SpannerBrat

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Re: Blanking off rev counter - to do or not to do?
« Reply #10 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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