Author Topic: Slow rev counter?  (Read 3524 times)

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Offline JD

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Slow rev counter?
« on: August 21, 2013, 05:36:45 am »
Hi Ive just completed my project cafe 1978 CB 550 which has taken me best part of a year, and today was the first time in 4 years the bike has been out for a run, approx 20 miles round trip for its MOT.(which it passed no problem)
but i think my rev counter is faulty or very slow to react, has any one come across this problem before, while sitting at 30 mph in 4th my rev counter is at 1800 rpm at 60mph in 5 its at 2000 rpm, if the bike is standing still and i rev it  the rev counter will not go above 3700 rpm?? ive checked the exhausts and all 4 are hot but im not sure if im only running on 3 sometimes 4 cylinders, would this have that effect on the rev counter? the carbs are balanced and the timing is correct, i think! :-\

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Offline 2strokeTrush

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Re: Slow rev counter?
« Reply #1 on: August 23, 2015, 08:15:01 am »
The Tach reads off the Cam, So if your only running on 3 I would assume the cam is turning slower. But if you are doing 60 I Would think you could tell if you were on 3.
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Offline calj737

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Re: Slow rev counter?
« Reply #2 on: August 23, 2015, 08:27:23 am »
The tach is cable driven. First order of business would be to inspect the cable inside the sheathing. Disconnect it from the motor, and clamp the metal spade in an electric drill. Spin it and verify it turns the gauge. Then, lube the cable well.

If you're riding in 4th gear at 30MPH you're not doing your engine any favors. These motors prefer to be revved well above 5,000 RPMS, mostly between 6,500-8,500. Many ride well above 8,500-9,500 constantly. Even on a "new" motor, revving the engine is not a bad thing, just vary your engine speeds and avoid sustained RPMS for the first 50-100 miles.
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Offline scottly

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Re: Slow rev counter?
« Reply #3 on: August 23, 2015, 07:30:43 pm »
JD, you would get more input if you posed your question in the proper area. You must has missed the warnings that this area is not for questions. ;)
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