Karben's 83 Nighthawk thread

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karben
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Karben's 83 Nighthawk thread

Postby karben » Fri Apr 10, 2015 9:47 pm

I've yet to hit a highway yet. It's my first bike and I'm absolutely loving riding. My tachometer is shot, everything else in the housing works beautifully so it may be a lose wire or something. But just a quick question... at what MPH are you guys shifting at while driving around the 'burbs? Around my house I'll rarely hit 55+ mainly putter around 25-45. I've only driven a 5-spd on a car and I realize they rev up a bit lower than bikes. I feel like, when I'm just cruising I'm shifting a bit too early... Shit, sometimes I'll hit 5th @ 45mph. I guess I'm just not used to riding around at such high revs. So, When you do guys shift (by MPH, remember, tach is broken)?

2nd-10-20
3rd-20-30
4th-30-40
5th-40-50

Is this way too early? If I EVER feel like I'm bogging down or the bike feels too high a gear with too low MPH ill down shift.


Bonus round!!! Is it bad for the clutch to have it depressed while in gear and rolling? Should I be releasing the clutch after each down shift, letting the engine slow me down?


Thanks guys! Happy CB summer to all.

http://i.imgur.com/VndikEW.jpg
1983 CB650SC Nighthawk

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Folsoml
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Re: At what MPH do you guys shift/cruise?

Postby Folsoml » Sat Apr 11, 2015 6:29 am

Welcome to the forum!

I can't tell you the MPH to shift, but I will say to run the RPMs higher rather than lower. The charging system in these bikes is such that it does not begin recharging the battery until 2500 to 3000 RPMs.
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Re: At what MPH do you guys shift/cruise?

Postby cb650 » Sat Apr 11, 2015 11:21 am

Your mph sounds about right. Downshifting and releasing the clutch wont do any harm unless u try 1st gear at 60mph. Where in KS are you? I have a extra tack if you want one. There are usually some on ebay also.
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karben
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Re: At what MPH do you guys shift/cruise?

Postby karben » Sat Apr 11, 2015 11:58 am

Folsoml wrote:Welcome to the forum!

I can't tell you the MPH to shift, but I will say to run the RPMs higher rather than lower. The charging system in these bikes is such that it does not begin recharging the battery until 2500 to 3000 RPMs.


Funny you say that. Guess I've been driving it like grandma. Had to bust the charger out cause she died after my dad tried to start it 4-5 times. Here's to hoping the stator isn't going bad.

Overland Park, Kansas BTW.
1983 CB650SC Nighthawk

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Folsoml
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Re: At what MPH do you guys shift/cruise?

Postby Folsoml » Sat Apr 11, 2015 12:46 pm

The charging system on these bikes is notoriously weak. It may not be charging at all. Hook a multimeter to the battery and rev it up. You should see the voltage go to about 14.5 volts or so. If it does not change, or starts dropping slowly, you may have a charging issue.
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karben
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Re: At what MPH do you guys shift/cruise?

Postby karben » Sat Apr 11, 2015 2:00 pm

So... is it possible to fix these tachometers? I saw someone repairing a cb750 tach on youtube where he had to resolder the ground to the vibrating circle doo-hickey.... :D

Anyways, is it possible that a wire somewhere janked loose or a fuse blew somewhere? If it needs to be resoldered, etc I'll probably just try to purchase a used gauge cluster close to my mileage (on that note, is it possible to dial the used cluster to my mileage?) Anyone know a vid or a guide on removing the cluster and/or trouble shooting the tach?

edit: I don't have a multimeter but I can't count how many times I wish I did. Maybe ill go score one for 20 bucks @ AAP. I would ground the black and pop the red on the positive terminal, then have someone crank the throttle? What am I watching for on the meter?

Thanks!
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Folsoml
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Re: At what MPH do you guys shift/cruise?

Postby Folsoml » Sat Apr 11, 2015 4:20 pm

The tachometer should be entirely mechanical. What model bike do you have?
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Re: At what MPH do you guys shift/cruise?

Postby cb650 » Sat Apr 11, 2015 4:45 pm

See you have 83. Way diff than the 79/82. Tack is electric on yours.
I do have a cluster from a 84 if you interested.
Did you clean the tank out?!?!?!?!

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Folsoml
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Re: At what MPH do you guys shift/cruise?

Postby Folsoml » Sun Apr 12, 2015 5:16 am

cb650 wrote:See you have 83. Way diff than the 79/82. Tack is electric on yours.
I do have a cluster from a 84 if you interested.


Thanks. I somehow missed the signature. :oops:
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Re: At what MPH do you guys shift/cruise?

Postby cb650 » Sun Apr 12, 2015 11:30 am

I did too untill his last post asking about electric tack.
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Re: At what MPH do you guys shift/cruise?

Postby karben » Mon Apr 13, 2015 8:57 pm

So, looks like my Speedo is janking out as well... Yesterday (it's been rainy/moist lately...) the speedo didn't register at all until about 5 min into my drive, then it worked as normal. Today, same thing, wasn't working. Then, a few min into my drive I noticed it was "stuck" at ~20MPH. Could this be related to my tach issue? I really don't want to lose my entire gauge cluster :/ . I can handle the tach not working. But I kind of need my Speedo... Any videos about removing/cracking the gauge cluster open would be awesome. Thanks guys.


Edit: if the '84 cluster would work on my 83 I'd be glad to take it off your hands if the deal is sold. BTW, I changed my sig after I saw you guys asking what model I have... you're not going crazy.
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Volker_P
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Re: At what MPH do you guys shift/cruise?

Postby Volker_P » Tue Apr 14, 2015 2:31 am

At least for the SOHC, the oil pump does not produce full pressure below 3000rpm so one should not ride at load below that.
Your shifting mph's sound right and safe to me, I'd think transmission is not that different for the DOHC.

Opening the mechanical, circular speedo/tach is described here:
http://www.salocal.com/sohc/tech/speedo/spedo1.htm
Not sure how this looks like for the 1983 however.
Cosky's great (free) online manual: http://cosky0.tripod.com

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Folsoml
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Re: At what MPH do you guys shift/cruise?

Postby Folsoml » Tue Apr 14, 2015 2:39 am

karben wrote: BTW, I changed my sig after I saw you guys asking what model I have... you're not going crazy.


Whew! :lol:

According to the fiche, 1983 bikes up to frame number DM008695 used assembly 37100-ME5-671--and it was only used on that bike. After that frame, they used 37100-ME5-672--and it was used on both the 83 and the 84. What the difference is in frames, I do not know.

Your speedometer it still mechanical. A cable runs from the front axle to the back of the speedo. As the front wheel turns, the cable spins and activates the meter. Check your cable to make sure it has not broken. A broken cable will work sometimes, but not other times.
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Re: At what MPH do you guys shift/cruise?

Postby cb650 » Tue Apr 14, 2015 5:33 am

Well we are going crazy or already there. PM me about the cluster. Where u at?
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karben
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Re: At what MPH do you guys shift/cruise?

Postby karben » Tue Apr 14, 2015 9:13 am

Folsoml wrote:Your speedometer it still mechanical. A cable runs from the front axle to the back of the speedo. As the front wheel turns, the cable spins and activates the meter. Check your cable to make sure it has not broken. A broken cable will work sometimes, but not other times.


Do you have any pics? I've peeked around in the Clymer manual and it seriously just says, 'Remove gauge cluster as reviewed earlier in the chapter' the damn thing is referring to an exploded drawing of the cluster. Literally zero details about removal or even inspecting the cables.

Edit: Also, PM sent
1983 CB650SC Nighthawk


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