A couple of issues

A couple of issues

Postby CBX1000chris » Sun Jun 09, 2019 11:02 am

Good afternoon all,
Over last winter I decided to give my carbs the full treatment, the bike had been starting poorly often on 4 or 5 cylinders. Everything was stripped and cleaned and a Randakks rebuild kit fitted. I did make one mistake, I didn't record the number of turns out the idle mixture screws were set to, in the end I went for 2 1/2 turns out after the rebuild. During the rebuild I did make sure all six carbs were getting fuel from the accelerator pump as a 'jet'.
When I started the bike up, very cleanly on all 6 cylinders, everything seemed OK until I increased the rpm, there was a definite hesitation at about 3000rpm, on the road this seems to show itself as a hesitation just as you open the throttle after changing gear. Once through the hesitation the bike seems spot on.
Today I checked the valve clearances (again) before balancing the carbs (again). The valves are all within tolerance but I did notice all six plugs were showing what I would consider to be just a bit too lean. Given the jetting ought to be OK (an assumption I know!) I opened the idle mixture screws to 2 3/4 turns out (apart from #3 cylinder - I'll do that one when the engine is cold). I also did get the balance to be closer than it was.
I'm just back from a 35 mile ride and the hesitation has almost gone but because I changed two things, pilot screw and sync, I can't be sure which has helped.
So, my first question is would the idle mixture screw play a part in any hesitation during acceleration given the throttle is opened from the closed position during a gear change?
My second issue is a very pronounced 'clack, clack, clack' that appears occasionally and disappears just as quickly, this is something new this summer. I have a clue as to what it might be, when the lights are off it never seems to happen so I suspect it may be the alternator clutch slipping under load from the lighting circuit. Does my description of the issue, and my suspicion about the alternator make any sense at all? I did fully charge the battery and try again, same thing, no sign of a problem until the lights are on.
Thank you all in advance,
Chris.
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Re: A couple of issues

Postby Rick Pope » Mon Jun 10, 2019 7:31 am

It's likely that the noise you're hearing is the alternator clutch slipping, because of bearing drag. Remove the alternator and see if you can feel any drag or roughness in the bearings. If so, replace both bearings and the seal. The bearings can be sourced at any good auto parts store. They're a 6201 and 6203, inner and outer, respectively. The seal is also a common one, but I can't remember the measurements. Do a search here on how to remove the outer bearing.
Rick Pope: ICOA Rally Director.
Either garage is too small or we have too many bikes. Or Momma's car needs to go outside.
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Re: A couple of issues

Postby CBX1000chris » Fri Jun 14, 2019 2:11 pm

Hi,
I removed the alternator and inspected the cluctch, it was badly scored. After a long spell with 'wet and dry' on a surface plate the surfaces came up very well. The spring measured just over 29mm which was too short going by the different messages on the forum. Fortunately I had a washer that was a perfect fit, and thickness, to set the preload as suggested by Mike Nixon in his CBX Alternator article. All back together now and as soon as it stops raining I'll go for a ride with the lights on. The bike is definitely charging though at more than 2000rpm as tested with a clamp meter on the cable between the battery and solenoid.
Regards,
Chris.
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Re: A couple of issues

Postby daves79x » Sat Jun 15, 2019 8:00 am

Good so far Chris - BUT, there was a reason for the spring sagging and the plates being scored. Bad bearings is a common one. As Rick said, do not overlook them. They are cheap and easy to replace.

Dave
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Re: A couple of issues

Postby CBX1000chris » Sat Jun 15, 2019 10:14 am

Hi Dave,
When I bought the bike a couple of years ago I treated the alternator to a coat of paint and replaced the brushes when I had it all apart. I checked the bearings at that time and they were OK. What I didn't know about was the way the plates wore so overlooked the problem. I did check the bearings again the other day when working on the plates and all was well. However, thank you for the input, it would be easy to miss this.
Regards,
Chris.
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