SOHC.co.uk Forums > CB500/550
Mid-Suffolk CB500 Update & Parts Enquiry
Roxy John:
Morning all, it's been a while since I last posted so I thought I would update after the first proper ride out after a lot of tinkering.
Saturday was pretty much the first dry weekend day for ages so I took the CB for a shake-down trip - approx 30 miles around various lanes and a bit of dual carriageway. When I first got the bike in January it wasn't running well and was very reluctant to start. Fearing a blockage in carbs after I cleaned the tank, I stripped the carbs, ran them through the ultrasonic cleaner and re-built with Julie's o-ring kit (thanks Julie - excellent service and very good price!). The floats were all over the place so set them all to 22mm and vacuum balanced when all back together.
I also fitted 4 new plugs, new battery, changed oil & filter and checked & adjusted valve clearances.
The bike still doesn't want to start easily but once fired-up, settles to a nice even idle. However, during the ride on Saturday, when pulling up to junctions and waiting at traffic lights, the idle hung around at 2000 (ish) rpm before settling down and felt like it would die at any moment. I pulled on to petrol station forecourt and it did indeed die. It fired-up again having filled up and while riding, responds well to the throttle, pulling very nicely throughout the rev range with no hesitation well up to 8000 ish - any ideas why it may struggle at idle? I wondered about an air-leak but have sprayed carb-cleaner over all the inlet rubbers and no change in revs. It has the DSS electronic ignition which is set correctly.
Also, rather annoyingly, I lost the generator cover plate during the ride - I can get one from DSS but £90.... anyone have a spare or are they so rare that the price is the price?
Cheers, Phil
McCabe-Thiele (Ted):
Sounds like an air leak on the induction side somewhere - check between carbs & head - another member here had a similar issue recently.
As regards changes in idle speed I've read somewhere that it's the nature of the beast on these older design of carbs?
Sesman:
Hanging idle is nearly always attributable to the pilot jets and/or pilot drillings. I put my carbs through the U.S. cleaner several times without success and eventually had to use aerosol carb cleaner in the pilot jet ways, sequentiality blocking the three points of entry/exit. I used STP carb cleaner, two tins of it. I then heated the pilot jets to ‘ash’ any fuel deposits and then pushed through the #40 jets with #38 probe. It worked, the hanging idle disappeared and the throttle response returned to factory standards.
Roxy John:
--- Quote from: Sesman on March 27, 2023, 12:11:23 PM ---Hanging idle is nearly always attributable to the pilot jets and/or pilot drillings. I put my carbs through the U.S. cleaner several times without success and eventually had to use aerosol carb cleaner in the pilot jet ways, sequentiality blocking the three points of entry/exit. I used STP carb cleaner, two tins of it. I then heated the pilot jets to ‘ash’ any fuel deposits and then pushed through the #40 jets with #38 probe. It worked, the hanging idle disappeared and the throttle response returned to factory standards.
--- End quote ---
Thank you for that - sounds like that's what I need to do then. I've got plenty of STP carb cleaner so will take it all to bits again. Not a job I relish but has to be done! Thanks for your help 👍👍
Oddjob:
https://www.ebay.co.uk/itm/354154761826?hash=item527544ce62:g:57gAAOSwt~9iyFMV&amdata=enc%3AAQAHAAAA0Ihxg7lWlgyHaFk4hgMBd%2BjxT5faV3GbWHzg8ElFWifVm%2BUJR8q8q0c4zW5ve9JV2HoLFoPYvsmO%2FSNgG2ikl0KZ0HfWsQFCq9TrifVJYqamNGDQi%2F6lWRrr3FtaohdoBt%2Fzbu9vpo1PLEtSAcxG9JhbsHKNE2rN%2BL9S9%2Faf4S9dlGPmU2wCabTAwQodm4ExuskN%2BQdT4Ov6r4F3CnO1TVTG%2Bzo7xN%2Be3tkU8RsyTOgGC0buzD7GwM%2BaV%2FYMs4ykw09XN%2B9lU6RxksCYyoh2Im8%3D%7Ctkp%3ABk9SR5Tt_rvkYQ
Or
https://www.ebay.co.uk/itm/203778550584?hash=item2f7225eb38:g:eLIAAOSw-ldh0aZV&amdata=enc%3AAQAHAAAAwMRnPMXyr1txyl8SX8U5Fla5zb3k4%2Bt7D75c3CMHMx5JX6tiApmxWi%2BhNyLwb29E46T6vp4k6v9FjkrZA36nplnP4H%2Fyp6IQUEuC%2BJFcJnCy9N28IWC5aiGTYPWxcc0kn2cpiifXyVf2v5ZiRIBSGOG%2FuoY5T8sytXwn7LAjByEvjmV5Fk%2FgbE6LYsj%2FKa1efCUmg5cQbgED7O84knuFO%2FjhGq0BCDiNWala1axa2NozNx8J0bvk9TNW%2F0kOFOdT6g%3D%3D%7Ctkp%3ABk9SR47ijbzkYQ
I bought one from Shire Bikes, the seller above, last year and it was £46 which I thought was dear then.
The cover is held on my 3 small spring clips which grip the pegs as they are inserted, they are only mild steel and tend to rust to bits, that causes them to lose grip and the cover falls off. Buy new ones or you'll lose the new cover as well, cover them in grease before fitting to protect them as well.
The other alternative is to fit the generator over off a 550 which looks the same except the Honda logo is actually part of the cover and you can't lose it. The only downside is you can see the 3 screws holding the field coil in place. Finding one in decent nick is the hard part.
Like this
https://www.ebay.co.uk/itm/354463125979?hash=item5287a611db:g:Mo4AAOSwnw5joE48&amdata=enc%3AAQAHAAAA0JnuH4kpS0aBZfxSPo4YVeHdJzOr9vskzZwSJYOurfuFtU5SDkal6%2BFlpNVquh7iu3wrKIO58ct02GgxkXojng2owRkUYgVgI17hOjl%2FDNnPCSONM5pp6mQcvScLBRASXS%2FcvaLBnS1YVJH7DtRYcgg%2FOP70c9%2BV4T2vQN3u0Qm%2BWGxh%2F5lrxF91OaS5VOLMytF3lFBRRvA9rQVSe3ps9UQGD3stdcML0F8QJnE3UwJqDSA%2BCoCO8XMDRemS8HVQgN5O9lpsA0SBRzuY3uynB5I%3D%7Ctkp%3ABk9SR6KnurzkYQ
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