Topic: Sluggish 500

[ben.cb500]

my bike runs like crap.

1st year I had it I rebuilt the carbs with a keyster kit. ran crap.

this winter i had the head a cylinders sent out and reringed it...better, starts effortlessly, but still seems gutless.

I have done the tappets, points, condesors, plugs, timing but no carb sync. other than on the bench

today i went for a ride and it just seems like its being held back....removed the air filter, suspect it is cogged, although clean in color. it ran much better but still not great. often dies out at idle.

I get about 45 miles to the tank.....fwiw


so I dug out the old KEIHIN carb bits thinking maybe the Keyster stuff I put in is junk....The emulsions tubes are different, the original KEIHIN have a much different design. And the are 100's and if I am reading it right, 18's its stamped 18??  The needle are one rung up from the pointy end....

Any value in tearing down the carbs and replacing with the old stuff, save for new seals....or should I try something else.

I just get the sense that there is more power but i havent figured out how to tune it. i suspect a modern scooter would have no issue keeping up with my bike as it is.

any input?

[dave500]

that 18 might be 98?one notch up from the lower end is rich,try it in the middle.

[Retro Rocket]

I could be wrong but i am sure i read somewhere that keyster carb kits were crap, even if they are not, always try and use genuine Honda parts.....If you are only getting 45 miles to a tank something is very wrong......Also, try posting for another Toronto member to give you some help, there are some very clever guys on here in your part of the world.....

[dave500]

was the ignition timing done with a strobe?is the advancer not siezed up?check it with a strobe light and make sure it moves.

[ben.cb500]

will do with the strobe and check for advance.

The original Kiehin carb bits are stamped 100 Mains & 18 Slows both with the Kiehin logo on them. Have them soaking in SeaFoam to clean them up for reinstall. The original needles I pulled were set to second rung from pointy end, the KEYSTERS i put in were set at the middle.

Would it be reasonable to have 18's in it? The mileage was 47K miles when I got it. The pistons were in std spec and the cylinders just honed...

Will try with a strobe and see whats happening....any input appreciated.

[domer]

that is most definitely a 98 slow jet! I'd try for a plug chop (after checking what everyone else said) just to give you a better idea of whats going on in there...

[dave500]

the slow jet wont be 98,,more like 38/40/42?the discharge end of the slow jet is lucky to be one mill wide let alone have a .98 hole drilled through it.,look here.
http://forums.sohc4.net/index.php?action=dlattach;topic=5410.0;attach=3002

[domer]

  im an idiot.... reading and typing at the same time.... meant to say that is not a 18 on the slow jet. sorry.

[ben.cb500]

the original kiehin slow jet is marked 18....checked them all...closely......should I be hunting down 40's before I rip into the carbs?

[TwoTired]

the original kiehin slow jet is marked 18....checked them all...closely......should I be hunting down 40's before I rip into the carbs?

I don't see how it could run with #18s as pilots.  #40 was stock.  You sure the ones you have weren't drilled?
An 18 would have a .18mm hole within, instead of the usual .4mm

Are all the head pipes getting even heat?
What are your spark plug deposits telling you?

Stock paper air filters are really only useful for about a year on American models.  Then replacement is required.  For economy, I switched to the UNI NU 4055.

I don't trust the Keyster kits.  Unless the Honda parts are corroded/damaged, I much prefer them.

[phil71]

bad mileage and no power point to wrong mains and/or needles set too high.

[ben.cb500]

My apologies to everyone trying to help me out...they are 40s...i was looking at the jet that fills the bowl...?? Im very tired...


Just finished putting the old keihin stuff back in. Started at puck drop fired at end of bostons thumping of vancvr...she runs way worse. Wont idle, no power suspect no fire in one or some cylinders.

Could i have put the 100 in upside down? The 100 markings stick out, narrow passage sits inside near needle.


Running outa steam....shldnt be this tough

[dave500]

the jet id should be visible,have the carbs been blown through with compressed air?have the emulsion tubes been removed and cleaned?is someone close by who can maybe have a look?when you put the cam back in it was timed correctly,not one tooth either way or something?