CB500T wont idle, slams and running rough.

C

cbSwede

New Member
Hey all

I'm not getting my CB500T to work well .

It does not want to idle , and once it starts it laps up to about 4000rpm slams and poffs some misfire loudly and running rough for a few seconds to eventually die.

After it dies , I have to wait a while before it would start again , like it does not get enough gasoline.
The spark plugs are also very black (not oily ) after that short bit of running.

Things that I've done.

Adjusted valves for spec .
Checked timmingen on the drive chain
Set pointer to spec and timing.
Renovated carburetors with new jets and gaskets.
The compression in both cylinders is 180.
Checked for air leaks.


I have pod filters and new exhaust, I know it affects the running but shouldn't affect that much!
when i got it running I will probably have to re jet it.

Please help with more ideas what could be wrong. I still have not given up with the carburetors, they lie on the workbench and will be disassembled tonight for cleaning ( they have not been synced and the needels have not been adjusted)

kind regards
Patrik
 
If your valves, timing, compression are done correctly, and you obviously have spark it almost certainly is your carbs

rebuild them, keep the original brass, and clean the shit out of them. what kind of pods and exhaust are you running? If you kept your carbs stock, you will need to jet them to appropriately suit what you're running. make sure you synchronize the carbs too. What could be happening is one of your slides is getting stuck which is what accounts for the revving, make sure they're lubed up and going up and down appropriately. but running aftermarket exhaust and pods will most certainly call for carb tuning.
 
Sync carbs first, make sure both throttle arms move at the exact same time. Best to loosen the idle screws until both of them no longer touch the stop. Then adjust the throttle cables until both arms move the same. Then screw the idle screws back down till both just touch. 1 and 1/2 turn on both of them after that to start with.

Cheap pods will cover one of the air ports on that side of the carb. That will cause major running issues as the slides will not rise correctly, they will probably rise to early enriching the mixture too soon. If yours do that I suggest tossing them or at least using the old intake boots and attaching the Pods to the end of them, that will at least help smooth the airflow out and keep them from blocking ports.

Did you set the float level correctly?

I like asking this question because it tells me if you set the points right... what did you end up with for gap measurement on the right side?

Changing intake and exhaust from stock on a bike with vacuum actuated carbs will change things quite a bit. The carbs are designed to work BEST with the stock systems. Anything other than that will take tuning, head scratching, and some pain. They will respond better to free flowing exhaust that is the same length as the original system usually just a slight upjet on the main is all you need. Air filters are where things get screwy, they like the stock air boxes the best.
 
.
clean the spark plugs.

remove the air filters and try again . . if it does the same thing check the float level, it may be too high . . if it is ok, lower the needle all the way . . if it still has a prob, go down 4 sizes on the main jet.
 
ok! seems like my Carbis are out of wack., but im now putting my old Keihin´s on the shelf and switching to Mikunis.
It will probably take a week for em to ship to Sweden but I let you no the progress.

BTW heres my little Honda
 

Attachments

  • IMG_2544.jpg
    IMG_2544.jpg
    4 MB · Views: 319
That exhaust is plenty long, shouldn't effect the running that much. Looks like the same muffs I have on mine.

Looks like a nice little scoot, what's the black cable running from the handle bar across the tank and under, throttle? That's pretty tight bend if it is....
 
450s/500t's will run alright with slide carbs. They will be a little more jerky as they will stutter some when the slides open but that will solve the air filter problem.

I do suggest getting K&N filters though, they look nicer and perform better.
 
frogman said:
That exhaust is plenty long, shouldn't effect the running that much. Looks like the same muffs I have on mine.

Looks like a nice little scoot, what's the black cable running from the handle bar across the tank and under, throttle? That's pretty tight bend if it is....
Click to expand...

Thanks! The bend cable is from the tacho! not the throttle.
Im more use to slide carbs hens my change to Mikunis and easier to sync witch a gauger.
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light

    • Spread the Love

    Back
    Top Bottom