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Discussion Starter #1
Please help

My cb 500 f has a problem. When running I have to open te choke a little bit otherwise it holds back.

This doesn't go away when the engine is hot(but even with choke a bit open there is no black or blue smoke coming out of the exhaust).

When driving faster say 130 km/h it holds back again and I have to adjust the choke again (picture this me driving 130 km/h with throttle open bike holding back and me changing the choke and offcourse the bike takes of towards 160 km/h.Leeving me with one hand on the steering wheel and the other holding my classic racing helmet and goggles). Any ideas what is wrong?

When taking the throttle of there are noumerous explosions in my marshall exhaust. (like harley Davidson)

Carburators vacuum is the same. it runs fine stationary (I hope this is the correct name for it) It starts without choke (not with choke)


Please help

rockerz rule
 

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if you have to use the choke it means you're running lean. you should check your float heights and adjust them to spec, the bowls may not be filling up enough under throttle. if the carbs haven't been cleaned in a long time it might be a good idea too because your float valves could be gummed up and not opening properly. when did it last run well, last season?
 

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Take your main jets out and clean them. If that doesn't work then proceed to Jeremy book length article on what to do.

Aaron
 

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I had simular problems on a cb550 that I built for a man in chicago. I had the carbs cleaned and rebuilt and it still wouldn't pull. It was a pooch, I'd be cruising in 3rd at 25-30mph and it would fall on its face. No boot leaks, or float adjustment problems. I asked a friend and he suggested timming. I went and looked...well it was way off. After adjusting the timming it pulled clean, and strong. Just my input, it may be worth looking at before rebuilding carbs and dropping all that money.
Good luck
-Matt
 

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I agree with the timing input. I think its safe to say everything needs to be right. Including the valves and clearances, compression, air/fuel mixture, timing etc... but JD's right, your lean. Your "noumerous explosions" in the exhaust when rolling off tell you your lean as well.

Aaron
 

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im with aaron on this one. you can try a plug chop too. if you can get it up there. if there is an aluminum coating the plugs, youre lean.


jc
 

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Don't overlook the petcock screen and fuel cap vent. Most Hondas have a sediment bowl with a screen in it as part of the petcock. A 10mm wrench is usually what is needed to unscrew the bowl for inspection. Also check the underside of the cap for excess varnish and or tank sealer in the vent hole. I've seen a couple of tanks sealed by idiots that just poured the sealer in, closed the cap, and swirled it around. They chased their tails thinking that the sealer was gumming up the carbs when it was just a vaccum in the tank. To check for a plugged cap that looks OK, ride the bike until it acts up then open the cap and see if it gets better. Good Luck
Bret @ Glass from the Past
 

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the aluminum coating thing was a joke. if yuou see aluminum, that would be pistons melting.

jc
 
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