XBR running rich

[blew]

I rebuilt my knackered xbr over the winter,using an xl 600 top end.The bike seems to be running well.With a 600 barrel,piston and camshaft,it should produce maximum power at 6,000 rpm.It runs to 6,500 in fifth-it will probably do more,but I haven't tried.It will hold 80 quite happily.It starts easily,idles well etc.etc..But the spark plug is always black -petrol,not oil.It was ok as a 500.The carb is on standard settings-152 main jet,mixture screw 2 turns out,and the needle is non-adjustable.I tried it without the air filter,but it made no difference.Apart from the plug colour,the only obvious indication of richness is that it will idle happily when cold with no choke.I presume it's due to the bigger bore somehow.Any suggestions from the xbr boffins???

[SteveC#222]

Choke plunger in the carb stuck or cable sticking? 

[pete]

Funny enough just been there. Symptoms/not simpsons for simmos benefit..were over reeving after start up and as you power off.Good ol' strip down and lube cured all....not me...the cable.You can feel the choke cable not returning at the lever.

                                                                                                 Keep trying,Pete.

[blew]

When the choke is off,there is free play in the cable at the carb end.I didn't think of the plunger itself-I'll have a check.I don't have any over-revving.And it no longer "twitters" through the exhaust on overrun- I used to like that!!Thanks.

[blew]

The choke cable and plunger are both working normally.I've altered the idle mixture screw to just 1 turn out-it idles perfectly.I'll try it again to see if it's better.Very odd.