carb problems?

[Guest]

hi guys ,I have a 1981 gs550ex, my problem is it pulls like I train up to 4/5k then begins to stutter and bogs down between 6/7k. I have just finished building her. I have done a compression test and am getting 110 psi on all cylinders, the the valve clearances are within spec, the carb boots and o rings are new as is the airfilter , running stock airbox I believe the jetting is standard,i am running a marving 4/1 pipe they say it should run ok on stock jetting it has cv carbs, running b8es plugs, I have checked for airleaks all seems fine, any ideas?what is the stock jetting for this bike?,do we think its a jetting issue? a friend suggested the petcock, but it has the same problems running on prime. any ideas chaps?

[tom203]

Does this "studder,etc" occur in all the gears as you run up? Or just the higher ones?
over here the gs550 came stock with 92.5 main jet

[badladjohn]

it occurs in all gears I think

[tom203]

it occurs in all gears I think

Then it sounds like a ignition issue... Check your charging system output- it might be giving your ignitor fits!

Do this simple test and report all 6 results

http://www.thegsresources.com/_forum/showthread.php?164993-Charging-System-QUICK-TEST/page2&p=1272192#post1272192

[badladjohn]

super, I will get the multimeter out tomorrow and post the results,

[badladjohn]

results

super, I will get the multimeter out tomorrow and post the results,

hi sorry for the delay, work got in the way, so here are the results, key off, 11.71 v,key on with lights 11.48v, idle 12.9v,2500rpm,14v,5000rpm 15.36v key off 12.2v.... is this looking like the battery is toast?.

[tom203]

Your key off starting point of 11.7 volts is a discharged/ dying battery. Can you charge it up with a charger and repeat the test? That 15.3 volts @5k means trouble to me- I don't like anything much above 14.5 v. , as it's tough on batteries.

[badladjohn]

right wow! here goes, after an overnight charge, here are the figures,key off 13.3, on with lights 12.4,idle1500 14.6,2500 rpm 17.0 , 5000 rpm 18, key off 14.0,so your suspicions were correct!.so whats the verdict new reg/rectifier?, and thanks for the help so far!

[JTGS850GL]

R/R is toast. Time for an upgrade to the SH775.

[badladjohn]

thanks for the info, really had me stumped that one, hey but I have learned something !.. once again thanks

[badladjohn]

here is an update, fitted new R&R, its now charging properly, ie 14.5 v at 5000rpm, but the problem still persists, any ideas before I burn it?lol, have fitted a new set of plugs today too, checked the wiring for dodgy connections,bad earths and the such , all seems fine...HELP!!!!