My wife has tidied up and now I cannot find my Haynes manual, bless her. I fitted carbon cans a few days ago and now have a slight backfire and popping on overrun, I’m guessing I need to up the pilot jet size and might as well increase the mains at the same time, could someone tell me the standard jet sizes for a 1996 M900 please, also what model Mikunis are fitted?, I can then call NRP tomorrow and order some larger jets, thanks Mark
here's a start:- I have a vague feeling that despite same engine in some cases, Monster equivalent jets may have varied from above slightly over the years. Can't lay my hand on any manuals as not at home but i'm sure others will add more soon.
Thanks Chris, I think you’re right and they do differ, I’ll have another look for my Haynes tonight, Christ knows where she’s put it!
so no sign of overrun popping before new cans fitted? only say this because (as you probably know) a few other things might cause this like slight out-of-balance carbs or even idle mixture screws and circuits slightly clogged/not working as intended.
I can’t absolutely rule it out Chris, I didn’t do very many miles on it before swapping the cans due to the weather but it did backfire slightly once or twice I’m sure, it is even now only slight with the new cans fitted and was potentially doing it before, but the popping was potentially being masked by the extra silencing, so it could have partially blocked pilot jets, or leaks at the inlet rubbers, but I don’t want to strip the carbs, find no issues and then have to wait for new jets to arrive, I’ll give NRP a call shortly they probably have all the info on the bike already, reading other threads I think I need 42.5 pilots and 150 mains, I’ll probably order new emulsion tubes as well, just in case the current ones have worn oval.
After a bit of messing about (mainly from a UK carb specialist that will remain nameless) I’ve ordered two carb rebuild kits (O rings,needle valves etc) from NRP carbs, plus 150 mains and 42.5 pilots (and 45 pilots just in case) plus new emulsion tubes, hopefully I’ll get time to have a play this weekend.
I fitted the 45 pilots, (the 40’s that were fitted were partially blocked as we guessed), no more popping or backfire on decel, I found it already had 150 mains fitted and tapered needles that were all in great condition so I refitted those, the emulsion tubes looked good too but I fitted the new ones anyway + needle valves etc, there was a lot of dirt in the bowls and on the diaphragms but nice and clean now, rides really well , plenty of torque , when I first went to start it the starter was stone dead! , quick phone call to Nelly and he pointed me at the small white connector on the back of the solenoid, he was right of course, thanks Nelly.
