xj650 seca carb revelation

Here is a tidbit of advice about rebuilding hitachi carbs. I rebuilt a set cleanly and carefully but the bike would
never idle smoothly. I had replaced parts that looked warn out and left some of the components intact. Later when the bike ran like crap I had a brain fart while wondering why. Maybe all the parts that come in contact
with each other need to be replaced as matched sets from the same manufacturer. Tearing those carbs apart
again, I replaced the float needle and seat as well as the accelerator needle emulsion tube and main jet with
matched sets. After reassembly The seca started up with almost no choke and the idle held steady at 1k rpms
even after a test drive. So guys, for best performance don't mix old and new parts. Duh

 

thanks for that - I am considering a good clean of mine rather than full rebuild kits as the float needles etc look so undamaged

 

The partial kits usually come with new float needles and seats. the rubber tips on the old
float needles won't seal properly if they are the least bit warn. Remember, these bikes are
36 years old and you never know what experimental combinations have been installed
in your carbs. It's cheaper and easier to replace all the parts that need replacing while the
carbs are off the bike rather than having to take them off the bike repeatedly

 

agreed - yes I really don't have time to take them off. I do have other questions -
is it ok to use the main bearing shells from my old engine in the new (old) cases I just bought, I don't mind buying new ones. I also have changed my mind about pod filters and am keeping the airbox, is there a kn replacement for the standard paper filter?

 

Not sure about the bearings, something tells me you're going to have to check clearances as I believe they are different depending on the cases. As far as filters go i recommend just getting a stock replacement from Xj4ever. The kn ones are available but may require some fiddling with the carbs. @Jetfixer had one, removed it for a stock one and says bike runs noticeably better