Mikuni bsr42 tuning full#

Main jets (too worn out to see the marking but I believe they are stock)Д«efore I put this thing back together I was thinking about re-jetting this carb with this kit for the BS34's from MikesXS and wondering if it they are worth it since this kit says it helps with aftermarket filters and exhaust which I have on this bike.ДЄnd while taking them apart I stumbled upon a problem I tried to solve before I took them apart for this second time.

Idle jets that are in the throat of the carb by the air filter And you all were right about idle circuit being most likely dirty, there was some dirt in the circuit that I believe caused the idling issue. From what I found these carbs seem to be completely stock when comparing them to the pictures 5twins posted. Okay so I did some tearing apart, cleaning, and investigating of these minikuni carbs. So I'm at a dead end here and don't know what to do, any suggestions, videos, or links to similar threads that would help me alleviate this problem would be more than welcomed! So this whole time on idle it has been running on one cylinder practically and the left side doesn't kick in till high RPMs. When I do this, I notice it takes a lot of choke and throttle to get the left side running at all, and adjusting the idle screw does practically nothing. So I switch sides to the left carb and disconnect the the right cylinder spark plug. So I tune the right side carb with the fuel mixture screw and it goes pretty good its running pretty well on this one cylinder. Then I proceed do what a post on here recommended, which was disconnecting the spark plug on the opposite side you are tuning (just to be safe though I connected up a spark plug to the unhooked wire and grounded it to the bike). So I know I am dealing with a crab issue and I go to adjust the fuel mixture. So before I tried to adjust the fuel mixture (because I thought that might be the problem) I tested the compression which was great (150psi), checked timing chain tension which was good, checked valve clearance which was good, checked the spark plugs and they look good, and then checked the timing whcih was spot on. The problem started as soon as I started the bike after I got it all together. Then I put the carbs back on the bike with a new pair of gaskets and boots. Now when I took them apart I cleaned them to the best of my ability and made sure everything was in working condition and checked the slides(including the diaphragms) and noticed that they were in good condition. So when I first got the bike I did a almost complete rebuild and cleaning of the fuel system, including the carbs. I'm somewhat new to motorcycle carbs and was wondering if they are supposed to go up or down at all? Could that be part of the problem? Also I have noticed, with the filters off,that the slides in the carb do not go up and down when the RPMs go up to max or down to idle.

Mikuni bsr42 tuning full#

Then when I hit the throttle when it is warmed up it will really hesitate and be at low RPMs until about 2000 RPMs, then it picks up and I get full power with some backfires sometimes.

Once the bike warms up though the idle will smooth out, but it seems to idle pretty low considering the idle adjustment screw is turned all the way in. If I do try to throttle it while it's warming up, it most likely stumbles and the carbs make a hissing noise and the bike tries to die and every now and then there will be a backfire.

When I first start up the bike I have to run it on choke for awhile before it is able to run on its own, and there is no throttle response until it is warmed up.

The carb is a BS34 Mikuni and I have no clue if the main jets have been enlarged. I have pretty much got this thing ready to go but I am having a carburetor issue(or at least that what I think is the issue). I have a pretty much stock 1980 xs650 that I am trying to get back into road worthy condition.