Hi All

I have a Mikuni HSR 42 coming this week, got a real good deal on one so I jumped on it.I have read that they are pretty much a bolt on for most application with some fine tuning needed,

My question is this I have an 88incher with SE203 cams and S&S air cleaner and SE-1 slipons, will the factory settings be ok, if not what jetting would you recommnend? Dyno runs in my part cost 100.00 an hour at the local dealer but I have lost trust in them, the only other place that do Dyno runs is out of town, and honestly can't afford it right now.

THX

 

call mikuni and ask them for jetting recommendations. they are very helpful. jetting depends on your setup and your altitude.

 

Unlike the stock CV carb. which only has a couple of jets/needle that work good, the HSR42 tends to have a large range of jets/needles that need picking between.

On the last bike I fitted one to, I found that what I ended up with was nothing like the factory recommended settings. I set this up with my own O2 meter and many hours of test riding.

Compared with how it ran on the factory settings, it was a different bike. Power was down compared to the CV carb and I had a lot of carb farts going on. A proper tune woke the HSR42 and I got the benefits.

I really recommend that you get it on a dyno because it is not a carb that can be setup in a reasonable way by feel. You might get lucky and get it running half decently but what's the point in that? Its supposed to be a performance upgrade.

 

Dont waste your money on having a Dyno tuner try and tune this carb. Most tuners dont even know how to tune one of these carbs to spot on, and besides tuning on a Dyno cant simulate many rideability issues that occur in the real world.

You run that carb, you better get familiar with the tuning features and expect to have it off and on about 10 times tinkering with the settings t get it just right. Its a great carb once its setup. Here is some info that will assist you.

https://www.hdforums.com/forum/gener...0-or-50-a.html

https://www.hdforums.com/forum/dyna-...-a-mikuni.html

Hope that helps you.

 

THX Parts eeter, those links sure helped,