Another Carb Issue??

[foreda]

Lesson learned

Ok.. Earlier in this thread I talked about one of my sets of BS34 II's being very lean @WOT and falling flat on its face. I went back to the bench and tore these apart to perform a root cause failure analysis. I first looked at the Main Jets which should have been 137.5. When I built this set, I had bought (on ebay)a set of Yamaha Factory Jets that were supposed to be 137.5's to install in this set. When I pulled these I found them to actually be 112.5 jets!!! I learned a good lesson here.. Always check the stuff you buy from ebay before installing!!!! No wonder it was failing!!!!!

[Crazcnuk]

heh, yes. I found out the hard way to look at what was actually IN my carbs!

I was going by what the book says, but our Canadian models are apparently a little different.

[foreda]

Plastic Floats

I received the set of plastic floats I ordered for my original set and installed.I checked the float height on these and found these to be set @ about 23 mm. I re-set to 25.7 mm and reinstalled on the bike. She is running much better now although #1 seems to still be a bit rich. The RPM still rises a bit (Vacuum Advance advancing) but it is not bad. I suspect my sticks have some crap restricting and I am not getting an accurate sync causing the vacuum issue. I ordered a new set of carb sticks from Morgan Carbtune across the pond and will re-sync. I also bought a Colortune plug to go with this so hopefully I can get her spot on.
One thing that I did learn from all this is that float height is VERY critical and if you don't get this right from the start, you can chase your tail all day!!

[petejw]

Hey Foreda,
yeah sorry bout that, i knew they were a bit different but couldnt remember if the diaghrams fitted the same way.
With the rpm rising you might be running lean with the slide needle, are you able to raise the needle a notch?
but before doing that id probably wait til you have the correct main jets. Youre doing well, your getn there. :-)