Yet Another Carb Question (Sorry!!)

Hi Guys

I've just stripped down my carbs for cleaning using Rick's excellent guide and now rebuilt them. I've been reading through as many posts as I could find reference to the butterfly valves having a gap that you should measure with feeler gauge, piece of paper, WD40 straw etc. What I would like confirming is the gap that needs measuring is the bottom of the butterfly and the carb body? I've looked at this on my carbs and they shut completely, you wouldn't be able to fit a gnats private patrs in there!

Now, if they are supposed to have a small gap am I right in thinking that the middle adjustment screw is the first one to move, then match 1 & 2 together and then 3 & 4 together? This is really bugging me and I'm really sorry if this has been mentioned before. I just need confirmation before I start screwing around with the setting I have.

Thanks in advance
Lea

 

Yes, you have the correct idea on where to measure; the gap where the butterflies close down.

I used a narrow strip of paper, and judged the amount of force to slide out the paper once the valve closed down onto it. Tried to make the force even across all four carbs.

The thing to keep in mind is that this is supposed to be a rough estimate - this is where, once assembled, you use vacuum gauges to sync the carbs.

Z

 

Thanks for the info WeAreZilla, gonna try it this evening. I'll let you know how I get on

 

I found it difficult to measure under the butterflies because the gap varies as you come off of dead bottom. Sometimes my "feeler" would grab, others slide loosely through.

I opted to eyeball them by holding up to a light, looking for a similar ,very slim, crack of light on all four. I then opened the idle stop a bit so the bike would have a chance of idling. The bike fired right up and runs great (I think I did have to turn the idle back down though). Turned brutally cold right after I got them on so I haven't checked 'em with the gauges yet.

 

They are easy to adjust by eye so they are all in sync without any gauges. Look for the small holes in the top of the inside of the bore and adjust the butterfly so the edge of it just starts to open over the first hole. You need to adjust the idle speed screw so the first one is open then set the others to match it and they will all be in sync. If your rubber boots have any cracks in them it will throw off the vacuum readings later if you check the sync with gauges but don't let that fool you into thinking they are not in sync.

 

Thanks Guys, after using Steve's method then backing up with MiCarl's method, it looks like they are all now in sync. Once my new float arrives I'll be able to get them on the engine and check them with a guage.

Thanks again
Lea

 

I have used the shank of a 1/16 drill bit.
Just remember when your done matching them all up, you can adjust the gap on all of them at the same time by simply adjusting the idle speed screw.