Topic: Vacuum Port Adapters

[Scootch]

Maybe everyone knows about these but for anyone who doesn't...
These are handy. Install them on your carbs for vacuum sync. I installed them on my carbs and left them. On the inner carbs I ran a length of tubing out to the side and capped it off. That way you have easy access to the ports for sync. I originally looked for something like this because the port on one of my inner carbs was stripped. It would not make and maintain a seal. Drove me nuts attempting to do sync until I realized what was going on. You can install these in the carbs with your favorite thread sealant if you choose. Be aware that there are 5 and 6 mm versions. You will need to get the appropriate ones for your carbs. They also sell a kit that includes the adapters, hose, etc. for the inner carbs. Many places sell them...  Motionpro, Summit Racing, eBay...

[ekpent]

Which size fit your carbs ?

[Scootch]

Which size fit your carbs ?

For mine its 5 mm.

[Kenzo1979]

If you do this, make sure you buy a gross of appropriately sized and good quality vacuum caps.  Keep some under your seat.  unlike the original screw, if the vacuum cap on your port leaks from cracks or swelling, etc., You will start to experience some issues.  Exhaust popping and erratic idle at stops.  I have done this on a couple of my bikes, and I do like it for syncing convenience. But just be aware of the symptoms of a bad vacuum cap as well if you’re going to do this.

[PeWe]

Hopefully not a straight spigot so rubber can glide off.
Better if like most spigots for hose.
My Mikuni carbs have sync connections. Rubber caps sit where they should.

I have extra to replace if rubber start to get old and crack.

[Doobie]

How often do you balance the carbs that you need to install adapters?

[BenelliSEI]

How often do you balance the carbs that you need to install adapters?

Good question! I find on a fresh top end build, with rebuilt carbs, I like to do it 2-4 times over the first few thousand miles. After that not so much. My K1 and K4, that get used regularly, haven’t been synced for years.......

[RAFster122s]

Given that pulling the carbs is tough and can create leaks having the ports easy to hook up to your gauges can be a bonus. Long term they can turn into a liability, easily fixed as long as you adapt your troubleshooting to include them as a source.

[Kenzo1979]

It is true that it’s not something that you need to do often.  But it is very convenient just slipping off those vacuum caps and not messing around with threads when the bike is hot. It’s one of those things where It’s not exactly necessary, but it’s also not wrong. Just a matter of personal preference.

[MauiK3]

Here, rubber has to be checked on often, it seems our marine environment makes rubber go rather quickly.