Carb sync ports

[headshrink]

I'm getting ready to sync my carbs, and have purchased a Motion Pro manometer.

The only problem is, although I am learning more and more what all the hoses do, I am not quite sure where to connect it. I have read Vex's DIY (is he still on this board) and like the custom ports he created, but just want to plug it in without making modifications at this point. The SM isn't real clear on which hoses these are.... So where do I plug the manometer hoses, without additional modifications or adapters?

[g21-30]

Sorry, but with all the problems you have been encountering, I'm reluctant to tell you! If you screw that vacuum hose up, it will cost you $65 for a factory replacement.

[headshrink]

Originally Posted by g21-30

Sorry, but with all the problems you have been encountering, I'm reluctant to tell you! If you screw that vacuum hose up, it will cost you $65 for a factory replacement.

Awe yes, but I am learning and gaining confidence.... although the road is frequently a frustrating one, I am still financially ahead on this service, barely due to some new tools, but next time will be CHEAP. When I break things, I also tend to only do that once.

[g21-30]

If you REALLY want to do this, then you should cut the hoses and add the "T"s, per VeX's DIY and cap them when not in use. Check out how kkim did his. Look at the Carb diagrams and you will see that each carb has vacuum line.

[Momaru]

Dunno if it's any help but...

Here's a photo from when I was working on my carbs that show where I attached my carb synch ports. Sorry it's a little blurry, it was late and I was operating on caffiene. Unfortunately since the fuel/vacuum still needs to get thru the hoses, I think you're gonna need to attach at least 1 T-junction in there somewhere.

DSC04861.jpg

The connections secured with blue zip-ties are new for the carb synching, as is the white T-junction. I used 5/16 inner diameter fuel line instead of cutting the stock.
I just re-used the spare junction port coming off my #1 cylinder carb hose (the black T-junction) from having unhooked the Kleen Air system. Cylinder #2's vacuum hose (the one that arches over the runners to the engine intakes) got the new T-junction. The synch hoses are the thick ones running out of the frame to the left behind my hand (cyl #1) and to the right at the top (cyl #2). It would be easy enough to just leave those hoses off and cap the connections at the junction instead, to have fewer hoses to worry about.

[headshrink]

I think I will make custom ports... I was tired of going to the store, but I have to return something anyways, so I guess now is the time to do it right. I also just remembered I have an old carb from ebay in a box that's sole purpose is to be cannibalized for parts.... that is where I'll get the extra hose.

Thanks for the pic and descriptions.

EDIT: I just looked at my parts carb, and the tube was petrified.... I'll pick some up then. Is 5/16 ID the correct OEM size?

[headshrink]

I just installed my ports. The only difference is I did carb#2 closer to the connection at the fuel tank.

I didn't have as much time to tinker as I would have liked, because I had to be at work, but I ran through my first carb sync attempt. It was a little more difficult than I anticipated, mainly because of the tight space I was working in (fuel tank on, but propped up), and I was using the Milwaukee [almost] 90-degree driver (might spring for the proper driver next time), which had difficulty fitting and keeping stable. No worries though. I did notice, that when I got the 2 sides close, if I increased the throttle at one carb would rise higher than the other. Therefore, if it was even at idle (or close since the conditions made it difficult to fine tune it like I would have liked), it would get out of wack when I twist the throttle. Is this right? I thought I read mention of this in Vex's post, but need clarification. Theoretically I would THINK it is better to have the carbs synced at 1/2-WOT.... I would think anyways.

Am I off here?

EDIT: I just went back to the OP, and am finding a little more discussion on this than I remembered.... not done yet, but if I am following, it is more important at lower RPM.

[kkim]

Originally Posted by headshrink

I did notice, that when I got the 2 sides close, if I increased the throttle at one carb would rise higher than the other. Therefore, if it was even at idle (or close since the conditions made it difficult to fine tune it like I would have liked), it would get out of wack when I twist the throttle. Is this right? I thought I read mention of this in Vex's post, but need clarification. Theoretically I would THINK it is better to have the carbs synced at 1/2-WOT.... I would think anyways.

Am I off here?

That's the same results I get, too. I tune for equal draw at my set idle speed, then let the carb vacuums get further off as the throttle is twisted.

I tuned several times for even draw at both idle and at 3k and preferred the way it ran when the vacuum was equal at idle. Try playing with the carbs at different settings and see what works best for you.

[headshrink]

Thank you Kelly, that affirms I am not TOTALLY nuts

[Momaru]

Originally Posted by kkim

I tuned several times for even draw at both idle and at 3k and preferred the way it ran when the vacuum was equal at idle. Try playing with the carbs at different settings and see what works best for you.

Well, Kelly's spoken so that's pretty much that

But for what it's worth I did pretty much the same thing: tuned for synch at ~4k and compared to synch at idle. Preferred the response with idle synched so have been keeping it there. My right cylinder also pulls harder initially.