Carb sync (You knew this was coming)

[GAWildKat]

Mike's doing the sync now. He keeps losing vacuum on #3 the hose is sealed well. Any ideas? Pics of before http://img.tapatalk.com/d/14/04/27/ehyva3a9.jpg and current as of post sync too. http://img.tapatalk.com/d/14/04/27/sedamyza.jpg

 

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[Yammer Dan]

You got 2 screws on right side and one on the left. Have to adjust right side then adjust left side to the right.

[GAWildKat]

Got the screws adjusted...it was the vaccum issue on #3 Mike had issue with most. It finally did lvl out @26cm across the carbs

 

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[Flyinfool]

I had that one time while doing mine. it turned out to be a sticky linkage that was allowing one plate to do its own thing. Got all kinds of goofy readings from that one cylinder.

[StormRaven]

Got the carbs sync'd to the point where 26cmHg was the high bounce and 25.5cmHg was the low bounce on all Cylinders. Took it out for a test ride and...WOW what a difference in ride. No more surging idle at the stop lights, no more light popping on decel, smooth as glass takeoffs and landings without a jitter. Cruises nicely at 95 and holds airspeed quite well at 10,000 feet.

 

I downloaded Kbran's instruction PDF and drove myself batty for half an hour trying to find the screws it was talking about (came to the gentle realization that the images were of a 2nd Gen and the screws are probably different on my 1st Gen Mk2. I need a new rubber mallet:starz:). At that point I figured, what the heck, I see the one screw on the left, and two screws on the right that look just like it in shape, and the idle screw hanging down. I tied in the hoses of the carb tune to the designated vacuum ports on the engine (dampers didn't fit in and not my tune so I'm not forcing it. I'll just make due...which turned out just fine in the end), cranked him up and let it get to just a bit below operating temp. At that point I started fiddling with the screw on the left with the idea of "What's the worst that could happen? I blow the engine?" and saw the changes on the tune for cyls 1 and 2. I got those evened out at 24cmHg, then went to work on the right side. Tried turning the back right screw first, and saw that it was making the adjustments on 3&4. Lucky, I chose the right one. Got those two sync'd at 26cmHg, then I started working on the right front and evened all of them at about 25cmHg. Gave it a few quick revs....and when they settled back, 3 was down to about 20cmHg with 4 staying at the 26 line and 1&2 were even at 27-28. Well..took about an hour of doing, but I eventually got all four settling down at 26cmHg and sounding better than he ever had (I think the problem may be a stuck float in 3 that finally worked itself loose).

 

It was just about 10 minutes before killing the engine for cleanup and reassembly that GAWildKat told me what Dan posted about which screws did what...which I did backwards to what Dan apparently said...but it worked, so I'm happy.

 

And one final note: I attached the Cylinders to read left to right 1,2,3,4 on the carb tune so you can tell which cylinder is reading what in Kat's pictures above. She did not get a picture of the final read.

[skydoc_17]

Hey Mike,

Sorry I didn't see this thread sooner, here is the link from the First Gen. Tech Library on the Carb. Sync. for a First Gen. with a CarbTune.

 

http://www.venturerider.org/forum/showthread.php?t=56723

 

The linkage is connected with Nylon Bushings that are NO longer offered from Yamaha. A squirt of Silicone Spray on the linkage helps to keep it from binding, and also helps when you are using the throttle.

Just an FYI!

Earl

[Grolli]

Just out of curiosity.. what happens if you sync below 26ish?

[GAWildKat]

Just out of curiosity.. what happens if you sync below 26ish?

 

I don't think it's anything bad, it's just where hubby's bike leveled out on the sync.

[bongobobny]

Just out of curiosity.. what happens if you sync below 26ish?

Your exact idle speed will determine the level. What's important is that they are all the same!

 

BTW from what I remember the procedure of which carb first is opposite from 1st gen to 2nd gen I think...

[Grolli]

\Got it. I sync'd at 1000 RPM but cant remember if I leveled them out at 24 or 26. Just wanted to make sure I didn't bugger anything up.

[Venturous Randy]

Be careful when syncing carbs that you do not have any vacuum leaks anywhere. If you do have a vacuum leak, you will be trying to compensate for it while syncing that carb.

RandyA