Members who have donated towards server costs
Join Date: Jun 2008
Location: Flushing, NY
can you help walk a newbie through carb resync?
The engine vibration on my bike starts as the revs approach 3K, and by 4-5K it's very noticeable. This does not happen on another VN750 I have that is 10 years older, so I know it's not normal.
From reading the Verses and other threads, it seems to me it's very likely to be a carb sync issue. I did have to get the carbs cleaned when I got this bike in March (it had sat in a garage for several years) and I think the shop did not sync the carbs as they should have. (I had also told them to look into the sticky clutch on my older bike when I brought it in for inspection and a brake fluid change, something I haven't tried to do myself yet as it's supposed to be tough to do solo, and they said they lubed the cable and charged me the labor for it, but it felt EXACTLY the same afterwards and all it needed was a new cable... Not going back there... They also have never heard of "lubing the splines" as necessary maintenance, even though they're a Kawasaki dealership and have serviced "tons" of VN750s.)
Anyway, to try to make a long story short, I got a TwinMax and I'm not sure I'm using it right. I read about the hand-made $4 manometer but I'm leery of attempting to do two new things at the same time (jury-rig a device I've never used before, in a process I've never done before) without someone on hand to guide me. So, I found a deal on a TwinMax on Craigslist and figured it would make my life easier.
It came with two rubber hoses and an instruction sheet. The Verses helped me find the vac ports on the two carbs easily enough, and told me the front (left) carb is the reference one on our bike. Also with the help of the Verses, I found the adjuster screw under the fuel tank between the two carbs, labeled with a yellow stripe as described.
The directions for the TwinMax seem pretty simple. This is how I would summarize them, let me know if I'm missing steps or got any of these wrong:
1 - Ensure engine is warmed up before commencing balancing.
1b - (Kill engine, I suppose, since later they say to start the engine.)
2 - Connect the tubes to the carbs (use A for the ref cylinder) (left/front)
3 - Turn "sensitivity" knob to MAX (turn power on too I suppose), adjust ZERO knob until needle is at zero
4 - Turn Sensitivity back to MIN, start engine and let it reach idle.
5 - Turn Sensitivity knob until it starts moving off zero, then adjust back to zero.
6 - All done!
OK, sounds easy enough. But when I get to turning the engine back on, the needle on the TwinMax is shaking wildly, it's not settled on one number! It's centered on zero, but oscillating between -1 and 1. Is that normal? Or does that indicate some problem other than carb syncing?
But, if I fiddle with Sensitivity, somewhere around 3/4 to MAX the center of the oscillating needle moves over from zero to -1, and at MAX goes all the way to -2. This is indicating the carbs do need syncing, right?
"Until you have the courage to lose sight of the shore, you will not know the terror of being forever lost at sea." (Despair.com)