punkwood2k

Ok, first I did search quickly through the forums, and didnt find a question like this, so please hold the flames....

I synched my carbs this afternoon, and I had to split the difference between idle and 4k rpm. First off, having to split the difference means that my valves are probably out of adjustment, right???

2nd.. When I run the bike up to 4k rpm using the throttle grip, I get my oil levels that I am looking for.. But when I run the throttle up using the spring pulley on the carb (instead of twisting the grip) the readings are WAYYYYY out of whack. Using the spring pulley, one cylinder drops to almost nothing, and the other shoots to the top of my yardstick.. does this mean anything?

3rd.. Not sure if you can help with this or not.. but I made my own manomometer (sp) using the yardstick and clear tubing method.. I used 3 in 1 oil for my fluid... I have it synched to 3" difference at idle with one cylinder higher than the other.. and at 4k rpm, its 3" difference with the OTHER cylinder higher.. Does that matter?

mboe794

I consider the reading at idle to be more important than with some revs. I always have differences between them too but I don't worry about it. Three inches sounds like a lot to me however.

As far as the pulley verses the grip I would use the grip because that is what is happening during normal operation. The linkages can cause some funny readings when disturbed. I just did a synch on a buddy's I4 (had to try out my new Motion Pro tool) and I learned some interesting things. Just trying to get the screw driver to the adjustment screw had the columns dancing all over the place. Touching anything near there had an effect. Sometimes I wasn't even sure if I was touching anything. It's just that sensitive.

punkwood2k

I dont have any experience to compare it to, thats why I said I used 3in1 oil. I do know that different fluids measure differently.. 3" of 3in1 oil might equate to 1" of water or .25" of mercury although I am just guessing. 3in1 oil is pretty damn light in terms of weight, so I know it would measure out more than coolant or 2-stroke oil that others use, but it still seemed like a lot.

Tweety

Yeah, I'd say it's a bit to much perhaps... Get it down a bit and then call it a day... Some small difference is hard to get rid of using a home built manometer...

The difference in height are just difference in length the vaccum has to travel... Try to keep the tubing as short as possible and it should be reduced...

Nope... a difference from idle to 4K doesn't mean you need any adjustment at all...

It's perfectly normal, as at idle the air going into the velocity stacks and jets are relatively undisturbed, and at 4K you are supposed to be rolling and have airflow... That will make huge difference, and so will interference inside the airbox... You can never get it spot on at both... And as said, use the throttle...

Torque Junkie

3" vacuum of oil is barely noticeable on a Mercury Synchrometer. As Mercury (Hg) is about 13 times denser than oil it takes a lot of vacuum to raise it in the tube. Synch the carbs with the throttle and split the difference between idle and 4K is what I did. There are lots of reasons for differences between the vacuum readings. Minor Air leaks in the boots, valves, rings. Above 4K the main jets kick in which are different sizes so don't worry about what happens above 4K. 3" of oil is really very little difference in vaccum. I had over 12" vacuum difference in oil before I synched and actually sucked some in the motor before I could shut it down. I used ATF which is not harmful to the motor in small doses.