Carb Sync Question?

[kj5ix]

Carb sync question?

 

Now before yesterday I haven't done it, and found it to be really easy with the carbtune First experience with that too, great product. Now for the question of the day.

 

Not having a tach, but a 9/8's deaf ear,,, I set the idle with the idle set on the right side to what I thought was or felt like 1000R's +- of course. Preceded with the sync, which went well. During one of the rev-up blips I noticed that the tubes would rise to the top, and stop at about 3/4, then fall back to where they were. So just for the heck of it I held what I thought was between 2500 & 300 and looked at the carbtune. It was rock steady, and indicated that #3 & #4 were a bit higher than the left side ??? ( I was having a little trouble getting them together ) So I run the set up to about that level of RPM's. Then adjusted the right side, and resync'd the four to flat. Took about 1 min for that. Dropped it back down to 1000+- and did the Blip, several times, and they were flat and even.

 

Any thought here on that.

 

It ran well for the test ride, but it was seemingly running well before the sync, and after I got all 4 hitting again.

 

[Seaking]

I have a buddy who can actually set idle speed by ear (sonar specialist in subs)..

 

Its best to get a tach and set it by that.. you'll know you've set your idle speed properly and that your carb synch will be spot on..

 

I don't think I've ever spiked my carb tune up like you described it..

[kyle]

I set mine at a hi rpm every time, maybe around 2000 2500 and it seems to make it easier. It also seems to run smoother at speed. how often do you cruise at idle???

[kj5ix]

Kyle

You drinking out of the same cup I did,,,,,,

It was easer to set the right bank, and then sync all together ( or it seemed to be )

[Seaking]

I set mine at a hi rpm every time, maybe around 2000 2500 and it seems to make it easier. It also seems to run smoother at speed. how often do you cruise at idle???

 

I hear what you're saying.. there had been a lot of discussion about synchin at idle vs higher revs, even up to the 3000 rpm.. I'm not qualified to give any proper reasons why one would be better than another.. though I wish there was a simpler answer..

[Condor]

I think I read somewhere... maybe it was from Goose... that syncing the carbs is for low end performance, and once the butterflies were open it didn't make a lot of difference on the sync..as long as they were close.. That's why they are synced at idle, and easier to sync at higher RPM's. Syncing at idle will give better performance when starting off in 1st. So buy the tach. Or.... you can always buy a 1stGen just to know what 1000rpm sounds like....

[Seaking]

That's close to what I remember about 'why' to synch at idle..

 

MIND you, I did a lot of testing on that last summer when I synch'd my carbs.. I found that if you push against the screws as you were turning them you would impart an irregularity into the carb adjustment so that they wouldn't be 100% spot on when you finished.. I fine tuned my technique and found that though the engine at idle didn't change much, it DID make a huge difference when at highway speeds..

 

I bought a new set of gauges to do my carb synch, the bank of 4 dials with needles, to try instead of the carb tune.. sorta felt the carb tune with it's metal rods might be giving me odd readings.. I dunno, gonna give it a try to see if I can get the synch down proper..

 

And I synch when ever I do an oil change, plugs change, clean the air filters and fuel filter.. Or before a large road trip . Its a quick process to do so no worries.. Luckily this spring I did all of the above so the carb synch should last a while..

[kj5ix]

Yea I discovered that pushing on the screw moved the speed up a tad, and had to be easy with it. When I was watching the gages during the little blip of the throttle I did see that it settled down and that they were off some. I think the right was close to 3/16 higher than the left, with just a tad difference between the two right jugs. When I ran the idle up it was way easer to set the right side together, and then sync the right to the left. I do know that after that they were flat at idle even down way below what I thought was normal idle. Probably around 500, just before it wants to die. I have a fairly good feel for the rpm's up to about 1500 by feel and sound. Yepp I does need to get a Tach for sure. That is the biggest thing I miss, and use it to ride by on the Honda,,,

 

On my other thread about carbs, or coil I attached the readings of the sync. I didn't think to take any photos at high idle, cause I wanted to get it done and not mess around with the camera while it was churning that high.

[MikeWa]

I have noticed if I set my idle at 1000+ rpm the bike seems to slam going into first gear. If I keep the idle lower say to around 950 it doesn't. So I tend to keep my idle on the lower side. I purchased a cheap digital tach. Less than $30.00. The one wire hookup just wraps around any spark plug wire. It does all I need.

Mike

[Seaking]

Yea I discovered that pushing on the screw moved the speed up a tad, and had to be easy with it. When I was watching the gages during the little blip of the throttle I did see that it settled down and that they were off some. I think the right was close to 3/16 higher than the left, with just a tad difference between the two right jugs. When I ran the idle up it was way easer to set the right side together, and then sync the right to the left. I do know that after that they were flat at idle even down way below what I thought was normal idle. Probably around 500, just before it wants to die. I have a fairly good feel for the rpm's up to about 1500 by feel and sound. Yepp I does need to get a Tach for sure. That is the biggest thing I miss, and use it to ride by on the Honda,,,

 

On my other thread about carbs, or coil I attached the readings of the sync. I didn't think to take any photos at high idle, cause I wanted to get it done and not mess around with the camera while it was churning that high.

 

Keep in mind that when your revs are higher, the readings are much faster and balancing out swifter.. if your revs are slower, you can actually see a wide bounce action therefore getting a better adjustment out of it.. I dunno.. something like that..