I've sync'd before, and used the search, but i'm still not happy with my last sync, or with my search findings, so i'm hoping for more opinions...

1) When I sync should i do it with the engine at operating temp? If so, what is considered operating temp for this? Last time it was sitting idling, and obviously getting hot enough to turn the fan on, basically running at 190-215 degrees during the sync.

2) Do i perform the sync at idle, or while revving the bike? If while revving, then what rpm do I hold it at? This is another question i've had varied responses to. What is your opinion and why?

James

 

I didn't do it at that high a temp. My logic was that the bike spends little time there hopefully.

If I recall its at idle and 3k but I think idle is more telling since its more stable.

This is just my memory, others may know better.

 

Joe: how do you keep the temps lower during sync?


Any more input? Anyone?

James

 

Meaning I hooked everything up and started the bike & did the sync before it got real hot. Was also a cool day and my fan is on an override switch so can keep it going.

 

1 Bike must be warm enough that the enrichener circuit is fully off and at what you consider it normal operating temp.
2 Syncing at idle is most important, that is when the vacuum in the intakes is greatest and any difference between the two cylinders will be most apparent.
3 With idle sync matched then set your idle mixture screws, turn in and out till idle drops and set half way between those points. (some people go by RPM but I find that by watching your sync gage you can see the idle drop better)
4 Sync again if mixture adjustments changed things.
5 Now check sync when slightly cracking the throttle to ensure the throttle linkage is opening both carbs evenly.


Not specific to the VTR but I have seen bikes that had linkage problems. You could set all the carbs to match vacuum at idle but when cracking the throttle some cylinders would lag behind. Have also had bikes with sticky enrichener cables / adjustments that would not stay in sync. If bike will not stay in sync look at those areas.

 

I sync the carbs at full operating temperature. I'll go for a very short ride if I have to before I sync them.
Fortunately, I have an electronic sync tool, so, it makes the job much easier and quicker for me. I also check at 4000rpm's. As Pidge said, if at higher RPM's it comes out of sync, check linkage.

 

I use a commercial duty pedestal fan at full blast aimed at the front of the bike. I only do this during the cooler months as a 95-100+* garage causes my brain to overheat and the bike doesn't like it either.

 

Sync'd perfectly at idle using the two bottle method. When i rev it up it goes out of sync.

Frankly i'm tired of fiddling with it, and i have no clue about fixing the linkage at this point, so i'm gonna ignore it

It was a good day to do it here, as engine temps stayed at 159/160 while doing it.

Also got the idle adjusted to 1200 and verified sync there... Amazing how off it was.

James

 

Crazy, hey? People think that when they pull off thier carbs to change jets, that since they didn't mess with the linkage, they don't need to sync thier carbs. I do it every time and it's amazing how far out of sync they get sometimes. You can be as careful as you want not to touch that linkage, but somehow they still need to be sync'd after pulling the carbs.

 

 

So how do i fix the stupid linkage... Sigh... Lol

James

 

This is so common that is should have a FAQ section.

You can not sync the carbs at any speed other than idle with the stock stacks and airbox.

The reason is you have 2 different length velocity stacks.


Now if you run Dr Honda or similar stacks or 2 long or 2 short stacks, you can check the sync at a higher RPM.

Carry On

 

Ahh... Makes sense. Different length velocity stacks, hrc style slide (plugged), so the carbs will function different once the slides are open and stack length really comes into play.

So i'm sync'd at idle, so should be good ?

James

 

James,

I always do mine at idle and about 81 degrees C.

that is the most common temp I see on my bike.

I always give it a few blips on the throttle and watch what happens when returning to idle.

Anytime I do anything in relation to the carbs I always re sync them.

I have a simple tool, just 2 tubes with a ball bearing in each but it does the job.

I don't know about you but I can tell by the sound of my engine usually on the over run that the carbs need syncing.

I find that I very rarely get any farting through the carbs but if I do I check the sync and usually find it is out.

Part of the fun of owning this bike is the carbs in my opinion.

 

That is all I ever do and I even have equal stacks in mine

 

Maybe I'm just stupid....did Hawks carb set up this weekend......hardest part was syncing the carbs. I just could find the right combination of screwdriver or 7mm socket...etc to make turning the sync screw easy. Kept burning my had on the water pump valve. What do you use? screwdriver? 7mm socket with extension??

BTW - even though the sync is not perfect bike runs much better now. Low RPM throttle transition so much better.......many thanks to 8541Hawk.

 

Driver handle, 4" extension, 2" flex drive extension, 7mm socket.
Adjust screw , pull driver and socket OFF the screw, blip throttle, check sync

 

Thanks for that, I had read elsewhere sync was to be done at fast idle, i.e. 1800rpm due to the fluid jumping around in the tube (tranny fluid in tube method that I use). I did this by winding in idle screw until it sat on 1800-1900rpm. But when returning the idle screw back to 1200, the sync would be out. The latest sync I did (3 days ago), I ended up holding the throttle at about 1900, checked the sync tool, let go of throttle and then adjusted, then held throttle open again. Holding the throttle at 1900 did actually require a different adjustment to winding in the idle screw.

This time however, I will do it at idle...

 

I've found i can sync about 4 times as fast by simply doing the following:

Remove seat.
Undo quick release gas tank cotter pins at front of tank.
Prop tank up.
Connect 2 bottle sync gauge.
Use 7mm open end wrench to dial in carb sync.

I used to use the flex joint method but it wasn't exact enough and i had to chase it around a while. With the 7mm open end wrench i can make minute adjustments in a short amount of time. Saves me a lot of time.

James