Topic: carb syncing - order of operation

[evinrude7]

carbs are synced as of last spring with a morgan carb tune.  however i wonder if i should have set the mixtures screws to factory settings before doing so or at least had them all the same.  does this matter before syncing?

all other maintenance items were taken care of prior to carb sync but not sure if the ims were all the same. 

[jgger]

The way I understand it is sync is to set all the slides so you dont have one carb " leading"  or opening different. But as always I could be completely full of crap.😬

[evinrude7]

The way I understand it is sync is to set all the slides so you dont have one carb " leading"  or opening different. But as always I could be completely full of crap.😬

yeah but i wonder if the ims affect the vacuum syncing process.  my guess is they don't because of the lack of comments.   

[Deltarider]

I've never seen any difference in vacuum as result of me turning the airscrew* in or out, not on a 4 cyl. engine where the other three cylinders will force the piston down also in the cylinder measured. So I'd start syncing with all 4 airscrews in the position that is given in the manual. This does not imply all 4 have to remain in that position after the syncing is done. In fine tuning afterwards, they may well end up in different positions. Resistance in the narrow channels the idle mix has to go towards the little hole in front of the carb slide (engine side) may differ. But why not test it yourself and share your findings when they differ from mine?
* BTW, I have little or no experience with the IMS screws that are on the later PD carbs. 

[pjlogue]

I haven't experienced any change in sync adjustment after adjusting the air screws on my 750.  This is adjusting the air screws withing normal settings.  Sync changes might show up if you seat the air screw or turn it way out.  I used the carbtune.

-P.

[DaveBarbier]

These bikes are pretty forgiving so it won’t make a difference. But, why don’t you set the mixture screws and then throw on the carb tune again and see if it’s still in sync? For a better test, put the carb tune on first to verify sync, then remove the carb tune and adjust the mixture screws, then check sync again.

[evinrude7]

thanks for the info. 

[Deltarider]

Provided yours has the 4-4, you can become an expert by listening to the puffs at the rear end of the exhausts and check the sound of all four. A breathtaking experience no doubt  . Uche... uche... uche. Takes quite some exercise to judge equality .
Rich is a fat sound like blub, blub, blub, blub, lean sounds thinner. Please report back!

[evinrude7]

i do have the four into four original exhaust.  pretty sure i'm tuned in the ballpark of about right.  on occasion i'll get to wondering about mechanically improving things on the bike even more than i have, so for example i posted the question above.  weather in nashville this week is mid 60s during the day.  my next job doesn't start up until jan 2nd so i'll be riding as much as possible.