carb sync???

[thrashin88]

hey, i got a 1980 gs750 that i just installed a dynojet kit to run pod filters and it seems to run pretty good but i was wondering is a carb sync necessary at this point or should it be alright to go? ive heard of plug chops, is that basically a diy carb sync or different?

one more question while im at it, all the air screws are at 3 turns out like the kit says to do but on the fourth carb its stuck at 1.5 turns out. ive used carb cleaner, penetrating oil, and all that and it wont budge, the little screw is definitely gonna strip before that thing comes out. is it gonna be a big deal running one of the carbs like that or should it not be too big a deal, im really wanting to drive this thing today but i dont want to mess anything up. thanks

[Dave8338]

Once you change the jets, IMHO you need to resync the carbs as things will draw differently, run differently, and won't be optimum for sure.

Plug chops are a great indicator of how rich or lean the bike is running but again, they don't give you any measure of balance between the carbs.

IF you want the bike to scoot the way it was designed, not give you vibrations in various RPM ranges and pull hard through out...a good balance is required.

I have run several bikes with a VERY CAREFUL bench sync but that pales in comparison to the real deal. my 2-cents

As to the air screw...in order to do it correctly, you'll need to get that little bugger loose.

[ryonker]

A carb sync syncronizes the amount of vacuum that each carb has (or is sucking), so it is more or less equal. Most folks bring the vacuum up a little on 1 and then 4 so 1 and 4 are just a tad higher than 2 and 3. This is different from plug chops (which checkes the air/fuel mixture and resulting combustion. You can use a colortune to check that as well. There are others who can explain this better than me.

As far as the screw goes, there is still hope. put a screw driver on it and tap it gently/moderately about 100 times (don't mash it). Keep soaking it with PB blaster. Use a socket drive screw driver which is easier to hold and gives you much better leverage. Amazingly, I have stripped more screws using an impact driver (they never budged) than just using the tapping method and a socket drive screw driver.

Hope this helps.

Rick

[mike_of_bbg]

I recall reading that the cross-pipe on some GS exhausts between 2 and 3 allows them to flow more, which is why 1 and 4 get set higher (2 and 3 take more of the work). By that reasoning, if you don't have the cross-pipe or are running an aftermarket exhaust you probably want to keep them even.