Synchronizing screws on carbs

[bunnysZ]

have a set of 1977 carbs ,(off bike) and want to adjust the synch screws so all valve throttles are the same height in the carb. manuals states 0.7mm/0.028 in clearance from bottom of carb bore to throttle slide ,its suggest using a wire under it and adjusting nuts
silly question time ....
is this measurement 0.028 the same as a feeler gauge measurement , as it seems very thin to me ,
does anyone have a suggestion of what to use which is this thickness.

[Pigford]

To set/balance carbs, you can use any size wire/drill etc. I used a 2mm drill on mine last time as thats what was at hand.
Start by setting master slide (manual will say which one is master, but usually the one thats directly connected to cables) and then set all others to same distance. This is also applicable for Mikuni RS carbs and probably many others. The throttle stop can be adjusted to get correct idle afterwards.
??? Well woth doing at regular intervals, especially when idle gets a bit rough/lumpy!

[chrisu]

probably ok as a start point but I'd still put gauges on them once the bike is running to get them balanced closer.

[hanskloss]

don't laugh but I used a 50p sewing needle set, picked one with 0.7mm and one with 0.8mm diameter measured with micrometer , put thread through both (green for the 0.7 and red for 0.8mm just to know which is which) and set the carb slides with the 0.7mm one first so it would slide in the cut freely, took about 10minutes fiddling with the adj screws, have to be gentle with the screws as it easily affects the opening, than rechecked that the 0.8mm ones won't get through, that way you know it's between 0.7 and 0.8mm as per book - job done, I was quite surprised how accurate this method is when measured with set of Davida vacuum gauges on the bike - nearly perfect setup

[Steve S]

Read a tip somewhere about using ball bearings to help set the carbs slides up,by using four of the same size you can gauge if the slides are lifting together by watching when the balls drop through.
This method however should not be used with the carbs fitted to the engine due to the large amount of spanner work involved afterwards trying to retrieve said balls from engine.
Good luck

[Jeff Saunders]

A small paper clip measures out very close to the .7mm - and when you partially uncurl them, they have a handle on them.

[Rich]

The 0.7mm is only a figure to ensure the slack is taken out of the system, the desired result is that they are all at the same hieght which is then altered by the tickover adjustment. Pin, paperclip, fuse wire, as long as they are all the same it doesn't matter.

[hanskloss]

Rich I thought 0.7 was a minimum opening at the small cut when the throttles are fuly closed, so if set smaller the idle speed might be affected? just a guess

[Rich]

Idle speed is adjusted by the tickover screw which does all four carbs at once, the 0.7mm is a setting to ensure that all four slides are set at the same opening.

[hanskloss]

any reason for it being 0.7 in the book ,not say 1 or 2 mm?

[Pigford]

I think 0.7mm is chosen as set up value, coz if left at 0.7mm and bike is run up, it won't be idling too fast. It probably makes allowance for some numpties forgetting to reduce the gap with idle screw, before refitting & starting the bike & it goes straight to the redline, not good for the manual producer as expensive litigation may follow!

[Surfdeneige]

A picture would help to show where this pin is being poked in, cheers.

[Surfdeneige]

or just confirm that the airbox needs to be off

[Pigford]

Put your gauge (pin) in throat of carb so it just fits between bottom of slide and bottom of carb throat. You may need to adjust idle stop screww to get it in!

[Surfdeneige]

so airbox off then?