Picked this up a few months ago but haven't used it yet.
Was planning on using it to set the idle balance on my KH400.
Managed to own multi-cylinder 2T bikes for over 30 years now without one, but maybe I've been missing out all this time?
If you've used one in the past, tell us about it please.
(https://i.ibb.co/6nK43m9/0207-A1-B7-042-F-4-CF2-8-B9-D-8-AF62365-D1-AC.jpg)
I have one and it works.
However I find it easier to manually sync the throttle cables by feeling the pressure coming out of the exhaust pipes and comparing them by putting my hand up to each exhaust.
Ask and you will receive :thumbs:! Many guys don't realize there are 2 totally separate sync's to carbs, first is vacuum, and the second is slide lift. The vacuum HAS to be done first, then the slides.
https://www.youtube.com/watch?v=sNjR3abv2CM
On my RD i always just synched the carbs by slide lift, which seems to be good enough. But on twin cylinder 4 strokes with CV carbs, it is another story. Bikes like BMW and Ducati. What I found is that many vacuum gauges are not sensitive enough, at least not "carb stix" and "davida". So I used 2 pcs of transparent vinyl hose, filled with red ATF, and fixed to the garage wall. One open end maybe halfway up the wall, then looping down to the floor, back up to the ceiling, then down to the carb vacuum port.. That gives a super sensitive vacuum gauge, 10 mm equals around 0.8 mbar or 80 Pa. The only thing to watch out for is closing the throttle abruptly at higher rpm, as the vacuum then can be high enough to suck the AT into the engine........
I've always done the popsicle stick trick, then make sure that my idle screws are synced.
About three years ago, I bought a Mac toolbox at a storage unit clean out sale. The box itself had been largely cleaned out, but it had some things I couldn't identify. When there are no new posts on here, I go back and read stuff from before I joined the site, such as this thread. Now I know what this weird little tool is, AND that it might even be useful to me! Thanks, Jim :wave:
What about this style of EMPI? Will this also work, and if so is there a preference/advantage between the two?
EMPI 43-5712
(https://www.amazon.com/Empi-Universal-Pro-Sync-Carburetor-Synchronizer/dp/B073RPTLZM/ref=asc_df_B073RPTLZM/)
the empi one is easier to use IMHO but may be a size issue to fit in the frame.
I used to use my old scat one(same as 1st one) for the triples pretty regularly. :twocents:
I just used mine a few days ago, and again today to set the slides for idle on the LC.
Because these dang PWK's have the janky plastic idle screws both on the left side of the carb body, I found it easiest to rough balance the cables, then wind the slides up with the cable adjuster at the switchgear till I had a smooth idle at about 1500rpm. I then used the Uni-syn to fine tune the cables so they were well balanced and backed the idle down to about 1000rpm
Then I pulled the carbs out of the manifolds and foud a drill bit that just fit under the slides at idle height and wound the idle screws in til they were just touching the slides, reinstalled the carbs, and then backed the adjuster off at the switchgear.
Then I whacked the throttle a few times to bake sure the cables were seated right and fine tuned the cable balance with popsicle sticks.
Lastly I used the Uni-syn again to make sure the idle was still good ... and it was.
Sounds complicated on paper, but it was really easy, and I'm sure eveything is lined up good.
When detailing the idle height with Uni-syn, having the choke on helps raise the idle speed enough to keep it running smooth while blocking the air on one side or another.
As Mark said, it's easy enough to do without on a twin, but really helps to have for a triple.
fyi, you can swap out the plastic screws for m5's (i used allens and knurled the heads). you have to lathe a round end on the slide side of the screw but thats it. just a suggestion if you get tired of dealing with them.
I whipped up this one when I did the carbs on my 75 CB400f. The rack system and the total PITA it is to remove the airbox on that bike made my normal setting methods too time consuming to be practical. It is super accurate and has excellent resolution, so much that I had to put some old pilot jets inline of each hose to dampen the pulses and dull down its "reactiveness". Total cost was around $20.00 and worked well.
That being said, for bikes that have easy access to the carb slides and separate cables per carb I usually just set the slides equally, make sure they lift equally using the drop method with equally sized drill bits and set the mixture screws equally and that usually gets pretty close, beyond that a tach and careful listening can usually get me the rest of the way there by tweaking the mixture screws. Of course, that's usually on twins, I'd imagine that a triple would make that method at least 50% harder.