The $10 Carburetor Synchronization

I just finishing synching the old Hitachi's this morning. The realize that there is "nothing new under the sun", however, I used two homemade tools that I thought might be worth mentioning (or re-mentioning). Together they cost me around $10 to make:

1) The first is the infamous YICS tool. I used the "Norm Kokes" directions found here. I had to go a size up on the threaded rod (it was all my local hardware store had), but other than that it was the same.

2) The Oil Tube Manometer - While the YICS tool is discussed frequently here, I haven't read much about folks using homemade manometers, directions here. While it only allows readings from two carbs at a time, I found it to work great; synching 1 to 2, then 3 to 4, and then 1&2 to 3&4 with the middle screw.

I guess the point here is that being broke (or just cheap) is no excuse for not synching your carburetors...

 

I done a sync twice with mine- Thats about 7 bucks per sync.

 

The problem with that YICS tool is the lack of a seal between the fender washer and the cylinder casting. That "junction" (where the fender washer presses against the outside of the motor) needs to be airtight or you can get a vac leak on #1 (or #4 if you install it from the RH side instead.) Install some form of seal behind the fender washer to correct it.

 

Are you saying that with a seal behind the fender washer it would get the "BigFitz Seal of Approval"?

Actually, the first seal (closest to the fender washer) is "supposed" to sit right on top of the number one "YICS hole". I had a nice round (but off-centered) witness mark (or bulge ) where it sealed on that journal. I may adjust tool to better center on journal next time. As I understand it, the other two seals go "in between" other journals rather than on them. Have I got it wrong?

 

As long as it "stepped on" the #1 YICS passage like that you should be good I guess.

The factory tool's configuration, though similar, does all of its blocking in between passages, and seals the opening to the outside as I described.

My only thought would be that where the passages are blocked between ports, the YICS passage itself is still open to each individual intake tract, just isolated from the others. That one would not be open to the YICS chamber like the other three. I don't know if the difference in volume would throw off the vacuum reading or not.

 

Thanks for the feedback. The synch seemed to go quite well. However, there still seem to be some carb gremlins... The bike runs marvelously (perfectly) until it doesn't. It hasn't died on every test ride, but it has bogged out and stalled more than once. I have always been able to restart and ride it home (with help from the choke/enricher/whatever it's really called). Maybe my wet set wasn't as spot on as I thought. I've also read some posts about "the other" float tangs needing tweaking (for float hang?). Additionally, I guess it's time to break down and buy a Colortune. For now, the mixture screws are back where I found them before the rebuild. Just hoping I don't have to pull the carbs again...

 

NP, I honestly can't say if that one detail would matter one way or the other.

Those symptoms sound like a pluggy gas cap vent or a balky petcock. (But it could also be a case of needing a "mixture" sync like you said.) The float "downstop" issue would cause a suddenly rich condition (stuck float) so the enrichment wouldn't help. If using the "choke" helps, then it's run lean for some reason.

 

Gas cap vent?? Do I have one of those? As for the petcock, I rebuilt it, but maybe next time I take the bike out I'll leave it on prime as a test?

 

Is this the gas cap vent you are referring to?

 

Yeah, that one.

Refurb: http://www.xj4ever.com/gas%20cap.pdf

 

Hmm, I think I may have found my problem. I had cleaned the outside of it, but...