Carb Sync Going Wrong - Fluid keeps sucking into bike

[thedeatons]

Hey guys... A little background: I have the carb sync extenders installed (Honda nipple on front cylinder with piece of vacuum tubing run under the seat, TEE installed in rear vacuum hose, with piece of vacuum tubing run under the seat).

I have the vacuum line to the petcock removed, and plugged (I didn't plug the vacuum port on the petcock).


I have the home made carb sync gauge (yard stick with 20' of clear tubing, with a few inches of Stabil installed as fluid). Each side of the tubing is connected to one of the vacuum line extensions run under the seat.

When I first started the bike all the Stabil just ran into the bike through the hoses. After that I installed the original VTR size 45 pilot jets into each end of the clear tubing, then tried again.

The Stabil moved much slower this time, all the way into the bike through one of the tubes. I tried to adjust the sync screw on the rear carb back and forth, but I couldn't make the fluid stop.

#1 Question: Do you guys think the Stabil is too low of a viscosity to use for this? It seems really thin, and moves super easy.

#2 Question: Does any part of my process sound incorrect?

#3 Question: Can I get it close by listening to/watching idle speed

#4 Question: Any tips or pointers?

Thanks!
James

[Smokinjoe73]

For me in the same situation, I used valves made for aquariums to regulate air flow and calm things down. Baring that, try kinking the tubes, but its only a couple bucks (quid) for the valves.

[MikaelJ]

I had the same thing happen to me, finally got it to work as the bike had warmed up enough.

The bike needs to be at operating temp for it to not suck the oil in one cylinder.
Once it is at temp it shouldn't do that and should be fairly easy to adjust.
A small adjustment goes a long way.
Also some restrictors in the tube helps a lot, I used the old pilots I took out at the time hooked into the line and it worked great.

[VTRDark]

I have the vacuum line to the petcock removed, and plugged (I didn't plug the vacuum port on the petcock).

This does not sound right. The vacuum should still be attached to the petcock nipple for syncing the carbs as this will affect things. For the rear you put a T piece in the rear vacuum tube and branch of that.

As for the oil issue, sorry I can't help there as I have never used one and use a carbtune. But on a sidenote and which may be causing the issue with your setup. With the carbtune there is a smaller diameter pipe about about 2-3cm long that is inserted in between the main vacuum sized tube that one connects to the take off's on the bike. This has a venturi effect that smooths out the flow otherwise the gauge fluctuates quite wildly and makes it hard to get an accurate reading. So what I suggest is to either pinch the end of the hoses slightly with your fingers (not ideal and takes your hands away from doing anything else) or cut the last 10cm of the tube off, just before where your connect it to the vacuum take off's on the bike, and insert a slightly smaller diameter pipe that fits snuggley inside, then put the 10cm you cut off back on the other side of the smaller pipe.


Like this....


(:-})

[thedeatons]

I installed vacuum restrictors in the form of size 45 pilot jets originally from this VTR. That slowed the movement of fluid quite a bit.

[VTRDark]

Same principle and does the job.

(:-})