Carb stix, new one on me...

[great white]

I've always used mercury carb stix on my bikes. Been doing it for more than 20-odd years now.

I've never had an issue using them on my (or my friends) bikes. Everything from little twins to big v4's.

But I hooked up my FJ1200 the other day to do a quick check.

Warmed it up, hooked up the stix and thumbed the starter.

Little bugger pulled the mercury right up all 4 tubes, past the  restrictors and almost into the intake before I could kill the engine.

WTH?

I've never had a bike do that before. There shouldn't even be enough "vacuum" to pull that much mercury that high. It's even higher than available atmospheric pressure, which is theoretically not possible on a NA engine.

I tried it a couple more times with the same results.

I wasn't blipping the throttle if that what you're thinking. Just a normal warm engine start at idle.

What am I missing here?

For the life of me, I can't think what's going wrong here.....

[ribbert]

I believe the FJ's have a huge amount of retard at idle to mellow out the snatchiness at low revs, IMO.

Noel

[chiz]

Bet you that if you connected the instrument after you start the beast the results would be different.
Chiz

[Steve_in_Florida]

Well, that SUCKS!

Personally, I use an old set of Motion Pro mercury sticks, and have not experienced this action.

Yes, it pulls the Hg up the tube about 3/4 of the way on startup, but then settles down.

You'll need that special Mercury Magnet to clear out the cylinders.   

Steve

[FJmonkey]

Wow! I have a Motion Pro mercury stick as well, only used it a few times since I got it, but it has never pulled that hard. I do the same thing, get it all warmed up, shut it down, connect the manometer and start it back up. Maybe a restricted air filter?

[great white]

Wow! I have a Motion Pro mercury stick as well, only used it a few times since I got it, but it has never pulled that hard. I do the same thing, get it all warmed up, shut it down, connect the manometer and start it back up. Maybe a restricted air filter?

That seems like a logical thought.

It's a k&n (PO installed before I got the bike). I'll give it a look after work.

Bet you that if you connected the instrument after you start the beast the results would be different.
Chiz

I will admit I didn't get that. Might give it a go and see what happens.

Well, that SUCKS!

Personally, I use an old set of Motion Pro mercury sticks, and have not experienced this action.

Yes, it pulls the Hg up the tube about 3/4 of the way on startup, but then settles down.

You'll need that special Mercury Magnet to clear out the cylinders.  

Steve

It only made it to the tubes. Didn't make it to the engine.

I believe the FJ's have a huge amount of retard at idle to mellow out the snatchiness at low revs, IMO.

Noel

Even so, I don't think that would account for what it's doing or everyone would have the same issue?

I'm convinced there's something simple!e going on here. I think I'm just too close to the problem to see it.

Maybe I'll wait a couple days and have another go at it...

[FJ_Hooligan]

Start it with the choke slightly on.  That will dump extra air right at the vacuum port and hopefully reduce the signal.

Then feather the choke off as it stabilizes.

Or, up the idle speed temporarily.  It is closed throttle plates that creates the vacuum.  The more closed the throttle, the higher the vacuum.

Are you giving it throttle when you start the engine?  Snapping the throttle shut will cause a large vacuum spike.

[FJ1100mjk]

Have used mercury sticks in the past, but I've been using a Morgan Carbtune http://www.carbtune.com/ now for years. There's no mercury used with them, so no risks.

[great white]

Well, I don't know what it was, but I got it done today.

First I set the idle screws to the factory 2 1/2 turns. then I tried starting it, getting a stable idle and then attaching the carb stix. #1 and 2 acted normally, although the mercury was all over the place. But at least they were rising and falling together.

#3 pulled nothing. Nada, zip, zilch zero.



#4 pulled the mercury right up the stix and started to pull it towards the carb. Shut it off before that happened.

After scratching my head a bit and some WTF moments, I tried it again.

#1/2 normal again. #3 tried to suck the mercury out now! I'd done nothing to the bike.



More head scratching. Then, in the very definition of insanity (IE: trying the same thing over and over expecting a different result), I tried it again.

#1/2 good again. #3 pulled high, but stabilized there. #4 pulled normally now.

Not wanting to poke the carburetor gods, I kept it running. I popped #3 line off to let the mercury return to the bottom. Plugged #3 back in and now it pulled normally.



So, with it now working, I adjusted the carbs. Got them essentially dead even and it only took the smallest of a turn either way (I'm talking like 1/100th of a flat) to get them all in line. A couple light throttle applications and it kepts its synch.

All said and done, it needed an idle tweak up of about 100-150 rpm. I went closer to 1050 than 1000 as it seems a little happier/smoother there.

While it's not a whole new bike, it runs a bit smoother now.

Hopefully it helps with the 1000-1500 rpm "snatch/grumble" I get when I'm a little too quick with the clutch engagement.

But mostly, I'm just glad I was able to get the synch done/confirmed. The carbs are worn, I know that and will be doing a rebuild this winter, right down to needles and emulsion tubes.

But I still don't understand the odd behavior that it started with.....  

[FJmonkey]

I hate that! "Fixed it by fiddling with it" I call it. Well the best you can hope for now is that it never happens again.

[Ranman85FJ]

I'm glad I'm not the only one who had this exact problem with a Motion Pro.  My first time using this tool was extremely frustrating; it did not want to stay calibrated and I kept getting air bubbles in the tubes in addition to almost sucking the fluid into my motor on each try (not sure what kind of blue fluid is in this model (SyncPro), but I really don't think it's mercury any more.  Maybe that's the problem).   I was tempted to place it in the freezer to thicken it up a bit to keep it from flowing so easily.   And yes, I had the restrictors in place, no air filters attached and I followed the instructions to the letter. 

Quite possibly the worst $100+ I've ever spent.  The Morgan CarbTune appears to be much higher quality and easier to work with.

Randy

[racerrad8]

I'm glad I'm not the only one who had this exact problem with a Motion Pro.  My first time using this tool was extremely frustrating; it did not want to stay calibrated and I kept getting air bubbles in the tubes in addition to almost sucking the fluid into my motor on each try (not sure what kind of blue fluid is in this model (SyncPro), but I really don't think it's mercury any more.  Maybe that's the problem).   I was tempted to place it in the freezer to thicken it up a bit to keep it from flowing so easily.   And yes, I had the restrictors in place, no air filters attached and I followed the instructions to the letter. 

Quite possibly the worst $100+ I've ever spent.  The Morgan CarbTune appears to be much higher quality and easier to work with.

Randy

I too did sucked the fluid out the first time I used the new style sync pro, but frankly I did not read the instructions.

I then read them and established the sync pro cannot be use the same way the old mercury sticks used to be used.

My first trouble was I did not back out the calibration screws all of the way and I did not adjust them with the calibration manifold either.

Once I backed out the screws and then set them with the calibration manifold, I hooked them up and it worked great.

But as I did with the other mercury tool as well, I always kink the hoses when I do a throttle chop to make sure the high vacuum does not suck out the fluid.

And finally, if you are consistently getting bubbles then there is a problem with one of the o-rings that seal the clear tubes in the lower block which is allowing air in. Here are the refill instructions and it talks about the o-rings popping out: http://www.motionpro.com/images/documents/08-0415.I8-0415.pdf

I have the refill kits in stock and they include new o-rings: SyncPro Fluid Refill Kit

Randy - RPM

[Pat Conlon]

Hey Randy (Ranman85FJ)  I had the Motion Pro (wet stick) and a couple of years ago switched to the Morgan CarbTune (dry stick)
Here's what I learned : The wet stick is more accurate because it's has a larger area to display the vacuum signal. The Morgan Carb tune uses shorter tubes and stainless steel rods and you have to make sure you hang the CarbTune vertically so as to get no friction between the glass and the steel rods. You can get a hanging rod which will give you a false reading.

I did a side by side test between the CarbTune and the Motion Pro. I adjusted the carb's first with the Morgan, as close as I could get it, then put on the Motion Pro stick to see how close I came according to the readings on the wet stick. I was close with the Morgan, the columns being about 1/2" off as shown on the Motion Pro wet stick. The Motion Pro wet stick with it's longer columns allowed just a tiny bit more fine tuning.

I've sucked the Mercury out of my wet stick. It's a rite of passage.

I'm going to try some high quality vacuum gauges next. I like how you can lay them flat on top of the engine while you tune. I still like my Morgan CarbTune, don't get me wrong, but you do have to be careful with it and because the columns are shorter than the wet stick, you lose some accuracy.

Just my experience.

[racerrad8]

I'm going to try some high quality vacuum gauges next. I like how you can lay them flat on top of the engine while you tune.

Yeah, that is all we personally use anymore. The only reason I was trying out the new sync pro was because a customer was coming to pick up his race car and wanted the sync pro as well. He asked if I could demonstrate it to him before he left for home and I then sucked all of the fluid out...

I told him, "I have never had that happen at idle before, I better read the instructions because I have not used this new style before".

That was followed by pulling a second on off the shelf and giving him that one because I did not have replacement fluid on the shelf at that time.

Randy - RPM

[Pat Conlon]

Thanks Randy (RPM) that's a funny story. If you're gonna screw up with a new product, be sure to do it in front of your customer.

Of course....I will buy my vacuum gauges from you. That way you can demo them for me (Ha! Hold my beer, watch this...) Show me how to adjust it to calm the dancing needles.