Trying my first carb sync

[MattMan]

Hey all!  I have purchased a very lightly used Motion Pro mercury carb sync tool and want to try and sync the Bandit tomorrow night.  My bike can be very hard starting sometimes and stumbles at certain RPM's when held there, but if I go WOT it runs like a raped ape.  Yesterday the bike was out in the sun all day so the metal likely got up to 100 degrees, but the bike didnt want to start full choke, half choke, 1/4 choke, or no choke at all.  I had to give it a little gas and hold up the RPM's to keep it running til it warmed up a little.  Are all of these things signs of carbs out of wack?  The bike also got only 35 mpg last tank.

I unbolted the tank to see what I'm working with and I see all sorts of tubes coming out of the thing.....what the hell do I do with these things?  Don't I need to take the tank off and insert the gas line into a gas supply?  I'm not sure what to do with any of the other vent and vacuum hoses.  The hoses appear to be too short to just lift the tank up in the air and get in there to work on it. 

Also, I've never done a sync before, so if someone could give me a walkthrough I would be forever indebted to you!  I might even be able to take some pics for a write-up  .  Thanks!

-Matt 

[txbanditrydr]

Lot of questions... here a a few answers to ponder.

Poor running could be a result of so many things it's hard to say if a carb sync would help.  Some things to look for are bad gas, clogged air filter, dirty carbs, improper float levels, among others. 

Under the tank there'll be 2 vent hoses, possibly an electrical connection for the fuel gauge (don't know which generation you have), the fuel line to the petcock and a vacuum line to the petcock... all of those need to be disconnected and the tank completely removed from the bike.

You'll need to plug the vacuum line that attached to the petcock and hook an alternate fuel source to the fuel line (spare gas can, etc.)  You'll need a fan in front of the motor to provide cooling while the engine gets to temp and during the sync procedure.

You'll benefit from installing some carb sync extension to the carburetors - it's much easier than trying to connect the MotionPro tool directly to the carbs.  A good example is shown in the Jet Kit Installation Guide found in our downloads section.  The extensions only have to be added to carbs 1 thru 3 since the 4th carb (right side as sitting on the bike) is easy to access.

I personally like to warm the motor prior to hooking up the carb sync tool to avoid sucking mercury back into the carbs caused by too high of RPM's.  Once the motor is warm, the tool is hooked up and the fan is running it's time to make the adjustments.  Get the motor up to 1,700 RPM by using the idle adjust screw or throttle lock.  Between each pair of carbs (1 & 2 / 2 & 3 / 3 & 4) you will find a screw that's accessible by looking straight down from overhead.  These are the adjuster screws and they're very sensitive.  Do not push the tip of the screwdriver into the screw head - use very light pressure or else you'll make things worse and not have an accurate reading.

You'll see the 4 columns of mercury will be likely at various heights while the motor is running - the actual amount of vacuum is not important... you are trying to balance so all four columns are equal in height regardless of where they fall on the scale.  Start by turning the screw between carbs 1 & 2 - you will see how the 1 & 2 columns will get closer or further apart on the gauge... make them as equal as possible.

Next, do the same thing with the screw between carbs 3 & 4 - get those two columns as equal as possible.  Do not worry about 1 & 2 during this adjustment.  Now that 1 & 2 are close and 3 & 4 are close you can use the middle screw (between carbs 2 & 3 to balance each PAIR of carbs.  Sounds more complicated than it really is.

You may need to repeat this a couple times - balance 1 & 2, then 3 & 4 followed by balancing those pairs to each other. 
When all four mercury columns are at the same height your carbs are then synced.

Reassemble the gas tank and don't forget to remove the plug from the petcock vacuum line.  Make sure all hoses are connected properly and not kinked in any way.  Hope this helps.

[MattMan]

Wooo!  Thank you thats jsut what I need!

  I always forget to say this, but it's a 2005 1200.  I recently changed the air filter and plugs, so they should be good to go.  For what it's worth, I ran some seafoam through a tank a gas, but had no change (I didn't really expect one but figure what the hell).  I'll add more once I get out of work

Thanks again txbanditrydr!


-Matt

[MattMan]

Ok I've had a chance to read your post about 7 times lol.  The 2 vent lines that just attach to the tank:  Do I just unhook these and leave them venting to the air? 

I'm looking for the jet kit installation guide, but I can't find that specifically in the downloads?  Could you draw it out in crayon for me LOL.  Is it a subfolder or something?

It sounds like you're talking about putting some sort of extensions onto the carb nipples to make hooking it up easier?  Is it obvious which line off the petcock is the fuel line and which is the vacuum line for the petcock?  And by just shutting off the petcock I can remove all of the lines and it won't spill any of my gas right?

I don't think the bike has ever had the carbs synced so I'm hoping this clears up the running issues.  I don't know much about adjusting float levels and whatnot 

Thanks again!


-Matt 

[txbanditrydr]

The two vent lines off the tank just lay there after being disconnected - they don't connect to anything on the other end anyway.

Click on Downloads tab and then Shop and Owners Manuals under File Repository - It on page 2 of 3 but then again I had troubles with the actual download (Site owner is working on that).... I'll see if I can post up some pics in a bit.

Fuel line and petcock vacuum line are very different - no trouble telling them apart.  The fuel line is the larger of the two.

There is no "off" in the petcock.... leave it in the "on"/"run" position and it won't drain as long as there's no vacuum applied to the (wait for it....... ) vacuum line.

Edit - Found a picture that might help......

[txbanditrydr]

Another overview of all the components under the gas tank.....   

[MattMan]

Ah, the pictures make it so much easier!  Thanks!

So they are indeed little hose extensions to reach those nipples.  Do i need to remove the carbs to install those hoses?  It looks a liiiiitlle tight from the top down view there.  I had read someone else's few year old post and they talked about putting on those extensions too.  I think they suggested 3/16" vacuum line?  I'll have to look it back up.  Looking at the directions now though, it seems I unhook the airbox from the carbs and slide it back out of the way to hook up those extension lines?

My other worry about this is sucking the mercury into the carbs.  I'm afraid the bike's carbs are so out of wack that the second I hook it up it's going to gulp up my mercury!  The guy who sold it to me did mention something about using a restrictor on the vacuum lines to make sure that didn't happen, so I'll have to see if I have one.  Can i just pinch the vacuum lines a bit if I don't have a restrictor?

Sorry for all the questions, but your help is greatly appreciated!

(p.s. I was also having trouble accessing that manual)

Thanks!

-Matt 

[txbanditrydr]

The carbs don't have to be pulled but it's a tricky maneuver.  In some respects (ie: throttle cables) pulling the carbs is harder.  Unhooking the airbox will not help for the addition of the extensions.

To avoid sucking mercury out of the gage simply do not rev or blip the throttle.  My engine takes a little throttle from a cold start so that's why I suggest you warm the motor up first, then shut it off and attach the gage.  It should start up without a lot of throttle input.  You have to really hammer it to draw enough vacuum to goof up - just take your time and take it easy.

Don't forget... you'll need to plug those extension hoses when you're finished.  If you look close at the picture you'll see little aluminum plugs - some use bolts or similar.  Leave them on the carbs and your next sync will go quick.

Another reminder: Plug the petcock vacuum hose while doing the sync.

[MattMan]

My bike can be a bit of a bear to start even if its warm sometimes.  I'm hoping that issue is resolved once the carbs are done.  I'll just be patient with it and use a delicate wrist lol.  I'm happy I don't need to remove the airbox, because that's one less thing for me to mess up! 

So most of you just leave the tubes connected, but plugged, to ease future carb syncs?  Thats not a bad idea.  Anything to speed up the process and make life a little easier.  I'll have to swing by a parts store on my way back to the office and pick up some hoses and connectors for this bad boy.  Thank you for your help, I appreciate you walking me through this.  Once I know how to do my bike, my buddy is going to come over and I'll help do his.


Oh and the link that you are talking about in the downloads section, is that the Stage One install that you posted up or just the GSF1200 manual?  I'm having trouble accessing both of those.  I was hoping to find what size vacuum tubing is recommended and connectors etc. 

Thanks!

-Matt

[mademiriam]

what a great walkthrough txbanditrydr  its looking like sticky material to me
just a quick note on the restrictors with the motion pro kit, our new motion pro kit (finally gave in a bought one we used to hang a long bit of line with some two stroke oil in it...) comes with four small little 'restrictors' which in your case the previous owner should have put in the lines. Its basically a plug with a very tiny hole in it, and one of them should be in all four lines attached to the kit.
I personally like having something restricting the lines as it seems to make it easier to tune or at least used to back when we were ghetto tuning can't say with the motion pro as I haven't tried it yet.
Also I may just have missed it but make sure your carb extensions are all the same length. Sorry if thats redundant.

[txbanditrydr]

just a quick note on the restrictors with the motion pro kit, our new motion pro kit (finally gave in a bought one we used to hang a long bit of line with some two stroke oil in it...) comes with four small little 'restrictors' which in your case the previous owner should have put in the lines.

I remember seeing something like that on mine - right at the top of the hard tubes or right where the flex lines connect to the hard tubes IIRC.

I didn't realize the extensions needed to be the same length (mine are only due to a certain amount of A/R on my part) - how would that affect the readings??

Thanks for the kind words too...

[MattMan]

just a quick note on the restrictors with the motion pro kit, our new motion pro kit (finally gave in a bought one we used to hang a long bit of line with some two stroke oil in it...) comes with four small little 'restrictors' which in your case the previous owner should have put in the lines.

I remember seeing something like that on mine - right at the top of the hard tubes or right where the flex lines connect to the hard tubes IIRC.

I didn't realize the extensions needed to be the same length (mine are only due to a certain amount of A/R on my part) - how would that affect the readings??

Thanks for the kind words too...

Oh yeah, htxbanditrydr has been a HUGE help!  I tried to name the thread and be clear in my wording so that any other newb's like myself can  easily find the thread for future uses!  With the quality and clarity of this advice I also agree that it's sticky worthy.  If I can find my gf's digital camera I'll take pictures of the job incase anyone wants tham.

Now that you mention it though mademiriam, I do think that those plugs are in place in the lines.

By the way, I found the old thread where the guy made his own tester.  I too am curious if they need to be the same length, especially if no hose is even put on the 4th carb. 

http://forums.banditalley.net/index.php?topic=4800.0

Thanks!

-Matt

[mademiriam]

as I understand it the length of the line has an effect on the vacuum, due to drag etc.
Its not just me being crazy either I just checked and the motion pro instructions say to use 'equal lengths', however I'm not sure how much of an error a slight difference would make, it very well could be negligable had I paid for some more school I'd be able to figure it out for us  

EDIT- the diffrence is most likely very small, I found a handy calculator http://www.gates.com/industrial/pressure/airFlow.cfm and the Standard Cubic Feet of flow has a drastic effect on the amount of loss, the answer would be YES there is an effect but if you don't live with an aircraft mechanic /perfectionist the difference might not be worth worrying about.

[rhithyn]

as I understand it the length of the line has an effect on the vacuum, due to drag etc.

I think it's due to the elasticity of the air... If you have more air in one line over another. The mercury will read lower  with the same vacuum.  It would be negligible, but would show a difference still, especially factoring in the heavy mercury of the testing unit.

[MattMan]

Ok my evaluation of what happened last night:

Epic Fail.

It was horrible.  I spilled gas everywhere.  Apparently I swayed from starving the bike for fuel to flooding it and having gas drip out the overflow tubes onto my boots.  After just sticking the fuel line into a clean beer bottle filled with gas I saw it was not sucking fuel out.  So I figured it was gravity feed and just poured gas into the line.  That worked for a bit, but was incredibly messy.  Thinking back, I saw a video for balnancing the throttle bodies on my TL1000S and the guy had a fancy little bag with vents in the top that hung off of the handle bar....I'm guessing this is what I need to properly to the job?  But it appears the bike would just suck in all of the gas and pour it on my foot though?

Also, it's almost impossible to balance the damn carbs with the "lean sneeze" or "lean cough" that is occuring.  The motor makes a clunk/cough sound and you see the column of mercury for the cyclinder that just "coughed" drop to zero then immediately jump back up.  It happened mostly between cylinders 2 and 4, but more on cylinder 4.  So does it sound like I need to yank the carbs and drill out that brass plug to adust the idle air-fuel misture screws?  Thanks.

-Matt 


Side note: Did the forum crash last night?