Article [13] ST1300 - Throttle Body Synchronization

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Scott
Joined
Aug 17, 2008
Messages
561
Location
Fort Scott, Kansas
Bike
2022 KLR 650 Adv
This is my first attempt at a How to article so bear with me.
Starter Valve synch for ST1300. Special thanks to Blrfl for letting me borrow his Carbtune manometer.

Remove seat. Move seat bracket to maintenance position. Loosen 10mm bolt holding rear of tank down.
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Remove two 8mm bolts holding down front of tank.
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Locate prop rod located under where the rear seat would be. Raise tank by pulling backwards first and then lift front up. Install prop rod as shown. You can remove one of the chrome caps if you wish, and place end of prop rod in bolt head.
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Now you should be looking at the top of the air box.
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I like to go ahead and unclip the IAT sesor (white connection on rear of air box). Then proceed to remove all screws holding down top of air box. nine in all. A good magnetic tip screw driver works well as if you drop a screw, it may be gone for good. However usually the wind up on the rubber mat under the Throttle bodies. DAMHIK.

Once the air box lid is removed you should see this.
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Remove air filter. Remove snorkles and bases. Two screws hold each snorkle on. Each has a metal tab bent over it to prevent it from backing out. Use a flat blade screwdriver to gently pry them open. Once the snorkle is removed two screws hold the base on. Some people have had trouble getting these loose. This is where a good screw driver comes in handy. Although some have found a impact driver was needed. I was lucky and all mine broke free easily. Remember where each snorkle came from as it will make reassembly easier.
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Once you remove the last base, you will gently pull up on the air box base and find that there are two rubber hoses attached. The back on is easiest to remove first. They are held on with a spring clamp. You can squeeze them by hand to remove. I find it better to remove the clamp untill reassembly as they tend to slide on the hose.

Once the air box base is out of the way you want to look for this.
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This is the T that you will disconnect each hose from to obtain your readings.

Before we can remove the vacuum hoses first remove the IAT sensor from the air box lid and plug it back into the connector. Now start the bike and allow to warm up to operating temp. Shut bike off. Remove each vacuum hose that leads to each cylinder. One will remain as it runs to the map sensor. Block off each PAIR suction hoses. In the picture you can see the green things I use to pinch off the hoses. Start bike (you may have to give it a little throttle) and hold engine speed above 2000 rpm for 5 seconds or more untill FI light blinks. The bike should idle now. Attach your vacuum hoses to your guage and adjust each cylinder to match cylinder number 1.

Adjusment screw.
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Once all are adjusted correctly it should look like this.
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When finished. Reassembly is in the opposite order. To reset the ECM. Find the ECM connector located under where the rear seat would be.
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With the engine stop switch in RUN and the iginition off. Jump the brown and Green/pink wires. Turn the ignition on. Remove jumper wire. The FI lights for about 5 seconds. During this time short the wires again. The Fi light should start blinking. Shut off ignition.

During reassembly if you forget how a snorkle was aimed, there are indicators on the snorkle and air box base that you can line up.
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Reassemble and start. Check idle and adjust if needed.

Overall not a bad job. I would reccomend placing some anti-seize on the screws that hold the snorkle base down to the throttle bodies. Also remember that snug is tight enough for the snorkle, base and air box cover.
 

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Re: ST1300 - Starter Valve Synchronization

Nice writeup. So how far off were the settings before you adjusted them? Does it run any different?
 
Re: ST1300 - Starter Valve Synchronization

Thanks. Wasn't off too far. Maybe two or three inches of mercury. I guess thats not much.
Haven't had time to ride it yet. Hopfully tomorrow. However the idle seems smoother.

If anyone sees anything I missed, let me know so I can add it.
 
Re: ST1300 - Starter Valve Synchronization

Thank you for taking the time to write this up and post the great pictures.
 
Re: ST1300 - Starter Valve Synchronization

Scott, good article thanks. :)

A suggestion: immediately following the removal of the snorkels in the air box, stuff rags down the throttle body inlets.

Question for you: the pic of the vacuum gages shows them up at around 23 cm vacuum--was this reading taken at idle? Mine only draws that much when the engine is at mid-level RPMs. At idle, mine draws around 13 or 14 cm.
 
Re: ST1300 - Starter Valve Synchronization

Question for you: the pic of the vacuum gages shows them up at around 23 cm vacuum--was this reading taken at idle? Mine only draws that much when the engine is at mid-level RPMs. At idle, mine draws around 13 or 14 cm.

Yes this is at idle. Rpm of 1,000.

Odd that your reading is lower. Could be different gauges.
 
Re: ST1300 - Starter Valve Synchronization

Question for you: the pic of the vacuum gages shows them up at around 23 cm vacuum--was this reading taken at idle? Mine only draws that much when the engine is at mid-level RPMs. At idle, mine draws around 13 or 14 cm.

Higher altitude. ;)

We loose about 1" of vacuum for every 1000' of elevation.
 
Re: ST1300 - Starter Valve Synchronization

Great post, thank you for taking the extra time to document tall of his work!

Tim D.
 
Re: ST1300 - Starter Valve Synchronization

This is an excellent post- wish I'd found it before I did my starter valves. I used the Carbtune as well, but hung mine from a PVC frame with a 2" wide velcro strip- vertical, neat, out of the way and easily visible. I also took a suggestion from this site and moved the 5-way out from under the mess.
 

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Re: ST1300 - Starter Valve Synchronization

I finally got around to doing the SVS on Roxanne. I neglected to check this site and pick up a few good tips. Most of the work has gone "ok". Replaced thermostat - that was an interesting foray into the wilds of my ST.

I had to adjust my idle screw to get ~1500 RPM and that put #1 about 200mmWC (I was using needle gauges ...didn't have access to one of those fine manometers). Only #4 was really out sync and it was REALLY out. Got a smoother idle after lining it back out.

While doing this little job, I found what might be another interesting issue that I'll have to explore in another thread. Seems like when the fans came on, the alternator quit that annoying knocking noise... hmmm.
 
Re: ST1300 - Starter Valve Synchronization

Just did my TB sync for the second time. First time was at 7k miles now at 41.5k miles. Needed tweaked again.

Got to say you can REALLY go crazy trying to even out the mercury tubes if you're anal. Then the fans kick on, put a load on the alternator, which changes your idle. I'd have to wait till the fans cycled off again to keep working.

You CAN just plug the tube for the pair valves where it goes into the airbox. Noticed that the idle would go up with the tube open and down with it plugged.

I wanted to keep it plugged so no decel. popping out the mufflers, but causes too many other problems.

My 5 way was already moved with longer vac, lines.
 
Re: ST1300 - Starter Valve Synchronization

Nice right up.
As long as you're going to be in there, this thread is worth a review.
https://www.st-owners.com/forums/showthread.php?15358-ST1300-Base-Funnel-Screws-(Air-Box)-Fix

I'll add that to have NO problem with those screws and all screws on the bike get a JIS screwdriver. If you or someone else hasn't messed up the heads they will work fine for the life of the bike.

Here looks like a good one only $9. Also with a good description of how and why the 2 styles of cross tip screws.

http://www.ebay.com/itm/New-Vessel-...661?pt=LH_DefaultDomain_0&hash=item3cd22364b5

I bought one from Ames tools years ago, just checked no longer available. Strange.
 
Re: ST1300 - Starter Valve Synchronization

I bought this Craftsman bit set years ago ... nice selection of various bits (i think there's 80):

cm-bits.jpg
 
Re: ST1300 - Starter Valve Synchronization

Any JIS bits in there?
 
Re: ST1300 - Starter Valve Synchronization

I'm in the process of accomplishing this procedure. I'm curious as to why the PAIR hoses are being blocked? They're not blocked during the normal operation of the bike.
 
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