Throttle body balancing

[Bixxer Bob]

Hopefully one for Stretch or Mustang....

I'm doing my TB balancing sometime this week and have an idea for a very low cost balancing tool which hopefully matches the performance criteria of commercial products costing £40 -£60.  If it works,  I'll post it up here.

In the meantime, and so that I can buy some before I pull her apart, what internal diameter hose do I need to connect to the TBs please?

Thanks guys!!!

[Stretch]

what internal diameter hose do I need to connect to the TBs please?

1/4-inch.

Bear in mind that the ports in the Girly throttle bodies are not vacuum ports, but are the engine's sole source of air at idle.  The throttle valves themselves are completely closed at idle, with flexible hoses running from the ports to the Idle Air Controller and Stepper Motor.  

You're going to need to run the idle up in order to take some of the vacuum away from the ports.  Otherwise, the ports will have too much vacuum and the fluid in the manometer will be sucked into the engine.



Anywho, brief instruction for balancing throttle bodies...

Remove the fuel tank...  http://tigertriple.com/forum/index.php/msg,32393 (http://tigertriple.com/forum/index.php/msg,32393)

And the airbox...  http://tigertriple.com/forum/index.php/topic,5146 (http://tigertriple.com/forum/index.php/topic,5146)

Then re-install the battery and improvise a way to run the bike with the tank off...  http://tigertriple.com/forum/index.php/topic,5749 (http://tigertriple.com/forum/index.php/topic,5749)  and  http://tigertriple.com/forum/index.php/topic,6321 (http://tigertriple.com/forum/index.php/topic,6321)


The Triumph manual states to run the engine at 1200 RPM.  A cruise control o-ring would be handy to hold the throttle steady...  http://tigertriple.com/forum/index.php/topic,4599 (http://tigertriple.com/forum/index.php/topic,4599)

Unplug the flexible hoses from the small intake (vacuum) ports and connect the Carbtune tool.

The throttle body for Cylinder #1 (far left) is not adjustable.  The other throttle bodies are adjusted to match the setting of Cylinder #1.  Note that adjusting any one cylinder will slightly affect the other two.

Keeping the engine speed at around 1200 RPM, set both adjusters so that all three throttle bodies have an equal vacuum reading.

No photos, I'm afraid.  I just copied these instructions from the Triumph manual.  But once the bike's apart, you'll see it's not too difficult with the proper tools (Carbtune).

[Mustang]

I use one of these and it was well worth the money
balancing throttle bodies or carbs is a 5 minute deal .
it has no liquid to be sucked up and is deadly accurate

you need to use the tiniest id hose you can find to restrict the vaccum or your homemade one will fluctuate so badly you will bin it and buy the carbtune by morgan


see the short length of white hose in the pic ....with the morgan carbtune you cut that to the length they dictate and put a pc in between the regular 1/4 inch black stuff , the ID of the white hose is like needle small . without it the vacuum is far too great .

[Bixxer Bob]

1/4-inch.

Bear in mind that the ports in the Girly throttle bodies are not vacuum ports, but are the sole source of air at idle.  The throttle valves themselves are completely closed at idle, with flexible hoses running from the ports to the Idle Air Controller and Stepper Motor.  

You're going to need to run the idle up in order to take some of the vacuum away from the ports.  Otherwise, the ports will have too much vacuum and the fluid in the manometer will be sucked into the engine.

   Or if I actually did that  

My idea involves fluid, but not a lot of it.  I had, however - and as a precautionary measure until I get it working - foreseen this possibility and so planned a fluid trap with a capacity greater than that being used, so none would get as far as the engine - same principle as the airlock you get for wine making if you've ever done that, except I'll use a fuel tank from a model airplane I have kicking around somewhere.

[Bruincounselor]

The throttle valves themselves are completely closed at idle, with flexible hoses running from the ports to the Idle Air Controller and Stepper Motor.  

As much as I knew this, it strikes me now that by using one port for my cruise control I'm only running on the remaining 2 cylinders at idle. Above idle this isn't an issue as the throttle plates are open. Is this inviting a problem at idle or causing an imbalance somehow?

[Stretch]

If you didn't notice the bike idling poorly when you first performed the mod, it's possible that the throttle body port is pulling adequate idle air through the  cruise control's vacuum system.

As you said, the only ill effects would be felt at idle, as the idle intake pulses would flatten out as soon as the butterflies open.

If it bugs you, you might install a Tee that will allow you to run both the cruise control vacuum hose and the Idle Control Valve's flex hose.

[mrazekan]

Bixxer,

I balanced my TBs with about 8meters of clear tubing from my local hardware store.  I nailed the midpoint of the tube to the lowest point of the wall.  The top nail is six feet above the bottom nail.  The remaining tube length goes to the bike.  I've tried dyed water, viscosity too low, 2 stroke oil, too high, and I'm currently using ATF, still too high.  It works well.

If you come up with a way to trap water from being pulled into your engine, then I'd use water as it is the most sensitive.  I really would only have a problem with that if the hose came undone from the throttle body.  

Stretch is right about the idle though.  It will take a bit of throttle to start the bike and then a bit more to keep the bike running.  A cruise control helps immensely with this!

good luck!

[REGULATOR]

Doesn't Tuneboy work for this?


I think I saw that on my Rocket when I had it opened last...

[Stretch]

Doesn't Tuneboy work for this?

I don't think so.  A Tuneboy only has an ECU cable, yes?

Balancing the throttle bodies is done with hoses affixed to the throttle body idle ports, and then turning adjustment screws to match the vacuum readings across the three throttle bodies.

[iansoady]

Some people have said that Tuneboy will show the depressions across the throttle bodies but I must say I've never worked out how that might work.

[Bixxer Bob]

Hi guys,  this'll be on hold a couple of weeks owing to me getting a blue-light ride to hospital and the Girly being at a friend's house.  As soon as I'm allowed to go get her I'll be back on track.  Not an accident btw,  just a chest pain scare.  I'm ok but house bound for a bit.

[Bixxer Bob]

Bixxer,

I balanced my TBs with about 8meters of clear tubing from my local hardware store.  I nailed the midpoint of the tube to the lowest point of the wall.  The top nail is six feet above the bottom nail.  The remaining tube length goes to the bike.  I've tried dyed water, viscosity too low, 2 stroke oil, too high, and I'm currently using ATF, still too high.  It works well.

If you come up with a way to trap water from being pulled into your engine, then I'd use water as it is the most sensitive.  I really would only have a problem with that if the hose came undone from the throttle body.  

Stretch is right about the idle though.  It will take a bit of throttle to start the bike and then a bit more to keep the bike running.  A cruise control helps immensely with this!

good luck!

I plan to balance one body against the next rather than a weight of fluid.  this should be easy enough as shown below with the fluid traps to stop anything being drawn into the engine.



As the idle speed needs air from these points,  I was thinking about  bridging the two pipes and adding a bleed air valve like this:



My physics is a bit rusty, but I think, if I have the valve completely closed she'll not idle and will need the throttle cracking open a whisker.  If I have it fully open she won't idle - too much air.  So I'll start with it closed.  Provided the bodies are somewhere close the fluid should go off-centre and adjustment bring should bring it back.  I'll then start to open the valve until she idles correctly and then adjust them again.  Once the valve is set it shouldn't need touching again.  If I can't find a valve sensitive enough,  I'll try sealing the end then drilling progressively larger holes until I get it right.  I have some watchmakers drills so should be able to get it right.  I also haven't worked out what to do with the third body while I'm doing the first two, maybe connect it to the idle valve and blank off the other two idle valve pipes??  

Maybe I should just get my wife to buy me a set of gauges like Mustang's for my birthday.... :roll:

[Mustang]

Maybe I should just get my wife to buy me a set of gauges like Mustang's for my birthday.... :roll:

yep , neat and tidy and they work and the price isn't that bad , best money  I ever spent for bike maintenance

It's only £55 and available here  http://www.carbtune.co.uk/

[Bixxer Bob]

Well,  I had a go at this today and,  to keep it short,  it was a spectacular failure  :oops:

Luckily I'd put the fluid traps in place and used some fairly thick oil because my TBs were so far out (or - this setup was so sensitive) that it all shot into one fluid trap on the starter even before the engine fired.  :shock:  With her running the pulsing from the engine wasn't being damped at all so it was impossible to read a level.

Carbtune gauges are now in the post....  

[blacktiger]

Doesn't Tuneboy work for this?

Tuneboy will read the pressures sent to the ECU from sensors in the manifolds but only on the Keihin injection systems. On our Girlies we have SAGEM injection systems and it doesn't have the necessary sensors so Tuneboy will not work for this.

Bixxer,
What's needed here is a proper mercury manometer like the original Morgan Carbtune. This is a closed system with a vacuum at one end and the engine connected at the other with the mercury in the middle, so the mercury will not be sucked into the engine because the closed vacuum will always overcome the suck from the engine.