After a major session sorting shit out on my 1150 i needed to re balance the throttle bodies. Guess which muppet messed with the throttle stop screws
The bike is running ok ish, but is there an easy way of sorting out my tremendous fuck up
Damn and blast
- Thread starter Flipfly
- Start date
After a major session sorting shit out on my 1150 i needed to re balance the throttle bodies. Guess which muppet messed with the throttle stop screws
The bike is running ok ish, but is there an easy way of sorting out my tremendous fuck up
Search on here or adventure rider for zero-zero throttle body balance.
Plenty of people say it's a nightmare and it's true that you shouldn't do the procedure if your bike is running fine but it's the only diy way I know of to reset the throttle stops (unless you happen to have a carb flow bench in your garage
).
Plenty of people say it's a nightmare and it's true that you shouldn't do the procedure if your bike is running fine but it's the only diy way I know of to reset the throttle stops (unless you happen to have a carb flow bench in your garage
).
Yeti
Registered user
A friend of mine on a 'round the world tour managed to loose one of his throttle stop screws. He replaced it but the bike wasn't running too smoothly when he got to my house. I did a quick search over on ADV and learned of this technique:
Make sure your TPS is set correctly. Attach your TwinMax or whatever balancing tool you use. Set the left stop by loosening it until the throttle butterfly is fully closed, and then use the stop screw to just open the butterfly. Just a wee, wee bit is what you're going for.
Then, loosen the locknut on the right stop. Screw both Big Brass Screws all the way in, ie minimum idle. Start the bike. Balance the cylinders using the right throttle stop. Secure the lock nut. Then set the idle using the BBS and balance the cylinders as you normally would.
After we did that, he pronounced his bike better running than ever before.
See here, especially post #7: LINK Even involves a little info from your very own Steptoe.
Make sure your TPS is set correctly. Attach your TwinMax or whatever balancing tool you use. Set the left stop by loosening it until the throttle butterfly is fully closed, and then use the stop screw to just open the butterfly. Just a wee, wee bit is what you're going for.
Then, loosen the locknut on the right stop. Screw both Big Brass Screws all the way in, ie minimum idle. Start the bike. Balance the cylinders using the right throttle stop. Secure the lock nut. Then set the idle using the BBS and balance the cylinders as you normally would.
After we did that, he pronounced his bike better running than ever before.
See here, especially post #7: LINK Even involves a little info from your very own Steptoe.
How do you "make sure the TPS is set correctly" when you've changed the throttle stops? The closed throttle TPS voltage gives the ECU a reference voltage (and hence fueling) for the correct idle air flow.
If you've changed the air flow using the stops, then setting the TPS to 0.371 (or your chosen voltage) is pretty pointless unless through luck or experience you manage to guess the perfect initial left stop setting (Steptoe can probably do this, the rest of us, I'm not so sure...).
All the zero-zero does is to try to establish the correct initial left stop setting by using the TPS to measure the butterfly angle from zero. You then balance the right stop against the left (with equal air screw settings) to get the stops (and hence idle air flow) the same.
I suppose you could guess the initial left stop opening at a "wee bit" as above but from there you're basically doing a zero-zero by any other name.
In the end, through whatever method you choose, you have to arrive at a left throttle stop base setting (corresponding with a TPS voltage of 0.371). From there it's pretty straightforward if you understand what's happening with the throttle bodies at idle.
I've read the AVD thread posted above and this is all the various posters are doing - they just have different methods (or ways of guessing) the initial left stop setting. Steptoe's post in that thread is pretty cryptic - while "Don't touch the stop screws" is sound advice, if you've already messed with them, then you've got to find a way back somehow...
If you've changed the air flow using the stops, then setting the TPS to 0.371 (or your chosen voltage) is pretty pointless unless through luck or experience you manage to guess the perfect initial left stop setting (Steptoe can probably do this, the rest of us, I'm not so sure...).
All the zero-zero does is to try to establish the correct initial left stop setting by using the TPS to measure the butterfly angle from zero. You then balance the right stop against the left (with equal air screw settings) to get the stops (and hence idle air flow) the same.
I suppose you could guess the initial left stop opening at a "wee bit" as above but from there you're basically doing a zero-zero by any other name.
In the end, through whatever method you choose, you have to arrive at a left throttle stop base setting (corresponding with a TPS voltage of 0.371). From there it's pretty straightforward if you understand what's happening with the throttle bodies at idle.
I've read the AVD thread posted above and this is all the various posters are doing - they just have different methods (or ways of guessing) the initial left stop setting. Steptoe's post in that thread is pretty cryptic
- while "Don't touch the stop screws" is sound advice, if you've already messed with them, then you've got to find a way back somehow...
At the Airhead weekend we set the tps to 0.371 (thanks Canuck and Steptoe 
).
This being the case, can I not set the throttle stop screw so the TPS reads 0.371 and therefore bringing it back to where it was
If I balance the right side to match then that should be pretty close I guess
I only messed with them because I've fitted a Y piece and an Accelerator plug in and the tickover was quite high and screwing in the Big Brass Screws wouldn't get the revs down enough (they seem to be screwed in most of the way already. On reflection though this may be because there is no slack on the left cable. I'm guessing I may have unseated it from the cable splitter box when I replaced the battery box rubber mounts.
Doh!!!
I've got the bike ticking over balanced at around 1000 rpm and it seems to ride well (apart from backfiring now on overrun, even though I have sealed all the exhaust joints it shoots a little flame out of the can now
).
I've read a load of threads and the voltage of the TPS seems to differ depending on who is commenting at the time. What is the significance of the TPS voltage
). This being the case, can I not set the throttle stop screw so the TPS reads 0.371 and therefore bringing it back to where it was
If I balance the right side to match then that should be pretty close I guess
I only messed with them because I've fitted a Y piece and an Accelerator plug in and the tickover was quite high and screwing in the Big Brass Screws wouldn't get the revs down enough (they seem to be screwed in most of the way already. On reflection though this may be because there is no slack on the left cable. I'm guessing I may have unseated it from the cable splitter box when I replaced the battery box rubber mounts.
Doh!!!
I've got the bike ticking over balanced at around 1000 rpm and it seems to ride well (apart from backfiring now on overrun, even though I have sealed all the exhaust joints it shoots a little flame out of the can now
).I've read a load of threads and the voltage of the TPS seems to differ depending on who is commenting at the time. What is the significance of the TPS voltage
This being the case, can I not set the throttle stop screw so the TPS reads 0.371 and therefore bringing it back to where it was
If I balance the right side to match then that should be pretty close I guess
Yep - as long as you haven't messed with the air screws in the meantime (and as long as you did have slack in the left cable when you set the TPS)
I only messed with them because I've fitted a Y piece and an Accelerator plug in and the tickover was quite high and screwing in the Big Brass Screws wouldn't get the revs down enough (they seem to be screwed in most of the way already. On reflection though this may be because there is no slack on the left cable. I'm guessing I may have unseated it from the cable splitter box when I replaced the battery box rubber mounts.
Doh!!!
I've got the bike ticking over balanced at around 1000 rpm and it seems to ride well (apart from backfiring now on overrun, even though I have sealed all the exhaust joints it shoots a little flame out of the can now
I've read a load of threads and the voltage of the TPS seems to differ depending on who is commenting at the time. What is the significance of the TPS voltage
The TPS idle voltage sets the fuelling at tickover by sending a voltage corresponding to the idle throttle position to the ECU. After that the TPS sends the 'live' throttle position to the ECU so that it can alter the fuelling according to the built in map.
However... If you've just added a Y piece and an accelerator plug then you've just introduced two quite significant variables to the fuelling - the motronic will be trying to fuel according to the standard map - the changes you've introduced will inevitably change the fuel requirements across the rev range. Setting the TPS and air screws from here will be a bit of suck it and see.
It's usual good practice to only mess with one thing at a time...
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