Throttle body balance - zero=zero etc...

[MattW]

Check the resistance across the injector electrical connections. They should be around 16 whatitscalled, might even be 0.16, i just turn my electric meter to the bit i know measures whatsitsnames

If there's a difference betwen the two there's your problem.


[URL="http://www.ukgser.com/forums/showthread.php?t=77539&highlight=german"]HERE'S[/URL] one i did earlier in 2006 (never did get a beer ).... at the time i'd only seen the problem a couple of times. But over the last couple of years it's becoming fairly common as the bikes age and the mileage clocks up. .

Thanks Neil - I'll check this out .

 

[MattW]

Check the resistance across the injector electrical connections. They should be around 16 whatitscalled, might even be 0.16, i just turn my electric meter to the bit i know measures whatsitsnames

If there's a difference betwen the two there's your problem.


[URL="http://www.ukgser.com/forums/showthread.php?t=77539&highlight=german"]HERE'S[/URL] one i did earlier in 2006 (never did get a beer ).... at the time i'd only seen the problem a couple of times. But over the last couple of years it's becoming fairly common as the bikes age and the mileage clocks up. .

Just got back home and tested the injector resistance. Both measure at 15.8 ohms so I guess they're ok

Just a thought, but are you sure that there is some play in the "choke" cable? I only ask because I recently spent a lot of time trying to work out why my '96 1100RS (single cable - new) didn't tick over properly only to find that a piece of grit had lodged in the pulley preventing the "choke" shutting properly. Dunno why it affected tickover balance, but it did. Just saying.

Just checked this too - play in all the cables and the throttles are resting on their stops

I'm going to get the CO checked this week - if that comes out ok then I'll have to investigate further and possibly do the zero-zero thing.

Cheers

M

 

[Deleted account 220427001]

Firstly, I know the zero-zero procedure is a last ditch thing and has a lot of (justified) bad press, but...

Try as I might, I cannot get good throttle body balance on my 1100 ('94' single piece throttle cable). I've tried u-tube manometers, gauges etc but I can't get decent idle balance (all cables slack' butterflies on their stops) - the manometer says its right but it's not smooth and the brass air screws are a turn (or possibly a bit more) different. The throttle bodies are clean and blockage free (refurbished and rebushed by Scriminger a few thousand miles ago).

I've a feeling that a previous owner has fecked about with the throttle stops and I'd like to at least rule this out and reset them.

The only way I know of to do this, is the zero-zero thing (short of a carburettor flow bench, with I don't have in me garage ).

Has anyone had any success with this procedure, or can offer any pearls of wisdom?

Cheers
M

check the o rings on the injectors meay be worn or perished sucking in air somewhere !

 

[MattW]

Holy old thread batman...

Well, I finally got the CO checked yesterday at my local MOT station and it read at 2% or so.

I think that's the last possible thing to check before resorting to throttle stops.

So far, I've:
Fully serviced it (new plugs and all fluids, new fuel filter)
Checked valve clearances and rocker end float (fine).
Checked compression (same both sides)
Checked that TPS voltage is stable through the range of throttle opening and returns to idle voltage reliably (fine)
Checked TPS idle voltage (tried several settings between 0.36 and 0.8 - no improvement)
Taken the CO pot off and checked resistance through its range of travel with a meter (fine)
Checked CO (fine - 2%)
Checked injector resistance (fine)
Checked for air leaks on intakes (visual check and slight greasing of all o-rings and seals and check with brake cleaner- fine)

With all this I can't achieve smooth running at idle and on very slow throttle opening, there's a slight hesitation as the throttle come off their stops. The manometer / gauges say its in balance but the brass air screws are a turn or more different and it's lumpy at idle with a hint of surging at small throttle openings.

I can't thing of anything else to try so I think I'm going to have to try and reset the throttle stop screws using the zero-zero thing. Thanks for all the advice and ideas

 

[Smug]

Dribbling injectors that are not giving a fine atomised spray at idle?

 

[MattW]

Dribbling injectors that are not giving a fine atomised spray at idle?

Good call - I'll check.

 

[Colonel]

I've just done mine (1150 GSA) and it was not that difficult - the results, so far, have been amazing. However, I had fairly clear evidence that the throttle stops had been dicked about with

http://www.ukgser.com/forums/showthread.php?t=344259

 

[monkeyboy]

This stuff is a mare. I've just ordered a new cable set (£120) to throw at mine to see if that helps. I'll do the 0 thing again too as I have in the past had the throttles apart to replace the bearings.

Have you tried just manually turning each throttle individually at idle just to see what the effect is? Just simply sticking your finger in and giving a gentle push to see if it's even possible to get it running smooth at all on idle? surely the hesitation off idle implies a little slack in the system somewhere? Again, I would just sit on the bike, grab the throttles with my fingers and gently push together to see if there is any hesitation there at all.

 

[Jiffy176]

Matt. Have you considered a TB rebuild. My rh rattled so I had both done by Vern. Massive difference and for the first time I would get an equal balance up the rev range.

 

[bwprice100]

Are you getting a false reading on the manometer, perhaps one of the vacuum take off points is partially blocked.

Brian

 

[MattW]

This stuff is a mare. I've just ordered a new cable set (£120) to throw at mine to see if that helps. I'll do the 0 thing again too as I have in the past had the throttles apart to replace the bearings.

Have you tried just manually turning each throttle individually at idle just to see what the effect is? Just simply sticking your finger in and giving a gentle push to see if it's even possible to get it running smooth at all on idle? surely the hesitation off idle implies a little slack in the system somewhere? Again, I would just sit on the bike, grab the throttles with my fingers and gently push together to see if there is any hesitation there at all.

Thanks
Yep tried manually operating the the throttles independently but without also adjusting the air screws, it's hard to work out what's happening. My gut feeling is that the throttle stops are miss adjusted which explains the turn or more difference in the air screws at idle. I think the hesitation off idle is the transition from the idle set by the throttle stops and air screws to the cable settings for part throttle. Part throttle adjustment is hampered by the stupid single piece cable fitted to early 1100's which means that adjustment varies through the throttle travel but I'm used to that - I set it to be balanced at a sweet spot for normal cruise speed (about 3500 rpm) and live with a very slight buzz either side.

Matt. Have you considered a TB rebuild. My rh rattled so I had both done by Vern. Massive difference and for the first time I would get an equal balance up the rev range.

They've already been done by scriminger a couple of years ago (before Vern started doing them) - made a big difference to noise and ease of balance but the underlying problem persists.

Don't get me wrong - it's not desperate and I've lived with it happily for as long as I've had my 1100 and been on many good trips but I know it should be better. After slowly working my way through every other option, the only thing I can think to try now it the throttle stops ...

 

[MattW]

Are you getting a false reading on the manometer, perhaps one of the vacuum take off points is partially blocked.

Brian

Thanks Brian

The TB's are spotless - they were refurbed by scriminger a couple of years ago and ultrasonically cleaned.

 

[Jiffy176]

Just got fot it Matt as long as you have a good manometer all will be fine. Give yourself plenty of time. Doing the pivot bearings was harder by a country mile.

 

[(RIP) Kaister]

lumpy is usually rich

you need a fine resolution rev counter to adjust for highest speed at idle using the brass screws and manometer.

highest revs equal correct mixture at the plug

you can buy ht lead clamp on ones

 

[(RIP) Kaister]

lumpy is usually rich

you need a fine resolution rev counter to adjust for highest speed at idle using the brass screws and manometer.

highest revs equal correct mixture at the plug

you can buy ht lead clamp on ones

 

[MattW]

So...

I started thinking about how I could check the flow through each throttle body at tickover (to see if there is indeed a difference) before resorting to adjusting anything.

The right way to do this is with a carburettor flow bench which measures the air pressure drop across the slide (or butterfly in our case) or sometimes with a mass air flow instrument (in the simplest case a weighted flap which pivots open in response to increasing air flow).

Unsurprisingly, I possess neither of these but I had nothing to do yesterday and got to thinking "how hard could it be?"

The answer is - not that hard really but in trying to make a device which will compare two throttle bodies in real time, I may have run into an unsolvable problem regarding lack of suck

Behold flow bench Mk1:

In construction - as you can see its made from stuff I had available in the garage.

Basically a central vacuum plenum connected to individual measurement pots, each with a tapping for a water manometer.

With the top plates installed and a valved air bleed into the plenum to give control over the vacuum (the suck is provided by the industrial Numatic vacuum cleaner I use for work but it doesn't have speed control).

Connected up and testing using a couple of penny washers to simulate the pressure drop over the closed throttle butterfly. I still need to sort out a suitable rubber gasket and hold down arrangement for the test platform so that the TB's will seal leak free against it. It's not apparent from the picture but the water columns aren't a U-tube - they're independent (both just pull from a bottle of water on the floor).

Thus far it's a qualified success. Starting with the air bleed open, as you close the bleed, both water columns climb satisfyingly and give a nice steady pressure drop 'reading' (as I've no idea of the air flow, there will never be a quantifiable 'figure' on this reading but it doesn't matter as I only want to compare the two).

But...
(And its a big but), when one test point flow is altered (partially blank one washer hole with a fingertip), both water columns climb together in response to the increased pressure drop.

I feared this might happen and it's because both water columns are really sensing the pressure drop of the entire 'system' rather than the individual test pots. I think the way to fix this would be to introduce a pair of matched orifices into the legs feeding each pressure pot. This pressure drop before the test points might allow them to discriminate to some extent. However I'm not sure that my vacuum cleaner can provide enough flow to cope with this and it'll be a pain to dismantle it as I siliconed it all together

Or just measure one TB at a time but it'll need careful operation and checking for repeatability.

Or just give up and do a zero-zero

 

[monkeyboy]

impressive

Is a zero-zero really that bad? I'm going to do it next week on my 1150. I'm going to set the TPS up with the throttle physically off the bike so I can get at the screw more easily. I'm guessing you're going to mark it as it is anyway?

Re your tool....... I know this is probably a stupid suggestion but could you not find a way of inserting 2 brass air bleeds like the ones off the bodies into the inlet tracts and use a twinmax on them. Chuck a couple of nipples or gromets in/on them afterwards.

 

[MattW]

impressive

Is a zero-zero really that bad? I'm going to do it next week on my 1150. I'm going to set the TPS up with the throttle physically off the bike so I can get at the screw more easily. I'm guessing you're going to mark it as it is anyway?

Re your tool....... I know this is probably a stupid suggestion but could you not find a way of inserting 2 brass air bleeds like the ones off the bodies into the inlet tracts and use a twinmax on them. Chuck a couple of nipples or gromets in/on them afterwards.

All I want to do is check the flow through each TB with the butterflies on their stops. This will tell me whether the stops have been messed with and hence whether I need to do a zero-zero. In answer to your question - yes, I'll mark the stops before adjusting anything

If I find that the flows are different, I'll do a zero-zero - not being able to put a figure on measured flows means I couldn't use my flowbench to set the stops (and I've no idea what the factory set flow rate is...)

"Is a zero-zero really that bad?" - well there have been plenty of reports of people fecking things up doing a zero-zero. My personal feeling is this is probably due to poor technique / lack of understanding of what's actually going on with the process and quite possibly doing a zero-zero on TB's that didn't need it.

I've also read several recent reports on here of people saying it worked and was pretty straightforward. I think mechanical aptitude and understanding are a big factor here...

In the end, *if* your throttle stops have been moved, then a zero-zero is probably the only way to reset them. People like Steptoe who've been doing this sort of stuff for decades probably have their own techniques developed from years of experience and don't need to do a 'zero-zero'. The rest of us have to do what we can

 

[monkeyboy]

All I want to do is check the flow through each TB with the butterflies on their stops. This will tell me whether the stops have been messed with and hence whether I need to do a zero-zero. In answer to your question - yes, I'll mark the stops before adjusting anything

If I find that the flows are different, I'll do a zero-zero - not being able to put a figure on measured flows means I couldn't use my flowbench to set the stops (and I've no idea what the factory set flow rate is...)

"Is a zero-zero really that bad?" - well there have been plenty of reports of people fecking things up doing a zero-zero. My personal feeling is this is probably due to poor technique / lack of understanding of what's actually going on with the process and quite possibly doing a zero-zero on TB's that didn't need it.

I've also read several recent reports on here of people saying it worked and was pretty straightforward. I think mechanical aptitude and understanding are a big factor here...

In the end, *if* your throttle stops have been moved, then a zero-zero is probably the only way to reset them. People like Steptoe who've been doing this sort of stuff for decades probably have their own techniques developed from years of experience and don't need to do a 'zero-zero'. The rest of us have to do what we can

I'm no engineer obviously and I wouldn't ever even think about making a tool like that. I reckon the pressures would be quite low and difficult to get something accurate enough. Good luck though.

I rebuilt my TBs a while ago with Cata's kit cos they were shaking like old peoples teeth and I'm sure I changed the stop position. I'm changing all the throttle cables (I discovered this weekend on dismantling that the left cable is freyed inside where it looks like it's been bent/trapped/restricted and 'hopefully' could be a cause of my running problems) so I might as well do the whole lot at once. What could possibly go wrong? Sounds like you know exactly what you're doing though.

 

[zeltus]

Bloody hell! I am in the presence of minor deities indeed. Anyone who can do any of this with confidence, efficiency and speed has my respect.

But it does give me the excuse to ask for as addition to the FAQ and/or Words of Wosdon section or whatever... to whit, what does yer average oilhead think it's doing at any particular time?

i.e.

1. At idle (xxx rpm) the TPS is doing such and such, the butterfly valves are at such and such a setting, voltages/amps/magic smoke may be measured at the following points and should be as follows.

2. At cruise rpm (say, 4000 rpm) the above settings change to [whatever]

3. If this is black instead of grey and that glows bright red instead of being "just" hot, then the following needs to be investigated.

Basically, I have but little idea of what goes on when I twist the throttle - and it would be good for my education to know.

All the best -looking forward to reading the end result of this thread

Bill