TB sync weirdness and an unresponsive co-pot

[gog]

I had this same issue when i did my last TB sync, meant to investigate but never got around to it. Installed 1200 injectors recently and today went to resync the TBs and same again.

Bike is an early (1995) R1100GS. I slacken the throttle cable on the right hand TB, set the big brass screws to 2 turns out which wasn't far off from where they were. I cannot get them to sync like this at all, the right hand TB always draws significantly more vac - i can almost get them equal by turning the BBS waaaay out on that side but obviously it's not right.

Now last time, as soon as i took the slack out of the throttle cable (just and no more) the vac returns to almost equal and the TBs can be synced as normal with relatively close BBS adjustments, almost exactly 2 turns out per side. Now this is fine, and has been fine since doing it this way last time. However in my mind with the throttle 'link' cable completely loose i should be able to get the TBs to sync with the BBSs independently. I think what is happening here is that i'm able to get them to sync only when one of the butterflies is slightly open with the small tension on the throttle cable.

i know it's long winded, hope it's clear enough what i mean.

on a separate issue, i went to adjust the co-pot to richen the mixture a tad as recommended by John (guy who does the chips) but my co-pot does nothing. Tried a full 3 turns either way and the revs don't change at all. I thought that because my bike has no lambda sensor and has the 'bridge' ccp that jumpers pins 87a and 30, that the fuelling used the co-pot to adjust fuel/air mixture.

any ideas?

 

[Steptoe]

Do you have the early single throttle cable for both throttle bodies or the later three piece junction box set up ?

 

[gog]

i think neil that it's the early version though i will need to check that it has not been 'upgraded' at some point.

 

[gog]

it's got one cable from grip to the left TB and a link cable from there over to the right.

JVB on advrider reckons that it could be a vac leak if it won't balance with slack in the throttle cables. i'll get the wd40 out tomorrow and check that.

 

[Steptoe]

it's got one cable from grip to the left TB and a link cable from there over to the right.
.

That is a single cable set up - completely different method of balancing throttles to the wY you describe attempting to synch them in your first post -- to get free play you have to slacken three cable adjusters, two on the left and one on the right. Then you can balance/ adjust the idle. And then the fun starts trying to balance them under load. Have fun

 

[uncle dick]

Best thing I ever did to my 1100 was bin the original cable setup and fit the splitter/twin cable arrangement. About an hour's work. Having said that, I think the balance problem you describe is due to spindle wear on the throttle bodies. Doing the splitter box mod would still be my first move though, as it is much more tolerant of worn spindles when trying to balance things up. Only then should you be thinking of TPS voltages and CO pots.

 

[gog]

that sync method with the 3 adjusters sounds... fun

funny thing is that its currently well synced on the manometer, at idle and draws vac evenly with throttle applied. engine feels smooth so im tempted to leave it as is for now (unless sternly advised otherwise!)

The cables look in grubby but solid condition, throttle action and return are smooth.

uncle dick ill keep an eye open for bits off a breaker to convert at some point. The TBs themselves are quiet (no ticking from the RH) so no reason to suspect serious spindle wear.

 

[Steptoe]

The cables look in grubby but solid condition, throttle action and return are smooth.

.

It's not cables, it's a cable.... singular, just the one single cable runs from the throttle grip around left throttle body then onto righthand throttle body.

And i expect the Co pot is unresponsive because the cable adjusters aren't slack meaning the engine isn't running on idle with the throttle butterflies closed.

 

[gog]

ah I thought it was 2 piece with nipples - hard to see whats going on with the pulley plate being where it is on the inside of the left TB - I assumed wrong. ill give it a clean and inspect it. I know I said I would likely leave it alone but more often than not such things niggle at me until I give in...

And i expect the Co pot is unresponsive because the cable adjusters aren't slack meaning the engine isn't running on idle with the throttle butterflies closed.

This makes sense, thanks. I didnt mention it before but i did have trouble getting the idle below 1k rpm. Its currently balanced but at about 1.2k at idle.

 

[gog]

And i expect the Co pot is unresponsive because the cable adjusters aren't slack meaning the engine isn't running on idle with the throttle butterflies closed.

thinking about this, im not sure thats it because following John's instructions, he says to hold the engine at 3.5krpm and adjust the co-pot until it increases to 3.55-3.6k. as the oilhead 'choke' just applies throttle and isnt an enrichener, the butterlies wouldnt be closed during his proposed adjustment anyway...

im not sold on John's method being the correct way to adjust the co-pot, though I certainly would have expected to see a change in RPM while turning the co-pot through 3 entire turns each way.

 

[Roger 04 RT]

Follow steptoe's advice not John's.

Do you have a "John" chip? He may have inadvertently invoked Closed Loop when he changed the chip's code. If he did, the CO Pot will be ignored.

Do you have the R1200 injectors installed? It is possible that with a John chip and R1200 injectors your fueling is so rich that the Pot does nothing.

Can you take a photo of your jumper so that we can see that you've jumpered 30-87a? If you jumpered any other pins, the CO Pot will be ignored. You could try removing your jumper and seeing if the CO Pot works.

The CO Pot should be adjusted at idle, not 3500 rpm.

When you turn the co Pot the voltage on its pin 2 (white/blk wire) should vary when you turn the Pot, does it?

 

[gog]

hi roger - yes i have a john chip. i will ask him to clarify, though if he has he didn't mean to as it was him who told me to adjust the co-pot after installation, and suggested doing so at 3500rpm.

i'll get the exhaust gas probed and see if the adjustment at idle has any effect whatsoever.

the jumper box is definitely 30-87a:

 

[Roger 04 RT]

I made a couple additions to my post, check them out.

 

[gog]

thanks. yep i've got 1200 injectors installed. i have a spare motronic with the original factory chip so i'll swap them over and see if it has an effect.

firstly though i'll check whether simply removing the CCP changes things.

i'll also check the voltage on that pin to verify the co-pot itself is working.

appreciate the help.

 

[sykospain]

All this about John-chips leaves me baffled before I get to synch the TBs on my recently-purchased-from-eBay-sight-unseen 04 Rockster next month on my annual month-long UK holiday. Instead of the 15kg tin-box cat underneath, sensibly it has instead a y-pipe and Laser end can - earplugs needed at all times says son Tim who collected it from the seller, riding from Coontee Doorm to Manchistoh. He says he thinks "it needs a tune" and I always thought the TB synch job came AFTER a full tappets re-set ? Otherwise the synch doesn't work too well. Is that right Steptoe ?
Mind you, we don't even know yet whether the ECU re-set has been done, to cater for the absence of a cat, but Tim said it went like effing stink down the A-whatever for 200 miles in the pigging rain 3 weeks ago.

AL in s.e. Spain