Hi All, I have mooted this question before, but didn't get a denotative answer - please forgive the duplication...but it is rainy, so this is a good weekend to tinker... On my 2002 955i I would say that the throttle is 'jerky'. By this i mean that at slow revs, filtering, setting the throttle pull away slowly etc, they throttle is either zero or "on" (I say "on", I only mean a bit) but it is enough to jerk the bike... I appreciate that any bike or car control is a subtle interplay between clutch and throttle delivery...but it is difficult at low speeds to gently bring the throttle in. At speed, or once on the move it is fine, or certainly less noticeable. I would imagine these are 16yr old throttle cables. I have tried squirting lube down the cable outers. I do have some free-play in the handlebar grip - not only is it heated, but also to allow for turning the bars. Any specific thoughts? I have had the bike 6 months now an I hoped I would be able to have a little more control of this surly beast...but I waver between almost stalling, and over revving at pull away... Should I just spend (another) 20 quid and just replace the cables...?
Hi Daniel, first off how standard is the bike, any aftermarket exhaust or air filter, any other engine related mods? Unless the throttle action actually feels sticky the problem is quite possibly elsewhere. The earlier injected models were never as smooth off a closed throttle as later models, Triumph gradually sorted the glitches as the years went by so it might be something you have to live with, however there are a few things you can look at. I'm guessing yours is before cat and SAI valve was fitted so that's one potential area to ignore. However it's still important to check whether you have the correct map loaded in the ECU, sometimes owners will load a modified map for custom exhaust then revert to the standard can when selling without putting ECU back to standard. But checking whether the throttle bodies are properly balanced is the first thing I'd check (after the throttle cables). TuneECU is a free downloadable software if you're handy with a laptop and spanners, just need to buy a suitable cable to connect up (£10-20), you can then check the loaded map and also balance the throttle bodies. Also when I had a 955i I remember there being some vacuum pipes made of corrugated plastic that went hard with age and split causing a leak, so give them a check over too.
Thank you colC that's really thorough and useful! Some bits are beyond my current knowledge but others sound doable. Mods wise I think it is all fairly standard. It does have an after market can - but not by me... however my local triumph chaps (Hughenden M40) checked the mapping for me a few months ago when I changed the baffle. The air filter is part of my servicing regime and on the list...I've not delved in there yet. It may or may not be aftermarket - how might I tell? Should I assume/hope/anticipate that any mapping check done would have picked up any required balance of throttle bodies...? I will get my torch out and look for these vacuum pipes...where might I find them...what am I 'google' searching for.... Many thanks!!
Another important thing to check is your Throttle Position Sensor adjustment. You’ll need Tuneecu to do this. It’s the base setting for the throttle position so that the ECU knows where fully closed throttle is and can then adjust fuelling for a given input. Once you get Tuneecu and a cable (only buy the Lonelec cable, others have connection issues) there are quite a few diagnostics you can do, as well as loading new maps. Here’s the website for more info http://www.tuneecu.com/
The pipes you’re looking for are under the airbox so you’ll have to get the fuel tank and airbox off. They’re on the throttle bodies, 3 pipes. The balancing of the throttle bodies isn’t something that’s picked up by checking the maps, it’s a maintenance action that needs doing when you start getting poor running or a lumpy idle.
chaps - both, thank you for your replies... I feel suitably daunted by connecting cables to laptops - laptops being easily as scary as motorcycle repairs! But I'll investigate. Is the software idiot proof? what about these vacuum pipes - just that they are still flexible and not obviously split? my feeling is, is that it is more at the grip end...but it is very slight...it just seems the difference between 'no throttle' and 'some throttle' is quite distinct - but it is merely that very first pick-up of zero to some.... almost like you can't open a hole up gradually...it is either shut or open...if that makes sense... anyway, I'll investigate... Thanks y'all!
Daniel, the software isn’t exactly idiot proof but as long as you don’t start altering maps or anything you’ll be fine. It’s a good diagnostic tool and there’s lots of info online to help, as well as here too. As for the pipes, look closely at the rubber ends where they fit to the throttle bodies and the IACV. It doesn’t take much cracking to introduce an air leak. It might be worth you investing in a Dyno session as they’ll be able to fine tune the bike’s fuelling to smooth it out, if you’re unsure of what you’re doing.
Found this pic on Google... These are the pipes you're looking for, personally I'd swap them out for rubber, the OE plastic ones always go hard and brittle and it's not always easy to spot any splits in the corrugations.
continued thanks for this, and the useful pic! I will certainly have a go at having a look...although, initially, I just see this...
I have - i think - resolved (partly) my sticky snatch! I was investigating (from yet another thread I have about mirrors) the ease/pain of bar end mirrors. In doing so I took off the bar end on the throttle side, and looking in to the hole and twisting the throttle there was a reasonable amount of corrosion. It looks like in the gap between the bar end and grip there's been some water ingress as there was visible rust. It looks to me that - and this is gonna get technical - there is a tube that rotates about another tube. And the corrosion was between the two. A good clean and lube...and voila...I think my throttle is more responsive (or less responsive, but in a good, non snatchy way)....!
