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Discussion Starter · #1 ·
Today whilst slowing down, I released the throttle and pulled the brake lever, then "out of nowhere" the engine revved - it practically redlined. It was so sudden my bike spun off before I could pull the clutch lever. I've been on it almost every day, never before had this - the throttle cable I do not believe was stuck (and revs initially dropped before it suddenly revved up).

Anybody else seen anything like this?
Is this on a parr with freak cosmic rays cause ECU malfunction?
(Toyota Recall Might Be Caused by Cosmic Rays)

I work in the avionics sector - in my field we know this is a real problem - but one would hope comerical ECUs have triple redundant systems these days...

Either way... so totally unexpected on what has always been until now a reliable sickle
 

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Discussion Starter · #2 ·
Today whilst slowing down, I released the throttle and pulled the brake lever, then "out of nowhere" the engine revved - it practically redlined. It was so sudden my bike spun off before I could pull the clutch lever. I've been on it almost every day, never before had this - the throttle cable I do not believe was stuck (and revs initially dropped before it suddenly revved up).

Anybody else seen anything like this?
Is this on a parr with freak cosmic rays cause ECU malfunction?
(Toyota Recall Might Be Caused by Cosmic Rays)

I work in the avionics sector - in my field we know this is a real problem - but one would hope comerical ECUs have triple redundant systems these days...

Either way... so totally unexpected on what has always been until now a reliable sickle
Or is this some weird effect of E10 fuel just to stirr that nest?...
 

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Discussion Starter · #4 ·
I have not heard of that.
Instead of Cosmic Rays did you happen to, oh I dunno, ride past a Cuban Embassy?
Haha no, but I did find an old post here where someone else had something similar... - apprently something in the way intermittantly at the throttle body end. Totally bizarre how it happened, will investigate asap
 

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When you figure it out, a report to the NTSB would be a good idea. It there's a pattern it needs to be identified.
 

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Sorry, didn't realize you're not in the US. Is there a similar reporting system in the UK?
 

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Discussion Starter · #8 ·
You're being sarcastic aren't you?

It'll be a cable routing issue or an intermittent air leak around the throttle bodies.
Haha yes and no to that question ;)

Can't find issue with cable routing - at least while parked up, butterfiles return snap shut, nothing catching it as per this thread for example:

Air leak - not removed but airbox but boots are on tight - but still not completely ruled out. That said, if throttle released then butterflies should be restricting peak air flow - this was more like going full throttle, not high idle - or are these systems more likely to go ape?
 

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Discussion Starter · #9 ·
One thing I've not done yet is check with Tune ECU that throttle position is correctly reported...
 

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Discussion Starter · #10 ·
Another thought - could fuel quality be a factor? This occured after refilling at a remote countryside station I don't normally use... the first time since the the idiotic panic buying started. Could fuel quality be deteriorating with the rush to get fuel out in tankers and into the forecourts? (And worse quality for remote non-branded stations?) Symptom is a bit like "dieseling" - ie if RON a bit too low... Shouldn't knock sensor deal with it though?
 

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Another thought - could fuel quality be a factor? ............................Shouldn't knock sensor deal with it though?
No, fuel quality wouldn't cause an engine to race. And there are no knock sensors fitted to Triumph triples (or indeed any Triumphs that I'm aware of).
As said earlier it'll be a cable routing issue, possibly intermittent on one lock or the other or an air leak, again possibly intermittent. Wouldn't hurt to check the closing cable, even though you say throttles snap shut, make sure it is actually pulling them shut.
 

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Discussion Starter · #12 ·
Its a Sprint, but yes, now I remember a discussion a while back - no knock sensor - its all done through inlet pressure differences...
Thanks dude will have another hunt around...
 

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Was the clutch pulled in and did the road speed reduce, irrespective of the engine revving, or,
did it feel as if the bike 'ran-on' even though the clutch was pulled?

I dont think the following sounds quite like your symptoms, but maybe worth mentioning anyway.

I had a failing stator that polluted the engine-oil with specks of insulation that had burnt-up and broken free a few years ago.
The symptoms were that the bike continued to 'drive-forward' for a second or so after I had pulled the clutch to slow for intersections etc.
Several people advised that I might have a warped clutch plate, so I ordered a new set of plates. However the stator failed completely before they arrived, so the bike got a new stator, and an oil change, and viola! the sticky clutch issue was solved.

In this situation the engine didnt "run-away" or max out, but it did continue to be turned-over at higher than expected revs (by remaining connected to the rear wheel by the sticky clutch) even though the throttle was closed.

cheers, Keef.
 

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i dont have a solution, but i look forward to hearing yours.

Buell had a weird problem, rare, the throttle shaft holding the buttefly in throttle body could crack then break.
also the little bushings the shaft rode in could deteriate causing problem.
then other was carbon build up that interfered when doing throttle position reset cause some to problems
steve ford probably has better input whether this info is of any use

sometimes the answer is in reviewing what was the last thing you did to the bike
 

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Depending on whether the clutch was engaged or disengaged makes a big difference. If the engine was not powering anything else than itself, then just a little throttle opening could trigger such a behavior.

If it happened just once and can't be reproduced, it means the cause is erratic and difficult to investigate.

I short, if it's linked to throttle cables it could have been a transitory routing problem like the sheath hooking something at the steering were the cables traverse the frame or between the handle and the frame.
 

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Discussion Starter · #16 ·
Was the clutch pulled in and did the road speed reduce, irrespective of the engine revving, or,
did it feel as if the bike 'ran-on' even though the clutch was pulled?
Cheers Keef that's an interesting one...

My clutch was still engaged as I was in low gear and engine breaking at the time, I released the throttle, and reached for brake, then engine suddenly raced as if I'd deliberately twisted full throttle. Didn't have any time to react. I remember now that this may have occured a few times over one or two days before, but at the time I was already at moderate speed and in higher gear, so the effect wasn't as significant / easier to control, so didn't think much of it at the time.
 

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Discussion Starter · #17 ·
sometimes the answer is in reviewing what was the last thing you did to the bike
Hmm... filling up with Super unleaded is the last thing I did!
As it stands, checked and rechecked throttle cable and butterflies - all seems good - it snaps back like it should, nothing snagging, return cable returns...

I suspect Terry is right about an intermittant air leak, but its hard to find something like that. I did put in a K&N air filter last year, and they don't sit that perfectly in the box - in fact I had to return the first filter as it was way out, the replacement was better, but not perfect. Could be a slight distortion, but you can't see or measure it properly without some swanky co-ordinate measurement maching. Going to try a standard paper filter when I get round to fixing it (now I've receieved a SH replacement fairing!). Strange that its only reared its head now if that is the case though.
 
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