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Throttle not responding at random during riding!

28K views 117 replies 31 participants last post by  roy rodriguez 
#1 ·
I have a triumph Bonneville t 100 2005 with 10,000 miles on her. I did a lot of repairs lately, changed the pickup coil, cleaned carbs and just about every other alteration that has been mentioned on this site for when the bike suddenly dies on the road in mid riding.

Without going into great detail (on the bike just turning off and dying part) the newest problem is while riding the throttle stops responding with the bike on. If I am cruising along at 70 MPH with a fixed position on the throttle, it is as if all of a sudden the bike just acts as if you stopped giving it gas and starts to slow down or sometimes jerks... if I rev the engine I get no response, the throttle seems to be dead or disconnected. Then as I’m coasting to pull over, just as mysteriously as this began, it comes “back to life” and starts to respond again. This happens several times mid ride and is very dangerous.

Please note when this occurs the bike is still running and has full power. It is just as if the throttle or the cable is disconnected or something.

I did take the throttle cables off when I cleaned the carbs but I thought I put everything back exactly as was and I checked all of the throttle cables and nothing looks out of the ordinary.

Any have any suggestions or have this happen before?

Cheers

RJ
 
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#2 ·
Check out the connections to the igniter.
 
#6 ·
Hi Chris,
I’m not following how the connections to the battery would be in play here as the bike still had full power, the throttle just stopped responding as if I hadn’t been turning it.

Ah yes! The CDI box, I have attached this and reattached this many a time but no dice. I’m not sure if that is it or not but it still weird that the throttle just stopped responding.

Thanks for the response though I appreciate your suggestions. Anyone else out there have an idea?

Russell
 
#9 ·
I'm thinking fuel delivery. Classic symptom is losing power then things mysteriously return to normal when you pull over for a few minutes and the float bowls have a chance to refill.
Fuel flow could be just enough to sustain steady throttle but not enough for hard acceleration, which drains the float bowls and causes the engine to lose power. Check the little fuel filter in the nipple that the fuel line slides on at the bottom. Check for kinks or pinches in the fuel line. Drain the float bowls in case you caused something to flow down into them when you had the carbs off. Check the vent hoses for the carbs and the vent for the tank for pinches or blockage.
 
#10 ·
Thanks guys for your responses,

Yes the fuel lines are clear and all good. I took those apart and thoroughly cleaned all of the components recently. It’s not fuel starvation either as the vent hoses and fuel lines are looking good. I can re-empty the float bowls if you think that will do the trick? Although they are both clean...

When I am riding it just all of a sudden starts idling even when the throttle is opened in the exact same position. In other words, doing 70 mph, throttle twisted open about 2 inches, cruising along for 30 minutes, all of a sudden it’s as if I let go of the throttle and the bike is in neutral even though I have not adjusted my hand position or changed anything. I twist the throttle to rev the bike and bring the RPM’s back but it does not respond at all and I have to coast to the side of the road. The bike is idling and not connected at all to the twisting motion of the throttle grip. After a few minutes the bike starts to respond as if it never had a problem. So weird.. any thoughts?

Thanks RJ
 
#11 ·
Tricky!



How does your throttle actually feel with the problem. Does it go light or feel different in any way?
I have only had my cables to bits once when i fitted my fcr. If i remember right there are a lot of holes in the linkage. Maybe you have placed the cable lug! in the wrong hole. I think i forsaw a possible issue but happend to choose the right option. Maybe someone has a photo of the oem setup.
 
#14 ·
Kev -
No it wasn't posted in September...it was 12-09-12 which is the 9th December in AMERICAN. They write it different to us Brits.

:rofl
You're absolutely right.

What a plum I am.

Well, I was reading the post over my cornflakes early this morning, with my eyes propped open.

Now I feel REALLY stoopid!!!

:biglaugh
 
#23 ·
The pitiful part is, if we're so open to changing things, why are we stuck in the stone ages regarding SAE vs. metric?! Now to work on a modern'American' vehicle, we have to have 2 sets of tools, so I guess things may slowly be moving that way, but my grandmother moves faster...

Anyhow, I digress. I agree with Ripper on it sounding electrical. RJ, didn't you just recently install a new pickup coil? If so, we can rule that out. When I read the OP, it sounds to me like the bike shut off. When this happened, did you pull in the clutch? I have a feeling the bike would have shut off if you did, because that's the exact way my igniter went on me.

Sorry you're having these problems. I know you've been at this for many months. A possible problem could be the coil, but the igniter is such a frequent problem that I'd, at least, be prepared for that possibility.
 
#18 · (Edited)
Back to the plot.....this sounds like an Engine Management problem. Doesn't the EMU have a 'get u home' mode it enters if there is a problem? Is this what it is doing perhaps? Or something similar.

My Thruxton was misbehaving and they found a loose connector block under the tank. Check all those. And that one on the side of the throttle bodies.....I was eyeing that with suspicion the other day......thats right in a place that will get really wet!

:dunno
 
#19 ·
You guys are funny, but back to the dangerous issue of the throttle just dying and the bike acting as if it is in neutral and as if you are not twisting the throttle at all, yes it is still happening.

Any suggestions?

thanks
 
#21 · (Edited)
I know that most people in this thread have suggested parts of the fuel system as the culprit but from the way you described the problem I can't help feeling that its electrical. Though I can't get my head around what you describe as the bike 'acting as if in neutral'. Are you saying that when the engine dies, there is no 'engine braking'? Does the gearbox disengage leaving the engine free revving? Or is it more like someone has switched off the ignition, or you have let go of the throttle? Because that is another item that I've seen a lot of posts on, corrosion or wet in the ignition switch itself. Yet another part notorious for its unreliability.

What you need to do is eliminate that igniter first. AFAIK there is no way of testing them so you would need to borrow a known working igniter and swap it over for testing. Another thing that could, in theory produce the same symptoms is the crank position sensor (the coil inside the alternator case). Check the gap on that and also its resistance with a multimeter. Forchetto should be able to tell you what reading you should get.
 
#20 ·
I'd borrow (cos they're expensive) another set of HT leads and ride the bike long enough for the fail to occur if it's going to. If it doesn't, I'd buy the HT leads.
 
#26 · (Edited)
Hotboppincat

QUOTE
"My Thruxton was misbehaving and they found a loose connector block under the tank. Check all those. And that one on the side of the throttle bodies.....I was eyeing that with suspicion the other day......thats right in a place that will get really wet!

Don't go fiddling around with the black plastic one on the side of the carb or you WILL have trouble :eek:

KREEMSICLE T100. To make things even more complicated we Brits are still half metric and half imperial in some things. We buy our petrol (that's gas in your language) in litres and use miles per gallon. Our weights are mostly metric, distances in miles. ...go figure that one out.
 
#28 ·
Thanks for all of the reply’s,

Yes I have a brand new Pickup coil installed, nology spark plug boots, new plugs, everything is new but the CDI box. The bike does still cut out but that is for another post. (I will try raising the seat off the CDI box with washers as this is the last thing I have not done)
The problem that tis more concerning at the moment is that the bike is running but all of a sudden it just stops recognizing the turning of the throttle. I can twist away, and the engine doesn’t rev and doesn’t recognize the twisting motion of the throttle (as if im not twisting it at all) the bike just idles and is running. Go figure?

Thanks RJ
 
#29 ·
Its beginning to sound like a possible culprit could be the TPS as well as the igniter (well, and/or). To my knowledge the TPS can be checked with a multimeter across its connector (unplugged, without removing the sensor) and the resistance read whilst operating the throttle slowly. It works like a volume control of a stereo, and just like those, its wiper can lose contact with the track. I think if this happened the igniter would be fooled into thinking that the throttle is closed.

Also I'm beginning to clutch at straws now, this is very baffling indeed. Does this always happen at around the same RPM?
 
#30 · (Edited)
Hmm, that's odd. Have you inspected where you removed the cables from the carbs to make sure the locking nuts haven't worked loose? They should be good and tight on the bracket.

I wonder if something could be working loose in the throttle assembly?
 
#32 · (Edited)
How about the carb diaphrams ? A small split or pinprick hole could cause such a problem....they'll lift under acceleration and fall back down on steady throttle. It's worth giving them a thorough inspection before laying out cash on other things.

To check the seat's clearing the igniter put a blob of plasticine or similar on the highest part of it, secure the seat, bounce on it a few times and see if the plasticine's been marked.
 
#33 · (Edited)
you need to be more specific about the issue with the throttle stopping to work, its a mechanical instrument that uses cables to open a slide, its not electric, so a failing throttle would be more obvious.
is the bike running on 1 cilinder? does it brake on the engine?
I agree on it sounding like an electrical problem, but I'd look at the battery voltage too, maybe its charging wrong/battery dead/regulator bust.
Installing new electrical parts should mean everythings fixed, but I seem to remember a brand new spark plug going bust in less than 10 minutes, and it is also possible that a faulty item was sent to you...
 
#34 ·
Will throw in my 2 cents even though not exactly comparing apples/oranges. Years ago I had my 68 Impala tuned/oiled/etc. at a shop. Shortly after the same thing would happen - car would die while running down the highway! Turned out to be the fuel filter that was installed backward at the shop that caused the problem. They discovered the problem - fixed it - and that was the end of that. Might be related to your problem?
 
#35 · (Edited)
Hi guys, I'm a Tiger owner so not familiar with the bike BUT some simple elimination could help here.

If it were a coil problem it would drop on to one cylinder but would still respond to the throttle, likewise any suggestion of carb diaphram, some throttle response would be evident.

If it was fuel starvation caused by a blocked tank vent, the bike would die, sit for some minutes unable to start, then start normally. While it won't start, opening the fuel cap will result in a "whoosh" of air into the tank.

If it were crankshaft sensor, it would die when hot, then restart normally once it had cooled down.

If it were a fault with the cable linkage it would do it all the time, not mysteriously fix itself.

If it has a throttle position sensor (TPS) it could be the problem, but my experience of this is that they tend to cause slight misfires, not a tickover throttle.

That only really leaves the CDI. If it's like the ones in early Tigers, Tridents etc they are know to play up so thats where I'd look

Just my two penn'th....

Sorry, had to break off as the wife brought my dinner.

Thinking about it, if you have carbs and a CDI, the CDI is only doing the ignition; the carbs and throttle cables are doing everything else so some sort of fuel starvation is the only answer. Anything else will cause misfires,a complete cut out or leave at least some throttle response.
 
#36 ·
I have an '06 Scrambler that had a similar problem, would just cut out randomly while riding. It really scared me a couple of times. Checked through everything and couldn't find an issue. Then one time it wouldn't start. I took it in to the local dealer and they replaced the ignition control module with an aftermarket one. That was the problem. It isn't a cheap thing to try, but it sounds to me like that's what it is.
 
#37 ·
When I had my '07 T100, it was the igniter that went out. It started dying unexpectedly, then would start right back up. Eventually, it kept dying more and more often, then died completely. Sometimes it would cut out and jerk instead of just dying. My mechanic replaced the igniter and placed an electrical box over the new igniter to protect it since it was directly under the seat. I never again had a problem with that bike. I was forced to sell it because it was too top heavy and injured my shoulder. It broke my heart to let it go. I don't know if this helps any, but that was experience with the T100.
 
#38 ·
When I had my '07 T100, it was the igniter that went out. It started dying unexpectedly, then would start right back up. Eventually, it kept dying more and more often, then died completely.

Was this happening while the bike was at dead stop idle? I have an extra ignitor that I was considering putting on the bike and taking it for a spin to see if this would cure the bikes hiccup.
 
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