Hesitation/ stuttering under full load

Ok so went for a good ride out today and was pushing fairly hard in places, sometimes when at full throttle the bike would hesitate for <second, then continue as normal. Only way i can describe it is someone flicking the kill switch off and back on again instantly, it literally stops pulling, then continues. Less than a second each time it did it, although once or twice it did it a couple times in succession.

At first i thought the rear wheel was losing traction, but i have ruled that out due to the fact that the roads it happened on were completely clear of debris/fuel and was a nice warm sunny day.

Any ideas anyone?? ( i have a couple of other issues also, but dont think they would be related? see my topics in the electrical section)

Cheers

Don't laugh . . . .

What was the approx ambient temperature ?

That sounds suspiciously like the dread carb icing to me. Did it feel like one or two cylinders stopped firing just for a moment ?

When you pulled over to stop was it gone when you got going again, or when you slowed down quite a bit it went away ? Only to return when you pressed on again.

no it did it literally for less than a second each time then carried on as per normal. no need/time to stop or even adjust throttle position,by time i noticed it everything was back to normal!

felt
like ignition or fuel was cut for a split second. possibly having a problem with the main relay sticking, thinking that could poss cause this also?

temp was between about 10- 15deg i reckon

Yeah , carb icing only happens at about +5^o and below. At that temp (when yer pressin on) causes small ice crystals to form inside the gubbins of the carbs and block fuel flow. It does have very simillar symptoms to those you describe. But hey ho, thought I'd try n help.

Seen your other post now too about the relay. DBD is a helectricery hexpert, when he comes on perhaps he'll be able to pass some wisdom out

Hope you get it sorted m8

Have you got a Haynes workshop manual? The wiring diagram might help you identify what could be the problem

The different problems you have had might be linked. I don't know that relay, but it could well be for the fuel pump. <sorry getting this and the other thread mixed up>
The level sender unit, I would have thought would have been a switch, either open or closed circuit and not a variable resistance as you'd find in a fuel level sender for a fuel gauge.

I have workshop manuals and diagrams etc, but cant see anything obvious to check. however if needs be i will get a multimeter on bloody everything!

Main relay (apparently in the one post i found on the net) controls fuel pump,starter and cdi. So im thinking even if it isnt the cause of the fuel warning issue, it could well be sticking momentarily and cutting out the CDI, hence no spark = hesitation?

Will have a proper look tomorrow if i get the time, hope so, and hope i can get it fixed else that means i have to use the Mrs car..... :(

Had exactly the same problem with mine when bought it. The issue was number 3 carb was massively out of balance compared to the rest at high revs

now that is something i havent looked at yet, and if im honest she is a bit "wooly" under 3k rpm so definately something to look at! cheers

Having the same symptoms.

Last week, noticed everytime, in the very same road, when I use all the gears, speeding (safely, without any traffic, so, late hours), she hesitates. A feeling like the back tire is skidding. Or, does not have that linear accelaration, and the full power you hang on to. That happens after 10kk rpm. I didn't notice with trans kit was applied, but, I think it was a similiar one to stock.

Changed the fuel, with brand one (BP 98 Octanes). She still does the same thing. Been using always 98 octane fuel, but the cheapest one I find.
Last time carbs were cleaned and tuned, 1 year and 6 months. She doesn't stop more than 1 week in the winter, so, ride her all year round when possible.
Does she need a good long trip to get used to be abused one or another time, or she is asking for a carb party? Again.....?

And good weather temperatures, no cold at all. Different times of the day.

Well, either way, tomorrow I'm going to take her to the mechanic. Whatever it was the problem, I'll say here what was the solution.

It's funny, how there are so many stuff like this on the internet, and some are old, and no replies of the author of the many different forums, saying what was the problem and what was done to fix it.

Got my guesses:

- Bad Sparkplug;
- Sparkplug Cable;
- Electric Coil;

No more important:
- Clutch (Don't think so, does not get Hi revs, and low speed of response, but will no be forgotten)
- New carb party.

If it completely cuts then I'd rule out anything that affects only one cylinder; when you drop a cylinder it just sounds a bit rough and sluggish.

If it's a full-on hesitation then I think the relay may be a suspect, or maybe even something as simple as a loose battery terminal. I'd also not be looking at fuelling as it is rare for this to produce a sudden hesitation, as you have four float bowls full of fuel even if the pump stops.

Electrical fault breaking down under full load. Start at the battery and check, clean and lube all connections. Could be plugs, plug caps or leads so it might be a idea to change them. The connections to the coils sit on top of a plastic plate under the air box so could be dirty. Could also be a suspect battery as well. Best of luck finding the problem.

Didnt really get to the bottom of my problem, i had the carbs balanced but made a negligable difference. Has however only re-occurred once since the ride after having the carbs done.

Let us know what was causing your problem!

The only times I've experienced the same issue was with frozen carbs (which is unlikely in this weather) and a bad connection on the voltage regulator.

Well, she's in the mechanic, and he is going to try and find out what's wrong. Some other thing I noticed, when the hesitating happens, the light also twitches. it's like i'm making pass signals. told him that symptom as well, and let's see what turns out to be

Lets hope he locates it quickly and it's not an expensive repair. Sounds electrical to me.

Okay, mechanical is all good. Now comes the exclusion of all electrical possibilities...

Sounds like a faulty TPS to me, I would check that out next mate.

That's what I thought too, but that should throw up a tacho error code (3,000 rpm).

Mrboss81 wrote: when the hesitating happens, the light also twitches. it's like i'm making pass signals.

Which light is this, headlight?

When the engine dies, does it feel like you used the kill switch?

weasley wrote:should throw up a tacho error code (3,000 rpm).

Yeah, but when something is faulty, especially intermittent, then all logic goes out of the window. My money is on the TPS

SteveCat wrote:When the engine dies, does it feel like you used the kill switch?

dean-j-Original Posting wrote:Ok so went for a good ride out today and was pushing fairly hard in places, sometimes when at full throttle the bike would hesitate for <second, then continue as normal. Only way i can describe it is someone flicking the kill switch off and back on again instantly, it literally stops pulling, then continues. Less than a second each time it did it, although once or twice it did it a couple times in succession.

@SteveCat

err, two different bikes, hence the Q. What am I missing

My question was directed at Mrboss81 and not dean-j, sorry if it has caused confusion.

What I'm trying to establish is if there is a 'total' electrical failure.
Mention is made the rear tyre is skidding and possibly the headlight is going off and then on again. Possibly the skidding is occurring because all 4 cylinders are not firing (as if the kill switch was off).

SteveCat wrote:err, two different bikes, hence the Q. What am I missing

My question was directed at Mrboss81 and not dean-j, sorry if it has caused confusion.

What I'm trying to establish is if there is a 'total' electrical failure.
Mention is made the rear tyre is skidding and possibly the headlight is going off and then on again. Possibly the skidding is occurring because all 4 cylinders are not firing (as if the kill switch was off).

My Bad Steve.