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Bike cuts out holding clutch in and down shifting

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DisAdam
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Joined: 09 Dec 2019
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PostPosted: 01:51 - 09 Dec 2019    Post subject: Bike cuts out holding clutch in and down shifting Reply with quote

Here's a video off the issue. Any ideas?

Its a Zontes Mantis 2018.

https://youtu.be/LAP6No_knl4

Can't upload as attachment?
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Teflon-Mike
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PostPosted: 03:29 - 09 Dec 2019    Post subject: Reply with quote

An engine needs 3 things to run; air/fuel, sparks and compression.
This bike runs, sol what ever is missing is only missing when the engine is a) presumably warm b) the throttle closed on the down-shift, and momentum driving the back wheel isn't being transmitted to the crank through the gearbox.

It would look like a fairly recent chinky bike, which suggests fuel injection, and a very lean 'map' in the squirter box, that likely nills fuel when the throttle closed 'cos of emissions, loik.

Silly Questions first; When was it last serviced... and was it done properly.. and dont assume that if it was done by a dealer it must have been....

3-things remember; spark, charge and compression.

If the thing hasn't been serviced or serviced properly recently, then you can loose compression from tight tappet clerances; you can loose sparks cos of a idirty plug, and on an EFI engine, charhe from all manner of things, starting the list with a dirty air-filter;' next usual suspect would be the THrottle position sensor, often a carbon track poentiometer some-where, that gets dirty and makes the squinter box believe the throttle's more shut than it is; then you have the exhaust sensor on a 'closed-loop' EFI system, which in crap weather of late could be giving errant signal cos of water vapour in the exhaust, or it's contact could have got dirty or been dislodged.. or or or.....

OR, and is usually the case, its a cumulative effect of a clusterchuck of 'little' problems... B-U-T you got the list; spark; compression; charge; you have the bike in-front of you, we don't, you poke and prod, and top tip, get a service manual, and start with the instructions for a normal 'service'.. change the plug; clean the air-filter, tickle the tappets, lube the throttle cable(s), change the engine oil, etc etc etc, and base line what it's NOT then go look for what it might be, after... good odds that basic service and new plug will 'fix' it though... but remember the clucterchuck effect... it may seem to go away, b-u-t, unless everything properly done, it'll be back....
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doggone
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PostPosted: 08:44 - 09 Dec 2019    Post subject: Reply with quote

They've probably adjusted the mixture too far on over-run so it can pass euro emissions tests.
My CRF did the same thing and needed a screw turning 180 degrees, there's good online groups backup for the CRF, not sure you can find any helpful info for yours, don't try random fiddling though, you can really mess things up.
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MCN
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PostPosted: 09:01 - 09 Dec 2019    Post subject: Reply with quote

Transmission Interlock Switch adjustment.
The engine should cut out if side stand down and gear selected.
Check side stand switch.
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DisAdam
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Joined: 09 Dec 2019
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PostPosted: 14:06 - 09 Dec 2019    Post subject: Reply with quote

Teflon-Mike wrote:
An engine needs 3 things to run; air/fuel, sparks and compression.
This bike runs, sol what ever is missing is only missing when the engine is a) presumably warm b) the throttle closed on the down-shift, and momentum driving the back wheel isn't being transmitted to the crank through the gearbox.

It would look like a fairly recent chinky bike, which suggests fuel injection, and a very lean 'map' in the squirter box, that likely nills fuel when the throttle closed 'cos of emissions, loik.

Silly Questions first; When was it last serviced... and was it done properly.. and dont assume that if it was done by a dealer it must have been....

3-things remember; spark, charge and compression.

If the thing hasn't been serviced or serviced properly recently, then you can loose compression from tight tappet clerances; you can loose sparks cos of a idirty plug, and on an EFI engine, charhe from all manner of things, starting the list with a dirty air-filter;' next usual suspect would be the THrottle position sensor, often a carbon track poentiometer some-where, that gets dirty and makes the squinter box believe the throttle's more shut than it is; then you have the exhaust sensor on a 'closed-loop' EFI system, which in crap weather of late could be giving errant signal cos of water vapour in the exhaust, or it's contact could have got dirty or been dislodged.. or or or.....

OR, and is usually the case, its a cumulative effect of a clusterchuck of 'little' problems... B-U-T you got the list; spark; compression; charge; you have the bike in-front of you, we don't, you poke and prod, and top tip, get a service manual, and start with the instructions for a normal 'service'.. change the plug; clean the air-filter, tickle the tappets, lube the throttle cable(s), change the engine oil, etc etc etc, and base line what it's NOT then go look for what it might be, after... good odds that basic service and new plug will 'fix' it though... but remember the clucterchuck effect... it may seem to go away, b-u-t, unless everything properly done, it'll be back....


it had a dealer service 600 miles ago,i also cleaned the air filter last week, planning on getting a better spark plug this week,

i am getting a new fuel pump fitted this week, but the revs stay above idle for a few secs if i rev the engine slightly. too

this video was coming to a complete stop, it aint the side stand (too the last comment)
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Robby
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PostPosted: 14:46 - 09 Dec 2019    Post subject: Reply with quote

If the revs are hanging I would be looking for an air leak between the throttle body and cylinder head.

If this started being a problem after you cleaned the air filter, than have a look at what you broke doing that job.
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iooi
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PostPosted: 14:58 - 09 Dec 2019    Post subject: Reply with quote

What happened to blipping throttle on down shifts?
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DisAdam
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PostPosted: 23:10 - 09 Dec 2019    Post subject: Reply with quote

iooi wrote:
What happened to blipping throttle on down shifts?


I do, still dont avoid it stalling, i'm also new to riding.
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DisAdam
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PostPosted: 23:11 - 09 Dec 2019    Post subject: Reply with quote

iooi wrote:
What happened to blipping throttle on down shifts?


this happened before the air filter and only helped increase top speed.
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jaffa90
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PostPosted: 23:54 - 09 Dec 2019    Post subject: Reply with quote

Does this bike have a 2 year warranty and why are you fiddling with it?
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DisAdam
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PostPosted: 00:08 - 10 Dec 2019    Post subject: Reply with quote

jaffa90 wrote:
Does this bike have a 2 year warranty and why are you fiddling with it?


Yes, and have to keep taking it back all the time and takes over a week to get a part, they think its fine for the small ass road test they do on it.

i'm not fiddling with it, but its stalling far to much and on a dual carriageway going to a complete stop is dangerous.
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Teflon-Mike
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PostPosted: 01:14 - 10 Dec 2019    Post subject: Reply with quote

Lets think about this for a second; there's a dealer; who'c supposed to have 'fixed' the thing, presumably has passed motorbike tests, and ridden bikes for a few years... and there's you.. probably a CBT no-nuffink hat has managed to wobble around a few cones in a car-park, and admits to not having a lot of experience? Hmmmm.... whose opinion do you think should hold more weight?

Oh-Kay.... now when you have finished spluttering.... DO you per-chance, ride on the gears, short-shifting, getting into as highj a cog as you can as early as you can, cos it sounds and feels like you are torturing the poor little engine else? Do you THEN, slowing down, 'rush' the down-shifts, essentially clutch 'in' coasting, as you try and crsh down all them gears you have short shifted 'up'? And THAT is when, throttle closed, EFI brain believing it dont 'need' chuck fuel in to keep the engine running, it 'dont' and the motor dies?

Right now, whilst I tend not to have too much faith in dealers or thier mechanics, I am S-O-R-T of leaning towards their point of view.. its probable that the bike isn't quite right, B-U-T, remember cluster-chuck effect, more than small odds that the 'problem' is largely 'user error'... A~N~F if you let the little fecker rev a bit, used the lower gears, and came down them a bit more sensibly, and gave it time for 'engine braking' to work, and motor the engine over when the throttle closed, it WOULDN'T die so easily, and the 'problem' would significantly go-away...

Give it a go.. try revving the little fecker asnd NOT spending so long, SO often in the taller gears, OR trying to do all your slowing clutch in, on the braakes... use that engine braking.
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Kentol750
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PostPosted: 02:13 - 10 Dec 2019    Post subject: Reply with quote

Pass the popcorn Pass the popcorn Pass the popcorn
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Nobby the Bastard
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PostPosted: 12:32 - 10 Dec 2019    Post subject: Reply with quote

Robby wrote:
If the revs are hanging I would be looking for an air leak between the throttle body and cylinder head.

If this started being a problem after you cleaned the air filter, than have a look at what you broke doing that job.


This. All of this.
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flea-rider
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PostPosted: 19:28 - 10 Dec 2019    Post subject: Reply with quote

that's the spark ..
you can hear it ..
had a prob with my bike ht lead into the plug cap sounded the same .. corrosion where they meet ..
ohh and a lump of glue ?
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DisAdam
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PostPosted: 21:19 - 10 Dec 2019    Post subject: Reply with quote

Teflon-Mike wrote:
Lets think about this for a second; there's a dealer; who'c supposed to have 'fixed' the thing, presumably has passed motorbike tests, and ridden bikes for a few years... and there's you.. probably a CBT no-nuffink hat has managed to wobble around a few cones in a car-park, and admits to not having a lot of experience? Hmmmm.... whose opinion do you think should hold more weight?

Oh-Kay.... now when you have finished spluttering.... DO you per-chance, ride on the gears, short-shifting, getting into as highj a cog as you can as early as you can, cos it sounds and feels like you are torturing the poor little engine else? Do you THEN, slowing down, 'rush' the down-shifts, essentially clutch 'in' coasting, as you try and crsh down all them gears you have short shifted 'up'? And THAT is when, throttle closed, EFI brain believing it dont 'need' chuck fuel in to keep the engine running, it 'dont' and the motor dies?

Right now, whilst I tend not to have too much faith in dealers or thier mechanics, I am S-O-R-T of leaning towards their point of view.. its probable that the bike isn't quite right, B-U-T, remember cluster-chuck effect, more than small odds that the 'problem' is largely 'user error'... A~N~F if you let the little fecker rev a bit, used the lower gears, and came down them a bit more sensibly, and gave it time for 'engine braking' to work, and motor the engine over when the throttle closed, it WOULDN'T die so easily, and the 'problem' would significantly go-away...

Give it a go.. try revving the little fecker asnd NOT spending so long, SO often in the taller gears, OR trying to do all your slowing clutch in, on the braakes... use that engine braking.


Buddy. I had a mechanic friend and someone with 30 years riding experience to try it.

My fuel pump has arrived and I brought a NGK spark plug arriving tomorrow,
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DisAdam
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PostPosted: 21:34 - 10 Dec 2019    Post subject: Reply with quote

Teflon-Mike wrote:
Lets think about this for a second; there's a dealer; who'c supposed to have 'fixed' the thing, presumably has passed motorbike tests, and ridden bikes for a few years... and there's you.. probably a CBT no-nuffink hat has managed to wobble around a few cones in a car-park, and admits to not having a lot of experience? Hmmmm.... whose opinion do you think should hold more weight?

Oh-Kay.... now when you have finished spluttering.... DO you per-chance, ride on the gears, short-shifting, getting into as highj a cog as you can as early as you can, cos it sounds and feels like you are torturing the poor little engine else? Do you THEN, slowing down, 'rush' the down-shifts, essentially clutch 'in' coasting, as you try and crsh down all them gears you have short shifted 'up'? And THAT is when, throttle closed, EFI brain believing it dont 'need' chuck fuel in to keep the engine running, it 'dont' and the motor dies?

Right now, whilst I tend not to have too much faith in dealers or thier mechanics, I am S-O-R-T of leaning towards their point of view.. its probable that the bike isn't quite right, B-U-T, remember cluster-chuck effect, more than small odds that the 'problem' is largely 'user error'... A~N~F if you let the little fecker rev a bit, used the lower gears, and came down them a bit more sensibly, and gave it time for 'engine braking' to work, and motor the engine over when the throttle closed, it WOULDN'T die so easily, and the 'problem' would significantly go-away...

Give it a go.. try revving the little fecker asnd NOT spending so long, SO often in the taller gears, OR trying to do all your slowing clutch in, on the braakes... use that engine braking.


I also tried bliping the throttle and sometime it still does it.

The mechanic "fixed" the rear break by placing the calibre yet its still spongy as fuck and shouldn't need to be pressed fully down to the end point don't feel much resistance or pressure. Also the bike rpms shoot up if u rev it and stay up for a few seconds around 3k rpm but happened to max 9k rpm at one point for 5 seconds

And no way shape or form did i say I'm some master riding I've only done 200 miles since owning it for a month involving no car parks neither, all roads.
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Robby
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PostPosted: 16:54 - 11 Dec 2019    Post subject: Reply with quote

Have you looked at what you broke when you were fiddling with the air filter yet?
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Easy-X
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PostPosted: 17:34 - 11 Dec 2019    Post subject: Reply with quote

Are you saying the revs are hanging?
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DisAdam
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PostPosted: 17:16 - 13 Dec 2019    Post subject: Reply with quote

Easy-X wrote:
Are you saying the revs are hanging?


some times yes
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Easy-X
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PostPosted: 17:29 - 13 Dec 2019    Post subject: Reply with quote

Classically revs hanging indicates a possible lean condition. Still sounds like too much air getting into the system, e.g. air filter not seated correctly, cracked airbox, split or loose inlet hoses.

These engines tend to be set too lean anyway for emissions so they don't need any extra air.
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Nobby the Bastard
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PostPosted: 20:01 - 13 Dec 2019    Post subject: Reply with quote

Spray wd40 round the throttle bodies and rubbers. If the revs increase you have an air leak into the 8nduction side.
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