50cc cutting out, idles but will only rev with choke on

lamnea · Two Stroke Sniffer Joined: 27 Feb 2012 Karma :

Hello,

My moped will start and idle easy but when throttle is opened the bike starts to rev then it either cuts out or you stop giving it any throttle and it will go back to idle.

Also if you run it for a short period and then try to start it it will not start, then give it a bit with the throttle wide open and it will start again.

But if you run it for longer periods it starts and idles no problem the next time.

All help is appreciated, thanks

Edit - Bike is a Honda Vision Ne50

Update,

Tried the bike with the auto choke disconnected from power (stuck on) and the bike runs without issue. But as soon as connected (Can turn off) it starts to die under throttle again!
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Honda Vision Ne50mff!

at106 · Brolly Dolly Joined: 16 Jul 2011 Karma :

What colour is the spark plug?

lamnea · Two Stroke Sniffer Joined: 27 Feb 2012 Karma :

Thanks for your reply,

It is coffee or rust brown with a golden colour around the thread
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darthbuttchin · Scooby Slapper Joined: 12 Jul 2011 Karma :

Has that got a choke on it?
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Boxing · World Chat Champion Joined: 13 Mar 2012 Karma :

lamnea · Two Stroke Sniffer Joined: 27 Feb 2012 Karma :

at106 · Brolly Dolly Joined: 16 Jul 2011 Karma :

The spark plug colour looks ok, but it does sound as though the choke is stuck on. From a bit of searching it appears this bike has an auto choke which can fail. On the carb there will be a black box with wires coming off of it which will go somewhere into the loom.

You can test the choke by following this guide https://www.pedparts.co.uk/blog/automatic-choke-unit-50cc-mopeds

But it is easier to remove the choke, connect its wires directly to the battery see if the plunger extends, then disconnect it leave it for 5 minutes and see if it retracts.

If the choke has failed its easier to replace it with a manual one Thumbs Up

baldy · World Chat Champion Joined: 15 Feb 2004 Karma :

lamnea · Two Stroke Sniffer Joined: 27 Feb 2012 Karma :

Okay so the choke is now off the bike, i am going to go about testing it tonight.

Some points,

When i had the u bracket off and ran the bike, if i were to push abit on the choke the bike ran correctly again.

However taking the choke tu just after the bike had been running it did seem to have extended, and then letting it cool it does seem to have retracted also? So say it is working, could it still be causing the issues?
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U_W v2.0 · World Chat Champion Joined: 07 May 2012 Karma :

not familiar with this bike but could it just be mixture screws are badly set?
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at106 · Brolly Dolly Joined: 16 Jul 2011 Karma :

lamnea · Two Stroke Sniffer Joined: 27 Feb 2012 Karma :

at106 · Brolly Dolly Joined: 16 Jul 2011 Karma :

lamnea · Two Stroke Sniffer Joined: 27 Feb 2012 Karma :

Okay so some updates,

Auto choke all cleaned and where it seats all cleaned and re fitted. Still no luck. However if i pull it up a little or to the left the bike runs as normal, so it must have something to do with the choke.

Tested the auto choke again to be sure and it extends / retracts as it should with no issues.

Any ideas Confused

????

To add the the list of things to repair the spring in the rear brake has decided not to work! Awesome
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Honda Vision Ne50mff!

lamnea · Two Stroke Sniffer Joined: 27 Feb 2012 Karma :

Updates,

Had a talk on the phone with my pa, tried the bike with the auto choke disconnected from power (stuck on) and the bike runs without issue. But as soon as connected (Can turn off) it starts to die under throttle again!

Any ideas? will add this to the OP also.
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Honda Vision Ne50mff!

at106 · Brolly Dolly Joined: 16 Jul 2011 Karma :

lamnea · Two Stroke Sniffer Joined: 27 Feb 2012 Karma :

[quote="at106"]

U_W v2.0 · World Chat Champion Joined: 07 May 2012 Karma :

i thought most of these plunger type gizmos had a spring to push the plunger OUT and an electronic magnet to pull the plunger IN when power is applied?
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lamnea · Two Stroke Sniffer Joined: 27 Feb 2012 Karma :

U_W v2.0 · World Chat Champion Joined: 07 May 2012 Karma :

well according to a question in the theory test leaving the choke on can cause problems slowing down/stopping lol.

but having the choke on when the engines fully heated your running it under abnormal conditions.

do me a favour, take a photo of each side of your carb and post it up for me please?
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at106 · Brolly Dolly Joined: 16 Jul 2011 Karma :

I've been thinking and you are right, when the choke is not connected to power it is on. So if your bike needs extra fuel to run properly and you haven't changed anything, i would check the following,

Start the engine with or without the choke so it will idle, then spray wd40 around the carb area and air filter rubber joints, if the revs change you have an air leak. If there is an air leak i would expect it to come from around the choke as earlier in the thread you said that if you pushed down on the choke the bike ran ok, so you may want to consider replacing the choke unit with an auto or manual one.

I would also strip down and clean out the carb making sure that all the jets and passages are clear, use carb cleaner to do this.