Lexmoto Assault 125 2016 running issue

[TheGazWaz]

Afternoon all,

I picked this bike up for my son this weekend. I got half way home on it and it started chugging and bogging to the point where it cut out.

I pulled over and messed with the choke. It's got a little lever on the carb that has three positions. I haven't a clue what position is what yet but I put the lever in the top most setting. Bike started straight away, off I went again. 5 minutes later it did the same thing.

It did it 5 times in 20 miles. I'm sure it's a fuel starvation thing and I intend to figure it out but I thought I'd ask on here first in case someone else has had the same issues on a chines bike.

I could take it back and get the fella to sort it out but I'm sure it can't be anything serious.

The bike starts and ticks over lovely although I'm not sure what position the choke is. It might be full on for all I know. If I put the choke all the the way to the bottom setting the bike cuts out if I don't keep the throttle on.

Apart from that I REALLY enjoyed the ride. I ride a ZX9R so the 125 was a bit of shock at first but once I got into it I love it.

Cheers all
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Went like this.. 43 years old(2013) decided to do CBT to get a 125 for new job. Bought 2011 YBR, loved it for three months then hated it because it was too god damn slow. Did DAS 4 months later then bought RF600 Loved it, sold it bought Bandit 1200(K3). EFFIN lOVED IT. Wanted something a bit more sporty so got Triumph Sprint ST 955i (53). Not sporty enough so now on my GSXR 1000 K3 and absolutely love it. 1 year down the line, nearly died way too many times on this bike. Sold it. Had a 6 month break. Missed biking so now, Aug 2019 have a 1999 ZX9r. What a beauty she is too.

[Nobby the Bastard]

Sounds more like the HT coil breaking down when hot.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[TheGazWaz]

I did wonder that but would it start up again so easily and quickly?

Surly they coil wouldn't have time to cool down that much. Worth a check though.

I'm so glad I bought him a naked bike. Much easier to work on.
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Went like this.. 43 years old(2013) decided to do CBT to get a 125 for new job. Bought 2011 YBR, loved it for three months then hated it because it was too god damn slow. Did DAS 4 months later then bought RF600 Loved it, sold it bought Bandit 1200(K3). EFFIN lOVED IT. Wanted something a bit more sporty so got Triumph Sprint ST 955i (53). Not sporty enough so now on my GSXR 1000 K3 and absolutely love it. 1 year down the line, nearly died way too many times on this bike. Sold it. Had a 6 month break. Missed biking so now, Aug 2019 have a 1999 ZX9r. What a beauty she is too.

[oilyrag]

I'm guessing, don't know the bike but from what you said it sounds like when the lever is up the choke is on, middle position is half choke and down the choke is off. It sounds like it only idles with the lever up (choke on) but dies with the lever down (choke off) unless you keep the throttle open a bit. To me that is either the idle speed is adjusted too low and needs to be increased or the idle circuit in the carb is blocked and the carb needs to be cleaned. I'd try increasing the idle speed. If that doesn't fix it I'd bring it back and let them fix it.

[Nobby the Bastard]

Just to clarify, did you take it off the top position on the rest of the journey?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[TheGazWaz]

[oilyrag]

[TheGazWaz]

I think top is full choke on, middle is half choke, down is choke off. If that's right the whole time you've been running it it's been on full or half choke. Put it to no choke and it can't idle. So idle speed is too low or idle circuit is blocked[/quote]

That would make sense. There's only one adjustment that I can see on the carb which I presume is some kind of mixtrue adjustment. Winding that out speeds the idle up but on choke it sends the revs way to far up. I'll have a play about with that but I'm thinking maybe blocked jet as suggested. I do love tinkering with these things.
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Went like this.. 43 years old(2013) decided to do CBT to get a 125 for new job. Bought 2011 YBR, loved it for three months then hated it because it was too god damn slow. Did DAS 4 months later then bought RF600 Loved it, sold it bought Bandit 1200(K3). EFFIN lOVED IT. Wanted something a bit more sporty so got Triumph Sprint ST 955i (53). Not sporty enough so now on my GSXR 1000 K3 and absolutely love it. 1 year down the line, nearly died way too many times on this bike. Sold it. Had a 6 month break. Missed biking so now, Aug 2019 have a 1999 ZX9r. What a beauty she is too.

[oilyrag]

There's some pictures of your carb. https://www.ebay.co.uk/itm/Carb-Carburettor-For-Lexmoto-Assault-125-HJ125-J/283332507698?hash=item41f7eef832:g:hckAAOSwMKxcNTJT

The choke is off in the pictures. You can compare the position of your lever to the one in the picture and determine if it's on or off. The idle speed adjuster screw is the brass one that's sticking out on the side of the carb. Only adjust that one. Don't adjust the mixture screw. If you lean out the mixture screw you can damage the engine.

You have to let the bike warm up and turn the choke fully off before you adjust the idle speed. If it won't idle with the choke off give it a small bit of throttle to keep it running and adjust the idle speed screw until the idle speed screw takes over. It should idle at around 1350RPM

If you can't get it to idle with the idle speed screw bring it back to the place you bought it and let them sort it out. If you just bought it they will have to fix it for free. If you take it apart and start messing with it they could say you caused the problem and you would have to pay for the fix.

[Nobby the Bastard]

Thata not bogging down, that's cutting out.

Check the rubber between the engine and carb as well an air leak will cause bikes to stall when hot and at tickover
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Nobby the Bastard]

Maybe you're just being cackhanded with clutch and throttle.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[TheGazWaz]

[TheGazWaz]

OK.. so I've sorted the bad earth and the corroded connector on the coil. I've cleaned the carbs although it was spotless in there. All the jets are clear. The float is at the correct height and functioning lovely.

I put it all back together. Set the idle up so it's running beautiful. Took it for a spin managed to get up to 70 on the clock down hill wind behind me.

5th gear wide open. Ran perfect for a minute then it started bucking again as if it was running out of fuel, or spark? Pulled the clutch in and it died. Sat for about 40 seconds, started up and off I went again. A couple of minutes later the same thing. Now, if I just run it at 30-40 round the streets it doesn't do it. It only seems to be when it's in it's higher speeds for any amount of time over a couple of minutes.

This is all with the choke off. It's hard to tell whether it's fuel starvation or lack of spark.

If I don't get a resolve here I'm going to start by getting a new coil and HT lead and spark plug.

The other thing I'm thinking is maybe valve clearance is a bit tight thus when the engine gets too hot they're closing up? I can do valves as they are rocker type like my old Bandit 1200 was but I can't find any info at all on what the clearances should actually be.

This is what you get for buying chinese I suppose. It really is a lovely bike to ride though so I'm determined to sort it.

Cheers for listening.
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Went like this.. 43 years old(2013) decided to do CBT to get a 125 for new job. Bought 2011 YBR, loved it for three months then hated it because it was too god damn slow. Did DAS 4 months later then bought RF600 Loved it, sold it bought Bandit 1200(K3). EFFIN lOVED IT. Wanted something a bit more sporty so got Triumph Sprint ST 955i (53). Not sporty enough so now on my GSXR 1000 K3 and absolutely love it. 1 year down the line, nearly died way too many times on this bike. Sold it. Had a 6 month break. Missed biking so now, Aug 2019 have a 1999 ZX9r. What a beauty she is too.

[Robby]

Fuel flow is easy enough to check. Pop the pipe off the carb, direct it into a milk bottle, and turn the fuel on. The fuel requirements of the bike are miniscule, so as long as you have a solid stream of fuel (rather than a weak dribble) then you have enough fuel.

By the sound of it the initial problem was a lot of corrosion on various connectors creating too much resistance (and then heat) in a few circuits. I would be going back over these areas in a bit more detail. If the connector was seriously corroded, chances are the wire leading to it is also burnt or corroded under the insulation. If I find blackened copper wire, I just replace that length of wire. There may also be more frame earth connectors that you haven't found yet, which will be similarly corroded.

Doing the valve clearances is a good idea. I think Haynes do a generic manual for Chinese 125s. Assuming your one uses one of the generic engines, the valve clearance settings will be in there. Otherwise just google it, but you may want to check a few places to find the most common setting - lots of poor information out there for Chinese bikes.

For the price of it, new coil/lead/plug is probably worth doing. I would just do the various bits in stages to find out what the problem is, rather than just knowing it is fixed.

(Dad-mode) If this is your son's first bike, there is also something to be said for giving him a bike that will comfortable do town speeds all day long but not allow sustained higher speeds until he has a couple of months experience, or until the worst of winter has passed. Depends on the roads where you live, and whether being able to maintain 60mph is desirable or not.

[jaffa90]

Had a similar problem many years ago and found the float height /fuel level too low, as Robby states check the fuel flow first.

[TheGazWaz]

Thanks so much for the info. I really do appreciate it.

I've gone ahead and ordered a new coil+HT and the Chinese Haynes manual you spoke of. It does state in the info that it covers just about every Chinese bike/scooter on the market.

I've also ordered a new spark plug. I've ordered everything from the main UK site for Chinese parts and according to the new spark plug spec the one in the bike at the mo is the wrong one. Only by a letter but that could be something.

I'm getting a good flow of fuel from the fuel line into the carb so I think I'm good there.

I know what you mean about "Dad mode", I'd be happier if he was on a 50cc I think. He's doing his driving lessons as well at the mo so I'm hoping he see sense and go that route rather than grow a passion for big bikes like his dad. lol.

I'll keep you updated.
____________________
Went like this.. 43 years old(2013) decided to do CBT to get a 125 for new job. Bought 2011 YBR, loved it for three months then hated it because it was too god damn slow. Did DAS 4 months later then bought RF600 Loved it, sold it bought Bandit 1200(K3). EFFIN lOVED IT. Wanted something a bit more sporty so got Triumph Sprint ST 955i (53). Not sporty enough so now on my GSXR 1000 K3 and absolutely love it. 1 year down the line, nearly died way too many times on this bike. Sold it. Had a 6 month break. Missed biking so now, Aug 2019 have a 1999 ZX9r. What a beauty she is too.

[Evil Hans]

Could it be that the tank isn't venting fast enough and it's creating a vacuum?

Check the breather in the fuel cap, if it has one.
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Triumph Sprint ST 1050. And it's Red.

[TheGazWaz]

[dynax]

these are available from most auto centres,

https://i.ebayimg.com/images/g/b-UAAOSwFMZWsOW2/s-l640.jpg
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Mike.
Bikes: Xena, Bridget,Florence
https://www.youtube.com/channel/UCmihUc0xXxYbR4_0l-F1FzA/videos?view_as=subscriber

[Tdibs]

[TheGazWaz]

[TheGazWaz]

Solved.

I was about to start fitting new parts to the carb when I found that they're only £23 Brand new for the whole carb.

Fitted it, all is good. I didn't even have to mess with the mixture screws.

Sat at 60 for 15 whole minutes without a single issue.

Phew.

Id fitted a new coil and HT lead and a spark plug, sorted out a few dodgy earths so the bike is in good nick now.

Cheers all for your comments.

Gaz
____________________
Went like this.. 43 years old(2013) decided to do CBT to get a 125 for new job. Bought 2011 YBR, loved it for three months then hated it because it was too god damn slow. Did DAS 4 months later then bought RF600 Loved it, sold it bought Bandit 1200(K3). EFFIN lOVED IT. Wanted something a bit more sporty so got Triumph Sprint ST 955i (53). Not sporty enough so now on my GSXR 1000 K3 and absolutely love it. 1 year down the line, nearly died way too many times on this bike. Sold it. Had a 6 month break. Missed biking so now, Aug 2019 have a 1999 ZX9r. What a beauty she is too.