Top 5 125cc Motorcycle Faults and How to Fix Them

Note: For point 2 it’s not a Fuel mixture screw it’s an idle speed screw!

The top 5 faults on Chinese HMC, Sinnis, Lexmoto etc 125cc motorcycles and how to fix them.
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wink1980 says:

that’s the idle screw fuel mix is under the carb

jimmy Lincoln says:

Very interesting, thanks for sharing

Vlad Billevich says:

How long do you own this bike?
are you happy to own this bike?

ibez07 says:

lovely bike, but errr what is it? it looks like the sinnis cafe/moto valient/sinnis scrambler/bullit,,,who makes this 1 and is it cheaper, i only wanna spend a grand,,cheers tom

Dan Phillips says:

You could use some loctite on your bolts I think.

DeadHead 1989 says:

I’ve got a 125 and need some helps desperately. My bike has never had a problem but the last two weeks I’ve noticed when I’m full throttle in 5th as soon as I come off the throttle Togo around a bend for example, if I get back on the throttle there will be a hesitation for a second then it will pick back up. It’s quite a big hesitation but don’t know what this could be

mike stevens says:

Great video, my only question is where did you get the after market headlight?

Sergio Terol says:

I got a solution for all those problems. Instad of going chinsese built bikes… go for the suzuki ones that are the exact same but built (put together) and QC by a Japanese company. Meaning gs/en/gn 125. Ive had mine for almost 3 years now… no hassle.

Lukes Aps says:

That’s the revs speed not fuel mix.

Fuel mix is underneath the carb

koudacyen says:

how to stop all and any faults , sell it! and don’t buy Chinese shit again!

Andy Reid says:

Smearing either silicon gasket goo or exhaust paste onto the threads of the exhaust manifold bolts will stop them vibrating loose yet will allow them to be unscrewed with a socket wrench when needed. (A very old biker’s trick).

The welds on the gas tank leaking is caused by the 5% ethanol content of the unleaded petrol we now have destroying the resin in the sealant material the Chinese manufacturer used. China does not contaminate its petrol with ethanol yet so still use resin based sealants. It’s a problem that classic bike owners are familiar with.

Use a ethanol and acetic acid (what ethanol degrades into on contact with air in the gas tank which causes it leach iron from the steel and eventually clog up the carb) resistant gas tank sealant.

Chinese 125 bikes now last as long as 1970’s and 1980’s Japanese 50cc to 250cc bikes did back in the past (15,000 to 20,000 miles unless it was a Honda CG 125).

Rowan Herbert says:

ty very much, very helpful

ScrewCaptain27 says:

Best solution? Buy Italian or Japanese. Especially if you can’t afford brand new.

roythearcher says:

Fault 1:- Check and clear the breather vent in the fuel cap.
Fault 2 :- Clean the air filter and check for air leaks making the mixture lean.
Fault 3 :- regular checking and if necessary, re-tightening of these bolts should be carried out as part of regular servicing.
Fault 4 :- see fault 1. but.. all fuel tanks should be pressure tested at the factory so if it’s leaking, send it back!
Fault 5 :- This is the only genuine fault you highlight on this machine that did not originate from a lack of maintenance and unfortunately can be expected from what are otherwise very reliable bikes! Chinese machines use cheaper versions of Japanese components in their electrics and while they work fine, their reliability is not up to Japanese standards yet!
My advice here is to replace with a regulator from either a YBR125 Yamaha, or a CG125 Suzuki as they will probably outlast the rest of the machine and are the same regulator!
If you find a faulty regulator, have your battery checked too as they can be damaged by a bad regulator and boil dry!!

simon carman says:

hi isn’t the screw on the carb just a tickover screw?

Daver Son says:

Get some spring or lock washers for your exhaust bolts.

Eselfar says:

Very interesting. I’ve planned to buy the Lexmoto Valiant which looks a bit similar. Hope I’m not gonna have these problems but at least now I know how to fix them.

5TU says:

Gringo Tom, Thanks for this video. It has made me feel so much better than I would have if I hadn’t watched it before buying my Herald. All these issues have pop up on my bike in the first 600km. I would have been well pissed if I didn’t know these where common problems.

Where did you get the Red bike stand from?

Rotherider says:

Thanks for the review. I was considering buying a Herald 250, but I don’t think I will bother now. Not until the manufacturers address these issues.

Ian Johnson says:

Very useful – thank you

crpth1 says:

Love the classic look of it. WD40 and silicone spray are always a great help fixing this small gremlins and perfectly valid for Japanese bikes also. A tiny squirt in the key holes, or in the electrical contact plugs make miracles on the good functioning of those components. Thumbs up.

Jay B says:

I wonder how many people actually buy Chinese bikes twice..

ian ball says:

looks like a mutt

Morten Kristoffersen says:

How about just making sure your tank vent (in filler cap) is not blocked?

It’s not a manifold, its just a header pipe. But on no bike they should come loose, it’s the other way around, they get stuck.

Seems like very shoddy build quality ?

Korsfestelse says:

Touch wood I’ve not had many issues with my Zontes, but it’s nice to see this video just in case! I’ve never needed to adjust my idle screw funnily enough – the bike seems content with the choke she came with, funnily enough haha. I like your bike as well, although I’d definitely have cafe-style bars on to complete the look. 😉

sportster1988 says:

I had a rectifier last 25 years on my bike, and I thought I got screwed. What the heck is a Herald any way? I have never heard of that model or manufacturer. Carb should be a descent one it said Japan on the side, Japs usually make good carbs.

michael koncal says:

Are you shitting me!!!? I will stick with the Usa,Brtit.,Jap., Italian and India motorcycles!

Yazrulnizal Mohd Yazid says:

can you show us how to remove the silencer baffle

Johnny Hayes says:

Great vid!

ha yes says:

what do u mean by the ‘choke’ what is it, where is it and what does it do?

Michael Evans says:

As of January 2017 all european bikes over 125cc will be fuel injected as they have to be A4 compliant plus A.B.S. BRAKES .

kellyjune1931 says:

Don’t label all Chinese bikes with these problems, I have a Sinnis Apache which is 4 years old and, has had none of these problems, in fact, it’s had no problems at all. These bikes are as good as any Japanese bikes I have EVER had, remember, Jap bikes had bad press back in the 60’s & 70’s now look at them. I also have Ducati 749 so, why would I bother with a cheap crappy Chinese bike? Because it’s great around town, economical, light weight, inexpensive to buy – should I go on?

theabstrakt84 says:

No Mash???

Keith Dainton says:

Should have bought a sinnis I had a vista for four years not one fault now got a sc125 now a year old no faults also they are cheaper.

Neil Cole says:

Or you could do your self a favour and not buy Chinese!! The leaking petrol on a hot engine fault, is pretty scary! just dont bother!! I think I would rather buy a pushbike!!

armadillo platypus says:

This bike looks to based on the old Suzuki GS125 frame and engine.

Henry A says:

The first thing you check if bulbs are blowing frequently is that the wiring has a good earth connection. Once you are happy with the wiring loom it’s time to check the alternator output and the function of the reg/rec. The most common mechanical fault on small motorcycles (of ANY make) is valve adjustment – particularly on machines abused by learners. In UK Haynes publish a manual specifically aimed at servicing small Chinese bikes. It is well worth reading as well as the owner’s manual that comes with each bike 🙂

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