125-200cc Husqvarna sms 125 weak and slow (?)

Hi. Some days ago i unlocked exhaust in my husky. But i think this motorbike should be faster..

My V-MAX is only 120km/h and i think something is wrong because i saw and read a lot of topics where people say this husky can go +140km/h unlocked

My setup is stock, with unlocked exhaust (Delolorto VHST 28, main nozzle 150, transfer 14t/49t)

Is something wrong? Or really this motorbike cant go faster? Please answer me.

your gearing could be the problem
if you have a bit of headwind or a climbing road it will not go any faster as it simply misses the power.
check your tire pressure, type of asphalt has also an influence on it.

then there is the age of the bike
how many Km did this bike already?
is the bike overhauled? (new top end)
check your wheel bearings.

another thing that really works well for small bores is having light weight sprockets and a no O ring chain
it does wear out quicker yet there is less rotating mass in the drive train

a 450 pulls through that additional weight but a power starved tuned for reliability small bore bike is a different story.

Robert-Jan

my bike has same engine and carb as yours, but has dep exhaust system, and will only go 70 mph flat out. I could probably eek 75/80 mph genuinely if changed the gearing but no more than that, people who say these bikes will go nearly 90mph are idiots, they're not geared for it like a sports 125 is, their speedo is wrong by at least ten percent. It's the same story as when people with tuned 50cc's say they got to 70 mph :/

Thank you both so much for answer.



I have no idea whats the right pressure for this motorbike but i checked it and i have 2atm in front and 1,8 in rear tire. is that good?
Bike have original nicasil cylinder and mileage is about 6000km.
It is a 2008 model.


I have one more question. My chain is in very bad condition and which one should i buy? Is D.I.D 520DZ2 ok? How many cells? 114? 116 for original sprockets?

I think motorrbike hasnt good main jet. I have 150 main jet but spark plug is very bright. What is your main jet, please answer i dont wanna to blow up my engine by not enough air-petrol mixture.

If your plug looks bright light brown/whitish you are running on the lean side.

a bigger size jet is recommended and you might have to play with the needle height.

6000Km for this engine is nothing when run in stock form yet you might want to do a compression test to see the status of the rings.

regarding the chain if you don't change it together with the sprockets you will wear out the whole set quicker

in any case go for a non O ring chain and buy the longest

its easier to adjust a chain shorter then make it longer without having a weak spot in the chain.

Robert-Jan

Could you please tell me something about the mixture screw?

Rich mixture = Screw IN or screw OUT?

Because i have this screw on 2 full turns and I cant screw in more because motorbike starts
interrupts and not going smoothly.

So which side = rich mixture?

robert-jan, the needle hangs on the end of the throttle cable doesn't it, I just changed mine over, but can you explain how this affects the bike? because it pulls up the slide inside the carb to allow the mixture through, what does raising the needle clip position do, or lowering it?

if it's an air screw it's backwards to a fuel mixture screw, so, it SHOULD be turn it into the carb to richen the fuel mixture, and turn it outwards to make it leaner, as you screw it inwards you allow less air through from the airbox and more fuel to flow

if you are more than three turns out I think you have to change the pilot jet, haven't actually done this but this video explains it a bit more


View: https://www.youtube.com/watch?v=YxpQjDQzX7g

I have only 2 turns and spark plugh is still birght, so i think i should buy bigger jets.

What is your main jet size? you have same carb as me, so whats yours?

you have 3 circuits in a conventional carb
idle circuit
low rpm circuit
high rpm circuit

idle circuit is effected by the idle jet and air mixture screw.
turn it in (clock wise) you have less air so more % fuel in the mixture.

the low Rpm circuit is effected by the slide and needle height.
you have different slide nr with a different size of cut away which effect the speed of the air and thus effects the % mixture between gas and air the needle does the same thing as it is a tapered rod in a hollow tube so it controls the restriction factor for the gas to be sucked out.

the high RPM circuit is needle and main jet.

the needle can have different shapes and different angles which effect again the restriction in the gas supply.
the bigger a main jet the more fuel can pass in a shorter time span through the jet.
the pull factor is created by the air forced through the carb as a result that the motor is sucking it through.


few things that have to be in place.
make sure your float level is set right.

to high and the fuel might be pushed in the venturi shaft (needle shaft) and results in not idle ling and poor low rpm performance.
to low and you get to less fuel in the % mix which mainly affects high rpm.

make sure you have a clean air filter.
blocked air filters result in to rich on the plug (less airflow is more % gas in the total mix)

make sure you don"t have air leaks between the carb and the reeds.

that would make the motor hard to control and air would lean the gas mix in the cylinder.


check your plug at moderate loaded bike at low rpm and at high rpm.

as the engine can be to rich in one circuit and to lean in another one, and yes all the separate circuits do have some affect on the other circuit.

then we have environmental influences like temperature, humidity and elevation.

a hot dry summer requires a different setting as humid damp conditions either hot or cold.


chasing a perfect setting can be time consuming and with jets, needles, slides also costly.

I am in the process to set a lectron on my SM (have it for a long time on the WR) and that is a totally different carb.

by far superior then the conventional carb if you ask me.

the biggest issue i had with the mikuni carb is the sensitivity on the environmental conditions.

living in the tropics if a storm was brewing during a trip I had to change my carb settings on the trail (not the kind of thing i want to do on a ride)


Hope this will help you with your bike.
check the plug at several RPM ranges I ve seen a few time a complete engine failure due to a low circuit to lean yet high circuit was fine.

Robert-Jan