Yamaha wr125x - 6th gear problem

[muruburu]

Hi guys,

Maybe somebody know why Yamaha wr125x on 6th gear has no power ?
Thats mean on 5th gear I can get ~62mph and on 6th gear speed going down to 58-60mph. Or if there is some wind on my face/ small up hill the speed is less then 55mph on 6th gear.
( it looks like 6th gear is completly useless )

The Yamaha is 2013 and mileage is 6000, everything is standard ( filters, exhaust etc. )

Regards
Pit

[stevo as b4]

Put bike on a dyno, once you have checked all the basics and serviced it, clean filters, new plug etc. If you get about 12bhp r/w it has nothing wrong with it. If it's a lot less you have lost power somewhere or have an issue with the driveline or binding brakes etc etc?

[Fladdem]

Are the sprockets standard? What are the revs like at that speed?

They may have been changed with the intention of making it faster but the engine isn't powerful enough to pull the gear ratio, the engine can't rev out. Or they may come as standard like that to improve reliability, stop ham-fisted teens from keeping it in the red line and all that.

I know my TTR 250 came standard as 14/44, it went faster in 5th. I run 14/52 now and it goes faster flat out now and has more grunt at the bottom, this is down to a lack of torque. Imagine trying to accelerate hard in top gear on a bicycle, your legs can't pull it.

Before booking an expensive dyno, try a nice cheap front sprocket with one less tooth. I say one less because it will make an easier gear for the engine.

If no difference or worse, put the original back on, it should only be a tenner or so.
____________________
Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[muruburu]

Hi,

Thx for answers.

No idea about revs, cuz WR has no revs gauge.

Yes, sprocket are standards.

I have read somewhere that I should try bigger rear sprocket. Standard is 53t so I should try 55t.

Its similar what you said Fladdem.
But its cheaper and easier change the front sprocket so I will buy some cheap 13t ( standard is 14t ) , and we will see.

If this not help, I will book dyno.

And 1 more question - what about alloy rear sprocket ?
Is better than normal steel sprocket ?

[Conzar]

It's a 125 6th gear isn't for pulling
____________________
Current ride: ZX6R 636 ------- Previous:KTM EXC 450 Supermoto --- ZX6R B1H --Hornet 600--CBR 600--SV650
11:05:35 Rob Fzs: i just wanna own an rd350 valve before they send us to war with durkadurkastan

[Fladdem]

Ally is rubbish. Unless you are racing or use the bike sparingly you will chew through them in no time.

Good luck!
____________________
Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[1cyl]

6th gear

Must be a Chinese knock off, as surely a "real" WR only has a 5 speed .
____________________
Chase my Witch up, Catch my Snitch up.
The SMC | The Pit | Stable

[muruburu]

From official yamaha site:

[trevor saxe-coburg-gotha]

My VanVan actually slows down slightly in sixth. Afaik, the sixth gear is intended for economy, an overdrive if you like - i.e. maintaining a steady 45-50 (you must realise the VanVan is a slow 125, and although it *will* touch 60 it is far more content a smidge south of 50).
____________________
"Life is a sexually transmitted disease and the mortality rate is one hundred percent."

Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[Fladdem]

[muruburu]

Hello,

New sprocket just arrive, but I'm not happy, because they made mistake and send me standard one :/
So, I need wait another 2 days...

I put new air filter - K&N... what it changed ?
1. ( I can feel ) better response on throttle ( bike is stronger )
2. its a bit louder.

Regards

[1cyl]

[P.]

All 125s with a 6th gear, unless tuned to actually make decent power or a 2 stroke will not have any significant power in that gear.

It is for cruising on long straights.

[stevo as b4]

Gearing changes to suit the rider, terrain, payload or preferences are all well and good.

In road tests the WR125R/X see's around 70-72mph indicated on the speedo, and assuming it's not too far out given the power available mid-high 60's real mph should be available.

If the OP's bike is not running right or making the power it should be then messing with gearing is not the answer to the problem.

I would agree though that for a very heavy rider or riding off road or in very hilly parts of the country with few flat fast roads, then playing with gearing could be advantageous.

[muruburu]

Hi,

Sprockets came.

Now I have another question about changing chain and sprockets, cuz I never did it before.

Can I change sprockets and chain on parking in front of my house, or better take bike to some garage ?

It does not look difficult... Do I need some special tools ?

[Conzar]

You need a ray blaster the only tool for the job
____________________
Current ride: ZX6R 636 ------- Previous:KTM EXC 450 Supermoto --- ZX6R B1H --Hornet 600--CBR 600--SV650
11:05:35 Rob Fzs: i just wanna own an rd350 valve before they send us to war with durkadurkastan

[P.]

[muruburu]

I have sprockets - front 14t and 13t , rear 53t
chain is D.I.D 428HD 134

I dont have central or paddock stand, so there will be problem to change rear sprocket... any suggestion ?

Do I need smth like this for chain replace?

[Fladdem]

You don't need a stand.

https://i1302.photobucket.com/albums/ag134/Fladdem/1545775_10201016702740040_7392258005290048820_n_zpsd5f633ff.jpg

Most chains should have a split link, like so:

https://www.doctordanger.com/projects/honda/forks/chainclip.jpg

Undo the clip to get the old chain off, bin it. You shouldn't need a chain splitting tool.

Remove anything around the front sprocket, remember how it came off. Replace. It's easy enough, if you are nervous about it, try to be methodical and take your time. If you need the bike on Saturday, for example, don't try it on a Friday evening, just in case it doesn't go smoothly, but it should do.

I wouldn't ever take my bike to a shop to do anything. I just can't justify the cost. The only thing I haven't done myself is when I snapped the swinging arm on my MT5 and it needed welding up again, but when I snapped the frame on my 250, I welded it myself. Bikes are easy enough, just give it a go and try not to break anything.
____________________
Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[muruburu]

Thx for the advice.

I have been in local garage , and they want minimum £75... £75 or more for chain and sprockets change, OMG.

So definitely I will do it myself

[muruburu]

[Fladdem]

Not all chains have one. If your new chain has one, then that is a lot easier. If you are definitely chucking the old chain, hammer and chisel/angle grinder will do it. Be careful not to slip and smash something you want.
____________________
Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[_Iain_]

[muruburu]

Hello,

I have changed sprockets. Tried many settings - 13/53 , 13/55 , 15/53 , 15/55 , 14/55 and definitely I can say that 14/55 is the best... Better acceleration, better top speed, stronger.
It pull well on every gear, even 6th.

I need more ride to say how much better is now, but... I did not change the chain, cuz dont have right tools.

But I spoke with my friend and we will do it tomorrow.

[_Iain_]