No power above a certain rpm(MRT PRO 50CC)

[Alec_B]

Hey guy's,

I'm from Belgium, but I'm trying to figure out my problem with my bike.

So I was riding my bike(with restriction = 50km/h) and at some moment I felt that I was losing power.
But because I was going to replace the cylinder and piston when the parts arrived I just drove it a few more kilometers, and over those kilometer's it was losing more and more power.

So I put the bike in the garage and waited for the parts to arrive and apparently the piston and cylinder was as dead as they can be :'(
https://1drv.ms/i/s!AiVA6AaDGvQHg_wRMVicle9av-82Qg
https://1drv.ms/i/s!AiVA6AaDGvQHg_wTAB4gd9FrZHh8dg

So I replaced them both and a few other things :
-Spark plug
-Cylinder
-Piston

But after trying it it didn't changed anything at all, so I was trying to figure out the problem.
I first blamed the problem on myself not reajusting the carburetor after putting the new cylinder on it.
But I've tried jets from 60-120 and it would still not run fine at neither of those jets and I've been busy adjusting for 2 whole days, so it's not that I'm not taking time for it.

Because that didn't changed anything, I replaced the membrane, which eventually also did nothing(it gave it a little more power).

So eventually I decided to blame it on the ignition system and I changed the next items :
-CDI
-sparkplug
-spark wire(or how it's called)

Neither of those new parts changed something about the problem, so I was still blaming it on the ignition part, but now specifically on the stator or pickup.

So I measured the stators with a multimeter and compared it with the workshop manual from my bike.
(The link of the manual will be on the bottom of the post)
And I found out that the coil which is responsible for providing the voltage for the spark is 130 ohm's more than it is in the manual, so I'm almost sure this is the problem.
But I'm asking if I'm right because I'm not totally sure.

----------------
Here are the results from the coils in the stator :
(keep in mind it has 10-20% tolerance at 20°c)

White & Red : Manual = 130ohm
On my bike = 135ohm

White & Green : Manual = 700ohm
On my bike = 880ohm
-----------------

Links :
- Workshop manual AM6 = https://1drv.ms/b/s!AiVA6AaDGvQHg-o0B-JBL1e7ru885A
- Workshop manual MRT PRO 50CC = https://1drv.ms/b/s!AiVA6AaDGvQHg-oxIIS1PkBYfcX08w

Kind regards Alec_B

[JonW]

I doubt very much anyone here has experience of your exact bike, but you may get generic advice. Is there not a forum for the MRT Pro 50 or Rieju bikes at all? I just think maybe someone with one may have had this problem before perhaps?

As an aside I love the look of these bikes, great baby motard.

[Alec_B]

There are forums from rieju and i already posted something there, but there is not as much activity on that forum.
It's almost only one guy that answers.

But maybe there is someone who can tell me what the symptoms are for bad stator.

And yeah i like them too

[hybrid]

It sounds as though you have replaced every other part but the stator.
When considering the entire system, there is only a couple of things left:

1) Carb/Fueling issue
2) Stator

As far as the stator goes, more resistance generally means less current flow.
Is the stator expensive to replace?

[Alec_B]

It sounds as though you have replaced every other part but the stator.
When considering the entire system, there is only a couple of things left:

1) Carb/Fueling issue
2) Stator

As far as the stator goes, more resistance generally means less current flow.
Is the stator expensive to replace?

Carb has been completely cleaned and the fuel flows nicely trough the fuel lines, how should i check if the carburetor gets enough fuel?

Because with the bike in neutral it revs's nicely up in to higher rpm's.

Does less current meant that I'll get a weaker spark, or will the spark be the same(or does it means something else?)?

And if so will it cause the bike to make less power with a weaker spark?

Because when i was busy with cleaning the bike before al this happened, i cleaned the chain and lubricated it.
And after a short test ride(to check if tension was good) i think(not 100% sure) i smelled something that had burned.
So i read online that if your stator melts or shorts that you'll smell like something has burned, so this intensified my blame towards the stator for causing less to almost non power.

BTW; A new original stator costs €300, because it comes with a new flywheel etc. But one from another brand which is also a known brand but not so big as others, costs €70-80.
Would you guy's recommend me buying a used original or a new b-branded stator?

Thanks already

(Sorry if my English is not perfect)

[hybrid]

Less current will mean less power at the same voltage.
I would go for the cheaper stator personally, but that's because I'm a tight ass

Is it definitely related to RPM and not throttle?
So when you lose power does it stop accelerating?
And if you close the throttle a little bit is it the same, or does it clear up?

If changing the throttle changes the behavour, it may be fueling, although you have changed jets etc.
If it's more of an RPM limit, then I guess it might be the stator because it may not be able to charge the CDI quick enough at higher RPM.

[Alec_B]

Yeah i was also going for the cheaper one

Yes even if i apply less throttle the bike would not go any faster, it is like it is limited(restricted) altough the restriction was fully out of the exausth and the cdi is not restricted.

And yes it just stops accellerating at a certain speed, it just would not go any faster not even a kilometer, with any jet from 65-110.

[Alec_B]

Update: I just noticed that i didn't put the exaust gasket in the exaust port.
the gasket helps a little bit but it is just 4km/h, it still will not run higher than 30km/h.

[hybrid]

What is the RPM when it won't go any faster?

[Alec_B]

I don't know, I don't have a rpm-counter.
But i tested the bike with several jets, and the sparkplug is wet when i pull it out.

So i think it is not completely burning the fuel, but correct me if i'm wrong

[Greasemeup]

Cable routing?


Sent from my iPhone using Tapatalk

[hybrid]

What oil/fuel ratio are you using?
It could also be the timing. But it won't be easy to check the timing on such a small engine without a degree wheel.

[Alec_B]

I'm just using the oil pump on the bike and how could the timing change, it has a fixed ground plate..

[hybrid]

The only other way it could change is a broken keyway, allowing the flywheel to move.
Is the oil pump adjusted properly?

[Alec_B]

Fly wheel can't move, i've checked it.
I don't know about the oil pump, but can it give so much trouble?
Because i've always used the pump, can it explain this behavior?