DT125R FORUM

No its a 3MB cylinder only modified lifted port timing and two huge sub ports for the exhaust (bigger then the SP)

Problem now lies in the stock exhaust, this will need a update.
Still want to beet the 30HP. But it turns out to be much tougher then I thought

I see its almost a year back sins my last post.

Not much has changed, currently at 27,7Hp back wheel.

Hope to gain some more with the use off a more suitable exhaust (currently waiting on a test exhaust so I have a indication witch dimensions I need to make it)

Engine changed a lot this can be read here.
www.tzr3ma.com at section Tzr125 trackbike

Currently mounting a zeel on my roadgoing bike, but have some problems with the setup.
Hope to do some runs with here ones it is setup correct

Cheers
Louis

Will probably feel like a massive improvement in the real world compared to the small increases shown by the dyno

Well standing on two feeds again that's for sure.
The shown dyno curve, are a couple off same runs they always have a small tolerance

Perhaps this is a better shown between stock and with the mod's

Orange curve is with ignition filter, that's way its so smooth.
You can see the progress

That is sounding much more realistic! I'd rather underestimate the power and demolish others in that class, than overestimate and lag behind!

You have a good point there.

Sometimes thinks do not go as planed.
When you belief in something that hard, and your are convinced that others have it wrong it will take you some time to conceder that they are right.

It turns out that my own dyno was not set correct, re calculated my drum an that gave a massive drop in the measurements.
Of course not very nice for me to know, as I thought I was going the right way.
Thankfully don't have a company/ or a tuners name to keep high so a note on my site regarding the wrong setting should be enough.
http://www.tzr3ma.com/dyno-correction.html

But specially here I post a personal reaction, because they told me here over and over it is not making a +30HP and I did not belief it.

So my apologies for that.

The trough now is as followed.
After the new settings the HP's where dropping faster than I could think off.
But fair is fair, if this is what it should be, so be it.

The results so far

Stock the TZR125 (trackbike) has a 22,3HP at the rear wheel
And with all the mod's i did so far (shortened exhaust, 6 degree more advance, changed carb rubber, open carb) it produced 24,8HP rear wheel.

Currently have changed the head to a O-ring conversion, but need to dyno it first.
http://www.tzr3ma.com/head-to-o-ring-conversion.html
It drops the squish from a 1,3 to a 1mm and combustion volume to a 11,2cc

Hope this will bring me a 1,5 a 2 HP and it end up around 27HP
(not saying it will, but hope it does)

After this like to do some other steps but that would probably bring more in the mid section than on peek power

Will let you guys know

Cheers
Louis

@Darty
''I'll dyno mine and we can square this up...
I thought 25hp max''

The 25HP is this with your latest setup?

@Calum
''No Dyno mate.
You can show me graphs all you like.
The true test is how does it go out on the road.
You can see from that video that this bike is FAR FAR behind that YZ. What's a YZ roughly?''

You got a 5UN00 cylinder that's a 2002/2003 engine.
You can not compare that with your DT125R, not at all.
Those engine's start with 32/33HP and most off the time they have performance pars on them as well. Bringing it to mid 30's (pipes, CDI's, reedblocks, etc)
Also gearing is plays up with comparing

Keep in mind I'm thinking with you not against you.

You need to know at least the peek power from your bike.
This helps you to set the ignition curve.

You aim on a 14 degrees at peek power there it is where it happens.
After peek power you drop it to a +/-5 degrees

''@louis I mean I got a 4DL engine with Zeeltronic ignition, underslung exhaust, ported barrel, altered head, VHSA 32mm carb all jetted and mapped accordingly, it's probably around 20bhp at the wheel.''

All those mod's you did gained you roughly 5 till 7HP (going from a stock 15HP DT125R to a+/-24HP)

Having trouble to believe that.
Did you dyno your DT125R?
What ignition curve do you use and what ypvs opening curve?
What is your exhaust length?

A 200cc NSU superlux from 1956 has stock 12HP and a tuned DT125R has a 20+
Is it just me that I'm thinking that's a bid low

For example her is a TDR125 (roughly the same)
4 degrees more advange and some changes

http://www.yam2stroke.fr/viewtopic.php?f=18&t=21900

How did they dyno your bike?

-fifth gear or six gear
-Lights on or off
-Tire pressure

There must be a reason way it is (from my point a few) a bid low

It took me a while to read through the older forum posts (because English is not my home leagues)

Now I know why my positive HP outcome is not taken that well.
I see that a DT125R has already having trouble to reach a 20+

I have explained that my 30HP can be reduced to a 27BHP (regarding the settings of the filter's)
This 27HP is with 4 degrees more advange (that gained me about 2HP) so the 'relative stock'' setting would be around 25BHP
And a small note regarding ''relative stock'' is a well setup carb (absolutely not stock)

So perhaps with a stock jetting the bike prudes a around 24BHP? (Don't know haven't dyno'd it then)

Hope this takes a way the trouble I have corse.

Not meaning that a nice discussion can bring new ideas.
Example, just measured the 4DL and 3MB servo's
http://www.tzr3ma.com/tzr125-servo-openings-curve.html
Having a 3MB servo on a DT125R would not be perfect if that bike has its peek power at 9000rpm or lower.

Just pointing it out

Cheers

''Really enjoyed your website''
Thanks,

''I have a TZR125R/4DL Y-1 3MB-P-00 top end , 134cc, with slightly larger port volume and appropriate port timing with 0.6mm, squish' cylinder head I'm testing.
The compression ratio slightly reduced.''
That is a interesting setup.
0,6mm squish that is pretty tight, going to race specifications.

''I need to tune the ignition and Powervalve timing. I have started with a basic map similar to that of a 4DL and can support there being a potential 2hp increase''
Ok that is positive, small step towards more

''I'm moving on to fitting a TM34ss with WR200 inlet manifold (slightly longer inlet tract) and VFORCE3 Reed block, However I can't isolate better running over a 4DL reed cage''
Have good results by enlarging the crank case volume a bid so don't thing the longer manifold will be a problem.
34mm carb, that would be the max I think regarding the inlet volume from the reedblock?

I have always believed that the 4DL Y-1/Y-3 was only good for 22-23bhp in stock configuration?
Don't know way you guys are all so low on the HP outcome.
In Germany they had to bring back the power to 15HP if a younster (16) want to drive it on the road (drosselt)
They did this by letting the exhaust valve closed, or mound it in restricted mode or by gearing or black box.

''I have yet to sort out my Dyno run, but I still don't believe it will be making an extra 6hp around 11,000 or so. But I would hope that is possible''
It will be strange if it won't!!!.
How much do you have right now?
What exhaust do you use, and where does that exhaust peek.10500rpm?

''What are your experiences with altering squish height with a 4DL? very interested to gain some insight''
Currently non, I want to change it in the future.
But for now like to see ho far I can go with a relative stock setting

''The design for the RR' Airbox is interesting, I am struggling to modify and work out a good increase in Air volume for this engine''
Yes the RR airbox is relative larger than the R airbox.
I'm running the rr airbox without airfilter and snorkels currently.
Mus say until now it works fine like this

Hello,

Have you checked if the powervalve is really fully open? When the servo is in the opening position?
By removing the exhaust and feel/see it.

Just pointing it out as you can mound that plastic thing two ways

http://www.tzr3ma.com/tzr125-4dl-restricted-ypvs.html

If you already know this, forget i have written this

''think we will have to agree to disagree about the engine output of the Belgarda 4DL engine''
No problem, remember I don't mean you any harm just have a different point a few.

''I was under the impression that the 4DL engine was going to be a monster. But it was poor''
No its not a monster at all that is for sure, your yz125 will kick its ass any time.

''I have examined both engines in great detail, there. Is nothing to suggest that the 4DL engine was 10 horsepower more than the DTX engine''
That I belief, apart from a slightly different timing from cylinder perhaps a tiny difference in head design.
Think the main difference is electronically, carb and exhaust compared with the 3MB engine
(Are there no restrictions in the exhaust on a DT125R (just a thought))

Have quickly draw a 4DL curve inside a DT125R curve.

As you can see after the 9300rpm the 4DL curve is different. (its designed to peek higher)
This is a big difference at about 10.300rpm the 4DL has 10degrees and the DT125R has 4degrees

That is a 6 degrees differences

For example if you see how much the 4 degrees pickup move does on the TZR it gained about 2,5HP
http://www.tzr3ma.com/tzr125-dyno-runs-two.html

So calculating it back lets say 26HP -6 degrees (roughly 3HP) will be 23HP this in combination with a stock exhaust (witch will peek less then a TZR one)
You end up with around 22HP??

Know its all guessing, its just a other point a few

The piston looks like you went to lean.
Google "lean piston" and you see many like them.

Don't know where your enthusiasm comes from regarding the HP outcome

Don't judge to soon regarding a 4DL engine.

Let i put it this way,
A TZR125 4DL has 26-27HP as completely stock.
A TZR125 SP should outperform a stock 4DL so they are close to 30HP

The 26-27HP is produced with the combination off all components. (carb, ignition, CDI, YPVS, Exhaust, TOP END, etc)

So if you only take the 4DL TOP END and CARB you wont see the 26-27HP back on a DT125R

Putting a 4DL top end on a 3MB bottom using stock ignition and exhaust wont do anything.
A TZR 4DL peeks stock around 10.300rpm.
By the looks off the ignition curve from a DT125R it peeks around 9250rpm?

So when the 4DL top end wants to give power, the ignition is already to low
Even if you use a performance exhaust the ignition is dropping to soon

Its not the top end only what makes the HP
We clearly have a different point a few about this. But that's OK.

After everything I have done, it's still no better than a stock Rotax 122 engine. As such I have decided to end the tuning on the DTR engine and begin looking at building a Rotax weapon.

Don't have experience with the Rotax 122 engine.
But I understand from you that a stock Rotax122 engine has more power then your tuned 4DL engine?
Unbelievable, how much has a stock rotax engine?
Can understand the frustration, how much did you end up with?

Wilt measuredyno all changes I make and report back.
This wont be a fast topick, but hopefully one with nice info for the 3MB/4DL riders out here.

"Compression increased and squishband altered"

Ah there you something.

You have probably used modern value's regarding the head

Higher compression tightened the squish (perhaps a smaller head volume)

Have done that to but with bad results
Changed the headvolume tightened the squish (0,8mm) changed the squish wideness. (to race specification)
It does not work on a older engine.

Most tuning stuff are copied from latest designs (RSA/RSW engine with the 50HP by Jan tiel) etc etc

Have had discussions on forums about this.
The material used on these real GP engines is different.
Have you thought about the stretching off your conrod at 10.000rpm or crank
The squish set on 0,9mm will not be a 0.9mm at 10.000rpm closer will be 0,6 or 0,7mm (or less)
Specially with the old designed crank and conrod in the 3MB or 4DL engines.

The higher compression will work agents you in the higher revs
It Will give you more power in the mid section.

You have changed so much in one time what did what?
The power you have now will be higher than a stock engine that's for sure, (but what did what?)

The ported cylinder from abbey gave you? (compared with stock)
The changed head gave you?
The zeel?
The exhaust?

Do you know what I mean?
Don't get me wrong, I'm not criticizing you but just have a different point a few regarding tuning

Step by step

For example: if you take your engine as it is now, but use a stock "p" head how does it perform then? do you lose 3HP or will it be the same?

Mention HP outcome is always difficult
Let just say my street 4DL has 27HP
That is with 4degrees more advange, a RR exhaust and a open airbox and well setup
will that be OK?

''The 3MB00P is not 30 bhp either''
Regarding the 30HP
Here you go: http://www.tzr3ma.com/dyno-readings.html

Interesting, What is your setup?
What CDI do you use? (stock advange or more)
What Carb (mm)
What cylinder head

30HP is measured with correction (factor 5) with factor 25 (is a lot) you end up with a 27HP

Factor 25 is relative much around 15 you will be good.
So a 29HP should be possible

Some pictures regarding this project

For testing some off my ideas I can use my street 4DL

For CDI ypvs testing I'm working on adapting my (testing machine)
So I can measure/test the 4DL CDI and YPVS motor

The project it self

Most can be seen on my site.

Slowly getting the feeling that nobody have measured the 4FL servo motor or any other one??

Cheers

Hello Callum,

I feel some passion in your reactions, that's good like that.

Kept me thinking for a while why you mentioned so low HP outcome.
But found it.
Have made a mistake in my info regarding this project, was to focused on my question about the 3MB servo that I named my engine also 3MB but of course this is not the case.

I use a complete 4DL engine with the ''P'' cylinder, "P"head, 32mm carb, en 4DL CDI (so a complete TZR125 4DL belgarda setup)

Have read that indeed the 3MB engine have a much lower in HP outcome than a 4DL do to a lower cilindertiming restricted head (ring) and a CDI (with a lower ignition curve), smaller carb (28?) perhaps also exhaust, etc ect

So my excuse for the mismatch in engine coding
Got my street 4DL at a 30HP currently (filtering factor 5) dynojet filtering would be 27-28HP

http://www.tzr3ma.com/tzr125-dyno-runs-two.html

You will never be able to port the 3MB barrel to the levels of the SP, the differences are a lot more than Nikasil plating. The port windows and timings are massively uprated. The compression ratio is dramtically different and they also contain two auxillary exhaust ports.

Never say never
I'm quit familiar with cylinder timing and the triple exhaust ports myself.
Also porting, making exhausts, and working on the CDI processor it self is not unknown to me.

I have a imitation SP 4DL cylinder lying in my workshop using that one will be quit easy.
http://www.tzr3ma.com/imitation-sp-cylinder.html
But then I'll be ignoring my own hobby and just go the easy way.

Like to do it step by step

The 3MB engines are not really designed for racing, they were great for reliability and commuting. But they do lack that oompf for performance.
That is correct the 3MB engine is not ideally for racing (also the gearbox is not good for race purposes) The 4DL engine is better but far from perfect its just better.

The older three wire Servos ran a separate unit to control the Powervalve I believe..
Yes the CDI runs the servo motor with a separated ypvs rpm signal
http://www.tzr3ma.com/tzr125-4dl-ypvs-measuring.html

A Rotax engine would suit that bike tenfold and in stock trim would be far superior to anything the 3MB engines could be made to do

If we keep it yamaha related and i could fit a TZ125 engine in it (and start with 40HP)

But no, will use the 4DL engine and go from there.
You will like the ideas what I'm planning for it

Hello Calum,

''What is the engine. Is it just a vanilla 3MB or is it the Belgarda SP barrel''
No, its for now a bone stock 3MB engine. (''vanilla'' )

''If you want a solid stock track bike then you need the SP which is incredibly rare to find''
Yes the SP engine does have the best papers, but the question will be how much better.
Its not that a SP engine starts wit 40HP at the back wheel.

May I say that a good 3MB (belgarda) has about 28HP at the rear wheel and a SP engine (around) 32-33HP
That about 5HP differences,
With some relative small changes you can get the 3MB (begarda) to 30HP as the SP engine is more difficult to change do to the nicalsil setup.
Also have my doubt regarding the inlet, the reedblock is bigger, but not enormously bigger. If you look to a TZ125 reedblock or 3MA reedblock they are bigger than a SP one

''If you are looking for performance and want it stock then it kinda looks like you have done all you can. Removing the weight is essentially your best friend in that respect''
Don't want to keep it stock, but my starting point will be a stock engine.
And measure the changes on my dyno when i have changed something.

The problem that I read on forums is that the tune the whole engine and measure it on the dyno.
Going (example) from a 25HP to a 30+HP but what does what.

I like to do it step by step and measure it

''The best bang for buck you can get is the Zeeltronic ignition system. It's jusf going to make the bike come alive.''
Yes fully agree with you, have two of them lying in my workshop.
But first like to see how far you can get with using the stock components (changing them a littlebit of course example by changing the pickup location)

''Also the YPVS is controlled by rhe CDI on the later DTR's. So changing the motor is going to achieve nothing''
Ok, but the first models do have the three wire setup?? all 3MB servo's
The example 4FL also have a three wire servo (if i'm not mistaken) it has a different part number so perhaps it has a different opening curve (could be)
Same idea for the servo's used on other models, like to know if the opening curve is different on them.

''Even then for a trackbike YPVS is unnecessary, the bike should never be dipped below 6000 RPM and that's what the powervalve helps with''
Fully agree with you, but sadly I'm not a GP driver. Just a hobbyist.
There will be a point that i may have picked the wrong gear, or something happened etc etc then it will be nice to have the ypvs kicking in.

''Replace every nut and bolt with aluminium to save more weight. Really tighten up the aerodynamics as well to reduce drag''
As I say I'm just a enthusiast. I'm 1.98m and about 100kg not even suppose to ride on a 125.

Just like to ride my rounds, and feel the differences I made.
Keeping it a hobby is important
Let the young guys race, let me ride it and having fun.

''As said if you want it bone stock then that's about all you can do''
Have a feeling I can do more
Will post it here

But nobody have tried or measured the ypvs openings curve from a 4FL or sachs, GPR, ect ????