TZR125 4DL (track bike)

[Calum]

@louis A bone stock rotax 122 is 26 bhp.

But they still use these engines in the super teen 125 series. Very good engine.

I am saying the bone stock rotax engine is better than a 3MBP 4DL. It's about on par with the SP engine.

[louis]

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.

[Calum]

@louis I ran the full engine bud, the casting on the engine wad appalling compared to the DTRE engine.

I think we will have to agree to disagree about the engine output of the Belgarda 4DL engine. I was under the impression that the 4DL engine was going to be a monster. But it was poor.

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.

Again I don't dispute that the SP made some magical numbers due to its limited production, but the basic 4DL 3MB00P engine is nothing fancy.

As said it's just a basic engine is all.

[louis]

''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

[Calum]

@louis You definitely sound very knowledgeable that's for sure!

[Darty]

@louis Welcome to the forum,

Really enjoyed your website.

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.

The tuning will be for pump 97 Octane.

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.

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.

There is not much information about modified 4DL's and I have always believed that the 4DL Y-1/Y-3 was only good for 22-23bhp in stock configuration?

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?

What are your experiences with altering squish height with a 4DL? very interested to gain some insight.

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.

[louis]

''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

[louis]

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

[Calum]

@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.

https://www.youtube.com/watch?v=n8NCG4xdbqY&list=PL66C1264C7D6205BB

https://www.youtube.com/watch?v=SQuHkq-22Xo&t=58s

That's my experience with the engine you're describing and it is not 30 bhp.

[louis]

''@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

[Calum]

@louis 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?

It may very well be different in your country, fuel octane will make a huge difference.

I'm just telling you how it is, these bikes don't make anything near 30 HP.

[Darty]

@Calum I'll dyno mine and we can square this up...

I thought 25hp max,

[Calum]

@Darty What you running?

There is a bike dyno near me, it's just never bothered me. Figures don't mean jack, it's how it goes on the roads/track that counts.

[Darty]

@Calum To be fair, it is something you need to do.

How will you tune the PV or Ignition timing without a couple of Dyno runs??

Can't just bolt this stuff on and expect the best results.

The data will tell me how to tune it all together the best I can.

Still, a stock (de restricted) Aprilia RS125 and Kawasaki KDX125SR will probably have similar numbers to a tuned DTR.

So waving HP numbers will be kind of pointless anyway.

But mine is lovely on the road so far, considerably more torque!

[Calum]

@Darty It's an all day event if you are on a rolling road lol. You could spend an indefinite amount of time sorting the maps out.

You can get "good" enough results just going up and down the road.

[Darty]

@Calum Nah, you can be happy getting good enough results after a few power runs. A day would be enough for that.

It's just I can't measure or test progression with a tune that accurately just going up and down the road. Feel isn't enough.

Too many variables.

I've spent far to much just to make do.

Incremental tuning, true could spend weeks on a race tune.

Go balls out, what's left after that? Job done for the summer.

[louis]

@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]

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

The 25HP is this with your latest setup?

[scrimsmustang]

@louis

Interesting, most powerful stock from the factory DTR,s are the first 4 years of production. The 1988 models, code 3BN1 is the european full power model sold in France and Italy, code 3FW1 is the Japanese full power model these are all rated at 21.4 hp. The restricted 1988 code 3BP was also sold in France, 3DB1 in the UK.

First of the full power flatslide carb 1989 models are codes 3PY2 for Italy and 3RM1 for France rated 22.9 hp. Restricted 1989 model code for France 3NC1, 3RN1 in the UK. Pretty much stay the same for a few years after.

[Minia]

I sort of understand what calum is saying. But personally, I'd run it by the numbers. I have no experience with rolling roads, Dynos and rebuilding engines etc... But I have plenty of experience with getting the maximum of performance out of computers. Now you can build yourself a nice rig and all and it can run your programs, engines, games or whatever absolutely fine. But if you don't tune your rig and set it up properly, then you're just losing some of the extra kick. And in which case, I then have to go and run the numbers

If you're happy enough with a smooth ride, that's fine. If you want to push it to the limit then you'll need the numbers.

https://www.youtube.com/watch?v=9D-QD_HIfjA