TZR125 4DL TRACK BIKE

[Martin77]

The V force made a very nice gain on mine at the top end...

I'm sure you've read a lot of info on the web about ratio of lengths, and rough diameters etc.. so I will just say personally I would aim for a total length from flange to the end of the baffle cone of about 900mm would be about right. This is to match the current curve peak rpm. (I would also suggest 32mm start diameter, 110mm belly, and 22mm stinger..but perhaps make an adapter at the tail end so different stingers can be slotted in and tested)

When I measure curvy pipes I break it down into sections, (header, then the diffuser etc), measure around the outer edge, then inner edge, add them together and divide by two to get an average. It's still really hard to be 100% accurate!

[2stroke]

That is good info for me regarding the rs125's, Interesting thing about the carbs, do the rs125 riders have good results with the use off a 34mm carb or do they all use the 28 or 30mm?
35Hp seems far away for the tzr125 at the moment.

Once, I've read on a technical magazine that a tuning specialist obtained 37,5 hp out of a RS 125 using a 37mm carburetor with handmade reed valve!
 
The Sport Production Championship in Italy during the 90's obliged all the bikes to have a 28mm carburetor. So the factories developed this solution with excellent results, expecially because on the tracks they are looking for maximum power at the highest RPM. So the 28mm with a perfect carburetion plus a racing exhaust did amazingly the job.

Since there was this limitation, almost nobody brought the 34mm carburetor solution to its limits :  so who can tell if a 28mm works better of a 34mm?   

The only one remark we can do regarding the Yamaha 3MB/4DL bikes is that the 32mm VHSA is more a "racing" solution than the 34mm VHSB. Another remark is that the TDR 125 R with the same (stock) engine and 28mm carburetor instead of 32mm, has 4hp less than the TZR 125 R. These four hps come straight from the carburetor and the exhaust. 

About the V-FORCE 4, this reed valve has twice the useful area for the flux of the air-fuel mixture: reed's stiffness and thickness are calibrated in relation to this peculiarity. The differences using a 34mm versus a 32mm carburetor could be minimal. This is a great upgrade.

By the way, I am preparing my new intake manifold with optimized and revised flows to make the most of the pressure waves and the original reed valve. We'll  see how it will go in the first tests, I'm really curious! 
As soon as I'm ready, I'll post something more on the forum to get you all involved. 

[casal-fan]

If someone has suggestions pleas let me know. The more info/ideas I get the better it will be

Ok, here it goes, you asked for it
Louis, have you tryed to check if main jet air correction on the dellorto can be changed?

Will try to explain myself, and please notice that this is only my opinion.
You got good results on the midrange by going bigger on main jet with the 34mm. This could be, and I underline could be, because the lower temperature on the pipe at midrange caused by the richer jetting, got the pipe working better in the midrange… but then the topend got rich and you loose both pipe efficiency as well as revs that also give you HP.
A bigger main jet air correction could maybe bring you the top end power back, if not more?
Hope you understand what I mean.

Anyway, the results are already very good in my opinion.

[Louis]

Hello Martin,

The V force made a very nice gain on mine at the top end...

That would be great if that does the same on my bike.
I don't aspect much gain, but if it creates a solid 27,5HP I'm happy

I'm sure you've read a lot of info on the web about ratio of lengths, and rough diameters etc.. so I will just say personally I would aim for a total length from flange to the end of the baffle cone of about 900mm would be about right. This is to match the current curve peak rpm. (I would also suggest 32mm start diameter, 110mm belly, and 22mm stinger..but perhaps make an adapter at the tail end so different stingers can be slotted in and tested)

First I'm gona try something stupid if that works I know witch dimensions I need to play with.
If its not working as expected, then I'll go back to the drawing table and I will be consulting you with the designs I created

[Louis]

Hello 2stroke,

The Sport Production Championship in Italy during the 90's obliged all the bikes to have a 28mm carburetor. So the factories developed this solution with excellent results, expecially because on the tracks they are looking for maximum power at the highest RPM. So the 28mm with a perfect carburetion plus a racing exhaust did amazingly the job

Do you know how much power those bikes had? Where they all above the 30HP

The only one remark we can do regarding the Yamaha 3MB/4DL bikes is that the 32mm VHSA is more a "racing" solution than the 34mm VHSB. Another remark is that the TDR 125 R with the same (stock) engine and 28mm carburetor instead of 32mm, has 4hp less than the TZR 125 R. These four hps come straight from the carburetor and the exhaust. 

That is one way to see it

By the way, I am preparing my new intake manifold with optimized and revised flows to make the most of the pressure waves and the original reed valve. We'll  see how it will go in the first tests, I'm really curious! 
As soon as I'm ready, I'll post something more on the forum to get you all involved. 

Im interested to, still have my own special engine to build.
Would be nice to see in what direction in need to go

[Louis]

Hello Rui,

Louis, have you tryed to check if main jet air correction on the dellorto can be changed?

The 32mm has the bleeding emulsion tube, sadly the 34 does not have the bleeding type. (it has the closed emulsion tube)
I can't change jets

Will try to explain myself, and please notice that this is only my opinion.
You got good results on the midrange by going bigger on main jet with the 34mm. This could be, and I underline could be, because the lower temperature on the pipe at midrange caused by the richer jetting, got the pipe working better in the midrange… but then the topend got rich and you loose both pipe efficiency as well as revs that also give you HP.
A bigger main jet air correction could maybe bring you the top end power back, if not more?
Hope you understand what I mean.

I know exactly what you mean. But sadly I can't change this on this carb

Anyway, the results are already very good in my opinion.

Thanks, with a bid off luck I can dyno the V-force this weekend

[Louis]

As Promised, tested the V-force today
Must say, they work better than a modified one.
On average they gain 0,4 a 0,5HP more and let the engine rev about 200 a 250rpm longer

Green V-force Red modified oem reedblock

A  bid more here: http://www.tzr3ma.com/dyno-results-v-force.html

Currently at 27,7HP with oem ignition and shorted stock pipe.

Next step is doing something stupid if that works I report back
If it not working you will be reading it somewhere on my site placed in a corner

[nic fan]

cool about time you had some positive results Louis after all the work you've put in.

[Martin77]

Is that with the 34mm carb? Would be interesting to try it with the 32mm as that seems to work best so far. Good improvement, though not as much as you'd like..

[Louis]

Hello Steve,

cool about time you had some positive results Louis after all the work you've put in.

Thanks, they are small steps. But in the end I will get there

Hello Martin,

Is that with the 34mm carb?

Yes this is with the 34mm Dellorto.

Would be interesting to try it with the 32mm as that seems to work best so far.

If my stupid nexst step is not working ill try the 32mm again

Good improvement, though not as much as you'd like..

Of course I had hoped a little more, but on the other side 0,5HP for only changing the reedblock is not bad either.



We could say the inlet is free off restrictions now (not much more can be done,without disable the whole engine)
Think the exhaust is limiting the HP's right now

[Louis]

Today I tested a Jollymoto SP exhaust.

I have done this for two reasons

1) I need to have some indication dimensions to work with in order to make my own exhaust.
2) Now I have two comparisons exhausts on the same setup witch gives a good indication witch direction I need to go.

I have made exhausts for the 3MA who are relative simple (completely straight) but now I need to make them with a bend which give a lot off work more.
Before I spend days and days working on a pipe who will not work correctly, I like to know in witch dimension I can play with.
And that I have now.

Back to the SP exhaust.
Must say I had hoped to see more, it gained me only a solid 1HP
Also it has a strange wide peek curve, witch I like to leaf out on my own pipe

Currently having a solid 28,8Hp


Jollymoto vs Changed stock exhaust


More info here: http://www.tzr3ma.com/dyno-jollymoto-sp-.html

It is still running with a stock ignition. (set 8 degrees more)
Next step will be to use the Zeel, now it can be set correct....

Don't expect to gain a lot from that, but perhaps I can squeeze it to a solid 29HP

Will continue my quest

[Martin77]

That's actually a really nice gain in my book, but I think the shape of the curve (the flatter peak, sharp drop off and step at 9500ish) suggests there's more to come with the zeel, as you can match the pv and ignition to the Jolly moto, and possibly get that sharper peak you want, along with better overrev.

I'm sure the Jolly Moto sounds much sweeter too!

[Louis]

Hi Martin,

I don't know perhaps its good, I only expected a bid more

Like to try the ignition first, and see if I can push it a bid more with a better advance curve.
Programmable ypvs will be the next step (need to score a ypsv motor first)

I still think its a somewhat strange peek curve, certainly did not expect that

I'm sure the Jolly Moto sounds much sweeter too!

Yes its makes the renga deng sound
https://www.youtube.com/watch?v=rVHtpfYQK1o&feature=youtu.be

[Martin77]

You need to adopt an objective attitude to testing.. 'lets see what happens when we try.....' rather than hoping for certain gains. Sometimes when things don't work you learn as much as when they do. Which is easy to say and harder to deal with in real life!

In real life, that little kick at 9500 would make it fun to ride.. mine has a similar kick and when you keep it above that point through the gears it's great..

Are you going to be able to take it out for real this year?

[Louis]

You need to adopt an objective attitude to testing.. 'lets see what happens when we try.....' rather than hoping for certain gains. Sometimes when things don't work you learn as much as when they do. Which is easy to say and harder to deal with in real life!

I can follow you on this, but my mind is fixed on getting that stupid 30HP (because I sad I would)
Ones I have reach that point I can give it more thought witch part does witch part and ease my mind a bid.

Whole internet is full of RS125's and MITO's that goes easily over the 30HP, and I'm struggling to get 28HP
Sometimes I think my little positive dyno went (after the correction) to a negative dyno.

Just need to find 1,2HP more and I can close this book

Are you going to be able to take it out for real this year?

I hope so, but wont make a promise