Hand made exhaust for cr 125 97 engine (PROJECT X)

[Crimas]

Look this, a new project for honda cr 125 of a friend, a total hand made exhaust for his 97 engine, I expect much more power, just a little preview with 3D paper model, fit perfect in the honda frame

[Sandblaster]

Wow!
That is sweet!
What software did you use to create the sections?
Also, how did you determine what sizes to make the sections as this will make a huge difference in power at specific RPM's?

[Crimas]

i have used plate'n'sheet professional to create a 2d draw from the 3d cone, autocad 2D to model the cone and make modification to fit exhaust on the frame and autocad 3D with loft command to create a fast 3d model for verify the right dimension
for the question about the determination of the right sections of the exhaust is a exhaustmaker secret hahahahahahah
seriously there isn't any secret, there are only a lot of calculation for determinate the right dimension of the exhaust, a lot of factor, rpm, piston port lenght, angle of the cone ecc, i have a simple program to calculate exhaust call exhaust calculator 2.0 but non isn't always accurate and be careful
For this exhaust i have taken the dimension from a messico pipe, cut and welder for a perfect erogation but a lot of crash have broken the exhaust and compromised the performance of the engine so i make my personal copy of the exhaust

[Sandblaster]

That's a great idea, very impressive.
I want to see your 97 on the winners platform this season
Just curious, will you be racing against the 250F's or do they have a 125 class in Europe?

Here is a pipe design I was looking at for my KX500SM:

kx500 custom exhaust.png (682.86 KiB) Viewed 14649 times

It would be a lot of work but you know that

[Crimas]

this is a real massive exhaust
have you made you this?
in italy if you have a 125 can ride with 2t 125class or with 2-4t mx2 class, but in mx2 with 2t in very difficult win against 2013 250f bike with more power and tecnology, but in the track behind mi house last summer race only 2stroke 125 and 250 win because the pilot was very good and ride every week in the track(is the owner of the track, he can ride when he wants xD) so if you can ride fast you can win also with 87 honda cr 125 against crf250 2013 all depends to the pilot's throttle, there are some pilots that ride 125 and the sound looks like a chainsaw xD
i don't know how the engine can run all at full throttle without blowup...

[Sandblaster]

Yeah, that exhaust is for a KX500 so it has to be HUGE
That is good they have 2T 125 classes where you are at.
I suspect that your 97 will be very competitive.
Again, nice job on the mach up, I really like what I see.
What about your cylinder, any port work?

[Crimas]

thanks but the bike is not mine, is owned by a friend but have a very excellent motor, the best 125 2t ever made by honda, but i ride it a few time on track and was very good, the cylinder il light porting, here a photo

the engine has enough power it doesn't need more power with additional porting

[Sandblaster]

Nice.
I am getting ready to port one of my cylinders then send it in for plating.
I will only do minor porting on this one.
I have two others that I need to do as well.
Each I will do progressively more radical

[Tardboy]

Wait that cr pipe is made from paper?

[Crimas]

Wait that cr pipe is made from paper?

yes, is a perfect real model of the steel pipe built with paper and paint
this is a simple 3d model drawing for check the right dimension with the cr frame