Yamaha Dt175 Mx Porting and Polishing
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- čas přidán 3. 06. 2022
- In this video I show you the process of Porting and Polishing a late 70s Dt175 Mx barrel.
Follow along to learn how its done!
This Porting/polishing should definitively add a few more hp to your Yamaha if done Correctly so why wouldn't you. - Auta a dopravní prostředky
Polish the exhaust, not the intake side.
Awesome work man! I have two 81 DT175s in the shop now and going to try this out on one and hopefully not ruin it haha.
Thanks man appreciate it, you will be fine just take ur time and it will run sweet as and I'm keen to hear how it goes for ya aswell.
Very nice work, you can be proud of yourself.
However, you don't actually need to reach a mirror finish. The experts I spoke to recommend that you stop at about a 180 grit, taking pride in your work is another matter, and I understand, especially when you have to show a client what you did, that doesn't fail to impress.
But it's proven that air flows better over a slightly coarse surface than it does across a mirror smooth surface, boundary layer and cohesion something, they stack, create drag and laminate, why it's called laminar flow to begin with... I'm not a fluid dynamics expert, I just heard it explained during a demo - but I was blessed to be able to see the principle in action.
I still can't help myself but get a mirror finish either, so no flak, just some food for thought.
Laminar flow is actually not what you want. Dimples like those on a golf ball, that's the next step forward, because they decrease drag. Counterintuitive as it may sound...
Dam that's some pretty advanced stuff, thanks for sharing I love learning new things.
I was going to post up and say the you should not polish ports that have 'wet fuel/air' flowing through them but you beat me to it.
Biggest gains are in the exhaust port and timing of the ports. Opening up the transfers by the base has no effect if you haven't opened them up by the actual port into the cylinder. Opening the boost port can loose hp also. I would suggest doing a lot of research on this subject. Too many people have theories. Only listen to those who have tried and tested it
I didn't explain in the video but that's what I did, spent hours researching on what problems need to be fixed on the dt175. Also talked to several friends at road racing who raced dt175s back in the day and what they did to get em to howl.
I didn't want to go to far as a lot of people do and make a junk barrel.
So far bike is going great 😁
Nice video. How much effect does this have? I mean, do you have some before and after stats? :-)
I have a later dt175 that I did this porting on, along with some other mods, carb, reed cage and pipe.
It's now a lot quiker than standard, maybe 5-6 Hp more
Will it affect emission?
It will slightly increase fuel consumption but you will get more hp as a result!
Hi bro I am India Yamaha dt 175cc engine spare gearbox which country bro
So do you need a gearbox or have one spare? Country New Zealand
Cheers Logan
Hi mate iam from india i have dt 175 head and cylinder
Don’t polish the intake side. Great channel though keep pushing along with the casting excited to see how it all goes
Yeah I may have gone slightly over board, yep should have another casting video in a couple weeks, so much to learn!
@@TheMotorcycleForge very industrious and motivating for me watching you designing something and producing it all in house I’ll be watching intently casting something at home has always been a dream of mine.
Yeah Gary, it's a ton of fun and I highly recommend giving it a go yourself!
Better to have a rougher surface texture. Orange peel oh shark skin texture.
Yeah well I wanted to test it out and it went surprisingly good
Not trying to be rude but that has got to run like shit. You are not supposed to polish the intake due to needing fuel and air atomization for a better and faster burn. With an intake polished the fuel will bead up and not flow. How ever, for the exhaust side, what you did to the intake is needed on the exhaust. Little to no performance will be made by only cleaning up casting flaws. Best way to make power out of porting is to, well port. Change the port timing on the exhaust and the transfers. Exhaust duration is where power is made. Higher degree the higher rpm the engine will perform better at. Transfer and basically your power curve that isn’t ignition timing. Transfers a big thing due to blow down. Take this for an example, exhaust makes power, everything else gets tuned to it. Otherwise everything looks good. Remember to keep intake corners rounded or a dull knife edge. Depending on your motor, you can knife edge the transfers without a dull but some people round them off. i’ve always kept a sharp angle on the transfer dividers for case port matching. I am a 14 year old kid. i know quite a bit but lmk if i got something wrong. Thanks! i hoped this helped.
You don't know till you try kiddo, you might learn something, also did you actually watch the video?
@@TheMotorcycleForge yes i did. I watched the entire video. Ive always kept atomization but with a polish like that i bet it flows like no other
@@done-wright_performance Much appreciated, I plan to do a video on testing the hp difference between the surface finishes, seeing which one has the most grunt, my gut feeling is on a air cooled engine it probably is pretty similar but will have to wait and see.
Most of the charge except for whatever slips through the boost port will go into the crankcase and be atomised there as it goes through and up into the transfers. If i remember correctly most of the boost port charge will act as an exhaust scavenge and probably get plenty off atomisation during that process especially with a good pipe.
"Run like shit"... a bit harsh! 🙂 Just cleaning up the ports will make a small difference but like you say you need to change the port timing if you want to make any big changes, having said that there is only 'so much' that a stock exhaust will allow. Yamaha designed the port timing to allow the engine to operate in a certain way, I guess you could call this its "performance envelope", you can change this envelope or shift it around but it will usually cost you something somewhere, maybe low end performance or maybe piston or crankshaft life. I had a DT175 MX years ago, I did a fair amount of work on it, it went very well, there is performance to be gained by sorting out the cylinder head. The nice thing about 2 smokers is that they do allow the home tuner to fiddle about with them. (I have an Honda MT5 moped, I had one forty years ago when I was 16, my current one is running up to an easy 55 MPH even with my bulk on it!). Anyway you seem to have gained good knowledge especially as you are only 14, keep it up!