yamaha dtr tuning and adding extra ports help needed

[reggie]

right my dt goes quite well as you can see here


https://www.youtube.com/watch?v=RqyZm7UqGnE

but i want more from it so i got thinking and after about 4 hours with a dremmel i got this


https://i142.photobucket.com/albums/r93/robin_crash24/dtr%20125/DSC00274.jpg



https://i142.photobucket.com/albums/r93/robin_crash24/dtr%20125/DSC00273.jpg

https://i142.photobucket.com/albums/r93/robin_crash24/dtr%20125/DSC00269.jpg

https://i142.photobucket.com/albums/r93/robin_crash24/dtr%20125/DSC00268.jpg


https://i142.photobucket.com/albums/r93/robin_crash24/dtr%20125/DSC00264.jpg


the above barrel is not finished

ive added exhaust bost ports like the tzr sp to a spair barrel ive got im also makeing the transfer ports huge and planing on matching them to the crank case

im thinking it would be wide to add a bigger carb aswell


please commen on what else i could do to improve it [/list]
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when the shit hits the fan make sure its facing the other way.

[chris-red]

[Blau Zedong]

You do know that just scalloping big lumps of metal out of 2T ports doesn't equal massive power? I have visions of hair trigger power delivery and ten minute piston life looking at your work so far.
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[Gazdaman]

The boss at Yamaha is kicking themself.

He's just fired their entire R&D department and hired a retard with a dremel.

I have a two stroke tuning book, and it's the most complicated thing I've ever read, I was seriously lost after the first two pages.

That'll never work properly.

Gaz

[iooi]

Hands up for rings bust in seconds......

You do realise that sometimes small is better, as it increases the speed of induction,which leads to better air/fual mix and more bang per buck. Make it bigger and while in can increase the capasity for more air flow. It does not mean it will, it won't be mixed enough, or will actually decrease power.

If it was so easy, do you not think that there would be no need for larger cc kits for bikes

Still nice try
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Just because my bike was A DIVVY, does not mean i am......

[chris-red]

This is on a level with the guy who used water the flush out the engine of his mustang, or the guy who ran sand through his intake to port his car.
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[DrDonnyBrago]

[gearboxkart]

jeez and i thought raising my rd350 ports 1.5mm was pushing it !

[G]

[smegballs]

Yamaha is da 2 stroke powaaah masters innit tho...

I take it you didn't do any sorts of calculations at all, just went nuts

From what I've read, even if you slightly enlarge the inlet and exhaust ports, only real masters even think about touching the transfers..

If you felt that passionate about it, why not just start by cleaning up the castings, trimming gaskets to fit perfectly etc etc before going all Two Stroke Dremel Massacre on its ass.....

[27cows]

I've seen mods like this actually work. You'd be surprised how useless the R&D of most Jap manufacturers is...which is how the vast Honda corporation came to launch a major new bike which destroyed its motor because of a glaringly obvious yet simple to rectify fault (VF750).

Main problem you have is that the port isn't cast. Drilling a new hole rather than working with what's already there will probably cause complications. I'd be surprised if one of the rings didn't catch, but then who knows.

At least this guy is showing some spirit of adventure, instead of just getting some tedious plastic clone bike. People used to do mad shit like this quite often in the 80s. Now and then people come up with something sensational (I can remember the idea of putting a Powervalve 350 motor into an RG250 chassis being dismissed as idiotic...until someone tried it and it actually produced a bloody good bike ).

Having said that, I do think the motor will probably destroy itself after half a mile. Either that or produce about 40 horsepower and go like the clappers
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[radical]

Just drop in a dt200r engine (30-33 bhp) if you can find one.

[Blau Zedong]

[reggie]

i have about 5 spair dt barrels i can aford to fuck one up!

the barrel on my bike i have cleaned up the transfers matched ports to the crank case, matched the exhaust to the it made a little improvement

i have not rased the exhaust pot at all

here are some pictures of somone elses atempt but with much better tooling




https://img219.imageshack.us/img219/239/walzedll00bsu2.jpg

this is were ive got the idear from




https://img194.imageshack.us/img194/9419/spzylauslass.jpg


tzr sp barrel



some of you sat the rings wont last/snag if thay can manage to not geting snaged im sure ther can cope not geting stuck in the side ports
____________________
when the shit hits the fan make sure its facing the other way.

[DrDonnyBrago]

Post a video when you are done, we will all be interested in seeing it regardless of how well it worked. .

[gearboxkart]

if you want more top end zing and narrow the power band you need to raise the exhaust port, easiest way on my rd's was to put 2 bottom barrel gaskets on and either skim the head to get the lost compression/volume back or just dont fit a head gasket ! that works on some but not all engines especially water cooled motors, i had my rd500 done by stan stephens donkeys years ago and the difference in power was amazing but looking at what he did you couldnt actually see any difference apart from all the transfer ports were polishes to a nearly mirror smooth finish, 2 strokes tuning is an art but when done properly on a decent motor is wicked, if you want decent power go look around for a 125 moto-x engine ! pretty easy to fit with a few engine mount mods and you will have a screaming demon

[reggie]

[Kickstart]

[gearboxkart]

polishing of all the ports was to remove all the stippley bits of ally from the original castings, all the ports were re-profiled but all transfer ports are polished to get as smooth an air flow as possible, if you look at a std barrel all those stipples have the air flow bounching all over the place, if you get a chance to look at a race motor 2 stroke the transfer port galleries are like polished mirrors.

[Kickstart]

Hi

As I understand it the rough finish on ports is actually a marginal benefit. Stops the airflow "sticking" to the walls. Same effect as the dimples on a golf ball. But people who have paid to have an engine tuned like to see the polished effect to think they are getting their moneys worth.

All the best

Keith
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[reggie]

[chris-red]

[27cows]

[Blue_SV650S]

This is cool ...

Have you checked that the ring end pins (and chance the end gap) aren't now running over a port*???? if they are, then don't even bother running it!!

If not, then go ahead!!

You might also want to consider some transfer windows in the piston or cutting a bit of skirt off to increase inlet duration ..

You also need a free flowing 'zorst ... and some bigger jets no doubt!



*probably on the back side to be honest - not where you have been playing - but worth a check!
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[reggie]

i have trimmd of the bottom of the cilender because it interpts the flow from the reeds and had no use as the piston never makes contact with it

im thinking of adding a 1mm thick alumineum base gasket because when the piston is at tdc it still dose not become levle with the bottom of the ports i will ned to get some matereal trimmed of the head or barrel to get back the lost compression
____________________
when the shit hits the fan make sure its facing the other way.