DT125R ARCHIVE

zander · DTR Senior Member

Germans opinion on Athena exhaust :)

zander · DTR Senior Member

"The Athena was a really good exhaust! My Topspeed was between 135-140km/h by 11500RPM... He get the most Power of 7500-10000RPM But i had other tunings too:
My setup was:
Athena exhaust + Silenzer
32er Dellorto from Yamaha TZR
No Snorkle and make the "Airboxhole" bigger
Make the YPVS with the Sandpaper more smaler for higher RPMs!

I tried the Dep and i dont think it went better then the Giannelli(restricted one) or OPENED ORIGINAL exhaust. All these
exhausts didnt bring the power that the athena bring.. The ATHENA have the highest RPM and a better acceleration too ! Yes the 32mm Dellorto made a really good topspeed of 138km/h measured by police! biggrins 0-100 in 6,3seconds thats very good for a dt! How i shoud explain that with the Ypvs^^ My english vocablary is not perfect.. I made with the sandpaper a little Dremel miller the Cylinder- Exit higher than can the explodet gas earlyer out and than you get higher RPMs! i dont know what the english word for Auslasssteuerzeit sry! Zunge rausstrecken
Here a video with athena ;)

http://www.youtube.com/watch?v=dfvp9gi-oco "

AND

"Yes I did!
Till now (I just changed the main valve of the carburator) I must say it's not a big difference. Though I have to change the clip position of the needle. You have indeed more torque. In first and second gear you have to be a lot more carefull. She want's to lift her front wheel biggrins
The top speed was at 120 km per hour. That's about the same I reached with the original exhaust system. Though I have to say, she got faster to the 120 km/h point.
Oh and the sound is way better! Till 6k rpm it's as loud as the normal one (good if you don't want attraction..) but if you rev her up. She get's nasty "

Calum122 · Guru

I really doubt that it's going to make too much difference mate. Either one's good. It'll just come down to personal preference. Our RE's don't rev to 10K so that aint going to help.

The DEP looks sweet. Havent seen the athena I'll just Google it. But either one you'll be happy with.

Lots of people on here have the DEP system and are very happy with it. I stick by the belief that you pay for what you get for.

Calum122 · Guru

If it's that black exhaust then I'd say tada sausage.

The chrome DEP really sets the bike off!

Makes it look badass. Probably High maintenance tbf. You spend £200 on it you'll want it to stay chromed up mush lol

zander · DTR Senior Member

I see...

Is it the cdi that's restricted on the RE/X ?

Calum122 · Guru

CDI is yeah. You'll need to change it for an R CDI. But a later model since earlier CDI's run on different Coils and generators.

zander · DTR Senior Member

Oh didn't see you wrote in the other thread of mine.. does that make the YPVS shut after 10 000rpm? or does it restrict the ignition?

Calum122 · Guru

I'd imagine it's both. The YPVS DEFINATELY retards. You can feel the power slip when you climb the revs. I know that our CDI's are restricted. So it's probably a combination. There's that derestriction to the YPVS where you earth the wire. That's suppose to stop it retarding but I didn't feel the difference. But if it did then yeah it's got to be the ignition.

zander · DTR Senior Member

I felt a huge difference when I earthed the wire, tried unearthed and wouldn't rev anything at all xD'

wierd though if NorDT has high rpm exhaust it doesn't retard, I don't think he's done anything to the cdi

Calum122 · Guru

Well then I best look at how I've eartherd that wire my friend haha!

If it is reving higher than 10K then happy days like. I know my 04 DT RE doesn't. Not in 4th, 5th or 6th gear. Just turns into a 4 stroke and climbs speed slowly.

zander · DTR Senior Member

I think your wire isn't earthed properly if you didn't feel a difference, for me it was huge,
When unearthed, and I drove in like 2nd gear and keep going without gearing up, it would just stop and a certain RPM and then go almost constant :D
hahaha XD

Calum122 · Guru

Yeah. That sounds like the YPVS retarding. O well you're the first person I've met who says they've felt a difference. I'm going to have to do that then matey.

zander · DTR Senior Member

I don't think the RE/X is any restricted in the CDI, maybe at like 12k-13k just to make you not overrev the engine :P

Calum122 · Guru

Well unless you've got a rev counter you'll never know.

All I know is, is that my bike won't rev past 10K

zander · DTR Senior Member

But if you didn't notice any difference when unearthening it, it's most likely it aint earthed xD

Try locate where the cable comes out from the cdi box, and make sure it aint broken anywhere, and look where you've earthed it, if it's earthed properly to the frame

Also, if you drive pinned open and you still cant get past 10k, it's cuz of your exhaust, cuz DEP aint high rpm exhausts, same with stock pipe.. I know Gianelli is, and they have a powerband to a bit above 11k rpm. I think thats why gianelli is faster, cuz the powerband is a bit higher... (NorDT told me)

With my stock pipe, I have quite good acceleration from maybe 6k to 9-10k rpm, but you can feel it loosing power when you get above 9k-10k rpm.

But it aint possible that you have another cdi on yours that restricts the ignition , I heard the german imported ones got really weird restrictions, like throttle restriction , maybe even cdi restriction not sure..

zander · DTR Senior Member

Well when you gutted your exhaust, did you remove that cone of sheet with holes in it? That's the main restriction in the RE/X's exhaust, the honeycomb thing is a smaller restriction... did barely notice any difference when I removed the catalytic converted, but when I removed the cone thingy, the bike got 10km/h faster and I were able to pull wheelies in 1 more gear... the powerband increased a small bit, not much though... but the stock exhaust is a low rpm performing exhaust anyways

-- Edited by zander on Saturday 18th of August 2012 07:52:05 PM

Calum122 · Guru

Well my expanny is stock gutted. The DEP full system won't stop you from reaching high RPM. It's designed for high air flow. It's a racing exhaust so it's suppose to be capable of any rev range. The way you design different pipes is to make the rebound sound waves force induction back into the cylinder at a certain RPM rev range. It will induces resonance which will see in a peak performance before it drops off again. That said it won't stop the rev range from reaching its max. Unless it has a restriction in it stopping the air flow.

Unless you've got an RPM counter install you won't know what your bike is actually doing.

Energized · DTR Legend

+1

My dep allows my DT to rev to 12,000 rpm.

AndyYam · Guru

The YPVS won't be restricting the bike at high revs. Asking as th YPVS is set the right way around and the servo motor is controlling it it will only be affecting the bike up until 6krpm. By this poInt it is fully open and the exhuast port is as it would be without the YPVS and the bike is running at its optimum performance ( exhuast port height wise).

As said before the the sports pipes will generally be giving more of a power band by offering peak performance around 6-9krpm. When racing it would be rare to be dropping out of of the power band much and he YPVS picks up any slack there. I personally will always go for a stock yamaha exhaust or an Athena. Yamaha, having designed that engine will have designed an exhuast to give optimum performance whilst retaining the reliability factor. Dep will offer more performance within a range and will be lighter but the yam pipe will be a better all rounder.

Which leads on to he Athena. They make gasket sets for the bikes and as many will know offer gaskets made in the same factory to he same quality as Yamaha. No one who wants their head gasket to last would trust any other pattern gasket for the head. This leads me to believe that Athena will be basing their exhuasts closely on the yamaha pipe but without the restriction and probably a lot lighter. If I were buying an aftermarket I'd go for an Athena. I've got a dep on at he moment as it came on the bike. As soon as I can get my heat shield off my de restricted 3mb I'll be painting it and putting that back on.

All my opinions there nothing solid but seems to make sense to me.

zander · DTR Senior Member

http://www.rrd-preparation.com/en/Exhaust-silencer-for-motor-bike-125cc-2-times/1699-product-1699.html
a bit closer look on the athena exhaust, put your pointer over the pic and you get a close zoom :)

Read the info on the page aswell

-- Edited by zander on Sunday 19th of August 2012 02:20:46 PM

NorDt · Guru

Are you saying that adjusting the powervalve to make it open earlier isnt making it faster ? XD

And i know for shure that the gianelli is better than the dep when it comes to speed and acceleration.

For the athena, I would immagine the athena exhaust to be optimised for the athena 170cc. But i might be wrong xD

And when it comes to how the powervalve opens and closes, I think its too slow, It opens too slowly. And thats why you get a stronger and better kick if you adjust it to open a bit earlier like i did !

GADGET · Guru

Utter bollox ?.........sorry read it wrong lol

-- Edited by GADGET on Sunday 19th of August 2012 07:54:19 PM

AndyYam · Guru

IMO it will certainly feel like a bigger kick but That will be at 6krpm or when he valve is fully open. The idea of the YPVS is to close down the port at lower revs to prevent loss of mixture. I'd be very surprised if Yamaha had made it to open too slowly. If the YPVS is set up correctly. At 3krpm it will be at it lowest point in terms of exhuast port height and you'll be getting he maximum bang for your buck possible. Without that valve. Losing down a % of the mixture is escaping down the exhuast port before the piston gets high enough to block it.

At 6krpm the piston is coming up fast enough so that it blocks the port before the mixture gets a chance to escape. Anywhere in between there should be the specific height to match the piston top at the precise time the mixture is is trying to escape. If you set it to open earlier I'd imagine you'd be losing mixture until you reach 6krpm. You'll feel more of a kick but that will be by comparison from losing mixture to suddenly igniting it all when you get to 6krpm or wherever the power and kicks in.

This is all based on my understanding of the YPVS so could be wrong.

AndyYam · Guru

I'd also be surprised if the Athena was designed for the big bore kit. You got any photos of the Athena exhuast? We motos one is tiny, hard to see properly.

Calum122 · Guru

The ypvs retards on the re models. Hense why the derestriction.

zander · DTR Senior Member

NorDt, making the YPVS open earlier wouldn't make it faster :P Though I'm not sure if it starts closing after it passes the hole but I didn't get any change in topspeed when I adjusted mine

AndyYam, I think Yamaha adjusted the YPVS for normal driving and city driving, not for wheeling xD that's why I like it to open a small bit earlier, becouse the kick you get at 6k get a small bit stronger but instead you lose a small bit power on lower revs.

Calum112, my YPVS works properly and I've only earthed the wire and adjusted it a tiny bit

The optimised kick would probably be to make it open fully when the powerband kicks in, but instead you would also lose lots on low revs

Calum122 · Guru

Yeh. I don't reckon i've earthed the wire correctly mate.

AndyYam · Guru

I remember earthing a wire on my RE. Until you just said that I always thought that wa to do with the with the read switch. Anyone got a link to the info about the RE retarding the revs. I remember it saying it retards them at 7krpm. I guess that means it would be closing the port off at 7krpm a bit which would restrict it as by this time the revs are high enough to block the port so blocking it at 7krpm would restrict it by using old mixture i guess?

I still don't think that Yamaha would set the ypvs to not run at optimum power and it may give you a sudden burst of power but thats the idea of the ypvs, to smooth it out and give you more power lower in the rev range.

If you lookded at a graph of the power it, with the YPVS working correctly it would look like an even curve and without it would be a slow climb to 6krpm and then a sudden rise from there. But either way the value at 6krpm would still be the same. It just might be more noticeable without ypvs.

If anyone ever has the oppurtunity to put their bike on a dyno id be interested to see the two results. One with the YPVS and the other without.

Calum122 · Guru

It was to meet emission laws. That's the only reason they did it. That's also the reason why it's so easy to derestrict.

AndyYam · Guru

Ah right where you get that from?