DTR power valve compared with DTRE power valve

[Deeteemx]

This was discussed as a possibility to change the way my DT125RE opens the valve, with the servo operating the opposite way from the older DTR's, it may make a difference and improve the performance. 

Worth a try i reckon  

Must admit i have never seen the numbers on the servo before, but i can't say i have ever looked for them. Are they under the rubber cover?

Edit: just another thought, but the servo is a basic electrical motor, if the + and - power supply were reversed i wonder if this would make the servo work like a DTR one.

I've not examined the operation of the DT125RE servo in detail, so don't know if they all operate backwards. It's certainly strange, and the bike's I've come across all seem to perform too well (without crossed cables) to have powervalves operating this way.

Have you earthed the green/black wire yet? I'm sure this effects the powervalve operation in some way.

And yes, the numbers on the servo are under the rubber cover.

As for reversing the power supply to the servo......I've got no idea if this would work!

May be worth a try (if you've got a spare servo in case it goes bang!)

[Guest MaD.VeZ]

I've not examined the operation of the DT125RE servo in detail, so don't know if they all operate backwards. It's certainly strange, and the bike's I've come across all seem to perform too well (without crossed cables) to have powervalves operating this way.

Have you earthed the green/black wire yet? I'm sure this effects the powervalve operation in some way.

And yes, the numbers on the servo are under the rubber cover.

As for reversing the power supply to the servo......I've got no idea if this would work!

May be worth a try (if you've got a spare servo in case it goes bang!)

Can't complain about the performance on my DT125RE as it is (does 65mph ok and 70+mph downhill, on the clock at least), the only reason i noticed the way the servo rotates was because OG suggested we compare as he seems to be missing a power-band. There are plenty of other videos on youtube etc. of the DT125RE/X servos and they all rotate the same as mine, so i don't see it as a fault.

Haven't had the chance to do the black/green wire yet (two family birthdays this week i nearly forgot about) but its on the cards for the next week along with a few other jobs i need to do. I will try to get some good pictures of how the servo is setup/working before and after the wire is earthed.

I'll check to see what cables do what on the PV out of interest. Swapping the wires was just an idea of how Yamaha could of changed the servo to operate in reverse.

[Airhead]

I wouldnt be happy if it were mine, no matter if i had seen others on you tube vids. The PV is tied in with CDI and servo so either one of them is faulty, or the wire thing will put it right,

[Guest MaD.VeZ]

I wouldnt be happy if it were mine, no matter if i had seen others on you tube vids. The PV is tied in with CDI and servo so either one of them is faulty, or the wire thing will put it right,

If you think about it logically, then if the valve was positioned correctly so it opened and closed with my servo as it is, then it makes sense to me.

When your DTR valve is closed by the servo, it positions the valve so the rounded edge of the valve is closing the port. Where as mine would use the flat part of the valve to do the same, resulting in a better surface for the gases to flow past imo. 

Quick sketch.

[Airhead]

I dont buy that VeZ, your PV is fully open with the pulley slot and drilled hole aligned just like mine, it even settles down to the same position at idle...ie a little clockwise from fully open. but then goes further clockwise with increasing revs does it not?

[Guest MaD.VeZ]

I dont buy that VeZ, your PV is fully open with the pulley slot and drilled hole aligned just like mine, it even settles down to the same position at idle...ie a little clockwise from fully open. but then goes further clockwise with increasing revs does it not?

I'm not selling it

What i meant was I just think its a better direction to have the valve operate, if it was setup so it settles in the position it does now that is.

All the other vids i have seen are all the same year as mine, so if it is a fault then its not uncommon.

Vez

Edited, decided to pm instead.

[Airhead]

I'm not selling it

What i meant was I just think its a better direction to have the valve operate, if it was setup so it settles in the position it does now that is. 

( Its Vez btw, not VeZ or MaD save your shift key people! .    MaD.VeZ was only supposed to be my login name and not my screen name, i stuffed it up some how at registration. Is there a way to change it ?)

Vez

Ohh ok veZ i get it

Any way I still dont agree, the way i see it in that case is that exhaust port is fully open all the time but then just offers a restriction in the exhaust. I might believe it though if each and every DTRE DTX does the same, that would be too much of a co-incidence.

[Vez]

Ohh ok veZ i get it  

Any way I still dont agree, the way i see it in that case is that exhaust port is fully open all the time but then just offers a restriction in the exhaust. I might believe it though if each and every DTRE DTX does the same, that would be too much of a co-incidence.

When in doubt.

http://www.yamaha-motor.co.uk/corporate/contact/contact.jsp

[Cynic]

When in doubt.

http://www.yamaha-motor.co.uk/corporate/contact/contact.jsp

Ok hows this for a theory.

OG, yours is an import from a market that is not as restricted as ours, so the powervalve is opening up to give the full fat performance that just requires more tuning with the carb and such to get?

Vez

Yours UK? Then we have the exhaust port capable of considerably more performance than the law allows so the bike is down jetted and the port timing is tuned to a more relaxed peak performance but giving you a smaller exhaust port area for more mid range performance and bugger the max?

[Vez]

Ok hows this for a theory.

OG, yours is an import from a market that is not as restricted as ours, so the powervalve is opening up to give the full fat performance that just requires more tuning with the carb and such to get?

Vez

Yours UK? Then we have the exhaust port capable of considerably more performance than the law allows so the bike is down jetted and the port timing is tuned to a more relaxed peak performance but giving you a smaller exhaust port area for more mid range performance and bugger the max?

Sounds reasonable to me. 

I do have alot of questions regarding who sets the bikes up with the restrictions for each country and how, mine is a UK model but was assembled in Spain like most are from the last of the DTR's. 

The only thing that bothers me is the reason we compared is because OG is missing his power-bands, where mine has them, albeit low power power-bands but they are still there. It just leaves me confused as to why mine could be faulty when it still runs quite well. I'm tempted at this point to take the servo off the Sachs to see if that operates any differently on my bike to clarify if it is the cdi controlling the servo direction or the way the servo is wired.

I've sent the videos with an email explaining my concerns to Yamaha, i will wait for a response before tweaking anything.

Vez.

[Vez]

Well got a reply from Yamaha,

So are they saying the cables need to be crossed or are they politely saying its faulty. 

Vez.

[Cynic]

Well got a reply from Yamaha,

So are they saying the cables need to be crossed or are they politely saying its faulty. 

Vez.

I think its saying "I work in an office and it doesen't come up in the options on my computer. Pop along to your dealer and let them say after charging you an eyewatering amount of money for the privelage.

If its of any interest the 350book i have shows the cables crossed and the valve should be closed when the engine is started.

[Vez]

I think its saying "I work in an office and it doesen't come up in the options on my computer. Pop along to your dealer and let them say after charging you an eyewatering amount of money for the privelage.

If its of any interest the 350book i have shows the cables crossed and the valve should be closed when the engine is started.

I think thats what I'm going to try Cynic   

Is that an RD350 book, just out of curiosity ?

[Cynic]

I think thats what I'm going to try Cynic

Is that an RD350 book, just out of curiosity ?

Yep, i generally hang on to the manuals for bikes i've had. Dunno why.

I still think its worth a look at a TDR/TZR 250 powervalve. They are very different if that picture that went up a while ago with the piston strike is anything to go on.

[Vez]

Yep, i generally hang on to the manuals for bikes i've had. Dunno why.

I still think its worth a look at a TDR/TZR 250 powervalve. They are very different if that picture that went up a while ago with the piston strike is anything to go on.

Sounds like a good idea. You offering to get your tools and camera out then ? 

[Cynic]

Sounds like a good idea. You offering to get your tools and camera out then ?

I have got to change the exhaust gaskets on the tdr so i could take some shots and measure up, wont be this weekend though (i think the exhaust mount is coming from japan via pushbike).

Have you got some decent shots of yours (missus) and some measurements so we can compare (oh behaave).

[Vez]

I will get some together this week, need to de-coke the exhaust port anyway. I'm in no rush, just interested on how they compare

[AndyDtr08]

I will get some together this week, need to de-coke the exhaust port anyway. I'm in no rush, just interested on how they compare

Good to get a reply, even if it is as vague as that. I suppose they have to cater for the average joe who might just get the garage to do any work. If they advise you to do somthing to the bike and it ends in a bloody mess along a road somewhere, your widow might call death lawyers4u or whatever it is!

[Airhead]

Good to get a reply, even if it is as vague as that. I suppose they have to cater for the average joe who might just get the garage to do any work. If they advise you to do somthing to the bike and it ends in a bloody mess along a road somewhere, your widow might call death lawyers4u or whatever it is!

Come on Andy

Check yours and let us know

[AndyDtr08]

Come on Andy

Check yours and let us know

Yeah, sorry, meant to do it today but the gf didnt go home til an hour or 2 ago and the bikes all tucked up in the garage along with the 3 other bikes in there and the folks car. Its like a rubix cube to get it out. It's all disconnected as well atm. Decided to disconnect to see what difference it made. As you'll know, said answer is "ALOT"!

Purchased myself a rather nifty helmet cam that some of you guys might be interested in so ill video it 2moro on that and upload. Good to show the quality of the cam as well as the PV!

*Edit*

On another note. My 02 Dt doesnt have the PV servo or cables etc. Does anyone know if its a unniversal unit? I.e can i use an 06 one on a 2002 bike? Got offered one recently for what i think is fair, but before i take the stuff off the 05 and onto the 02 i thought id see if anyone of you chaps have attempted this?