De-restriction of a 125 yam Tdr or Tzr
mike hall
I have a mate who has a TZR125 who also has the same problem.
Does anyone know how this is done or where it can be done.
My local motorcycle dealer says it can be done but they don't do it.
Perhaps you could help?
Many thanks,
Mike
Steve Coombs
mike hall <ha...@hallservices.freeserve.co.uk> wrote in message
news:8ea4me$n5h$1...@news5.svr.pol.co.uk...
> I have read an article about having a TDR125 yam de-restricted.
>
> I have a mate who has a TZR125 who also has the same problem.
>
> Does anyone know how this is done or where it can be done.
Depends on which models exactly you are talking about. If you are talking
about the early E to L Reg TZR's, derestriction is five minutes away!
Unbolt the exhaust downpipe, then remove the powervalve cap from the side of
the barrel. This is approximately an inch and a half across, is held on
with two allen screws and sits on the left hand side of the engine as you
look at the bike from the back.
If you look at the contents of where the now removed cap was, you should see
a peg locating the powervalve in one place. Remove this. I'm not sure if
you need to actually remove the powervalve in order to do this.
Whether you do or not, you will notice that the powervalve has a bolt of
some description in the middle. Slacken this off so that the powervalve now
rotates.
Now, stick your fingers into the exhaust port and move the powervalve so
that the flat edge becomes flush with the top of the exhaust port. Keeping
you fingers there, retighten the powervalve centre bolt and reassemble
everything else, remembering to leave the peg that was positioning the valve
out.
You will now find that the bike has less power than a hairdryer below 5,500
rpm, but will take off like a scalded cat above this.
To get the best of both worlds, you need to get a powervalve servo kit, as
fitted as standard to the TDR. As this has this already fitted, I assume
the restriction on these is elsewhere (I rode one once and found it to be as
flat as a fart). Possible places are a washer welded into the top of the
downpipe, or it may need a some wiring modifying to allow the CDi unit to
permit full power. I'm afraid you'll need to speak to a dealer if this is
the case.
Also, if the method above is correct, remember to tighten the centre
powervave bolt *RIGHT* up, or it will rattle the two halves of the
powervalve apart,and the central locator pegs will disappear into your
exhaust!
--
Steve
'Today, I have been mostly eating my own words..............'
TZR125 - Imminent, Citroen AX Diesel - Dogsbody, BMW325i - Attractive
Garden Ornament (For now!)
(Remove the word 'spam' from my e-mail address to reply...........)
Dave Martin
> > I have read an article about having a TDR125 yam de-restricted.
> >
> > I have a mate who has a TZR125 who also has the same problem.
> >
> > Does anyone know how this is done or where it can be done.
> downpipe, or it may need a some wiring modifying to allow the CDi unit to
> permit full power. I'm afraid you'll need to speak to a dealer if this is
> the case.
In addition to the powervalve adjustment, early TZRs and the DTRs did have a
restrictor in the top of the downpipe - a smaller bore tube rather than a
washer as such - which needs to be ground out. Hook a piece of wire around
it first so it doesn't disappear down the pipe. Upjetting the carb may be
worth considering at the same time. You don't want to run too lean and melt
a hole in the piston!
Like you said though, without the servo kit it's a bastard to ride
especially round town. Kinda like having a digital throttle. Nothing or
WAHEY!!
Cheers,
Dave.
Keith O'Brien
> I have a mate who has a TZR125 who also has the same problem.
>
Which year & model is it?
Keith
mike hall
Thanks for replying to my request, the year of the bike 1993, L reg.
Does this help?
Keith O'Brien <kob...@globalnet.co.uk> wrote in message
news:8ec1lr$eqd$1...@gxsn.com...
mike hall
mike hall <ha...@hallservices.freeserve.co.uk> wrote in message news:...
> I have read an article about having a TDR125 yam de-restricted.
>
>
>
Steve Coombs
Dave Martin <d...@eng.cam.ac.uk> wrote in message
news:8ebd8j$qie$1...@pegasus.csx.cam.ac.uk...
<SNIP>
> Like you said though, without the servo kit it's a bastard to ride
> especially round town. Kinda like having a digital throttle. Nothing or
> WAHEY!!
........I actually used to find them more fun like that!
Bit of a c*nt to ride from a standing start up a steep hill though -
couldn't quite keep the revs up enough as you changed from first to second
to keep it on the boil........
even...@gmail.com
> mike hall <ha...@hallservices.freeserve.co.uk> wrote in message
> >
> > I have a mate who has a TZR125 who also has the same problem.
> >
> > Does anyone know how this is done or where it can be done.
>
> about the early E to L Reg TZR's, derestriction is five minutes away!
>
> Unbolt the exhaust downpipe, then remove the powervalve cap from the side of
> the barrel. This is approximately an inch and a half across, is held on
> with two allen screws and sits on the left hand side of the engine as you
> look at the bike from the back.
>
> If you look at the contents of where the now removed cap was, you should see
> a peg locating the powervalve in one place. Remove this. I'm not sure if
> you need to actually remove the powervalve in order to do this.
>
> Whether you do or not, you will notice that the powervalve has a bolt of
> some description in the middle. Slacken this off so that the powervalve now
> rotates.
>
> Now, stick your fingers into the exhaust port and move the powervalve so
> that the flat edge becomes flush with the top of the exhaust port. Keeping
> you fingers there, retighten the powervalve centre bolt and reassemble
> everything else, remembering to leave the peg that was positioning the valve
> out.
>
> You will now find that the bike has less power than a hairdryer below 5,500
> rpm, but will take off like a scalded cat above this.
>
> To get the best of both worlds, you need to get a powervalve servo kit, as
> fitted as standard to the TDR. As this has this already fitted, I assume
> the restriction on these is elsewhere (I rode one once and found it to be as
> permit full power. I'm afraid you'll need to speak to a dealer if this is
> the case.
>
> powervave bolt *RIGHT* up, or it will rattle the two halves of the
> powervalve apart,and the central locator pegs will disappear into your
> exhaust!
>
> Steve
>
> 'Today, I have been mostly eating my own words..............'
>
> TZR125 - Imminent, Citroen AX Diesel - Dogsbody, BMW325i - Attractive
> Garden Ornament (For now!)
>
> (Remove the word 'spam' from my e-mail address to reply...........)
ogden
> Hi, I have a 89 TZR which has the YPVS, I have checked that it works. I took off the exhaust to see if there some kind of restriction there (I dont know the english word for it, but it is a narowing of the exhaust to restrict the axhaust flow), but I couldnt find anything, yet my bike only does 120 Km/h or around 70 mph. what can I do?
If it doesn't have the servo, then by default the valve will be in the position for low revs, and power will tail off quickly around 7k, or 70mph in top. You can turn it manually, as described in the post you replied to, but you'll lose all bottom end. Fun though - I did the same when I was 17.
The only proper fix to derestrict a TZR125L is to install the servo kit. But they're going to be rarer than rockinghorse shit these days. They weren't exactly easy to find in 1994!