TZR 125 1990... Does it have a powervalve?

Aleks · Two Stroke Sniffer Joined: 09 Feb 2008 Karma :

Hi guys, I'm not particularly good at the whole bike engineering thing but I'm giving it my best Smile

Basically I've got a 19 year old TZR with only 20k miles on the clock, I'm just basically cleaning the spark plug when suddenly I think "Why not go the whole hog and clean the engine! Seeing as it's never been cleaned it can't hurt, I'll even Derestrict it while I'm there!

Now... I've been doing a lot of googling and youtubing and I've gathered the powervalve is controlled by a servo... I'm fairly sure my bike doesn't have a servo, it's kickstart for gods sake Razz

Here's a picture of the engine, I really can't see where the powervalve would go or if it even has one... The bike's code is 3PC2 if that helps

https://photos-b.ak.fbcdn.net/hphotos-ak-snc3/hs406.snc3/24600_348491675891_584260891_3798845_4396487_n.jpg
Thanks in advance
-Aleks

Aleks · Two Stroke Sniffer Joined: 09 Feb 2008 Karma :

Oh yeah if you're wondering, the kickstart did snap off Razz

Fortuna · World Chat Champion Joined: 29 Oct 2004 Karma :

If it is, it will be where I've circled.
Looks like it hasn't got one though, no cables or motor.

Aleks · Two Stroke Sniffer Joined: 09 Feb 2008 Karma :

Thanks

Tomorrow after college I'll open it up and take a picture Razz

Cheers mate

Billing · World Chat Champion Joined: 12 Mar 2009 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

UK ones were restricted by leaving out the servo and control unit for the power valve, leaving it in the low rev position.

All the best

Keith
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Bikeless · World Chat Champion Joined: 27 Jun 2008 Karma :

When i was a kid you just took the powervalve out and turned it around so it worked at high revs but you lose low/mid range.

Fortuna · World Chat Champion Joined: 29 Oct 2004 Karma :

Aleks · Two Stroke Sniffer Joined: 09 Feb 2008 Karma :

Sweet

I've put the valve to open. Wide open.

I wonder, does this now require a rejet?
Also, if I half opened it, would I get the performance increase be equal in all ranges, or would my engine just explode?

Cheers guys, you're a great help Smile

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Not sure on the jetting, but don't think they need rejetting. The Yamaha manual didn't list any different jetting for UK restricted and non UK full power models (although it does for the Swiss market ones).

Turning the power valve part of the way would probably lose you some low down power and gain you a bit of top end power. But I wouldn't really expect it to be a good compromise (fairly sure in use the valve is just open or shut).

You need to turn the valve so the flat lines up with the top of the exhaust port in the cylinder. I think that the power valve adjustment holes are lined up when the valve is in the fully open position. As such if you have the pulley wheel then you should be able to put a pin in (4mm diameter) to the adjustment holes to lock it in the open position.

All the best

Keith
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Aleks · Two Stroke Sniffer Joined: 09 Feb 2008 Karma :

Thanks man, I'll keep that in mind, I'm considering doing some googling and/or ebaying and finding a powervalve servo and cables, I did a bit of looking last night and found one PV servo but the guy wants £60... Definately not worth the price. I'll just hunt around and find a servo and cables second hand for like £20.

Would my idea work though? I mean Yam made the bikes with the servo and everything, then took it off and bolted it shut for sale in the UK?
(I could be wrong on that, correct me if I am)
I like the idea of re-powering the power valve Razz

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

For the UK market they left the servo and control unit off. They were available as extras from Yamaha if you had a full licence, but few people bought them and they are as rare as hens teeth now (hence they cost a fortune to buy when they occasionally turn up 2nd hand).

All the best

Keith
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ben350 · Trackday Trickster Joined: 29 Apr 2008 Karma :

£60 is a fair price mate, I paid £75 delivered for one for my 125R as I couldnt be arsed riding to work on a light switch engine. You will find the early TZR YPVS servo very hard to come by as they were never officially sold here and if I remember correctly no TZR125 shaped like yours had a servo in the UK. Make sure you get the same number of wires on your wiring loom - the DT has 2 different servo's so you might find TZR's are the same Wink

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Vincent · Banned Joined: 16 Oct 2006 Karma :

Are the TZR servo and controller the same as the RD125LC (1GU) Question

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

The servos were available in the UK, but only (in theory) if you could prove you had a full licence. Suspect they were readily available in Northern Ireland (250 learner law in NI at the time, and the RD125, AR125 and a few others were sold in full power form).

Servo might well be the same as the late RDZ125LC (but then UK ones of those didn't have the power valve servo fitted either).

All the best

Keith
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