Powervalve fully open
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Hi guys, i was just wondering if any of you run fully open powervalve? I dont know if its better than normal ...... if you do can you describe difference is there any power boost or its only get bigger MPG ?
@Vcelicka said in Powervalve fully open:
Hi guys, i was just wondering if any of you run fully open powervalve? I dont know if its better than normal ...... if you do can you describe difference is there any power boost or its only get bigger MPG ?
You seem confused.
The power valve adjusts the port timing such that it better matches low and high revs.If you mess with it, you just make it stick to either low or high rev setting. In the former you lose peak power, in the latter you make the lower rpms suck.
It is not a manual crane to twist for some kind of optimization, it is automatic.
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Hi guys, i was just wondering if any of you run fully open powervalve? I dont know if its better than normal ...... if you do can you describe difference is there any power boost or its only get bigger MPG ?
@Vcelicka As a youth in the 90s I ran a pinned open powervalve on all my DTRs and it was very depressing. The factory powervalve kit at the time cost over £300 (a lot of money in 1993) and you had to have a full licence to buy it so most people just turned the powervalve round which gave good top-end performance at the expense of low-rpm torque.
It made the bike practically unrideable off-road and you had to rev it to the moon to make it do anything; combined with dual-purpose tyres which in practice manage to be crap on both tarmac and dirt it was a very unpleasant experience and quite antisocial around horse riders, dog walkers etc. on the lanes.
It wasn't until I got my 1st French import in 2020 I even got the chance to try a DTR with functioning YPVS and I can tell you, it transforms the bike and I found it more enjoyable than some bigger bikes. Once at a place called Pepperbox Hill near Salisbury this family out for a walk told me they were really impressed how quiet my bike was when I went past them slowly; 5 minutes later I was doing 70mph on the dual carriageway.
Take good care of your YPVS cables as allowing them to seize is a leading cause of knackered servos. If you want to make your own I wrote a how-to about this which allows you to lube them without taking them off:
https://dt125r.co.uk/topic/2971/home-made-quick-lube-ypvs-powervalve-cables
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@Vcelicka As a youth in the 90s I ran a pinned open powervalve on all my DTRs and it was very depressing. The factory powervalve kit at the time cost over £300 (a lot of money in 1993) and you had to have a full licence to buy it so most people just turned the powervalve round which gave good top-end performance at the expense of low-rpm torque.
It made the bike practically unrideable off-road and you had to rev it to the moon to make it do anything; combined with dual-purpose tyres which in practice manage to be crap on both tarmac and dirt it was a very unpleasant experience and quite antisocial around horse riders, dog walkers etc. on the lanes.
It wasn't until I got my 1st French import in 2020 I even got the chance to try a DTR with functioning YPVS and I can tell you, it transforms the bike and I found it more enjoyable than some bigger bikes. Once at a place called Pepperbox Hill near Salisbury this family out for a walk told me they were really impressed how quiet my bike was when I went past them slowly; 5 minutes later I was doing 70mph on the dual carriageway.
Take good care of your YPVS cables as allowing them to seize is a leading cause of knackered servos. If you want to make your own I wrote a how-to about this which allows you to lube them without taking them off:
https://dt125r.co.uk/topic/2971/home-made-quick-lube-ypvs-powervalve-cables
@HOTSHOT-III
Thanks for that massive reply . I will leave it like it is , guy before me opened it but i dont know if correctly. When i pinned it it would go first back and than open is it right this way? -
@HOTSHOT-III
Thanks for that massive reply . I will leave it like it is , guy before me opened it but i dont know if correctly. When i pinned it it would go first back and than open is it right this way? -
@HOTSHOT-III
Thanks for that massive reply . I will leave it like it is , guy before me opened it but i dont know if correctly. When i pinned it it would go first back and than open is it right this way?@Vcelicka Do you mean with the servo fitted? If so and if yours is an early bike, that sounds right. When you turn on the ignition on a DTR with 3NC or 3MB electrics (pre-'99) the servo should do one full cycle to clean itself, then settle in the fully open position. Then on startup it should adjust to engine speed (i.e close assuming you're at low rpm). Have you taken off the pulley cover and watched it operating? The forked section of the pulley should line up with the 4mm hole in the barrel behind it when it's done its cleaning cycle before you start the engine, and the actual valve should be flush with the roof of the exhaust port at this point (you need to take off the exhaust to check this). This explains it better than me:
https://www.youtube.com/watch?v=Wo_bI40UyWE&t=66s
Talk to @Calum about the later bikes as I don't know too much about these.
75mph doesn't sound too bad, some DTRs are faster than others, I always found 3MB to have a slightly fatter spark and give a bit more power than 3NC but if your bike was restricted, you'd struggle to get 60mph. What age is the bike?
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Oh - you mean that they removed the servo and put the valve in "low" as some means of restricting the bike?
What a terrible crime against the spirits of engineering! >_<
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Oh - you mean that they removed the servo and put the valve in "low" as some means of restricting the bike?
What a terrible crime against the spirits of engineering! >_<
12bhp max allowed on a learner license…
British bikes never came with a servo from 1988 to about 96 (I think). The valve was literally bolted in the closed position to give it low rev torque, but no top end revs…
Even after they fitted a servo in the ‘later’ bikes they restricted them in other ways…Total waste of what Yamaha intended…
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Well, I suppose they saved several pounds of cost for the servo for a while...
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I found the 3NC-00 cdi on my 96 French import wicked! revved to the moon and went off the clocks no problem on stock gearing
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I found the 3NC-00 cdi on my 96 French import wicked! revved to the moon and went off the clocks no problem on stock gearing
My 3nc is fine as well. But nobody said they were bad. Just that the 3mb were a tadpole better
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With the early bikes a fat strong spark can make a real difference. As soon as I put my lights on it zaps my tick over. I can see it going from blue to orange in my minds eye! …
