Powervalve YPVS

  • So for a while when I came bike from uni I’d had what seems to be a common problem of my bike randomly deciding to stop being able to rev out past 8k for no reason what so ever
    It’d stumped many people, caused me to think my engine was on the way out and all sorts of things.
    I decided to get the exhaust off align the valve and pin it, problem solved it’s revs out freely. It also sounds amazing too,I really enjoy riding my bike pinned in the right scenario however the only issue I’ve found is that past the 8.5-9k you get the worst throttle chop I’ve ever experienced. The throttle is still very responsive but under load at high rpm’s it’s like it revs backs off automatically and then will come back on whilst maintaining throttle position, this is the case even when just slowly rolling on the throttle with the RPM’s. I have wondered if the fact I’ve got a YZ 250 1/4 throttle and I’m still using the stock throttle cable which doesn’t fit 100% with the throttle because I still want to run the oil pump. *** on that note what’s a really good 1/4 throttle or fix that’d solve that *** I’ve also noticed whenever I’ve had smaller sprockets on and pulled harder in low gears that the throttle chop effects often worse unless I’m clutching in and getting the front end up. So in essence whilst pinning the valve has solved a problem it’s just kinda created a couple more for me but I’ll touch more on that later.
    Whilst it’s rideable and still fun I could only imagine now what this would be like without this issue unless it’s just a drawback of pinning a DT wide open?
    I wish there was a way the get all the benefits of the low down torque The DT is capable of producing and still feel that sudden sharp hit of power after 7k.
    I’ve spent hours now fiddling with the YPVS, I even thought the valve magically flipped 180 degrees by itself. Here’s the thing though with my exhaust off and the powervalve aligned flush the black plastic cable carrier is as far left from the aligning hole it can go, practically touching the 5mm Allen bolt that holds the casing. This means that the cleaning cycle would go left right but when valve would be aligned with the aligning hole it’s mean it’s closed which in my opinion doesn’t make any sense? The only way I can get it to align like that is by tightening the right cable as far as I can without it whilst loosening of the left as much as possible If memory serves me right this is meant to be the other way way around where the hole being aligned means your valves indicates as being flush
    I’d found photos of how it was originally set up and returned it that way so it was textbook perfect and tested it that’s when I had the same issue of it not revving past 8k.

    I’m just really stumped as to what’s caused this to happen or is causing this, I’ve spent hours fiddling trying to get it right only to find my results stump me further, typical.
    Time for the big boys

    Also a sidenote:
    I’d really like to get YPVS running again as I found out a while ago the switch to disconnect it is located just by the serve motor and within reach through your left radiator fairing so whenever I want to disconnect it for some fun with it pinned at a moment’s notice I can but still enjoy everything about the ypvs that makes it so good and what makes the DT pull very quick in those lower rpms. It’s also helpful it’s much quieter

    **ive cut this and edited it from my build post just as the topics more relevant here

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