07-27-2015, 05:01 PM
Mike. That should last awhile. 
Ed
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Todays Project - What did you do today?
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 Mike. That should last awhile. Ed 
07-28-2015, 08:46 PM
Too hot for us northern folk, 33 deg celsius so I retreated to the machine shop, 20 deg there.
Finished up this bracket, adaptor plate and clamps for a fellow. He plans to use this with the compound off his lathe do do some light milling. ![[Image: IMG_1813.jpg]](https://lh3.googleusercontent.com/-ujD9Kf3p2OM/VbgtlciPFlI/AAAAAAAADLw/LSOr4id-5Hs/s1280-Ic42/IMG_1813.jpg) Then made a rocker arm bolt for a Chinese engine on a generator. The chap who needed it claims they aren't available. Sorry no picture. Then started making up a set of block and tackle for Charlie, he wants it to tension a cable for running his camera on. Interesting note, had some old aluminum angle, was using a hole saw to cut out the blanks for the shivs, I've always used WD40 for cutting fluid on aluminum, but DR B had a 45 gallon barrel of kerosine so I took a couple of gallons figuring thats what is recommended for aluminum. The hole saw kept loading up and welding globs on the teeth with the kerosine, switch back to my usual WD40 and got nice clean cuts. HUM.
Free advice is worth exactly what you payed for it.
Greg
07-28-2015, 11:33 PM
Last time we were up north riding, the YZ250 spit out it's piston. Of course in typical 2 stroke fashion, the pieces then took out the cylinder and crank. Once we had it all apart, I noticed that a small piece had also broken off of the end of the power valve. Unfortunately, the valve itself is only available as a complete assembly for $180, so I decided to repair it myself. The part that failed was a 4.5mm diameter pin machined on the end of the aluminum valve, and the reason it failed was that it was machined with a sharp inside corner that fractured from the vibration of the motor. A surprisingly poor design for Yamaha. The fix was pretty easy. I machined off the end of the valve, drilled an reamed a hole in it and pressed in a steel piece that I made to replace the broken section, then cross drilled it for a dowel pin and machined the offset pin on the end with a boring head in the mill. The hardened steel wear piece pressed over the pin just like factory. The difference is that the pin is now steel with a proper radius in the corner for durability, so it should last the life of the bike.
Tom ![[Image: 046_1.JPG]](http://photos.imageevent.com/tomgriffin/generalstuff/large/046_1.JPG)
![[Image: TomsTechLogo-Profile.png]](http://tomstechniques.com/wp-content/uploads/2013/11/TomsTechLogo-Profile.png) 
07-29-2015, 07:42 AM
Nice Job Tom Love to see that apart before and after if you have another pic ? never got that deep in a 2 stroke interesting to see .
Very Ingenious ... machinist like .. but without having more info I do have one Q . How do you know your fix is not too good ..lol....Excuse me for asking but without knowing the function of a power valve I had to ask. So What I mean what happens when something else blows apart cuz the fix is over engineered. Also Tom do you ride the competition bikes ? Btw Its been over 30 years since I ripped up some dirt. These machines are crazy and todays riders are thrill seekers ... . I know one thing im not getting on one no more ... I see they have allot more power and some narley suspensions these days ... 
07-29-2015, 08:45 AM
Kenny,
The steel part I made is the round part on the right with the dowel pressed through. It has a 1/2" long pin on the left that is pressed into a hole on the C/L of the valve. The offset pin is machined on the far right with the top hat shaped wear piece is pressed on it. The power valve adjusts the size of the exhaust port as the rpm's change to widen the power band. It's a pretty low stress area, so the repair should hold just fine. In fact, the actuator has been riding on the aluminum end of the power valve for who knows how long and it barely showed any wear. We have a Yamaha YZ250 2 stroke and I just bought a WR450 4 stroke. That gets us around the trails and through the woods as fast as our skill and courage allow. :) Tom
07-29-2015, 12:06 PM
(07-29-2015, 08:45 AM)TomG Wrote: Kenny,Gotcha on the parts ... Both of those bikes are "sick" what I mean ( lot a power) biggest dirter I ran was 250ci im sure that WR450 has a lota room high end Quick fast and POWERfulllllll...... How many gears on that bike ? Btw I have an ole friend that still rides competition. Tries to keep up with the youngsters and do what they do .. However he'd dislocated shoulder , messed up both arms , hands nerve damage ect... still gets up and back on once he heals .... took a good beaten a few months back goin over board on some sort of jump into another jump .. all I say is no thanks not fur me no more at least at that level .. I have enough issues staying out of harms way on my Hog on NJ roads if ya know what I mean ...  .
07-29-2015, 12:26 PM
They are both 5 speeds.
At 62 I don't take chances anymore like I used to. Now they are calculated risks. That along with full body armor has kept all of the parts where they are supposed to be :) Tom 
07-29-2015, 01:24 PM
Great job Tom. I made many repairs to those power valves over the years, especially when I was a dealer for PSI Performance back in the 90's. Their top end kits used power valves that had some inherent issues and they would only sell them as a complete assembly. Needless to say I too had to get creative and I ended up repairing them in-house. I caught some heat from PSI because as a dealer I was supposed to be purchasing them from the manufacturer but they were failing at a high rate and I was trying to keep sleds on the snow and customers happy so an in-house repair made more sense.
Mike. 
07-29-2015, 05:33 PM
made these four pieces for some sort of lock on a car lift, they some how lock the arms that you swing under the vehicle to lift it with.
the black one was a sample that I was supplied with, guy said they didn't have to be identical and he supplied the stock, some carp that looked like it was a flange off of a hunk of H-Beam
dallen, proud to be a member of MetalworkingFun Forum since Apr 2012.
If life seems normal, your not going fast enough! 
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