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Yamaha SDR200

I had recently repaired - modified a YPVS control unit and also made a custom SDR200 leak down tester tool for Matthew(UK). The Sdr200 is a unique bike with a Trellis frame. The YPVS exhaust valve curve is also unique to this model. 

And here are the YPVS settings, specific to the SDR200 model.

Recent posts

This blog is now 8 years old.

Time goes by like a two stroke motorcycle and this blog is now eight years old. 
P.s I suppose I should have posted this on the 6th of July but better late than never.

Leak Down Testing on a Lambretta

Mark(UK) performing a leak down test on a Lambretta TS1 238 cc engine with his custom tool. Many thanks Mark and I hope everything goes well with your project.


Yamaha DT200R 37F '86, YPVS Curve

I just repaired a YPVS unit for a Yamaha DT200R 37F bike, that belongs to Tony(UK) and I have another one rare YPVS curve to share. This unit doesn't seem to use the regular DT200 ypvs curve but instead uses the one below.

P.s Dt125 and Dt200 owners might want to give it a try.



Nsr250 PGM Key Ring

A low budget birthday gift for a friend...




CR125 HPP, Altering the Exhaust Valve Timing

A recent modification on a '98-'99 Cr125 bike that alters the exhaust valve timing. A simple spacer made on the metal lathe that adds some preload on the governor spring hence retarding the engagement with the exhaust valve linkage. This mod can help for enduro use or with bigger carbs.
I mostly followed the instructions from the below link though I made the spacer slightly thinner at 2mm thick.
Link at :
Honda 125 - HPP setup TIPS & TRICKS & TUNING @ thumpertalk.com








YPVS repair, Yamaha 34X IC chip transplant

Another one interesting repair job that got me scratching my head for a while. The below RD/RZ500 YPVS unit belongs to Mark(UK) and needed a repair job to be done.

The IC chip was badly corroded and lots of the pins didn't made contact with the PCB due to the oxidation. This is not rare on Yamaha YPVS units but I'm not sure I have ever seen one at this state.  Any attempts to clean the pins and put new solder on them was at least discouraging as the pins cracked in half by only slightly touching them. There are some tricks that can been done as to trigger the circuit from different pins but this proved to be inappropriate in  this situation as well. After hopelessly looking at the YPVS unit for a while, I accepted my defeat and I informed Mark that there is nothing that I can do as to repair his unit.  A few minutes passed by and while randomly searching at my "junk" box, a possible solution caught my eye. I'm not sure why I always find solutions among things th…