The new TR1 engine - softer valve springs for longevity (part 32)

The everyday TR1 has to follow two very contradicting goals:

1. be quick as f*ck, i.e. fast
2. be reliable and not wear out its components prematurely.

Previous posts mostly dealt with how to make the old girl go faster, this one won't, but much the opposite. Thanks to extensive research of Sepp Koch it became apparent, that the Yamaha engineers must have accidentially bumped their slide rules, when calculating the seat pressure on these engines and funnily enough even more so on the 700 and 750 heads. Funnily enough they went all the other way with the later BT and XVS1100 (V-star) engines and lowered the seat-pressure over 30kg, resulting in a redline of (only) 6500rpm.  As such I decided to lower the seat pressur down to around 100kg static and the easiest way to achieve that is by running yellow inner springs and blue outers. The stock setup is blue inner and outer spring.

When taking the head off, it became apparent that the liquid gasket used as a base gasket couldn't fill the gap anymore, once the head was lifted as the cylinder is only bolted down on one side to the engine case. So a case of clean and reseal everything.

And then get started on re-installing everything. Admittedly the pistons didn't come this clean out of the running engine. But the carbon deposits were only very minor, meaning that the new piston rings are doing their job alright.

 The only tricky bit was to install a cylinder without making a total mess of oneself and leaving sticky marks everywhere.

Timing the engine gave me a night of very bad sleep, as I was pretty convinced I had my timing off by one tooth. It turned out, that marking the timing mark with white paint makes it a lot easier to find the mark when you need to.

The last job on the list was to try out a softer ignition curve, intended to give the internals an easier life. Add that to the fact, that due to the more efficient squish the engine should run a lot nicer, I expect next to no performance loss. 

Oh and that's what it sounds like:

At the time of writing this post, everything is assembled and I am playing around with several ideas on how to modify to centerstand to make it work with the new exhaust.The most stunning effect of tightening up the squish in connection with the new needles and the new db-killer-inserts with slightly larger bores has yielded some surprising results. The bike feels faster by an incredible amount, but actual data won't be gathered before the weekend, when I have some time (and hopefully good weather) to actually find out just what she can do.