Tuesday, July 10, 2012


This post has been a very long time coming!

I've been short of cash and so things had to slow down. I had been
promising detail as to engine condition after tear down. And the news
was mostly all good. The rings seated well enough and the Wiseco
pistons are certainly tougher than the ancient design cast ART's I was
using in the first iteration of this engine! I can't get the head off
this engine with the engine in the chassis so I decided to buy a fiber
optic scope to get a "good" look at the pistons. Just pull the spark
plug and stick the business end of the scope down the hole. The piston
wash was substantial which of course indicates rich operation. After
busting up two different cast pistons, I was leery about chasing the
main jet way down. Once the engine was out of the chassis and I pulled
the head, it was clear that the jetting wasn't close. The under side
of the pistons showed no color at all. Which means that I was way off
on the jetting. I suspect I have been giving away 4-6 HP for no real
good reason .... other than my lack of skill. Even at that the engine,
at tear down, was at 78 HP with a very linear power delivery. I am
very looking forward to putting this engine back together with
detailed port work, head work and new pipes appropriate to the
displacement. Gary at HPbyGD is busy on the pipes, porting the
cylinders and making new inserts for the head. We are going to try a
knock sensor bolted directly to the head. Gary is encouraged by his
preliminary work on the mule engine which is a DT 200 and we hope will
transfer to the 400. I will have a new base line for jetting to work
from (courtesy Gary) ...... and will watch the plugs and deto-sensor

The reason the bike has come all this way is that Gary has indulged my
maniacal desire to find power to rival a modern 600 (and of course
THAT bar keeps moving .......). My role in development is to ask
annoying questions - which Gary indulges - as he continues doing the
hard work of finding more HP in a reliable design. Tricky at best. The
first role for this bike has always been as a street ride. I am asking
him to serve two gods.


  1. I would like some advice on using a Zeeltronic to de-restrict my TZR250 SPR 3XVC. Could you email me at aradune@hotmail.com?



  2. So... forward a few years.. where is this bike at?

  3. I'd like to know that too as it's a good project. Interested to hear what happened in the end.

  4. I'd like to know that too as it's a good project. Interested to hear what happened in the end.