Well hi again!
As the Btitish would say, I've run into a spot of bother.
Here's what's hapening:
I was getting promising results with the high compression head.
It hasn't been running too well the last couple of days, till
this morning it was hard to start. Once running it would die
at around 8k, unless you brought the rpm down.
Checked compression, and it was up to 135lbs warmish.
The plug however, was all but destroyed. Signs of melting
on the tip of the ground electrode, and cracked insulator.
My question is a general one. Can a cast iron, air cooled cylinder,
be run with 135lbs compression, at high rpm (11K+) with proper
jetting and timing of course. Should it be able to stay reasonably
cool when properly set up? If so, I'll keep working on it.
Tuning differences I have from low 100lbs compression setup,
which gave no problems:
Increased main jet from 120 to 125
Retarded timing by 1 degree.
Spark plug heat range is NGK 8
My question is a general one. Can a cast iron, air cooled cylinder,
be run with 135lbs compression, at high rpm (11K+) with proper
jetting and timing of course. Should it be able to stay reasonably
cool when properly set up? If so, I'll keep working on it.
Great takeoff power (after initial hickup), and best of all, full speed
rpm down to 11.something k . Still close to where the power is. See? I
am starting to accept that peak rpm close to max power is best.
Top speed was around 55mph.
Yes, they know that of which they speak
Is the TDP Malossi also? Just one half, or the complete pulley?
Would you say Malossi variator makes a noticeable difference
over the Tecnomoto? (Almost embarassed to ask this...)
forget tuning the stock carb without the airbox 135 mainjet is way too big but still it didn't make any difference, why? b'coz the needle is too thick, you can even run it without a mainjet & still it won't make any difference.
if i were you i'd start looking for a PHBG19 to 21mm carburator.
Thanks Big B.
There's still the mystery of why the top speed didn't go up,
with about 700 more rpm, after shortening the header.
You remember I tried heavier weights, but it didn't help,
top speed was the same at 11.8k, and 12.5k. I'm
wondering if the transmission heating up might have
something to do with it. Maybe hotter belt is harder
to push up the variator.. more sticky.. I don't know,
but I will also try venting the transmission.
forget tuning the stock carb without the airbox 135 mainjet is way too big but still it didn't make any difference, why? b'coz the needle is too thick, you can even run it without a mainjet & still it won't make any difference.
if i were you i'd start looking for a PHBG19 to 21mm carburator.