engine woes

[fward]

hey - anybody with any ideas on this one -
I am going into the fourth day of this problem with the mechanic and the electrician - dont seem to be getting closer to solving it.
Bike starts perfect from cold, runs super for 20 minutes or so and then in an instant runs rough and immediately cuts out. I then need to leave it 5 minutes before it will start again. After this first cut out it cuts out every 2 or 3 minutes ( with those 5 minute breaks in between) all the time the intervals becoming shorter and shorter

Even though the engine is crazy hot we found that it was easier to restart the engine quicker with the choke pulled out - imposible without !

Engine seems to be running incredibly hot ( after 30 mins) - even putting a cold spark plug removal tool in for 2 seconds results in your fingers almost getting burnt from holding the moments earlier cold spark plug tool.

noticed this cutting out problem first whenever i attacked a steep incline - this is a sure way to bring it on.

Sometimes when it cuts out you can immediately hear the fuel pump tick ticking for a few seconds as if there is no feul in the pump but this anomaly is only intermittent

Electrical or mechanical?


Bike is yamaha tenere 89
Recent work - recoiled stator, crankshaft straightened and new crankshaft bearings and thorough carb clean (500kms ago)
new piston, timing chain and valve seals (1000kms ago)

new piston was standard yamaha but too small for cylinder so cylinder had an inner sleeve soldered in to facilitate fit - (never sounded great from day it was replaced to be honest - loud)

Im presuming the electrician has it wired correctly as it sounds and rides perfect for those first 20 minutes . .


Any ideas would be really appreciated -

from the darkest of perus

thanks

f