Find that fault. I

This is the first in what will no doubt be a series of fun fault finding exercises.

I will present information to you as I found it then talk through my process of elimination to find the fault. I'm hoping these will be useful in helping you recognise a problem with your bike better through the faults I have come up against.
Some of these faults are very complicated and have multiple answers. In these circumstances I try to separate them where suitable. However as these things do sometimes come along in a group of problems; be prepared for less than straight forward answers.
So knowing I am riding a mildly tuned RD250 E with VM32 carbs TZ250 G expansion chambers and an electronic ignition system lets have a look.

Symptoms

The bike was on the dyno the day before having recently had a new ignition fitted and was running well with good power and safe temperatures.

Engine started well on choke.

In the waiting area for the Pembrey practice session; the bikes tick over was noticeably high with the right cylinder temperature climbing at a much higher rate to the left.

Right pipe was running smokier than the left  which would seem to balance somewhat when revved.

During riding temperatures rose to near correct running temperature with left reading slightly lower at 138/149 max. 

Power delivery was very lumpy, bike seemed much happier wide open throttle.

Riding was terminated due to another fault.

Investigation

• Changing tick over screws made no difference, 
• Spark plugs were brown and slightly wet,
• Spark was crisp and blue,
• Fuel lines were unrestricted,
• Float chambers were getting fuel,
• Air screws were at 1.5 turns out.
• Jetting was unchanged,
• Slack could be felt in the throttle, 
• Throttle Slide balance was out by 1mm,
• Cable adjusters and carb tops were taped,
• No air restriction, carbs open,
• No exhaust restriction some leaks present.

The cause

The diagnosis for this fault was carried out with other faults in mind so would not be relevant here.

The cause for this fault was the right throttle cable guide popping out of it's seat on the carb top despite being taped. 

The tape made this hard to see and was only noticed when the cable was manipulated after spotting the throttle slide imbalance. 

The temptation here was to re adjust the throttle cables but even with the best prevention techniques, things can still work loose during transit. 

As it was unlikely the cables locks had moved: cable guide seating became the prime culprit.