WONT REV OVER 4000 RPM!! HELP

hey my mrs's has a 81 xj650 trike, was sat in a shed for a few years but had it runnin well and on the road for a few months then sudenly it wouldnt run over 4000 rpm. i have cleaned tthe carbs more times than i can remember. changed the coils checked all earths and connections and still no joy. im about at my wits end with it. realy hopein some one ght know wat it is. thanks for takin the time to read this. . howzie

 

What happens out of gear? Will the bike rev higher?

If it will and steadily, then it suggests the TCI/pickup side of things is ok.

4000 is really low - is that on the road? It could be a carburation issue as I believe the pilot jets take care of things up to 3000 then the main jets take over.

When I still had my 600, I found that if you rode below 3000 the engine went to sleep!

The next thing is fuel supply: Have you fitted a filter recently or perhaps you could try riding the bike with the fuel tap in the "Pri" position?

 

If it runs well but just has no power it could be that the TCI isn't advancing the timing. Might be worth sticking a timing light on it and having a look.

You should see a smooth advance of the timing mark from about 1500 to ~4K (the advance is maxed out at about 4k).

You need to look at the timing of the 1-4 spark and of the 2-3 spark as they're functionally separate.

 

If you could somehow safely manage to ride the trike, and spray ether/instant start into the intake, briefly, and see if it picked up, then it's fuel delivery.

And we need pics of the trike, and the missus !!