I've had a couple of requests for an update.
Buying parts for jap bikes isn't the same as buying airhead parts. After a frustrating delay waiting for parts to arrive the FJ is back up and running again. I've got to say it's a great bike now it has 4 cylinders
turns out the previous owner bought it on ebay from a chap in Newcastle, who bought it on Ebay from a chap who sold it because it wasn't running right. The Newcastle chap put new carb diaphragms and new inlet and carb rubbers in (ouch! £££) assuming the problem was an air leak. That diidn't fix the issue so he flogged it on ebay.
I''m glad it has new rubbers because it made the job easy for me. New Rubbers and diaphragms would have been well over £200
I ultrasonically cleaned the carbs. Couldn't believe the crap that came out of them.
and fitted a new head gasket while the head was off.
A new exhaust valve was needed along with a complete reshim. Barrels and pistons are reassuringly wear free.
The Thundercat front End is superb compared to the original FJ items and looks like it should have been part of the bike from day 1. The R1 brakes are in a different league. to be honest I can't tell any difference between the 17" front wheel and the original 16.
The only downside is for somebody used to Airheads is the speed is a bit scary
Apart from that I'm impressed by the Yam, the engines a gem and so simple and easy to work on.
Total spend was £600 for the bike. £180 for the Thundercat front end and R1 brake calipers. £83 for shims and tool. £87 for head gasket, exhaust gaskets and a replacement valve. £25 for a Thundercat front mudguard. Total of £975. I still have the original forks, wheel, brakes and the givi panniers to sell to recoup some of the money.