I did a restoration project with Phil and this was done.

It's not so much the petrol or the addative, it's got more to do with banging a valve against the head as many times as 14,500 per minute ... even 10,000 times in a 1 hour 40 min ride is MILLION times.
That's why the valves are dished !!!

Mr Evil is quite right, these japanese engines even though old are made to take unleaded fuel.
check ur valve stem for wear.
grinding in ur new valves start wiith a coarse paste then finish off with a fine one, valves ur not changing just use fine paste.u`ll know its all good when u get the that nice perfect line finish around the valve seats and valves itselfs.
And make sure valve stems oil seals are off. dont fit new ones before u lap ur valves in.

I guys been busy as a bee but im back on the bike working hard!!
The inlets are all completely shafted the exhaust valves are also ruined!! So i have ordered all new ones and stem seals!! It cost so much!! The valve seats are a concern, im thinking to lap them in without cutting the seats, but a i know it would be a benefit to cut them!! But getting a valve seat cutter for a 400 up here in shetland is difficult!! so any advice?
Also here a list of parts that seem to be discontinued
Does anyone know where i can get them elsewhere?

For 1990 3tj
1:Damper chains front and rear
2:carb to engine rubber sleeves
3:Rubber swingarm protector from the chain

Cheers guys
Im hoping to get it all together and running for the next wkd so i shall keep yopu posted!

Try fowlers of bristol,i bought a chain guide rubber from them only about 6 weeks ago,and id bet theyd have the other stuff too,just make sure youve got your frame number handy to give to the parts guy over the phone.if i remember rightly the guide rubber was 14 quid-give em a try.

Why not get in touch with Mick C - http://www.400greybike.info/newforum/vi ... 17&t=14287" onclick="window.open(this.href);return false;

If his head is ok you could maybe just drop it straight on

Thanks guys! Just bought all the valves so would just be looking at the head if i need too, Going to wait and look at the wear with a new valve for comparison before i make my mind on a new or replacement head!
But im aiming for as good a job as possible for the bike so who knows!
Cheers martin