Top end rebuild

**bolla** · #1 5 Apr 2006

Hi
My XT 600 3AJ has done 63000 KMs
The base gasket has a slight leak, one of the exhaust studs has snapped and the other is very rusty. I am going to remove the head to get the studs taken out and also replace the base gasket.
Should I replace the cam chain and should the guides and spring also be changed at the same time.
I will get the barrel and piston checked to see if I need a rebore or just replace the rings.
Should I replace any thing in the head such as valve springs or guides.
Is there anything else I should change while working on engine?
Thanks

**aukeboss** · #2 5 Apr 2006

When you take the cylinder off anyway, I recommend that you change the timing chain (supposed to be done at 50.000 km) and the valve stem seals.

If your bike has not been consuming oil excessively it might work to only change the piston rings, otherwise have a rebore and oversize piston. Mind you, running in is also necessary with just new rings (first 500 km, engine speed below 4000, 500 - 1000 not above 5000 rpm, then oil change. During this first 1000 km, change engine speed and load frequently).

Succes!
Auke

**gwel** · #3 6 Apr 2006

Hi There,

Changed timing chain at 55000 km I also had a leak towards the cylinder base gasket.
The rest of the engine is ok I just changed the ring as I was cosuming a bit of oil, and since then it just run perfect no need a rebore yet, I found having much more torque with the new rings...
Hope this help..

Enjoy you ride

**bolla** · #4 15 May 2006

I took my engine out and on closer inspection the base gasket was not leaking ,the oil was comming from the crankcase where the oil fillter bolt was stripped. As my engine was not using any oil I decided to leave the head on and got the broken exhaust stud drilled out and had the cam chain replaced.
It is amazing how much quieter my engine is now, and will hopefully be good for another few thosand miles.