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Old 06-16-2013, 01:24 PM   #42
schattat OP
Beastly Adventurer
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Joined: May 2008
Location: Frankfurt am Main, Germany
Oddometer: 1,445
Day 3 evening I analyse the issue with the help of some friends from Finnland. Their mechanic helped me reassemble my bike. We had a hunch the the bottom of the cylinder head was no longer planar, but warped a bit. WE didnÄt have a glass plate or anything similar to check, but why else would the gasket not hold (new, tourqed down correctly)?
Day 4 starts again with me in the back, motivated and ready to go. I "nurse" bike at the beginning a bit, but eventually see it's holding up pretty well. A fews kms into the stage I come across my friend Guillaume who crashed and broke one of his left hand fingers, he's out unfortunately. The day is a long one, I ride the whole day with Ed and another English bloke. The transfer section mid-day was through the mountain region of Tunisia, a bit chilly, wish I had had a thicker jacket. We pass through many villages and see many locals, especially little kids. A lot of friendly waving as we pass by. Later during the day there is a faster hard packed section, I gun it a bit more since the bike has worked flawlessly for the last 155km. 5th gear hitting about 140km/h and it dies yet again.I stop and see a tonne of liquid spewing out from the left hand side. I think it's fuel from a hose gone loose and turn the fuel tape off. No good, still running out. I get off the bike, touch the juice and smell it. Hmm, not fuel but water. I check if one of the radiator hoses had gone loose, nope all tight. I try to find the source and it's the cylinder head. Darn, the next CP is literally under 1km away. Ed goes there, gets a towe rope and rides back to tug me to the CP where I let him go on and wait for you know who. At this point I was just fed up of having the rip apart the engine again, and with no more parts and limited resoursces, I figure it's time to not touch the engine any longer.
Only back home I take it apart to find this:

Incredible how much water pressure there was to cause this channel on 2 different spots on the bottom of the cylinder head and top of the cylinder barrel itself! For sure there was no way in hell to have been able to fix it during the rallye.
I had to have it welded. I then got some very fine grit sandpaper and shaved down the surface of the cylinder head to make it look new:

Nonetheless, the bike is running again, new cylinder installed and fixed head, all good. I have, however, gotten myself a new toy anyway, 2012 WR450F with EFI Can't wait for the next build thread (cough, rear tank subframe, cough).

I would also like to thank all the awesome people I was fortunate enough to meet during the rallye, including Jenny; the Finnish team along with their Estonian riders; the helpful sweep guys; Charlie, Dave and many other US boys; and many others!

BTW, I still have some nice GoPro footage, which I still need to edit and upload. Whenever I have enough time!!!
RNS - Rallye Navigation Solutions

Yamaha WR450F Rallye Spec
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