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Head Gaskets

By Birdie426,
in WR400F/426F/450F

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Birdie426

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I'm getting ready to pull the head off of my 01 426 to have a look at the valves and to re-ring. I went to my local yamaha dealer, who really isn't worth the powder it would take to blow his shop to...um you know, and he had rings and a base gasket, but no head gasket. No problem, as I was jetting down from the hi desert to Montclair, and figured I could pick up a gasket at Yamaha of Montclair, a truely premier shop. No joy. I tried the Yamaha shop in Saugus, Rancho Cucamonga, and Burbank/North Hollywood, and all had rings and base gaskets, but no one had a head gasket. Now, I might not be the sharpest knife in the drawer, but don't you have to replace the head gasket when you pull the head to change rings? Why wouldn't these parts departments stock head gaskets if they stock rings? One of life's great mysteries? Guess I'll order from YoT...

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Rising Star

Birdie426

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Indy-

I figured I would take a look at the condition of the valves when I pulled things apart. I have access to x-ray, eddy current and dye penetrant inspection equipment at work, and have inside and outside mics at home so I had planned on doing both a crack inspection and dimensionals. Hadn't thought much about springs, as I haven't heard of any failures. Do the WRs have a history of spring problems like the CRF's do?

What's the hot ticket for springs, retainers, and valves from a cost and durability point of view for these bikes? Stock? Pro-Circuit? Kibblewhite? I don't need any more power than the bike makes right now, so I'm looking for durability and trouble-free riding.

Thanks for any advice.

Birdie

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yz426onNOS

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Yes you do but you might as well change the valves/spring/guides/seats while you are doing the piston and rings.

If you dont your engine could end up like this in a very short time after your rebuild.:

http://www.xr250rdr.com/Beene/Mvc-012f.jpg

http://www.xr250rdr.com/Beene/Mvc-013f.jpg

http://www.xr250rdr.com/Beene/Mvc-014f.jpg

Hey that looks just like what happend to my 2000 yz426! Dropped an intake valve pinned in forth right before a shift to 5th. ? Except I punched a whole through the piston. Damn 2 pieace valves! ?

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Grand Master

Indy_WR450

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Indy-

I figured I would take a look at the condition of the valves when I pulled things apart. I have access to x-ray, eddy current and dye penetrant inspection equipment at work, and have inside and outside mics at home so I had planned on doing both a crack inspection and dimensionals. Hadn't thought much about springs, as I haven't heard of any failures. Do the WRs have a history of spring problems like the CRF's do?

What's the hot ticket for springs, retainers, and valves from a cost and durability point of view for these bikes? Stock? Pro-Circuit? Kibblewhite? I don't need any more power than the bike makes right now, so I'm looking for durability and trouble-free riding.

Thanks for any advice.

Birdie

You can inspect all you want but why take a chance. I am rebuilding my WR450 currently and I am going with all new Kibblewhite Titanium valves, springs , seats and guides. New piston, rings, bottom end bearings, rod bearings, new cam chain, new left side crank to replace worn cam chain sprocket which eats itself. While I have the cases split I will put a new countershaft seal on the gearbox. ?

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yz426onNOS

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You can inspect all you want but why take a chance. I am rebuilding my WR450 currently and I am going with all new Kibblewhite Titanium valves, springs , seats and guides. New piston, rings, bottom end bearings, rod bearings, new cam chain, new left side crank to replace worn cam shft sprocket which eats itself. While I have the cases split I will put a new countershaft seal on the gearbox. ?

Why don't you go with a stroker crank and/or 13.5.1 compression and a lareger bore? Might as well do all the seals to. Maybe some new cams.

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Grand Master

Indy_WR450

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The Falicon stroker heavy crank I want is $1000. and requires the jug to be resleeved deeper with a special process for an additional $800. I just dont want the bike down and out for 2 months. Falicon is backed up with orders 8 weeks out. I will do that on the next rebuild in 2 years on this bike and get a new fuel injected WR450 while I am at it and use this bike for a back up and buddy bike! I got to be up and running by the end of January so I am staying with a reliable rebuild and pump gas friendly 12.5: 1 compression. ?

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