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426 tick tick tick engine help? pics added

By Ztard,
in YZ400F/426F/450F/450FX

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Ztard

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2002 YZ426F checked the valves last month, with nothing but an oil change since then.

so after a long winter break i took the mighty YZ out to the local track. Warmed it up like normal, headed out for the first session....nothing abnormal. 2 jumps into the first lap, high pitched squealing noise and the bike cuts out. Kind like it is seized. Even if i pull the decomp lever in i can't kick it over. So after a long push back to the pits. I can kick it over with a bit of effort, I decide to give it a go. The bike fires, but with a loud and I mean loud clicking/ticking noise? Couple guys at the track said I sounds like i caught a ring and that is the noise I'm hearing.

What else can I do to diagnose this, or should i just bite the bullet and tear into the engine?

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jjj109

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2002 YZ426F checked the valves last month, with nothing but an oil change since then.

so after a long winter break i took the mighty YZ out to the local track. Warmed it up like normal, headed out for the first session....nothing abnormal. 2 jumps into the first lap, high pitched squealing noise and the bike cuts out. Kind like it is seized. Even if i pull the decomp lever in i can't kick it over. So after a long push back to the pits. I can kick it over with a bit of effort, I decide to give it a go. The bike fires, but with a loud and I mean loud clicking/ticking noise? Couple guys at the track said I sounds like i caught a ring and that is the noise I'm hearing.

What else can I do to diagnose this, or should i just bite the bullet and tear into the engine?

heard that noise before on a buddys yz426f. probably a crank is no good now. he had that same high pitch squeal then the bike cuts out. tore the top end off found some cylinder damage but the squealing noise wa coming from his crank. had to do crank & rod, bearings, cylinder, piston & rings. my buddys was cause a lack of oil. basically his dumb a55 fault for not checking the oil when he had a leak.

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Ztard

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OK, here is the damage so far...... You can then tell me if this is repair or replace on the head? I think I know this answer. Once I had the valve cover off I went to loosen the cam cover bolts...all but two were loose ??? But I think the bottom line is this failure was to lack of oil. Right? could loose cam cover bolts cause this, or should I keep digging? Oil pump?

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spark250

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cam looks smoked from the pic! Too bad, I feel for ya!

So if every bolt but two were loose is that something you might have done? Did you re shim when you checked the valves?

Still doesn't explain what looks to be a lack of oil like you mentioned though.

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jjj109

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OK, here is the damage so far...... You can then tell me if this is repair or replace on the head? I think I know this answer. Once I had the valve cover off I went to loosen the cam cover bolts...all but two were loose ??? But I think the bottom line is this failure was to lack of oil. Right? could loose cam cover bolts cause this, or should I keep digging? Oil pump?

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dsc03576o.jpg

dsc03579g.jpg

well you got her apart so its better to be safe then sorry. your probably still gonna find bottom end damage. I would spend the money on gaskets then have to buy more hard parts.

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Ztard

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The blank head (incl. guides and cam caps) retails for $787 ($707 at TT OEM)

That gives EDCo a lot of room to work.

Considering i paid $1700 for the whole bike, I'm struggling with the repair cost at this point. I plan on calling them once they open today.

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BRY_426F_

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My bike makes that high pitch squeeling sound every so often.. and my crank is freshly rebuilt. maybe 15 hours on it.. it doesnt seize up though.. i get freaked out a little and usually cut it.. idk good luck! make sure to check the lower gears down by the right side of the crank.. 426's have a rep for burning the crank, and breaking gears.

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Ztard

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Ok, the machine shop says the head and cams can be saved. ?

Follow up question: Is there any way to confirm my oil pump is ...well pumping with everything apart? Or do I have to split the case and pull it out to check it out?

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grayracer513

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Yes, but if the cam chain is still in place, you must find a way to hold tension on it so that it won't wad up around the crank and foul things up. The feed pump can be tested for basic function by turning the engine over (with oil in the frame) and watching for oil to be pumped up out of the hole where the external manifold that feeds the top attaches.

The return pump cab be checked with a small amount of oil in the sump by disconnecting the return oil line at the steering head and cranking the engine.

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Ztard

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Gray, as usual thanks. Once I get the jug back on this will be a bit easier to attempt.

I'd assume if it was your bike you'd just replace it? But at $113.00 for an OEM oil pump I need to know the money is headed towards what needs to be replaced.

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