yz426f help blown engine

will i need crankcase splitter and piston pullers. where can i get the feeler gauges i would need. i went to partsunlimeted.com but didnt see how to oder items.

bought craftmans torque wrench and feeler gauges what tools should i get next

the bottom end is ok i think the dealer said the crank rod might be bent. how hard is it too install new crank assembly and will i need anyting besides crank splitter and crank installer

I would be very careful listening to anything that dealer told me (after what you stated in your original post). Without you getting the motor apart and seeing the damage for yourself, you really won't be able to decide what is broken and what is not.

When you get engine back home, take some pics of the damage and post them here. There are several folks around here who have seen blown engines and they would be a lot better than I at telling you what needs to be replaced. Plus, they don't have a financial incentive to get you to replace a ton of parts (the dealer probably does).

Not all dealers are bad, there are two a few hours from me that I trust. But there are three less than an hour from me that I won't even buy a bottle of oil from because I have been burned by them before.

If you can trust the dealer, then use them. If the dealer is suspect in your mind, ask here or find a shop that you trust.

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I responded on the wr post too, what I would do is work according to the manual in the teardown process.

There's Lots to read on a full rebuild on this site - it's a pretty easy process if you can follow instructions properly.

There are some things you need to be really careful with such as torque values, but other than that - just find all similar posts on this forum - I think Greyracer has talked 100's through the rebuild process - you will find all you need to know in his replies to similar questions - if in doubt - ASK US - not your gearhead friends - they may not be accurate or want you to use a BFH at some point - people who own these bikes WILL be accurate and show you how to do things without the BFH.

*Note - BFH = Big F%^&* Hammer

Bakey,

Your head doesn't look all that bad. I am sure that it can be repaired for a lot less than new one. Used heads off eBay can be a crap shoot, so I would avoid that if at all possible.

Your cylinder doesn't look bad from the pic. Make sure to replace the timing chain when you put it all back together. Regardless of how good it "looks". They stretch and wear and you really won't be able to tell how far gone they are until they break and cause a ton of damage.

where do i send the head to get fixed ive been told to send to california to this shop forgot the name, i live in ohio. do my cams look ok?

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where do i send the head to get fixed ive been told to send to california to this shop forgot the name, i live in ohio. do my cams look ok?

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Send the head to Engine Dynamics or Millennium Technologies. It is hard to tell from the pictures, but as far as I can tell the cams look ok. Just make sure the cams aren't pitted or scored anywhere. It wouldn't be a bad idea to degree them to make sure the cam sprocket didn't spin on the cam.

called millenium and think i will ship out to them in a day or two. i think he said it was like 190 bucks to repair head and he would call me about the valves and checking my cyilinder

i found a very small schratch in the cyilinder. would it affect anything? it is abount the size of two dots from a pen

first off you should measure the bore to see if its even in spec still. If its scratched buy a new jug or get it plated. Have your local Yamaha shop give it a look over.

check it out i took a pic of the scratch its that little mark. do the lines in my cyilinder mean it has been bored out?

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the vertical lines are wear marks from your piston. run your fingernail along the cylinder and if you can feel notches where the scratches are then you should replace the cylinder or have it re-plated.

how did the piston look? if the piston looks fine, then 99% of the time the cylinder is fine.

since you will be replacing/inspecting your crank, I would highly reccomend replacing all the bearings in your cases too. It is just added insurance considering you had a engine failure after 2 hours.

Lastly, make sure you have the impeller update for your water pump.

the top of the piston got scared by the valve but i dont think it got any lower than that. how much do you think im looking at money wise if i send the head to get fixand put valves in for me and replace crank assembly/bearings and put new pisyon and rings in. and of course a timming chain that what cause this problem when it skipped

Head repair - 200

Valves - go with a good set like Kibblewhites 150 - if you go with a full kit - 200

Crank - 250

Bearings - 40

Gaskets and seals - 100

Timing chain - 35

Timing chain tensioner - 50

Piston and rings etc. - 160

So around 1000 for everything.

Judging from the bike's general condition - you just need to deglaze (lightly hone) that cylinder - the small mark will have little to no impact but spec the bore to be sure.

Head repair - 200

Valves - go with a good set like Kibblewhites 150 - if you go with a full kit - 200

Crank - 250

Bearings - 40

Gaskets and seals - 100

Timing chain - 35

Timing chain tensioner - 50

Piston and rings etc. - 160

So around 1000 for everything.

Why on earth would you use Kibblwhite valves in a 426 when the 2000 model uses OEM stainless valves that are at least equal to KW quality and about half the price? Also, springs made for stainless valves must be used if replacing Ti valves. Yamaha springs are less than $10 each. The KW spring set alone is $200.

And if you are going to suggest that a crank can be purchased for $250, you might include the brand and source. You can't get new OEM for that. ($425+)

great advice from everyone here. One thing I'd like to add is to make sure that your torque wrench is in INCH/LBS and not FT/LBS. VERY big difference there. It will be specially important when torquing the cam cap bolts. I got a pretty good 1/4" torque wrench from MSC Supply, better price than Sears and free overnight shipping. The wrench has just the right size to get in the tight areas when the engine is on the bike Here's a link: http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=20281356&PMT4NO=0 To torque the head you might need something like this: http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=20281360&PMT4NO=68682965 The second torque wrench I listed is in FT/LBS, which is ok for the head bolts, it has a higher torque range needed for the head bolts. Also, you might want to get at least a cheap impact wrench from Harbor Freight that can put out around 70ft/lbs, that will come in handy for removing the flywheel nut and may be useful on the clutch side as well. A flywheel puller will be needed too. A few months ago I had to split the cases on a 125cc 4-stroke engine to rebuild it, it helps to separate and organize all parts/bolts as you remove them, and take pictures every step of the way so you can compare later and see where everything goes.

Why on earth would you use Kibblwhite valves in a 426 when the 2000 model uses OEM stainless valves that are at least equal to KW quality and about half the price? Also, springs made for stainless valves must be used if replacing Ti valves. Yamaha springs are less than $10 each. The KW spring set alone is $200.

And if you are going to suggest that a crank can be purchased for $250, you might include the brand and source. You can't get new OEM for that. ($425+)

Yea grays correct, I wouldn't recommend KW on a 426... or any Yamaha for that matter. IMO a motor prone to cam chain stretch doesn't need any more resistance then needed. Besides stock valves last a long time if its maintained and ridden with respect. Stock are cheaper too.

If it was a 4 valve motor maybe..

IMO a motor prone to cam chain stretch doesn't need any more resistance then needed.
Prone to cam chain stretch? That's interesting, because none of the chains I've taken out of my bikes have been worn much at all. You could make a case for me being easy on an engine, but my son is another matter altogether.

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