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05 Sm Rebuild, Need Advice

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My 05 sm has 45000km on it and was burning a bit of oil so I figured it was time to do a little refresh. I bought a stock sized wiseco piston and was just going to use that but when I pulled it apart I found some scoring on the exhaust side of the cylinder. Running my fingers over it I can hardly notice it, but that mean I need it replated right? If that is the case I figure I might as well just buy a big bore kit for the couple hundred extra. Piston also is white-ish right at the intake side, would that be caused my an air leak? Valves have some built up stuff on them as well, can I just clean them up really well and reuse them or should I just buy new ones because of how old they are anyways? Also, there has been a big increase in head noise since I bought the bike last year, reading up on here I figured it probably is a worn cam chain, so I bought a new one as well as a mcct. Sorry for the overload of questions, just wondering what you all would suggest I do with this motor.

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12 minutes ago, cowpie said:

i'd get the big bore kit, replace the chain, and dont touch the head .. when your done make sure your jetted right ...

I'd like to see the area under the valves. There seems to be some rather chunky carbon build-up near the exhaust valves.

If the cams are in-spec and the valves haven't lost their coating, they'd be ok to reuse - but in my opinion - they have served their purpose. Buy once cry once - I'd hate to have to rebuild the head (or dropping a valve) shortly after spending money to get the cylinder in good order.

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1 hour ago, cowpie said:

i'd get the big bore kit, replace the chain, and dont touch the head .. when your done make sure your jetted right ...

I would've just gone with the big bore off the bat if I had known that the cylinder was scored, but I just got the stock sized piston kit to try and keep this as a cheap refresh

54 minutes ago, Gary in NJ said:

I'd like to see the area under the valves. There seems to be some rather chunky carbon build-up near the exhaust valves.

If the cams are in-spec and the valves haven't lost their coating, they'd be ok to reuse - but in my opinion - they have served their purpose. Buy once cry once - I'd hate to have to rebuild the head (or dropping a valve) shortly after spending money to get the cylinder in good order.

Just went out and popped all the valves out, how do I tell if the coating is gone off of them? and if I do buy new ones can I just used the old valves and some valve grinding compound to clean up the seats then pop the new ones in? Thanks. Sorry that the pictures suck, my phone has a junk camera. The seats look alot worse in the pictures than they actually are

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It does look rough in the pics.

Put the valves back in and do a leak test with solvent or gas.

 

You can't lap in the valves, they will cup almost immediately. How do yours look? If you replace the valves you'll need to have the seats cut by a reputable power sports engine shop.

 

 

 

 

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42 minutes ago, ohiodrz400sm said:

It does look rough in the pics.

Put the valves back in and do a leak test with solvent or gas.

 

You can't lap in the valves, they will cup almost immediately. How do yours look? If you replace the valves you'll need to have the seats cut by a reputable power sports engine shop.

 

 

 

 

The valves will cup immediately? Like it wont clean up the seat at all? I am just gonna order new valves anyways because that built up shit is on there good and I would rather not spend 2 hours scraping it off and polishing them pack up. I will go take better pictures of the seats in a minute I have just got to find my good camera, I spent some time with some scotchbrite pads and cleaned up the head a little as well.

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The valves will cup immediately? Like it wont clean up the seat at all? I am just gonna order new valves anyways because that built up shit is on there good and I would rather not spend 2 hours scraping it off and polishing them pack up. I will go take better pictures of the seats in a minute I have just got to find my good camera, I spent some time with some scotchbrite pads and cleaned up the head a little as well.

 

If you use lapping compound you will damage the valve's coating, new or used.

 

Google image search "cupped valve", do yours look like that?

 

Either run it how it is or do the job 100%. Anything less is a waste of time and money.

 

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4 hours ago, Gary in NJ said:

I'd like to see the area under the valves. There seems to be some rather chunky carbon build-up near the exhaust valves.

If the cams are in-spec and the valves haven't lost their coating, they'd be ok to reuse - but in my opinion - they have served their purpose. Buy once cry once - I'd hate to have to rebuild the head (or dropping a valve) shortly after spending money to get the cylinder in good order.

well, as has been noted above once you get into the head you might as well send it to a shop with some new valves to be rebuilt and get ready to put a dent in your bank account .. chances are the head would have been fine .. it didnt need to be cleaned, a good hard full throttle run down the street will clean it better than a scotchbrite pad .. but you wanted advice, your already ignoring it heheh ...

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56 minutes ago, ohiodrz400sm said:

 

If you use lapping compound you will damage the valve's coating, new or used.

 

Google image search "cupped valve", do yours look like that?

 

Either run it how it is or do the job 100%. Anything less is a waste of time and money.

 

Okay understood, I will pop the valves in tomorrow and check to see if they leak at all. Got some better pictures.

4 minutes ago, cowpie said:

well, as has been noted above once you get into the head you might as well send it to a shop with some new valves to be rebuilt and get ready to put a dent in your bank account .. chances are the head would have been fine .. it didnt need to be cleaned, a good hard full throttle run down the street will clean it better than a scotchbrite pad .. but you wanted advice, your already ignoring it heheh ...

I don't see how taking the head apart and cleaning it would damage it or why I would have to send it out to be rebuilt now, I can just put it back together as is. My top end kit came with valve stem seals anyways so it needed to be apart

 

The intake seats seem perfect to me, and the exhaust seats look like they are pitted in the pictures but you cant feel it when you run you finger on it. I guess I will just throw it together then

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