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Thread: 350 exc-f top end

  1. #11
    Fetus Moto
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    The entire bike is in bits for service and check etc. once the motor was out, it only took a couple of hours to clean it up with degreaser and get the the head barrel and piston out. Then most of a Saturday to slowly measure stuff and recheck it and clean up valves and decoke head,I like to take my time over checking and examining stuff and comparing with the data on the service CD. Also cleaned up the outside of the head and barrel with a dremmel as mud seems to engrain into the castings very well. once the new vertex piston arrives and the gaskets, valve shims and stem seals etc, I'd probably spend another Saturday rebuilding it slowly. making sure its all oiled up well and torque up everything.

    Swing arm has been regreased , forks and shock serviced by Dr Shox in Essex? New head bearings as the lower one was seizing ( water gets in thru the steering lock and rusts up the lower race) Frame has been resprayed and everything cleaned and checked.

    Then it'll probably take a couple of weekends , or a week of evenings to rebuild it all.
    Rob James likes this.

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  3. #12
    Adult Moto Rob James's Avatar
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    Awesome attention to detail!
    2017 350 EXC-F

    Previous, 2009 CBR600rr, 2008 SX250, 2004 CBR600SP2, 2002 CR250, 2001 CR125, 1996 CR125, 1989 YZ125

  4. #13
    Fetus Moto
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    NewPistonSide_zpswig22l2x.jpg Photo by DRZdave1 | Photobucket

    NewPistonLower_zpszqrdv8ww.jpg Photo by DRZdave1 | Photobucket

    New Vertex piston turned up today, links to pictures of new Teflon patch and also modified construction underneath piston compared to earlier pic of KTM one. New vertex one weighs 200G but old KTM one is 210G.
    I ordered up the gaskets and other bits from KTM dealer today who also told me it is OK to lap in the valves.
    Wasn't sure about the valves as the manual for my DRZ's says don't do it as they are stellite coated and once this is ground away they will wear and close up the gaps and need constant resetting. This seems to be the case with my off road DRZ but the road one that I haven't had to mess with is OK.

    Checked out the cam chain guides as well and there is no wear on any of them. Will also check out the clutch plates this weekend.

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  6. #14
    The "Moto" steveman's Avatar
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    Even the old piston looks good to me, shows smooth wear, color of valves in the head show a good colour, no overheating. All seems to be good :-)

  7. #15
    The "Moto" nickr's Avatar
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    does anyone know where I can buy some little square shaped stick on Teflon pads.
    SK400 likes this.

  8. #16
    Teenage Moto
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    Quote Originally Posted by DRZdave View Post
    NewPistonSide_zpswig22l2x.jpg Photo by DRZdave1 | Photobucket

    NewPistonLower_zpszqrdv8ww.jpg Photo by DRZdave1 | Photobucket

    New Vertex piston turned up today, links to pictures of new Teflon patch and also modified construction underneath piston compared to earlier pic of KTM one. New vertex one weighs 200G but old KTM one is 210G.
    I ordered up the gaskets and other bits from KTM dealer today who also told me it is OK to lap in the valves.
    Wasn't sure about the valves as the manual for my DRZ's says don't do it as they are stellite coated and once this is ground away they will wear and close up the gaps and need constant resetting. This seems to be the case with my off road DRZ but the road one that I haven't had to mess with is OK.

    Checked out the cam chain guides as well and there is no wear on any of them. Will also check out the clutch plates this weekend.
    Is there any reason why you chose to go with the vertex piston, rather than than OEM ?

  9. #17
    The "Moto" nickr's Avatar
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    Looks like there are quite a few of us reading this thread and thinking it's time to have a look. Probably gonna get one more ride out of mine this weekend, then it's time for action.

  10. #18
    Teenage Moto
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    Some pics of the "freshened" bike would be good !!!!!

  11. #19
    The "Moto" Pindie's Avatar
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    Quote Originally Posted by nickr View Post
    Looks like there are quite a few of us reading this thread and thinking it's time to have a look. Probably gonna get one more ride out of mine this weekend, then it's time for action.
    Uh oh. Not the old "just one more ride" line, "it was running the best it ever has when....".

    Peace of mind though once done. It's only expensive if it goes bang. Buying replacement parts is just wear and tear and no different to brake pads, chains, discs etc.
    This is all I can see when I open the throttle:

    Before https://www.youtube.com/watch?v=UWMWXJvX8e4

    After https://youtu.be/VtBLqkh5u8k

    Keep out the way!

  12. #20
    Fetus Moto
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    Reason we went with the vertex was cost, Its my boy (27) that rides it in enduros etc I only dick about on it the woods from time to time, otherwise I ride my Drz,s or XT660 Tenere, so he's paying for the rebuild but I,m doing the work ( I,m Pit Crew and Driver at any meetings!) I'd read that vertex make the KTM pistons which is born out with the VP mark on the base of both pistons. I,m still not sure if the Teflon patch is the reason to change the piston, as Steveman said it all looks pretty good inside, but as its a competition engine and a step up from the DRZ's I thought best we follow the book an look inside. once you've opened it up, what do you do? piston minimum, valve stem seals and re do the valve shims.
    Vertex piston ( rings pin and circlips) was about £165 plus £85 for head gasket base gasket 2 shims, 4 valve seals and a few other odds from AMS in Tewkesbury. Ktm piston is about £200 on its own or £230 as a kit with base and head gasket Cam chain is about £80! and needs further stripping and more gaskets which is why I left it, Ive only changed 1 cam chain in my DRZ's in 15 years of owning both of them, the off roader has been well hammered and hasn't grenaded and the on roader ( trails roads etc) has done 15000 miles. so 150 hours seems a bit cautious for the KTM.
    The KTM piston is a different case as there is so little of it and I,m new to this Teflon patch lark.
    We pressure wash the whole bike after any event but even so the build up of crap in all the engine nooks and cranny's is unbelievable, the last enduro he did in wales looked like the mud had been put on with a trowel and took about an hour to clean off, just to find the bike~! and it needed further cleaning with a brush an hot soapy water then. The frame paint had started to come of around the engine and the plastics were looking very second hand, I hadn't checked head bearings or swing arm since we got it so it seemed sensible to strip the lot and clean every thing ready for 2017 and another 150 hrs. I don't think you can get the head or barrel off without removing the motor , so once that's out there's not a lot left to strip.
    Besides I quite enjoy stripping and rebuilding stuff, that's part of the fun,. and so far nothing I've rebuilt has gone pop, that covers triumph twins a Harley, Kawasaki 2T triples, XT 500, XL250 TS250 DR125 gasgas250 DRz,s and quite few other dirtbike singles.

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