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Thread: Yoshimura Cams Query

  1. #1
    Join Date
    Aug 2016
    Location
    Dublin
    Posts
    94

    Yoshimura Cams Query

    Im aware of the numerous threads about cam pitting and the differences in opinion about causes and the seriousness (or not) of the issue
    The bullet points of my query are.....
    20k mile ZRX1200 that ive had since it had 8000miles
    Its been in to have valve clearances checked and intake camshaft has some pitting on a couple of lobes
    The mechanic is a VERY well respected ex Kawasaki mechanic and the only guy I entrust to do stuff I don't tackle myself
    He made me aware of the pitting as he knows how fussy I am about anything mechanical,but says if it was his he wouldn't worry about it (but we will monitor it)
    Im happy if he is happy ,cause like I said he is very well thought of regarding his attention to detail etc.

    I do however like to always know my options should we discover it gets worse
    With genuine cams no longer available (intake anyway) and likely to pit anyway even if I found some, what do I need to do IF I went down the yoshimura cam route?
    Im not chasing power or any different engine characteristics (just piece of mind) but I understand Yoshi cams may mean I need to change other stuff.

    Will the cams just go in and work fine once shimmed correctly? or am I into issues with ignition timing/carburation etc even though I am just trying to put a cam pitting issue to bed?

    I see there was a Yoshimura ST-1 listed but now it seems to be an ST-1M....anyone know whats the difference and what can of worms gets opened if I end up having to go down this road?
    Thanks in advance
    Current............., ZRX1200R (1200S Post Op) ,Transalp 600 Anniversary, Honda CRF1100 Africa Twin (Shocking paint quality)
    Recently departed .........Guzzi 1100 Sport , GSXR1000 ,Triumpg Tiger 800 and another ZRX1200R
    Awaiting.......Lottery win and that RC-30 that's currently on Ebay

  2. #2
    Join Date
    Jun 2005
    Location
    Farnborough Hants
    Posts
    9,148

    Re: Yoshimura Cams Query

    I have Yosh ST1 cams in my 1100, and have changed nothing else.

    It's s little more complicated in a 1200, and you may have to change the rockers as well.

    Rather than the expense of Yosh cams, why not fit the cams ond rockers from a ZZR1200.
    TPB-Founder member HCW
    Champagne ideas on beer money

  3. #3
    Join Date
    Jul 2015
    Location
    Hertfordshire, UK
    Posts
    747

    Re: Yoshimura Cams Query

    Best option if you need to go down the road of replacing your OEM cams is to have them surface plasma nitride coated . I suspect the difference in the new Yoshimura cams is an improved surface hard coating being used on the new "1M" cams

  4. #4
    Join Date
    Aug 2016
    Location
    Dublin
    Posts
    94

    Re: Yoshimura Cams Query

    Quote Originally Posted by Pal View Post
    I have Yosh ST1 cams in my 1100, and have changed nothing else.

    It's s little more complicated in a 1200, and you may have to change the rockers as well.

    Rather than the expense of Yosh cams, why not fit the cams ond rockers from a ZZR1200.
    Ill have to look back on everything ive been googling. (confused now)
    Do the ZZR1200 cams not have the very same issue with a dodgy hardening process from new?
    Thought my mechanic said that too
    My understanding was that 1100 cams and zzr1100 cams don't fit ....and that zzr1200 cams fit but they use 2 springs per valve (hence why the rockers need changing) ,,,but that the ZZR1200 suffered from the same issue
    I suppose if I found undamaged 1200 cams then maybe they are from a better batch
    I just thought id explore the Yoshimura option purely because I can get them new and wouldn't have what I suspect will happen with second hand cams ("yes mate they are perfect" only to have pitted ones arrive anyway)
    Ill open up the valve cover in a year or so to keep an eye on the current ones because these ones could be damaged early in their life and not getting worse...Its only because ive been made aware of it that im checking options.
    Apparently because the pitting is in the middle there is still plenty of material on the shoulder each side for it to not be an issue...........but the issue is that now I know its there lol
    First world problems I guess....but I like things to be right

    Im sure ill be wrong about some of the above...but ill be educated once corrected
    Last edited by mountainmile; 19th June 2022 at 11:01 PM.
    Current............., ZRX1200R (1200S Post Op) ,Transalp 600 Anniversary, Honda CRF1100 Africa Twin (Shocking paint quality)
    Recently departed .........Guzzi 1100 Sport , GSXR1000 ,Triumpg Tiger 800 and another ZRX1200R
    Awaiting.......Lottery win and that RC-30 that's currently on Ebay

  5. #5
    Join Date
    Jun 2008
    Location
    east of holland 50feet from the german border
    Posts
    7,583

    Re: Yoshimura Cams Query

    Quote Originally Posted by mountainmile View Post
    Ill have to look back on everything ive been googling. (confused now)
    Do the ZZR1200 cams not have the very same issue with a dodgy hardening process from new?
    Thought my mechanic said that too
    Yep, 1200 wunna fit in an 1100
    Ans yep, some are pitted, some aren't.
    i know peeps that have been running pitted cams for yonks without probs. Pretty bulletproof.
    Birdie num num........

  6. #6
    Join Date
    Jun 2005
    Location
    Farnborough Hants
    Posts
    9,148

    Re: Yoshimura Cams Query

    Quote Originally Posted by mountainmile View Post
    My understanding was that 1100 cams and zzr1100 cams don't fit ....and that zzr1200 cams fit but they use 2 springs per valve (hence why the rockers need changing) ,,,but that the ZZR1200 suffered from the same issue
    I suppose if I found undamaged 1200 cams then maybe they are from a better batch
    1100 cams won't fit in a 1200 without major mods, but ZZR 1200 will go straight in.
    You don't need to fit double valve springs when changing cams, only if you are fitting a ZZR igniter as the rev limit is raised and the double springs are needed to stop valve float.
    ZZR1200 cams can suffer with pitting but the later ones had different heat treatment, and some early bikes may have had these later cams fitted under warranty.
    TPB-Founder member HCW
    Champagne ideas on beer money

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