426 timing marks

5 replies to this topic
  • 510thumpstar

Posted January 14, 2011 - 12:51 PM


Hi guys i am puttin together my friends 425 and i really dont know what im doing lol . ive done top ends on two strokes a bunch of times but never on a four stroke except a bunch of big bore kits on 50's . this bike broke a valve and we removed the top end the crank and con rod are good but the whole top end is wiped out . since the bike is so old we bought a complete used top end from ebay .. i know were rolling the dice .. basically i need to know how to set up cam chain timing . and i think i can do the rest myself . If anyone could post some pics or just explain how to set up the chain timing i would really appreciate it . the poor guy bought the bike and it ran perfect then rode it for 5 minutes and the valve broke he is a dad with three kids and is outta money do were trying to do it as inexpensive as possible . thanks for any and all replys . Ricky

  • VFRCaptBob

Posted January 14, 2011 - 01:04 PM


Valve Adj. http://motoman393.th...ech/valves.html

In lash is .10 - .15 mm Ex. lash is .20 - .25 mm at TDC

There is also a down loadable Pdf. shop manual available for his bike. Check the sticky section at the top of this category for all the information you need.

  • 510thumpstar

Posted January 14, 2011 - 01:21 PM


oh boy i keep reading all these posts on how to do it and im getting scared lol .. i guess once its done ill be like duh that wasnt that bad .. its just a little intimidating i guess . Ricky

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  • jpgentry

Posted January 14, 2011 - 09:13 PM



A wr but this may help I hope

  • VFRCaptBob

Posted January 16, 2011 - 01:52 PM


The actual process is very easy however you have to do everything correctly to avoid a costly or time consuming failure. I've fished the cam cap register half ring from several nooks and crannies of the motor and hunted for a dropped shim for hours only to find it the next day under my truck in the driveway. Key is don't rush anything and follow all the steps.

  • Doete36

Posted April 26, 2011 - 08:23 AM



A wr but this may help I hope

Good post, better than the manual!! thanks for the help

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