no compression after rebild?????

24 replies to this topic
  • psellers22

Posted August 16, 2008 - 09:23 PM


make sure u got it timed right trust u dont want that piston slapping the valves....when you turn the motor u dont hear it clank do you....time your motor with the ( l ) very critical:bonk:

  • grayracer513

Posted August 16, 2008 - 09:25 PM


... with the way i have it now the exhaust valves would open to fast. and would blow my compression out the window. right?

I doubt it. You're only talking about 5 degrees or so. And you don't check by where the cams line up.

Rotate the crank forward to the TDC mark (assuming the flywheel is indexed correctly), then read the marks on the cams. If they don't line up perfectly, which they usually don't, imagine the mark being at the next tooth over. Better or worse?

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  • fastback959

Posted December 04, 2008 - 02:07 PM


well i got back to the bike after many months and found out that the yamaha shop sold me rings for a 400 and charged me for 426 rings.... so after instaling new 426 rings the bike started in about 2 kicks!!! and ran like a deer, the yamaha shop gave me new head gaskit and bace gaskit with rings for the truble. thanks for all of the hellp!

  • motojoe_23

Posted December 04, 2008 - 06:37 PM


And the ring End gap didnt tip you off when doing the build???

That should always be checked when doing a build. There are times when a ring will be slightly short or slightly long. It is not very common, but if it happens it can cause all sorts of issues. Similar with plug gaps. Sure they are normally right out of the box, but every now and then they are not.

  • fastback959

Posted December 05, 2008 - 07:06 AM


yes i will check my end gap every time for now on. lesson learned

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