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Post by tony1964 on Mar 18, 2018 9:48:31 GMT 1
Good morning, I went to fit my head gasket (genuine yamaha) yesterday and noticed the gasket is slightly over hanging the bore hole by about 1mm, the bore is now 1.5 over standard, will this cause a problem?? if so how do i rectify it Tony  PICT2632 by Anthony Baker, on Flickr |
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Post by tony1964 on Mar 19, 2018 9:42:35 GMT 1
Any Ideas anyone?  ? |
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Post by Tobyjugs on Mar 19, 2018 11:07:19 GMT 1
Yes carefully open it up with a dremmel or something similar. Make sure there are no burrs and no tiny particles between the leaves
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Post by tony1964 on Mar 19, 2018 11:23:44 GMT 1
Thanks Tobyjugs.
Does it have to be flush with the bores ??
Tony
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Post by Tobyjugs on Mar 19, 2018 12:46:27 GMT 1
Slightly bigger because the gasket will move around and you don't want it moving over and obstructing the piston crown in TDC position
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Post by tony1964 on Mar 19, 2018 12:49:21 GMT 1
Thanks Tobyjugs.
Not looking forward to doing this.
Tony
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Post by philmill on Mar 19, 2018 15:04:15 GMT 1
Sorry to jump in here Tony, I wonder if anybody makes an oversize gasket, there must be loads of bikes on plus 1.00mm or more rebores now.
Phil
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Post by Tobyjugs on Mar 19, 2018 15:42:58 GMT 1
Jump in as much as you want it's a forum😊
I have had to do this on my bike in the past and find it a PITA.
A nice solution is to get the head O-ringed, but it is expensive plus the compression ratio was too high. Once sorted it's a nice option.
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Post by tony1964 on Mar 19, 2018 17:55:00 GMT 1
Spoke to Stan Stephens, very helpful man, he said not to touch the gasket as it wont cause a problem and the dome of the piston wont touch it,he didn't recommend trimming them back as they could leak, he did say if i was worried to use a thicker base gasket but he wouldn't on a 1.5 overbore.
phillmill.
It would be nice if they did.
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Post by Tobyjugs on Mar 19, 2018 19:15:49 GMT 1
Turn a piston to TDC and check it's not interfering.
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Post by mattybeckett on Mar 19, 2018 20:52:11 GMT 1
Should be fine, unless the gasket protrudes down into the bore, which is highly unlikely.  |
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Post by midlifecrisisrd on Mar 19, 2018 22:13:59 GMT 1
I did think you wouldn't have to trim it on 1.5
Do check your powervalve clearance though just to be safe but again should just be ok at 1.5
The pistons don't actually reach the top as standard but as said checking does no harm.
Steve
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Post by bare on Mar 20, 2018 2:46:01 GMT 1
Spoke to Stan Stephens, very helpful man, he said not to touch the gasket as it wont cause a problem and the dome of the piston wont touch it,he didn't recommend trimming them back as they could leak, he did say if i was worried to use a thicker base gasket but he wouldn't on a 1.5 overbore. phillmill. It would be nice if they did. In his Dotage IMO. |
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