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Post by headcoats on Aug 9, 2017 10:48:18 GMT 1
Took my 1.00mm over Mick Abbey barrels to P J Engineering for what I thought would be the next size up rebore as there wasn't any bad scoring etc but was told when they did a quick measurement while I waited that it may need 1.50mm to clean up Well they just rang and now the 1.50mm hasn't cleaned up and now I have to see if 1.75mm does the trick ! Basically they said the inlets were well worn and the bore wasn't touching them ! Dilemma now is to have them at 1.75mm or have my spare 0.5mm standard non tuned barrels done instead so I would be semi scrapping my Mick Abbey barrels ?
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Post by muttsnuts on Aug 9, 2017 12:33:59 GMT 1
unfortunately this isn't unusual, the middle part of the bore (inlet area) tends to wear oval if you like, as there isn't much barrel material in that area, so it wears the most, I've had it several times and its sometimes hard to explain to customers why they have lost 2 or 3 lives out of a barrel
Have them out at 1.75, they will be fine, just be sure to trim the head gasket a little, if they are PV barrels, then check and if necessary trim the powervalves as well, and PV barrels are worse than LC barrels for wearing like this
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Post by headcoats on Aug 9, 2017 12:44:08 GMT 1
They are YPVS 350 barrels I guess the tune that opens the inlets up loads doesn't help that area either then !
I have some standard barrels on 0.5 and was thinking I should have just had them sorted but I like the tuned barrels
Will the head be OK with the larger bore ? Is it just trimming the head gasket then and checking the power valve clearance ?
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Post by LC_BOTT on Aug 9, 2017 15:55:17 GMT 1
My 350LC barrels have been at Grampian for several months now, thought it was just for a rebore at 1.75 over, but they called to say they were basically scrap, seems they have a common 'dig' out of the exhaust port, that cannot be cleaned up. I've been scouring fleabay for a barrel (or pair) since, and not found any decent ones so far, mine were slightly tuned, so would prefer similar. It's not a nice club to be a member of though
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Post by headcoats on Aug 9, 2017 16:38:12 GMT 1
No and I'm still waiting for them to call me to tell me if the 1.75mm bore was a success or not Might have a couple of expensive paperweights :-(
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Post by Tobyjugs on Aug 9, 2017 21:55:54 GMT 1
On my resleeved Ypvs cylinders (195cc) I have seen a lot of wear in this area. I personally think the barrel warms up and expands but the inlet is always being cooled down by the fresh charge causing this spot to be smaller and contributing to the wear in this area. Anyone else got some ideas on this?
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Post by headcoats on Aug 10, 2017 18:28:55 GMT 1
Was reading on another forum that when going towards 2.00 oversize pistons, you can run into compression issues Is this true and what would need to be done ?
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Post by headcoats on Aug 16, 2017 20:58:14 GMT 1
They rang today to say my barrels were done at 1.75mm rebore So that's 3 rebore sizes up from when I first took my barrels in to be done
Out of interest . what CC are my barrels now ? And as above what about the compression with the larger bore ?
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Post by KevtheRev on Sept 3, 2017 10:09:49 GMT 1
Check these babies out Heads , found 'em in the garage where they'd lain forgotten since someone gave 'em to my brother yrs ago . Reckon they've had a hone or two . Bit of polish should see 'em right , lol . Now , where's that other piston ?? www.flickr.com/photos/158728103@N02/shares/0y5D63
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Post by KevtheRev on Sept 3, 2017 10:16:44 GMT 1
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Post by KevtheRev on Sept 3, 2017 10:26:38 GMT 1
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Post by midlifecrisisrd on Sept 3, 2017 10:34:33 GMT 1
They rang today to say my barrels were done at 1.75mm rebore So that's 3 rebore sizes up from when I first took my barrels in to be done Out of interest . what CC are my barrels now ? And as above what about the compression with the larger bore ? 365.5cc Steve
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Post by headcoats on Sept 3, 2017 11:06:18 GMT 1
They have had to trim the powervalves too but haven't been to fetch them yet, I'm in no hurry
What is the procedure to trim the head gasket ?
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Post by midlifecrisisrd on Sept 3, 2017 12:15:59 GMT 1
Measure it first
If needed then Dremel it out
Steve
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Post by LC_BOTT on Sept 3, 2017 19:51:19 GMT 1
Check these babies out Heads , found 'em in the garage where they'd lain forgotten since someone gave 'em to my brother yrs ago . Reckon they've had a hone or two . Bit of polish should see 'em right , lol . Now , where's that other piston ?? www.flickr.com/photos/158728103@N02/shares/0y5D63Kin'ell they look massive, don't get you hand stuck in those ports, would like to hear how they run on the road
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Post by bare on Sept 3, 2017 23:09:38 GMT 1
Hmmm IF at all. Those look as well and truly bungled.
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Post by KevtheRev on Sept 4, 2017 9:58:53 GMT 1
Hmmm IF at all. Those look as well and truly bungled. Haha , God knows what they were at ! The liners are cut right into the stud holes . I must work out what cc they'd be .
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db8888
Thrash Merchant
Posts: 329
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Post by db8888 on Sept 28, 2017 20:52:39 GMT 1
Apart from the ports the main reason the bore wears more in that area is due to the angle of con rod which causes a side load on cylinder if you think about it at tdc the rod is straight as it goes down the angle creates a side load
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Post by mikee on Oct 13, 2017 12:32:34 GMT 1
cagiva mito barrels do this too , not so much wear but a collapsing of the bore , not a lot of support around the ports so the bore gets pushed away , barrel shaped bore is the result
mike
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Post by beardy on Oct 17, 2017 10:04:47 GMT 1
is a re-sleeve not the answer? before i joined this forum i did`nt even know that it was an option.
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Post by headcoats on Oct 17, 2017 11:05:10 GMT 1
Yes re sleeve can be done but you are talking best part of £500 with pistons You can see why some bikes have nikasil bores !
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