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REBORE
Nov 30, 2019 9:47:27 GMT 1
Post by stusco on Nov 30, 2019 9:47:27 GMT 1
The pistons didn’t come with which barrel they were for written on them in black marker
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REBORE
Nov 30, 2019 10:06:18 GMT 1
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Post by Tobyjugs on Nov 30, 2019 10:06:18 GMT 1
The pistons didn’t come with which barrel they were for written on them in black marker My barrels always come back like that. I'm lucky enough to be able to measure them myself and once I sent a pair back because they were too tight.
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Post by stusco on Nov 30, 2019 10:08:53 GMT 1
I now measure them myself after missing another summer because the rebore wasn’t up to scratch my new plan is always have two bikes so I never miss out
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Post by chippy348 on Dec 1, 2019 18:32:42 GMT 1
I got my lc rebored by pjm and the pistons weren’t matched I measured them and the barrels both were in spec the pistons were in sealed boxes so I don’t think it matters as long as the rebore is correct That's unusual, all the pistons I've had supplied by PJME with rebored barrels have been matched to the bores & marked R/H & L/H OEB If the pistons are difference in size we will mark the LH / RH if they are the same size we dont mark them. We are talking microns here so not something most home mecanicas can pick up on.
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REBORE
Dec 3, 2019 17:05:26 GMT 1
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Post by Tobyjugs on Dec 3, 2019 17:05:26 GMT 1
just had ypvs barrels rebored out to 1.25 oversized, the machine shop supplied the pistons , when i got the barrels back they had done a good job but the pistons dont look right, rear skirt on piston is flat with no cut outs and the ports look very round as opposed to squarish any one any ideas or am i being fussy Any updates on the situation???
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REBORE
Dec 4, 2019 16:10:57 GMT 1
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Post by headcoats on Dec 4, 2019 16:10:57 GMT 1
Yes don't let this thread die as we hope you have a successful result
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REBORE
Dec 4, 2019 22:46:22 GMT 1
Post by 4l04ever on Dec 4, 2019 22:46:22 GMT 1
It sounds like the rebore man just ordered LC pistons and did not know there was a difference. I am sure that Grampian would just send out whatever pistons were ordered. I have ordered loads from them and they are always the model I ask for.
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REBORE
Dec 4, 2019 22:50:33 GMT 1
Post by JonW on Dec 4, 2019 22:50:33 GMT 1
I agree with Rob. Its also not helped by the fact that in the UK they are all called 'RDx50LC'. The rebore guy may be an expert in our bikes but the person doing the ordering may not so just asked for pistons for the bike type and without knowing the year or saying YPVS etc.
Its an easy mistake to make, but also to fix. the reborer needs to sort it.
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Post by norman68 on Dec 5, 2019 12:31:35 GMT 1
Update. Got in touch with company that rebooted barrels , sent photos of pistons and he seen the problem right away, sent pistons back and he is going to replace with proper ones , will have to wait and see what turn up
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REBORE
Dec 5, 2019 12:57:58 GMT 1
Post by Shytalk on Dec 5, 2019 12:57:58 GMT 1
Update. Got in touch with company that rebooted barrels , sent photos of pistons and he seen the problem right away, sent pistons back and he is going to replace with proper ones , will have to wait and see what turn up So much easier to do nowadays with a quick picture showing the issue, sounds like you’re on the way to a good result.
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tab
L plate rider.
Posts: 28
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REBORE
Jan 12, 2020 10:47:12 GMT 1
st66 likes this
Post by tab on Jan 12, 2020 10:47:12 GMT 1
I always check each piston size and mark each piston to each barrel when doing rebores, I did a set of rd250 air cooled last year that the owner supplied own genuine new old stock pistons that were a big difference in each size that would have ended up with one been very tight and the other been very loose if he had replaced them wrong way round. There were clearly marked and the owner was advised what to do and why it was so important.
Regards Kevin.
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REBORE
Jan 12, 2020 16:51:23 GMT 1
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Post by tacky1 on Jan 12, 2020 16:51:23 GMT 1
Do the holes in the pistons matter though. I use Wiseco pistons in my 350s and they don’t have holes and the bikes run like champs. I run them in my 500s as well and no probs.
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Post by 4l04ever on Jan 12, 2020 17:04:41 GMT 1
Do the holes in the pistons matter though. I use Wiseco pistons in my 350s and they don’t have holes and the bikes run like champs. I run them in my 500s as well and no probs. I am sure Tobyjugs will confirm this, but he did some dyno comparisons with and without the windows and it made a big difference...
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REBORE
Jan 12, 2020 18:27:13 GMT 1
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Post by Tobyjugs on Jan 12, 2020 18:27:13 GMT 1
I dyno tested a set of closed pistons then made holes in them and dyno tested again. I think it made about 4 or 5 pk difference. Since I have done that test I have learned a little bit about 2 stroke technique and in my opinion the difference in the sizes of both holes in the pistons in this topic doesn't equate to much gain or loss.
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REBORE
Jan 13, 2020 9:19:08 GMT 1
Post by Denzil on Jan 13, 2020 9:19:08 GMT 1
I got my lc rebored by pjm and the pistons weren’t matched I measured them and the barrels both were in spec the pistons were in sealed boxes so I don’t think it matters as long as the rebore is correct That's unusual, all the pistons I've had supplied by PJME with rebored barrels have been matched to the bores & marked R/H & L/H OEB As OEB has said, I recently had a rebore at PJME and can confirm the New Mitaka pistons had been measured and had L & R on each one. They measure them and then rebore to suit. Denzil.
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Post by norman68 on Feb 8, 2020 21:01:51 GMT 1
finally got correct pistons all together and running
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Post by stusco on Jul 26, 2020 14:16:17 GMT 1
I got my lc rebored by pjm and the pistons weren’t matched I measured them and the barrels both were in spec the pistons were in sealed boxes so I don’t think it matters as long as the rebore is correct That's unusual, all the pistons I've had supplied by PJME with rebored barrels have been matched to the bores & marked R/H & L/H OEB While i was raking in my box of bits i found the pistons(old) in their boxes and written on the inside of the box lid was which barrel they were for it was written in highlighter pen and very faint,so the were matched but nothing on the pistons and I missed it😩
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REBORE
Jul 26, 2020 14:43:42 GMT 1
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Post by st66 on Jul 26, 2020 14:43:42 GMT 1
Ooohhhh that would so anoy the piss out of me some guy on a phone saying oh there correct they will work,,,, give your head a shake pal I know there wrong, you should know there wrong and your telling me there right,, sorry for the third person speak but just putting myself in you shoes I'd have been fkn livid,,,, took some sorting but glad they are dealing with it for you and sending correct pistons mate 👍👍
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REBORE
Jul 26, 2020 15:07:57 GMT 1
Post by jackjabba on Jul 26, 2020 15:07:57 GMT 1
I had the advantage of watching Mick do my barrels, so know for a Fact they were done correctly and that there was feck all difference in the piston size.
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