fabiostar
Thrash Merchant
the older i get the faster i was.
Posts: 399
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Post by fabiostar on Dec 19, 2023 21:22:30 GMT 1
long story short my lc250 started burning gear oil.. so crank seal time but when i had a look inside the we engine is still on standard bore, has about 30k on it so if poss wana keep the standard bore. Pistons atm still feel nice and tight, it hasnt had a hard life but thats beside the point.
the actual question is make of pistons, it doesnt get thrashed it just gets sunday runs and the odd blip in sunny evenings, whats peoples thoughts on make of piston to use, standard porting , up one on the mains and nikon pipes fitted otherwise just as it was made.
thoughts lads?
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Post by midlifecrisisrd on Dec 19, 2023 22:08:57 GMT 1
Probably not what you are wanting to hear but get the bores measured and check for being oval
Unless the barrels aren't original they must be worn
Steve
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Post by shaunthe2nd on Dec 19, 2023 22:14:28 GMT 1
..and worth doing a compression test too.
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Post by chrisg on Dec 20, 2023 11:44:15 GMT 1
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Post by steve63 on Dec 20, 2023 18:59:25 GMT 1
I've had a few re-bores done in the past but all of them have been because of blow ups of one kind of another never just because of wear. Am I the only one that thinks 30,000 on standard pistons without the bore being worn past service limits is quite possible?
The way I rode back in the day I'd say no chance but me riding now I'd say yes.
My A100 went from about 20,000 when I got it to over 50,000 on the same piston and rings and I'm pretty sure it was standard bore. It had a very hard life but performance hadn't dropped off much. I know it's related to state of tune, width and height of exhaust port but a standard 250lc is not that highly tuned.
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Post by midlifecrisisrd on Dec 20, 2023 19:19:25 GMT 1
I have had 2 bikes that were on 27k and 29k both were on standard bore and still looked in good condition
Also had a 64k motor on a very good 0.5 over
I did just fit new genuine pistons as the ring gaps were within spec and the bike was being built as a concourse bike that I knew would never really get used
I've also had low bore barrels that looked "OK" but needed to go up 3 sizes to get the bore true
Bores can wear on the thrust side at the exhaust port and at the inlet area so the piston play and ring end gap doesn't look bad as the wear areas are staggered but needs a large over bore to get it all back in line
Pistons are the most expensive bit, best not waste a set for the sake of £50
I'd prefer a fresh 0.25 or 0.5 over bore than a 30k standard set with new pistons
Steve
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Post by abar121 on Dec 20, 2023 20:04:09 GMT 1
I've had two bikes fairly recently with 'rebuilt motors', which had new pistons / rings in the stock worn out bores.
Get them measured, or you could be wasting your time.
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Post by muttsnuts on Dec 20, 2023 21:21:05 GMT 1
have you measured the bores to make sure its standard, had some engines in with cheap pistons fitted that didn't have an oversize stamped on the pistons, customer was a little surprised when I measured them and declared they where 1.25mm O/S !
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fabiostar
Thrash Merchant
the older i get the faster i was.
Posts: 399
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Post by fabiostar on Dec 21, 2023 20:34:54 GMT 1
have you measured the bores to make sure its standard, had some engines in with cheap pistons fitted that didn't have an oversize stamped on the pistons, customer was a little surprised when I measured them and declared they where 1.25mm O/S ! i dont have a bore mic but just measured using a set of calipers, they seem to be standard bore, the L/h barrel did have some light marks around the exhaust port, not really enough to feel but visable. heres problem number two, i live over the pond in northern ireland and i dont know of anybody here doing bores, im kinda leaning towards going up a size or two just to make sure but with who? i want them to be done by somebody with experience of strokers. |
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Post by reedpete on Dec 21, 2023 20:58:35 GMT 1
250 is a lot kinder to the bores than the 350:due to piston geometry, but I think the answer or suggestion to your situation rather depends on how many miles you plan to do across next couple of years and also how phased you are of taking the engine apart.
Thing is with these things… one you start where do you stop….
If the top end has done 30k without being apart then so has the bottom end and the box etc…
So might be that if the current pistons are reasonable happy as they are then changing the crank seal and a set of new rings and there’s a couple of thousand miles in there without worrying overduely , particularly if you are keeping an eye on things and riding locally… what’s the worst that can happen?
Alternatively… if you were planting an European tour… several weeks scratching around southern Europe, then it would obviously be prudent to refresh the motor in its entirety.
Every on I know in NI sends barrels to the mainland for rebores.
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fabiostar
Thrash Merchant
the older i get the faster i was.
Posts: 399
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Post by fabiostar on Dec 21, 2023 21:30:26 GMT 1
250 is a lot kinder to the bores than the 350:due to piston geometry, but I think the answer or suggestion to your situation rather depends on how many miles you plan to do across next couple of years and also how phased you are of taking the engine apart. Thing is with these things… one you start where do you stop…. If the top end has done 30k without being apart then so has the bottom end and the box etc… So might be that if the current pistons are reasonable happy as they are then changing the crank seal and a set of new rings and there’s a couple of thousand miles in there without worrying overduely , particularly if you are keeping an eye on things and riding locally… what’s the worst that can happen? Alternatively… if you were planting an European tour… several weeks scratching around southern Europe, then it would obviously be prudent to refresh the motor in its entirety. Every on I know in NI sends barrels to the mainland for rebores. well while the motor is apart im gona get a new set of mains in it aswell along with seals and gaskets, i bought the bike i think just over 3ish years ago. the guy i got it from done a handful of miles a year going by the last few mot certs, he said he had the motor apart for a refresh the year before i bought it and looking at the likes of base gaskets and clutch cover gasket it has been apart so that seems true. use wise all i do on it is stay local or take a spin up the coast the the local bike haunts, not thrashing it but a we blip as you would say...iv other bikes for setting my hair on fire lol |
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Post by strokeofgenius on Jan 6, 2024 8:32:36 GMT 1
There are still plenty of people on the island of Ireland doing rebores.My rg500 barrels are being rebored as we speak by a guy 30 miles away from me in Waterford.Southern Ireland I know but I would be shocked if nobody in the North is offering this service considering the rich racing history up there.My rd500 was rebored in the North in 2009 and still going beautifully.Admittedly its a lot easier for ye in the North to send and receive stuff from England.Since brexit posting anything valuable to or from England is a nightmare for us in the South.There is also the customs charge which means very little interaction between us and the Uk now.Such a pity.If you want I could ask the guy that built my rd500 who did the reboring for him.(he is a Belfast guy,Mark Kelly aka big man).
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Post by 4l04ever on Jan 6, 2024 10:43:21 GMT 1
You could get a Ferry over to UK mainland and visit Grampians, who are in Liverpool. If you book in advance, they have been known to do the work straight away so you can collect a few hours later. www.grampianmotors.co.uk/ |
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Post by chrisg on Jan 6, 2024 17:07:04 GMT 1
You could get a Ferry over to UK mainland and visit Grampians, who are in Liverpool. If you book in advance, they have been known to do the work straight away so you can collect a few hours later. www.grampianmotors.co.uk/Be prepared to be told that YPVS pistons are the best choice for your bike. Ive had issues with them in the past. |
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pistons.
Jan 6, 2024 17:32:21 GMT 1
via mobile
Post by midlifecrisisrd on Jan 6, 2024 17:32:21 GMT 1
You could get a Ferry over to UK mainland and visit Grampians, who are in Liverpool. If you book in advance, they have been known to do the work straight away so you can collect a few hours later. www.grampianmotors.co.uk/Be prepared to be told that YPVS pistons are the best choice for your bike. Ive had issues with them in the past. That's because that is what they have had on the shelf Steve |
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Post by 4l04ever on Jan 6, 2024 22:13:08 GMT 1
I had LC pistons last time I got some from them.
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