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Post by Bazille on Oct 6, 2013 14:26:25 GMT 1
whats the situation regarding big bore kits for the 4LO, does any body do them?
I see you can buy athena kits for approx 750 quid but they seem to be for the ypvs 350 motors, bolting them onto 4LO crankcases is not an option as the mounting holes are different dimensions.
colin
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Post by arrow on Oct 6, 2013 16:04:57 GMT 1
As far as I know the kits are for the ypvs motor only, but the Athena barrels are non power valve barrels, if that makes sense.
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Post by cb250g5 on Oct 6, 2013 16:18:13 GMT 1
I believe all the kits are made for the Banshee. Coincidentally that has the same crankcase to barrel studs as a YPVS.
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Deleted
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Post by Deleted on Oct 6, 2013 16:49:01 GMT 1
would you be interested in some liners for 4l0 to bring it to 400cc?
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Post by carioca656 on Oct 6, 2013 17:47:03 GMT 1
what pistons do you run with them?
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Deleted
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Post by Deleted on Oct 6, 2013 18:09:32 GMT 1
Not a clue. Ring Norbo he has the 400cc liners
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Post by somethingelsie on Oct 7, 2013 12:45:19 GMT 1
Rd lc lazy, I'm in the process of doing a 421 athena conversion with my ypvs f1, I'll be honest its costing a fortune lol
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Post by Norbo on Oct 7, 2013 12:50:32 GMT 1
They are not cheep you need to think ahead .
You need the barrels of course but if you go down the 4mm crank side you need different pistons and then you need to get the head dones machined . then you need special flanges or at least pipes making to use them you need a billet manifold to take bigger carbs you need bigger carbs . you need to beef up the clutch as they put out some good power if you tune them so New racing plats and at least TZ springs are a must. You may fined the rad is not big enough so may need a big rad as well then a special cover for the rad as its biger and nothing elce will fit then a Hi flow impeller to get the water around the big rad .
It will cost a lot to do a proper job but you get what you pay for they look grate and are very fast in deed with a wicked power band.
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Post by Bazille on Oct 7, 2013 14:53:41 GMT 1
so has anyone gone down the 400cc liner route for the 4LO barels?, as im very keen on doing this to mine!
I have a on the road 31K LC2 but i am reluctant to remove the engine from this to use in my Lc as its a perfectly good working bike.
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Post by slinger on Oct 7, 2013 16:24:35 GMT 1
Why not just use a stroker crank with the stock barrels, it's been done in the past and works very well. You could even add some aux exhaust ports if ya feeling fruity.
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db8888
Thrash Merchant
Posts: 329
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Post by db8888 on Oct 7, 2013 18:28:44 GMT 1
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Post by Bazille on Oct 7, 2013 18:43:44 GMT 1
db thats good, but where/how do you get hold of them there is no contact details, that kit would be perfect!
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Post by steeley on Oct 7, 2013 19:52:39 GMT 1
years ago I heard of a chap who used bultaco 250 liners and pistons and had rd 400 conrods on the crank.i understand it went very well.like all these jobs there is always much more to it.
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Post by midlifecrisisrd on Oct 8, 2013 8:33:52 GMT 1
years ago I heard of a chap who used bultaco 250 liners and pistons and had rd 400 conrods on the crank.i understand it went very well.like all these jobs there is always much more to it. Oh there always is more. You would also have to get the head machined and re profiled to suit the bigger bore and required squish and volume which is no guessing game and where would you get a head gasket from? Other thing is the transfer tunnels up the side of the barrels. We all know the difference it makes opening these up but if you go up 4mm in bore you are losing 2mm off each side which will negatively affect flow. Steve |
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Post by Norbo on Oct 8, 2013 8:40:50 GMT 1
I keep them in stock mate they are £250 supplied but remember you need to re do a 350 head as well to match the new bore size. .
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Post by bare on Oct 8, 2013 18:30:05 GMT 1
As above reduced port passages result
No need to even mention the bodge fit & heat transfer issues associated with stuffing in a larger tube.
Whereas the the OEM was cast in under elevated temps to ensure controlled expansion rates and efficient heat transfer.
Doubt the Bulto story, as those (at least Mine) didn't even feature adequate portings.
They were of Early/Primitive design. Far inferior to even 4Lo portings
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Post by scott on Oct 8, 2013 21:07:12 GMT 1
what about the 250lc barrels bored out or re-lined to take the dt pistons makin a 375cc,is this mod any good?
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Post by Norbo on Oct 9, 2013 7:35:36 GMT 1
barrels are often relined and I don't know of any one that has had issues with replacing the liners . I guess it depends who is doing the job . frankly id only get 1 bloke to do a re line job Farron.
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Post by carioca656 on Oct 9, 2013 16:20:23 GMT 1
how much does farron charge to reline cylinders
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Post by ianr4863 on Oct 9, 2013 16:51:47 GMT 1
I asked Ron last year about doing the DT175 mod to some cylinders . Im pretty sure he told me that he charges £400 to reline the cylinders and supply new pistons . He also re profiles a head for you .
He told me to send up 250LC head and barrels as they are cheap .
He is a very nice man .
He is a very very busy man .
You will wait several months to get them back .
I havent got round to it yet but he did re profile a 250 head for my 350 . I get much better low revs power and in the powerband it revs out much quicker .
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