Author Topic: RD350 CYLINDER KITS  (Read 622 times)

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Online dieseldoc

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RD350 CYLINDER KITS
« on: November 19, 2020, 08:26:15 PM »
Hi Guys, has anyone purchased a set of the 350 cylinder kits made in China that are for sale through eBay?
New - Kveldwulf Yamaha RD350 Left Right Cylinder Kit - Pistons Rings https://www.ebay.co.uk/itm/New-Kveldwulf-Yamaha-RD350-Left-Right-Cylinder-Kit-Pistons-Rings-Pins/284036949279?hash=item4221ebe51f:g:ygkAAOSwCl9ffQo0
Looks a bit cheap for me

Cheers,
Bob
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Offline CDBiker220

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Re: RD350 CYLINDER KITS
« Reply #1 on: November 19, 2020, 08:41:49 PM »
I was looking at those because the porting looks to be US spec not the low hp India spec that others have said the Chinese cylinders have. I emailed the seller and he confimed they are US Spec. I ended up finding and buying another 350 engine so I did not end up buying these, but I was curious about them.

Offline chrisg.007

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Re: RD350 CYLINDER KITS
« Reply #2 on: November 20, 2020, 10:09:58 AM »
They do look good VFM and with OE cylinders becoming harder and harder to find it may be worth a punt.

Some years ag I bought a full set from the US, including heads and on the original bore for just over £105 plus P&P.  Should have got 2 sets  ;)
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Offline tore

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Re: RD350 CYLINDER KITS
« Reply #3 on: November 20, 2020, 10:17:34 AM »
They are fairly good quality except the sleeves. The sleeves are too soft. You get a piston slap in short time.
Resleeve them and you have pair of good barrels.
Tore

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Offline Barnett

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Re: RD350 CYLINDER KITS
« Reply #4 on: November 20, 2020, 03:51:36 PM »
I heard somewhere that the transfer port "tunnels" outside of the sleeve from base to port were straight and not curved as Yamaha did? Weather I have got this wrong or if it makes any difference I have no idea.

Offline tore

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Re: RD350 CYLINDER KITS
« Reply #5 on: November 20, 2020, 05:36:25 PM »
I heard somewhere that the transfer port "tunnels" outside of the sleeve from base to port were straight and not curved as Yamaha did? Weather I have got this wrong or if it makes any difference I have no idea.
Indeed, you probably lose a couple of donkeys at the top RPM.

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Tore

RD350B (Indonesia) 1975
BMW R1150GS Adv 2004
HVA Roulette 1957
NV 125 1955
https://www.youtube.com/watch?v=k85mRPqvMbE

Offline Richard S

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Re: RD350 CYLINDER KITS
« Reply #6 on: November 20, 2020, 07:59:40 PM »
Hi Guys, has anyone purchased a set of the 350 cylinder kits made in China that are for sale through eBay?
New - Kveldwulf Yamaha RD350 Left Right Cylinder Kit - Pistons Rings https://www.ebay.co.uk/itm/New-Kveldwulf-Yamaha-RD350-Left-Right-Cylinder-Kit-Pistons-Rings-Pins/284036949279?hash=item4221ebe51f:g:ygkAAOSwCl9ffQo0
Looks a bit cheap for me

Cheers,
Bob
 
Hi I was the second person to buy a set ,I asked the question about porting and they are us/uk ones ,I bought a set .The seller has sold 18 sets ,so they can't be that bad ,l have had them running on my bike last week and sounds ok. Richard

Offline betty foRD

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Re: RD350 CYLINDER KITS
« Reply #7 on: November 20, 2020, 10:18:14 PM »
Dan runs some on his track bike, took a few attempts to pin the liners to stop them moving and recall he might be using other pistons .
Think without getting too deep the  has to be obvious. Not as desirable as OE ones , but much more plentiful and for the sort of miles most of us do in a year these, a welcome option.
There’s a few of us that have studied them in great detail in the past so plenty of info out there.
Take a look at Dans thread for starters. Certainly debunks the first myth which is they can’t be encouraged to make good power.

https://www.aircooledrdclub.com/smf/index.php?topic=61367.msg486146#msg486146
« Last Edit: November 20, 2020, 10:29:09 PM by betty foRD »
Rev 'em till they rattle

Online dieseldoc

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Re: RD350 CYLINDER KITS
« Reply #8 on: November 22, 2020, 09:59:18 AM »
Thanks for the feedback guys. I will bear them in mind as I am trying to decide what route to take with an old RD250 rolling chassis I have. I really want to restore it back to originality, but OEM parts are getting too expensive, so I might go the 'track bike' route.
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Offline c50

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Re: RD350 CYLINDER KITS
« Reply #9 on: November 24, 2020, 02:33:35 PM »
Are these definitely original 39hp porting and not the low power indian versions? Never come across full power versions. But why the hell have they got those YPVS pistons? Defeats the object! If you can buy them without those and they are 39hp spec I would have a punt. Used to be a good supply of 350 cylinders from the US of A but like many parts they have become silly money made worse with ludicrous postage costs then the post office parasites waiting to hit you with import duty and their costs  >:(. At least 350 cylinders are usually on a low bore size not like the rebore happy 400 versions. Lets hope for a trade deal with the US of A and some cheap nil duty RD parts  ;)

Offline Yamahaar

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Re: RD350 CYLINDER KITS
« Reply #10 on: November 24, 2020, 06:18:57 PM »
C50 what are the issues with using YPVS pistons in aircooled barrels? I'm not thinking of using them but just interested. For what its worth I'd never use cheap Chinese pistons in anything now. Experience has shown them to be junk

Offline c50

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Re: RD350 CYLINDER KITS
« Reply #11 on: November 24, 2020, 07:59:51 PM »
They are not suitable. They are designed for a YPVS cylinder with a centre bridge on the inlet. Also the taper and expansion characteristics are designed for a water cooled cylinder, that reaches a expanded size then stops expanding as the temperature is held fairly constant.  Aircooled cylinders and pistons can get a lot hotter and expand substantially more. YPVS or LC pistons also require a larger cold clearance by around 50%. So what are these chinese pistons you mention. Not sure which if any pistons currently made are made in china, maybe some Mitaka YPVS/LC, don't know? But they are mostly made around there that makes no difference and what is wrong with made in China? 99% of what you buy, premium brands too are made in China. Could this be yet another piston debate  :'( If i got those cylinders they would 100% get proper genuine Yamaha aircooled pistons, 360 dykes, 1A0, 2r9 or 2V0, which in standard size are fairly easy to get hold off. Otherwsie I wouldn't get the barrels, I would be far happier over sizing some old genuine barrels with cruzinimage pistons.