Author Topic: WR 430 maximum oversize Piston?  (Read 285 times)

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Offline Dewy123

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WR 430 maximum oversize Piston?
« on: July 05, 2017, 10:02:51 PM »
Hi,
Our poor old 1982 WR430 has seized its second piston on maximum 3rd oversize- 87.42mm.
I haven't got the bore parallel honed yet, to see if it will clean up well enough for a 3rd attempt at a 3rd oversize piston.
But if it doesn't, I was looking at husqvarna-parts.com and saw that you can get a 4th oversize 500cc piston- 87.94mm.

Will a 500cc piston fit/work in a WR430?
I also worked out that the reason why that it's seizing pistons is that the fly wheel crank seal has been leaking.

Thanks Ryan.

Offline 80-85 husky

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Re: WR 430 maximum oversize Piston?
« Reply #1 on: July 06, 2017, 08:29:16 AM »
that will do it every time ;D I see nothing has changed at Dewyworld...full rebuild 3 weeks before harrow ;D ;D

Offline bigk

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Re: WR 430 maximum oversize Piston?
« Reply #2 on: July 06, 2017, 08:29:36 AM »
I doubt a 500 piston will work in a 430 pin height is sure to be different, plus it's a different part number in the Wossner parts list. You need to be looking for a Wossner W58051D200 (4th OS, 87.92mm). There are two Australian suppliers of Wossner, give them a try.
K

Offline 80-85 husky

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Re: WR 430 maximum oversize Piston?
« Reply #3 on: July 06, 2017, 08:32:31 AM »
now for some actual assistance...see post above ;) (he beat me too it)

Offline Watto HVA 1

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Re: WR 430 maximum oversize Piston?
« Reply #4 on: July 06, 2017, 09:56:58 AM »
Air leaks are the main cause of issues like that.. I bought a Motion pro leak test kit.. every time I have a top end off.. I leak test before I put the engine back in the frame.. saves quite a bit of time (and money).. :o

Offline Dewy123

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Re: WR 430 maximum oversize Piston?
« Reply #5 on: July 06, 2017, 12:42:39 PM »
Thanks for the info. I haven't had time to ring an Australian Wossner Piston supplier yet. I have check with Phillip from Husky Parts USA and he is saying a 4th over size isn't available? Does anyone happen to have a spare barrel laying about? Also I know that you have to split the cases to replace the clutch side seal. But would of thought if it was leaking it would of been sucking gear box oil and blowing a lot of smoke? Or can it still be sucking air? I really don't want to seize this engine for a 3rd time. The first time I was running it at 40:1 so I thought that was the cause for it to seize. So second time around we went back to the good old 25:1 and it still seized so that why I went and checked the flywheel side crank seal that had definitely been leaking.
Thanks Ryan.

Offline 80-85 husky

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Re: WR 430 maximum oversize Piston?
« Reply #6 on: July 06, 2017, 02:14:50 PM »
90 % of the time its the flywheel side so it can be popped off and replaced in the frame. the flywheel causes just a tiny smidgeon of movement and this stresses the seal over time. let it sit and it goes a bit hard and then the fun starts......that's why I split the cases and replaced all the seals inside before caning it over and over again. if the gbox side goes, you don't need a gps to find your way home...just follow the smoke trail.

now you should be able to do that seal in a bees dick of time.

pm Big K about a 430 jug, he may know of one or Jimbo on the EBT forum

Offline Watto HVA 1

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Re: WR 430 maximum oversize Piston?
« Reply #7 on: July 06, 2017, 05:15:47 PM »
Going from 40.1 to 25.1  actually makes the bike leaner.. there is more oil..but less fuel.. the fuel does the cooling.. the oil does the lube..less fuel in the mixture = leaner..

Offline evo550

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Re: WR 430 maximum oversize Piston?
« Reply #8 on: July 06, 2017, 05:59:39 PM »
Going from 40.1 to 25.1  actually makes the bike leaner.. there is more oil..but less fuel.. the fuel does the cooling.. the oil does the lube..less fuel in the mixture = leaner..
:o

Offline pokey

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Re: WR 430 maximum oversize Piston?
« Reply #9 on: July 06, 2017, 10:41:18 PM »
uhuh yep mag side crank seal leak.  other side makes the exhaust stink and turns the gear oil milky from contamination.

Going from 40.1 to 25.1  actually makes the bike leaner.. there is more oil..but less fuel.. the fuel does the cooling.. the oil does the lube..less fuel in the mixture = leaner..

sort of right. yeah there isnt as much fuel and fuel does cool a piston  but so does oil as it has a wicking effect that draws heat to the cooler areas of the engine. easy way to understand it is look at any 4T oil cooled engine and check out the tiny fins . run those with low oil and they get very hot very fast. same with a 2T engine. Fuel cools the piston crown where oil cools the skirt and bore.

Offline Dewy123

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Re: WR 430 maximum oversize Piston?
« Reply #10 on: July 07, 2017, 07:36:19 AM »
Thanks for the response guys.
I'm not getting into the whole rich/lean oil fuel ratio argument. I just want to get my bike up and running again.
Where is everyone getting there barrels re-sleeved? I've had a bit of a search on google and it seams either Serco or Ian Williams Tuning in SA.
Has anyone had work done by either of these two company's? Or can recommend another company to do this work?
Thanks Ryan.