• Husqvarna Motorcycles Made In Sweden - About 1988 and older

  • Hi everyone,

    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

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Engine ID

Bengt Husky

Bengt Husky

Husqvarna
AA Class
Hi,

I've recently picked up this engine....The bore size tells me its a 430 CR, but the engine number tells me its an '82 250 CR. I didn't think the 430 barrel etc fitted the 250 cases ? The Engine number is 2088-1804IMG_0419.jpg

Any ideas...IMG_0361.JPG
 
Looks like an 420 automatic{86mm} cylinder and head on an 1981 250/430 lower end,check the stroke,and check to see if the piston comes up to TDC
 
If cylinder got 9 fins it's 430 , 10 for a 500, and that ones got 9 fins.

Husky John
 
cyl 430 le 25 avril 2011.JPG
picture my 430 CR 1981
9 fins !

numbers motors
2088 =250 /1983 ?
2086 and 2087 = 430 CR/WR/XC 1981/1982
2085 = 420 AXC
 
What makes me think its a 420 cylinder are the "corners" of the fins{more pronounced on intake side} on a 430 are more rounded,and the "rib" on the sides of the 420 cylinder are narrower,and straight from top to bottom,heres a photo of an 1981430cr 005.jpg #2087 on the bench.All 390's and 420 automatics have 9 fins also.Notice also the "brace" across the cylinder head fins on the 430 is wider also,and closer to the top of the fins.430's the sparkplug will be to the right of center also,on a 390/420 the plug is towards the left of center to clear the expansion chamber,when installed in service.
 
The cases are universal in the respect that Husqvarna used the same castings for 81 430 and 82+ 250,400,430,and 500 engines by having a reduction web to reduce the crankwell for 250 and smaller engines. The web need only be removed from 250 cases to be used for the bigger engines as the crank cheeks are similiar diameter between bigger models.

The difference between 420 and 430 is stroke only The 420 was an overbored cylinder on the 390 71mm stroke while the 430 has 74mm stroke. And any cylinder that fit on the 390 cases will not bolt down to the newer cases. Bolt circle difference does't allow it . I tried it myself with a 390 cylinder thinking I could make an aircooled 400.
 
1980 390 Cr/OR with engine serial #2080,all 420 automatics,use a cylinder with a different{wider} bolt pattern to accomodate a thicker sleeve.Husqvarna did this so they could use the same cylinder on several models.Uses base gasket 16-11-648-01,same as 1981 430 Some 390 autos use a different{wider} cylinder bolt pattern than the manual trans versions,but I have no knowledge of top end parts interchange on those.Wossner used to[maybe they still do} make 390/420 pistons up to 87mm bore, with both 35mm and 37mm compression heights,maybe thats why? I am curious to know if the 1980,#2084 390 WR uses the wide pattern also?
 
Main reason for spreading out studs was to beef up the cases as 78-79 cases broke the cyl base off the cases.
This also allowed for thicker sleeves.
Later George
 
Thankyou George.All 78-79's broke the cyl base or just the autos? What 390 would use the "short" 35mm CH piston? I have "tall" 37mm in both of my #2080's
 
jimspac said:
The cases are universal in the respect that Husqvarna used the same castings for 81 430 and 82+ 250,400,430,and 500 engines by having a reduction web to reduce the crankwell for 250 and smaller engines. The web need only be removed from 250 cases to be used for the bigger engines as the crank cheeks are similiar diameter between bigger models.

The difference between 420 and 430 is stroke only The 420 was an overbored cylinder on the 390 71mm stroke while the 430 has 74mm stroke. And any cylinder that fit on the 390 cases will not bolt down to the newer cases. Bolt circle difference does't allow it . I tried it myself with a 390 cylinder thinking I could make an aircooled 400.
Click to expand...

Got the barrel off the mystery engine....the bore is 86.5mm the stroke measures 65mm...?

I'm going to be stripping her down over the next week or so and will post more data as I reveal it....:)
 
Had another look last night and it looks like previous owner was halfway between converting her from a 250 to a 420 / 430 ?

The barrel is 86.3 ID and 85 depth, but the piston travel stops 20mm from the top leading me to suspect the rod is from the 250.

Don't you just love these old bikes....:eek:
 
Yep. Someone has put a 430 barrel on a 250 bottom end!

Bet that runs well - NOT!

Sounds like you got a good barrel though Steve.

Andy
 
The 250/390/420/430 all use the same connecting rod.You would only gain 4.75mm by switching to a 430's 74mm stroke crank from the 250's 64.5,so you still have about 15mm to go!
 
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