strange clunk

Ok, now you can see where the idler tangled and broke the case as a result. Worn kicker gear on back of clutch and the critical idler bearing is your cause.

I have had a bit of experience with these cases and clutch, obviously you will need a clutch basket, idler, needle roller and a left case half.
The clutch basket on yours will be the larger six spring job, same as the big bores, it will have a number stamped on the back, mine has "403" stamped on it and I assume yours will be the same.
You can use earlier clutches but may need to change the primary drive gear, which in turn could change your overall gearing, not good.
As mentioned, any single shock case 250-500 will be suitable, except the 250 needs an extra web machined out for the bigger crank wheels, 400-500 need no modification, these have a bigger swing arm bolt and bushes than the early twin shock bikes.
Also, after 1986 there is an extra hole for the clutch cover to bolt to in an attempt to reduce broken cases and clutch covers from kick back.
I wonder if a low oil level contributes to these bearings failing or is it just a high maintenance item?
Tony.

Here's a clutch:

http://www.ebay.com.au/itm/1987-Hus...ssembly-Ahrma-Vintage-MX-Calvmx-/352106482337

Kick start and idler:

http://www.ebay.com.au/itm/1987-Hus...t-Idler-Ahrma-Vintage-MX-Calvmx-/391833030069

This is good information. My 430 is an 81 twin shock with the 5 spring clutch, so I think I need to be looking for 1981-1984 case and clutch. Am I correct here? Also do you know what year they started putting the backing plate behind the idler gear? I definitely want that backing plate next go round.

My mistake, I thought you had a late model, I should have re-read your original post!
Tony.

81 style is 1 year only i recall and 82 and on all are the same.

If you add all the later year parts with the newer case it works out i think.
You need all the parts any how.
Never had a 81 430, just 82s and on.

the 81 430 cases were the new design (for Swedish Husky)

I hate to sound like a broken record but I need to make certain that I'm looking in the right direction for a set of cases. Am I correct in that Im looking for 430/500 cases from 81-84, meaning that the single shock cases from 1985 up have a larger diameter swing arm bolt and bushes? I understand that 250 cases would need modifying.

400, 430, 500 cases are the same basically
later ones as in 86 on had an extra threaded love for a clutch cover fastner
but yeah pretty similar
the big thing to look for is the kickstarter hole being oval
I have a few cases laying around, rare to find a perfect one
all these have typical flaws, they work but flawed, it is what it is, and these were LAST cast 30 years ago

Yes it was, but wasn't there a change in the idler gear mount or design the following year?

pretty much the same thing, they just added the "backing plate" in 82. the 81 case has 2 little bosses there but they arent tapped. you can install the newer style into and older one by tapping the holes. i used one from a wrecked case.

I ran across this interesting bit of info in the Early 80's Services Notices I have in my archives. It mentions replacing the clutch gear, kicker gear, and idler gear with a new stronger version.

I have no personal experience with early 80's stuff so I don't know if this actually applies to moto_surfer's bike.