HS40 rebuild

cncsparky

cncsparky

New Member
#1
#1
I'm rebuilding the HS40 for my Hustler after discovering gouges in the cylinder. Just got the block back from the machine shop and thought I'd post the rebuild here for future reference. Sorry I didn't get any before pics of the cylinder, it sure looked bad! My machinist wasn't sure it would clean up at .010 and thought we may have to go .020. Luckily, it did clean at .010 for the most part. There is a small scratch left, you can barely hang your fingernail on it. With Tec parts becoming rare, I thought I'd save my .020 piston for another day.





The intake valve was a little loose, so he installed a brass guide. Tec makes an oversize valve stem valve, but he said it requires special tooling to size the guide and also do a valve job since its an odd size. Also, I may have to take the block back to him after ass'y so he can set the tappet clearance if its off.

I hope to post ass'y pics soon.

Tom.
 
cncsparky

cncsparky

New Member
#2
#2
Forgot to post the cost so far. Total machine work was $86.63 and here is the breakdown:
$40 bore
$30 valve job
$7 Install intake guide
$4.50 Intake guide

I'll post the rest of the parts and their cost later.

Tom.
 
J

jimh

#3
#3
Looks good, but Tecumseh parts aren't becoming rare. They just stopped building small engines less than a month ago. As long as there's a demand for parts, they should be available for the next hundred years or so.:thumbsup:
 
cncsparky

cncsparky

New Member
#5
#5
Brandt told me that pistons, etc. are next to impossible to find now. He's trying to come up with an alternative. Worst case a custom piston could be built $$$. I was able to score 010 and 020 pistons earlier and I'm trying to find another 010 to have on hand to replace the one I used, but haven't had any luck yet :sadcrying4:

Tom.
 
cncsparky

cncsparky

New Member
#6
#6
A couple more pics. The piston was severely damaged on the valve side of the skirt. The rod has some marks on the journal, but I can't hardly feel them. I have a new rod for the engine.





Tom.
 
J

jimh

#7
#7
Wiseco might sell pistons for Tecumseh. I know they sell them for Briggs, just about any dirt bike, ATV, or street bike I've ever worked on. Quality as good or better than OEM stuff, and good prices too.
 
Ruppster81

Ruppster81

Member
#8
#8
Yup Wiesco would be my first choice on an aftermarket piston. I believe you can go right to their website and download a PDF file of a custom piston order form, You just need to know the dimensions of the piston and fill it out and they make it. I don't think their prices are to bad either. I'm sure with tecumseh going out of business they will probably be getting alot of orders for these and eventually will add them to their catolog and you will beable to order them and not have to worry about filling out a custom order sheet. I also plan on having some custom cylinder sleeves made to save some pretty bad engines that an overbore wont fix (they also do this) and a steel bore will be a nice bonus anyways :thumbsup:
 
J

jimh

#9
#9
Yep, the steel bore will last longer, and eliminate the need for a chromed piston. I've always had good luck with their pistons. I used them in a lot of motorcycles and they were the only source for some of the ones I needed. Usually they were less $$ than OEM parts that were available from the dealers.
 
cncsparky

cncsparky

New Member
#11
#11
Something interesting I just noticed. The new piston/rings look quite a bit different from the originals. The most notable is the width of the rings. The old rings are .094" and the new ones are .064". Also, the piston is different looking. I'll post a pic. Anyone know about when they changed designs? If I had a scale, it would be interesting to weigh each one. I suspect less width from the new rings equal less drag and maybe a little boost!

 
Ruppster81

Ruppster81

Member
#12
#12
I think they did alot of that with thier parts over the years. I've even noticed a difference between NOS and the newer crank seals. Towards the end they started making parts that work on the newer engines and still make them to work on the older ones as well. I think on those sleeves may have been LA Sleeves that I was thinking of. I've been toying with the idea over the last year or so and now it might be the only way we can keep our old tec's alive. I really dont need to do it as my super bronc engine was good for a std. ring job and the engine on my roadster 2 is NOS and has never had any gas/oil in it. I just have a few engines I would like to freshen up incase I need them someday or to have on display.
 
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