HS40 Rebuild Info Needed

#1
I am looking for some ideas/opinions on how I should proceed with getting my 40 year old HS40 overhauled. I have been restoring the minibike I had when I was a young kid and have concluded since it is smoking some under acceleration that I really should go ahead and have somebody that really knows these engines well rebuild it to factory new condition. I want to keep it stock.

Do any of you have any recommendations on who I should contact to get quotes and ultimately send it to? I want somebody that likes working on these motors and knows them well. This motor has never been opened up and is all original. I am in Texas, but do not mind shipping out of state.

What does a rebuild on one of these vintage motors usually cost?

I also would be interested in any interesting threads you would recommend me reading regarding overhauling Tec projects.

Thank you

 
#2
maybe the folks here could point you to a member who could rebuild it for for you.. for an amount of money. perhaps you could even ship to said person and then have it shipped back after it's rebuilt?
 
#4
Contact ATKRIDER. He is an expert on HS40 and has all the equipment to rebuild it. Then wait to see if he would have time to help you out.
Agree. ATK knows more about these motors than anyone I know. Not only that, when he sends you the stuff back, he includes extras. 100% stand up guy.
 
#6
Well, what color is the smoke?

If it's black, you need a carb adjustment as it is running too lean. No overhaul necessary.

If it's blue, you're burning oil. Re-ring, lap the valves with a suction tool, make a quick pass with a hone through the cylinder bore, and re-assemble per specs.


Easy enough to do yourself, the torque specs are available everywhere for the bolts. Gaskets, etc. are readily available & inexpensive.

Take a few pics of the guts of the thing with your cellphone. That will help during reassembly.
 
#7
Thanks everyone for your replies and subsequent recommendations. I do appreciate it. Regarding the smoke color, it is a blue color and you can smell the oil in the smoke.
 
#8
Well, what color is the smoke?

If it's blue, you're burning oil. Re-ring, lap the valves with a suction tool, make a quick pass with a hone through the cylinder bore, and re-assemble per specs.
None of that will accomplish anything and will be a total waste of time if the cylinder is worn oversize, tapered, or out-of-round. First, you need to take good measurements of the bore and compare them with Tecumseh "reject" specifications.
Michael
 

MB165

Active Member
#9
None of that will accomplish anything and will be a total waste of time if the cylinder is worn oversize, tapered, or out-of-round. First, you need to take good measurements of the bore and compare them with Tecumseh "reject" specifications.
Michael
Yes.
those aluminum bores wear fast, and major taper. honing a worn bore/ and once the rings seat again, you've lost even more...I bought a H35 that was "rebuilt", actually honed and re-ringed.... I tore it down and bored it, when I was done resizing it to ten over there were spots left that the finish hone didn't touch. it was worn to almost ten over, not a good way to put alot of time and money into only to have it continue to use oil and smoke.

If you need to bore it.. I have all the specific items from Sunnen to bore aluminum blocks, including the variable speed motor, almost a $1,000 for them, nice stuff. I can get them right on.
 
#10
MB165 is right on and this has been our experience as well. All too often on this forum with these old oil burning engines I see members (incorrectly) advising others to just put in new rings and hone it and you will be good to go-it is not that simple folks!
Michael
 
#11
I didn't mean to exclude anyone here. I mentioned ATK because I know he was building engines as a side job for awhile, and because he treated me very fairly on the price. I generally do my own Tecs and yes, I use a hone and measure the bore, and set new ring end gap per the book. I had ATK do my latest engine because I wanted newly cut seats, perfect specs, etc.

The OP was about getting a motor rebuilt, and I know there are quite a few people who have the knowledge and machinery to accomplish it. MB165's build-off bike for example was the one that gave me inspiration for my current project. :thumbsup: An excellent build, I might add.

It's not always economically feasible to spend 600 dollars on a quality engine build, when the motor is going on a 300 dollar bike. (parts, labor and shipping) To be honest, only once I ended up with blue smoke after a ring/hone job, but it was because I broke the new oil ring, and had to use the old one. (To be replaced later) :laugh:
 
#12
It's not always economically feasible to spend 600 dollars on a quality engine build, when the motor is going on a 300 dollar bike. (parts, labor and shipping) To be honest, only once I ended up with blue smoke after a ring/hone job, but it was because I broke the new oil ring, and had to use the old one. (To be replaced later) :laugh:


Exactly.

On top of that, people need to pull their heads out of their asses. Yes, aluminum bores wear a little more quickly than a cast iron lined version, but a quick pass with a hone, and a new set of rings will do you well. You may want to file the rings to end-gap specs, but it's not that difficult.


Some of you are talking about it like you're assembling an F1 engine.

Did that on plenty of koolbore briggs' & a couple Tecumsehs. Absolutely zero problems.


Trying to save OP a little bit of money here. As long as the bearings are good, as long as the piston & bore itself aren't worn & beaten way outside of spec, just do a quick hone, re-ring, break-in (allowing the rings to seat), & ride.



Just don't be that idiot caveman that takes a coarse ball hone & rams it through a tiny little hole at high speed, & then complains about it blowing their cylinder out to 10+ over.
 
#13
Exactly.

Trying to save OP a little bit of money here. As long as the bearings are good, as long as the piston & bore itself aren't worn & beaten way outside of spec, just do a quick hone, re-ring, break-in (allowing the rings to seat), & ri.
So am I. In your original reply to the OP you did not mention anything about first checking the bore to be within specs. You implied, at least to me, that all he had to do was re-ring and hone and he is good to go. If you already have the head pulled of anyway,it would be diligent and not cost much (if anything?) to have someone qualified take some accurate/proper measurements of the bore to check for an overly worn, tapered, or out-of-round cylinder. If (and ONLY if) everything was O.K and within specs THEN you can re-ring and hone as/if needed. It is crazy to throw money and time into a re-ring and hone w/o checking the cylinder first.
Michael
 
#14
Status/Feedback

I ended up going with ATKRIDER for the overhaul and I am very glad I did. I recently received the engine back from him and boy howdy dose it run great! I highly recommend him if you want a quality overhaul.

 
#15
I ended up going with ATKRIDER for the overhaul and I am very glad I did. I recently received the engine back from him and boy howdy dose it run great! I highly recommend him if you want a quality overhaul.
:thumbsup: Yep. It isn't hard at all to get these things running. The question is, "how well do you want it to run?"

ATKRIDER wont even mess with a motor that is out of spec. If you want a running motor and a bit of smoke, send it to Havasu Dave. :thumbsup:
 

jrzmac

Active Member
#18
Status/Feedback

I ended up going with ATKRIDER for the overhaul and I am very glad I did. I recently received the engine back from him and boy howdy dose it run great! I highly recommend him if you want a quality overhaul.

wow, did you make that Taylor style muffler?
 
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