Building a high performance HS40!

Rupp 72

Rupp 72

Active Member
#1
#1
Rebuliding an HS40 for a Black Widow, but hopefully with a bit more performance. I had the cylinder bored .080" oversize, and nickel silicon carbide plated cylinder wall. Pair that with a Wiseco piston and an ARC billet aluminum connecting rod. Also have a latter model EZ-Pull cam that should have a few thousandths more lift that original. I'm excited to see how it turns out!




 
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danford1

danford1

#2
#2
I think if you "port" the block to get rid of the sharp edges in both the intake and exhaust passages you would gain a little flow and power.

Looks like an interesting build. Keep us posted.

Danford1
 
Rupp 72

Rupp 72

Active Member
#4
#4
I think I'll give the porting a try Danford. And thanks Brian for all of your help up to this point! Can't wait to start putting it back together:thumbsup:
 
markus

markus

Well-Known Member
#5
#5
:drool: nice! I had one of the wiseco .080 over piston/rings awhile back but sold it off, In hindsight I should have kept it because I ended up with a few blocks with really trashed out bores but great shape everywhere else :doah: How bad on the wallet is the plating to have done?
 
J

Joe51

#7
#7
I am interested in the plater as well. I have a few HS40 blocks. One of them destined for a Blackwidow build.
Keep us posted with detail please.
Regards,
Joe51
 
delray

delray

Well-Known Member
#8
#8
guys, the place i sent nate to have is plating done was a company in plymouth wis called millennium technologies. i found this place last year in doing my research to have this process done on my ohh-build. they are one of the only companys that i found that can do this to a small engine. they also call this a blind boring process where it makes it harder for most companys to do the plating correct. need correct equipment for this type of plating and they had it.....:thumbsup:
 
chatten63

chatten63

#9
#9
delray said:
guys, the place i sent nate to have is plating done was a company in plymouth wis called millennium technologies. i found this place last year in doing my research to have this process done on my ohh-build. they are one of the only companys that i found that can do this to a small engine. they also call this a blind boring process where it makes it harder for most companys to do the plating correct. need correct equipment for this type of plating and they had it.....:thumbsup:
Click to expand...
So this place bores the block to the piston and then they plate it
 
delray

delray

Well-Known Member
#10
#10
yes rick,they bore the block and then plate it and then hone it to piston size....:thumbsup:
sometimes the plating will vary in thickness. that will depend on what's going on with the block. for example poor aluminum casting.
it may take more plating to bond correctly. good thing with tecumseh's the casting is good...:thumbsup:
i believe my plating only has about .005 to .006 and from the looks of nate's maybe the same. they say the surface wear is stronger then cast iron sleeve and you will wear out the rings before the plating. i think it's a great process for something like nate is doing and for that type of piston and rings he is using or for any racing application.
 
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Rupp 72

Rupp 72

Active Member
#13
#13
Hey everyone, sorry i haven't been on the site the last few days but Brian was able to fill you in!:laugh: Yes Millennium Technologies does great work and all of there prices are on line. A engine block is slightly more expensive than a cylinder jug because of the extra masking they have to do for plating purposes. But the end product is awesome! Brian really recommended it since boring .080 over will thin up the cylinder wall pretty good especially where that bolt hole is on the front of the block. That hard plating will ensure I don't ware the cylinder wall. :thumbsup:
 
Rupp 72

Rupp 72

Active Member
#14
#14
Update on what's been going on with the engine build. Deciding to go with a briggs animal spring and retainer that i had sitting around, i belive that spring should be about a 16 lbs spring so it should keep the valves from floating but not wear on the cam. Also went with a later model Tecumseh cam with the compression release and also has quite a bit more lift. The stock cam measuring in at .995 and the new cam measuring in at 1.053 inches across the lobe . Spent some time with Delray today fitting together the engine and figuring out what were gong to do for valve clearance and timing.


 
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danford1

danford1

#15
#15
Simply measuring the height of the lobe isn't the lift of the cam. You need to measure the base circle or small end of the cam too. Then subtract the small number from the big number for the actual lift.
Let's say for this discussion that the cam with the 1.053" measurement has a base circle that is 0.065" bigger than the other cam. Once you did the math you would see that the 1.053 cam has less lift than the other cam. Now, if Both cams have the exact same base circle, then Yes the 1.053 cam would have more lift. Also lift isn't everything. A cam could have less lift but more duration and a different lobe separation angle and make more power then the "bigger" cam. The power will be at higher rpm though and would probably have less tq on the low end.
Cams can get very tricky and a simple swap of an unknown cam could actually produce less power then what you had...
JMO Danford1
 
delray

delray

Well-Known Member
#16
#16
danford1, yes it does have more lift then the stock vintage cam and the other advantage it has the mechanical compression release where the valve closes once it's in motion and not have the valve always bump open on the back lobe like the vintage cams do.
i have use this cam in some of my tecumsehs and seams to work very well with few other modification done with it...:thumbsup:
 
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delray

delray

Well-Known Member
#17
#17
finish up rupp72 valve clearance. we decided to go with a newer cam that has the larger base circle and lift. wanted a cam that would still work well with a 19mm dellorta,factory header pipe and with the gearing the bike comes with and without a jackshaft there's not much gearing a person can work with. maybe larger rear sprocket. use this cam in the pass and seems to pull real hard up to 4500+ rpm's
with a bigger base circle i really didn't want to take all the material off the tip of the valve.
found a real simple way to grind the lifter down. fab up a small V channel out of a piece of angle and square it up with bench grinder. then just lightly spun the lifter against the grinding stone. after that i just chuck it up in my lathe and use a small square end grinding stone in the tailstock.



lifter ends came out real nice and square...:thumbsup:


couple options for aftermarket retainers/keepers
briggs animal, dynocams(need to machine a small area of the retainer for the spring to fit correct),or motorsports retainers(heavy duty)
briggs animal parts work the best. no modifications...:thumbsup:


valve clearance came out good, .007 tight on the int with a feeler gage and right on .007 exhaust.
with the briggs animal retainers and 16 pound springs combination everything fit just perfect.


before i set the lifter clearances went ahead and clean up the bowls little. didn't go crazy on this part. parts of the bowl area can be real thin aluminum.



also plug up the governor hole.



nate you should be ready for the next step.........:thumbsup:
 
Rupp 72

Rupp 72

Active Member
#18
#18
I have to say, there is no one better to help me than you Brian! I don't know how i got so lucky to only live 5 minutes away from you. I never intended to build this engine to quite the caliber we are but I'm thankful that you were able to point me in the right direction to really get some more performance out of this engine. It should be a great bike when it's all done!:scooter:
 
cdoublejj

cdoublejj

Member
#19
#19
i'm curious to see how this runs. i have the same piston and plan on getting the ARC billet rod for my HS40 as well. Best of luck and look forward to more photos. :)

EDIT: i still have no solid info on aftermarket springs and retainers, looks like i need to learn me some dimensions and sizes. glad to see there are options. The plated bore sounds sooo cool.
 
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