Hs-40 build

delray

Well-Known Member
How did you lengthen the swingarm on the rupp?
ole I had a extra control arm that was severely damaged in the front part of it . plus a good control arm. so I just took out 5inch's section out of the bad arm and fab it up in the new arm. I also took out the factory rubber bushing and installed a more solid bushing.
 

delray

Well-Known Member
Great job on the swing arm. I couldn’t tell where you inserted the extra section.
thanks ole4,one thing that really help on that rear arm was replacing the factory rubber bushing with a solid bushing. bike handles real nice now. before with the rubber bushing it was all over the place when riding it. it only took about 5mins of riding and I new the rubber bushing had to come out.....:scooter:


also there was no intentions to make the bike look nice or detail looking. bike would be running on a clay surface only and it's just going to get dirty. so I just kept it flat black. going to have to go back in the spring maybe and clear coat it with a low gloss automotive clear on the gas tank,so the gas doesn't trash out the paint...:thumbsup:
 

cfh

Well-Known Member
On the connecting rod, is the only viable alternative to a no governor tecunseh the arc racing $60 billet connecting rods? Or are the stock tecumseh HSK50 connecting rods a good low-cost solution?
 

delray

Well-Known Member
You gonna pull the Engine apart to see how your Mods are working?
I haven't really thought about it. the two biggest mods was the needle roller bearing and that needed to be spinning on a piece of harden steel. that should be good to go. the other thing was making a compression relief in my dyno cam and I can still here it clicking(valve) when I pull it over slow. porting bowls, modifying set of the briggs narrow stem ss valves,springs retainers/keepers,ignition,1 inch roller bearing for the pto side...etc... all that stuff is just going for the ride and won't be effect by anything.

one thing I did check the other day was the end play for the crankshaft and that was still the same....:thumbsup:
 

delray

Well-Known Member
On the connecting rod, is the only viable alternative to a no governor tecunseh the arc racing $60 billet connecting rods? Or are the stock tecumseh HSK50 connecting rods a good low-cost solution?
not sure about the newer flathead hsk50 rod? I do know the ohh-rod is strong. I have one in a motor that spins 4700 rpm's for two years now and has been holding good. I did polish the beams before installing it. I know only of one other person here that has done this too. he go's by Tecumseh power. he claims his engine turns 5000 rpm's in a gokart/race track and has never broke one. if that's true ? that's saying a lot on a gokart for racing.

here is a stock hs-40 rod that came out of this engine I built in this thread next to a ohh-rod. you can clearly see the difference in the two rods.


 

delray

Well-Known Member
so in my opinion cfh, a person is wasting there time and money by using the old hs-40/50 rod when rebuilding a motor. new ohh-rods you can pick them up cheap...:thumbsup: and you know what you call that ….cheap insurance.
 

delray

Well-Known Member
For those of us who don’t have a way to machine the compression release-
What can we expect?
I did post a video in the past on how to pull a non compression relief cam over. it's not bad if you learn how to do it right,but like ole4 said it will pull your arm if you don't watch it.
 

delray

Well-Known Member
one other thing guys about using dyno cam 245 without a com/relief and maybe using a stock ohh-steel cam with com/relief.
if you don't plain on modifying your motor with the correct parts? the 245 cam may not be for you? this cam will pull good to 6000+ rpm's and you will not really see any difference in performance under 3000 rpm's from a stock cam to a 245 cam.
this 245 cam doesn't really start to come on until you get above 3000+ rpm's and something else to think about too when spinning your motor at 6000-7000 rpm's. you will need to build a catch can or you will have oil coming out you breather all day. something I have notes in the past with other peoples builds when installing race cam in a hs-motor. none have really geared there bikes to the full potential of the motor or spun them up to 7000+ rpm's or they would of had oil coming out. just nature of the beast doing it. can't get around it. it will happen. at least with the older style breathers.
if you don't have the correct parts and modifications done and don't plain on racing it and all you are looking to do is just have a good strong runner?

I would personally install a steel ohh compression relief cam in my hs-40/50

with all the correct parts for that build and modifications you could easily pull good power up to 4500-4700 rpm's with that cam.
whats real nice with that cam you could advance the timing(which you will need to do) and not worry about yanking your arm off.:thumbsup:
 

cfh

Well-Known Member
so in my opinion cfh, a person is wasting there time and money by using the old hs-40/50 rod when rebuilding a motor. new ohh-rods you can pick them up cheap...:thumbsup: and you know what you call that ….cheap insurance.
Are you saying that the HSK50 overhead cam stock connecting rod is a viable alternative? Because those are only $15. The billet connecting rod from Arc racing is $60. That’s a big difference in price.
 
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