Spicing up Hs50

#1
I was wondering if anyone had any ideas of how I can add some pep to my HS50? I see people talking about a new rod and messing with the timing. Where can I learn how to do that and find those parts?

P.S. Im new to this forum so sorry in advanced if this has already been asked :)
 
#2
There are lots of Hs50 build threads here, from very talented ppl with tons of valuable info.
A lot depends on which bike it is going on and the tire size and gearing and the type of riding.
Also when you say spice it up, that is kind of a rabbit hole. How much “spice”?
Spice costs money lmao

i def recommend the ARC billet rod, do you have an aluminum flywheel?
Is it points ignition?
 
#3
To attempt to put the wealth of info in to one place... o_O

A little goes a long way with these motors. A good combination to get a pretty good motor would be: ARC #6282 billet rod, DynoCams 245 cam, and 18 pound valve springs with matching retainers and keepers.

- ARC #6282 is available through OldMiniBikes. Just search for it and it will appear. It's made for the Tecumseh OHH series of motors (OHH50, OHH55, etc...) but it fits in the HS series just fine. Remove the governor once you have this rod installed.

- DynoCams does not list the 245 cam on their website, but just call them and arrange for a regrind of your stock cam. It costs about $100. They do list the valve springs, retainers, and keepers, those are DCS-AN for the springs, DCSH102 for the retainers, and DCSH103 for the keepers. The retainers will have to be milled or filed down on the inside, as they are made for dual valve springs.

Pictures of the motor and the flywheel can help to decide where to go from here. Timing is completely different for points motors vs CDI motors. Also, if you are running a steel points flywheel, I suggest re-epoxying the magnets back in place on the flywheel. 40 year old glue and 5,000+ RPM's do not mix well!

There are a few other threads of builds. A quick browse of the Tecumseh forums will bring you some great results.
 
#5
Thank you guys for the speedy responses this is a really good constructive forum. Ill be sure to get that billet rod and remove the governor but is there anything I should worry about that will fail with the governor removed?

I'm kind of a scrub so I don't have an aluminum fly wheel or even know what points ignition is. Im kind of new to small horizontal shaft engines so im not completely familiar with everything.

Thank you guys for the help and tips I really appreciate it.
 
#6
Possibly the flywheel. I know clone flywheels don't like high rpm (over 5500 ish), but I'm not sure about Tecumseh's. And points ignition is what cars used until they went computerized. Watch a few Mustie1 videos. For this video skip to about 18 minutes.
 
#7
Thanks Ill be sure to watch the video.

After a certain RPM to the valves float? Im not sure if thats a thing on flat heads but know that can be a possibility on predators so im not sure If I will have to watch out for that
 
#8
The stock valves will float with stock springs.
But you can upgrade the valve springs like was mentioned.
Imho you should try to find an aluminum flywheel, they are lighter and allow the engine to spin up quickly compared to heavier wheel plus the magnets won’t come loose
 

delray

Well-Known Member
#9
number one thing is to post some good pictures of the engine you are actually working with. this will dicate a lot in which direction you can go with it and your ability to fab some stuff up. for example if the engine was a newer flathead with the small bore and valves and a cast steel flywheel? you may want to just keep it mild build and run a stock steel cam,better springs/retainers/hot coil/ header/billet rod/mild porting in the bowls /20-22mm carb. then try it out on a bike with a good clutch with a stall spring of at least 2500 or more and some good gearing. all that will be a day to night difference in performance and with a stock cam it will still pull up to 4700+rpm's easy and have no problems using a stock cast steel flywheel. personally a mid build is the way to go on your first adventure build.
need to post more info on the engine you are going to use.
 
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