Spark advance on points Hs50

#1
Hello
I did a search and found some threads on this subject, but all of the links are dead.
As far as I know, the points for Hs50 should be set at .035” before TDC.

This particular Hs50 has billet rod, .010” over, dyno 245 cam, decent valve springs and retainers and slide carb.
I am wondering if advancing the spark timing will gain any performance, but don’t want to advance too much and end up with kickback.
I am guessing that the way to accomplish this, is to change the setting to greater than .035” BTDC
Question is- how much is too much?
Or should I just set it up at .035” and call it a day?

Thanks. I know many here are much more knowledgeable than me just looking for some advice.
 
#2
No. The points are set at TDC to .020. The piston is then moved back .035 inches into the hole on that engine. At this point, the stator plate is rotated until the breaker points just open electrically as checked with an ohm meter and with wires off the terminal and the points terminal tight.

Advancing the ignition further for the 245 cam isn't going to give you anything, unless you feel like testing advance increments, then testing, then removing flywheel, shroud, etc, retiming, testing, etc. etc. At stock ignition timing of .035 inches advance, it runs good with 245 and Mik.

Delay did this with the later electronic solid state ignition. I didn't see any gains with points engines.
 
#3
Thank you Dave for your helpful response.
I remember using a dial indicator when I set the points on my last Hs50 and the ignition works great. But that was a few years ago and I kinda forgot the process.
Thanks for the reminder
I also have a degree wheel here but I’ll just use your method.
Thanks again
 
#4
I wish someone would play with spark advance on hot cams with those points engines. I did a rough guess on what timing was in degrees, and it was the same as when I used a fancy calculator, and it's something like 12 degrees BTDC. Delray says he is closer to 30 degrees with the solid state using a degree wheel and timing light. I would not try that with a points engine, because I know even a .005 inch error on the piston depth in the hole is enough to make the engine run rough. So I went with stock, and I was very happy at how it ran. (Same mods as yours, but HS40)
 
#5
Would be real easy to make a timing mark on the flywheel, and a pointer on the blower housing. Of course that is after finding top dead center, which is easy.
Then use a automotive dial back timing light to find how much advance and play around.

Back in the 70's as a punk kid, always wanted to find a way to make the magneto rotate with a cable or linkage while it was running.
 
#6
I know that some have advanced spark timing on the CDI engines with good results, just wondering if it is worth pursuing on a points engine. Or if it’s even possible
 
#7
Would be real easy to make a timing mark on the flywheel, and a pointer on the blower housing. Of course that is after finding top dead center, which is easy.
Then use a automotive dial back timing light to find how much advance and play around.

Back in the 70's as a punk kid, always wanted to find a way to make the magneto rotate with a cable or linkage while it was running.
Yeah, that's the thing. You can't really play around without pulling the wheel and then retiming it, then putting the wheel back on, retorquing the head bolts, retorqueing fly wheel. How many times do you want to do that to see see what an extra advance will do? Because to test it, you have to mount it to a load, chain, throttle, etc. etc. Not worth it to gain an extra .015 HP IMO. FYI, someone here did make a lever device of some sort and posted it here. It would not be impossible to do for the handy DIY'er, and for those cam'd engines, it might take out some of that kick back. The OHH 245's which is what he is using, do not have any CR on them.

I did get one custom ground this year from Dyno from an HS donor- MCR. They left the holes in there, so I do have a .245 cam with a MCR, but it was very pricey to get that done.
 
#8
I didn’t know if there was a known measurement or value that I could utilize while I have the flywheel and head off
Like if others had done it at .040” BTDC and had good results

Sounds like too much trouble to bother with though

Thanks again for the info
 
#9
Back in the 70's as a punk kid, always wanted to find a way to make the magneto rotate with a cable or linkage while it was running.
Harley did that from 1936 (without checking it could’ve been as early as 1930) to about 63 I believe...I don’t think the last two years you could “retard” the timing with the left grip....easy starting...albeit a distributor I think same principle but there again I know nothing....
 
#10
Harley did that from 1936 (without checking it could’ve been as early as 1930) to about 63 I believe...I don’t think the last two years you could “retard” the timing with the left grip....easy starting...albeit a distributor I think same principle but there again I know nothing....
Model T ford's had a spark "advance" lever near the steering wheel. That's where as a kid i got the idea from. Retard the timing so that a person did not break an arm while turning the crank by hand.
From what I understand, the modern pointless ignition have some advance built into the electronics.

Be really cool if someone actually put a timing light with the dial back or degree wheel, and see what the timing is at cranking speeds and 5000.
 

delray

Well-Known Member
#11
Hello
I did a search and found some threads on this subject, but all of the links are dead.
As far as I know, the points for Hs50 should be set at .035” before TDC.

This particular Hs50 has billet rod, .010” over, dyno 245 cam, decent valve springs and retainers and slide carb.
I am wondering if advancing the spark timing will gain any performance, but don’t want to advance too much and end up with kickback.
I am guessing that the way to accomplish this, is to change the setting to greater than .035” BTDC
Question is- how much is too much?
Or should I just set it up at .035” and call it a day?

Thanks. I know many here are much more knowledgeable than me just looking for some advice.
massacre just go with the stock setting for now, if you really want to play around with advancing the timing it will take little modifying and time and more on understanding how the mag is set up correct. i have played around with advancing the timing on my hs-40 and set it up with a timing light to see how far advance i have it. max i got out of it was about 28 degrees. works get for the racing i was doing with it. turns a easy 7000+ but then again it's a full roller crank....lol I just purchase a Indexing Dividing Spiral Head 3-Jaw Chuck so now I will be able to machine degree markings on my flywheel for more accurate timing. the newer electronic mags are set from factory at about 20 degrees and the hot coils or I should say the motorsports racing coil's are set at 30 degrees. the big thing you got to also remember with a flathead (like the hs-motors) you need to run a high stall. at least 3000 rpm's and alot of gear(jackshaft) to make these little guys fly. just no real big bottom end power when you start to get into racing cams in a flathead. you should be able to use a 22mm carb with a 125 jet/15 pilot for starters and a real good header.
what kind of bike is it going on? lighter the better......:scooter:
 
#14
Corrrect me if im wrong here, but according to my tecumseh book, Tecumseh engines mechanic handbook 3 to 10 hp. It calls for .050 BTDC for HS50 and .035 BTDC for HS40. I have set both engines hs50 and hs40 to these specs and they run great.
 
#15
Corrrect me if im wrong here, but according to my tecumseh book, Tecumseh engines mechanic handbook 3 to 10 hp. It calls for .050 BTDC for HS50 and .035 BTDC for HS40. I have set both engines hs50 and hs40 to these specs and they run great.
The flathead service manual posted on here lists it at .035 for both engines
 
#17
Wow, I have no idea.
Does whether it has points or CDI matter?

I set the timing on one of my Hs50s today. Not the engine I started the thread about, but a lighting coil and flywheel install on a relatively stock Hs50. Points are the same except for the green kill wire. I had some new points here so installed those. I have a new condenser too, but I noticed that the condenser that is on my lighted stator was a lot bigger so I just kept it. Also had to change to a longer bottom bolt for the stator, because the lighted stator is thicker on the bottom portion than the original.

I timed it as per spec, and H Dave’s suggestion.
.035 before TDC, attach leads to meter, rotate stator until circuit just breaks, tighten stator. I figured out a way to use a head bolt to attach the stand for the dial indicator.
Spun over by hand, had spark.

Bike fired right up ran great.
Lighting coil works too
 
#18
Advancing the ignition further for the 245 cam isn't going to give you anything, unless you feel like testing advance increments, then testing, then removing flywheel, shroud, etc, retiming, testing, etc. etc.
Haha true
But I have 2 basically identical setup Hs50s here so I could go that route so I could get there in half the time
;-)
 
Top