Valve Cover/Breather

#1
Hello,

Is it possible to lose enough compression through the valve cover/breather area of an Hs50 to make the engine not start? I can hear air hissing out from that area when I pull it over, and the engine has spark, and is timed correctly. Valves are opening at the correct times, points break open at the correct times.
Wonder if the breather is clogged

Freshly built engine and flywheel key is not sheared. There is a slight groove in it on one aside though. Will not fire over even with starting fluid. Only thing I can think of is a compression leak. I have a new head gasket coming because I thought the head was warped, but it’s not. Deck also seems flat, not warped as checked with a straightedge. Gasket is suspect though as it is really old and I got it used.

I built another Hs50 using the same methods and that bike starts first pull and runs great.

Any suggestions? I’m stumped. I thought for sure the flywheel key would be sheared but it is still in one piece.

Thanks and have a good day
 
#2
Wanted to add that this magneto and points, condenser and flywheel worked great on my other engine. So to me they seem like known good parts. Flywheel was lapped, came out nice and gray.
 
#4
I just need to go through everything again, now that we have had thunderstorms, the heat and humidity have lessened lol.
Both of my cars broke. minibike, etc and have been sweating right through my clothes for a couple weeks and am just kinda overheated.
I know it’s something simple, just gotta cool down and then do some troubleshooting.
Prob should not have even started this thread, sorry everyone
 

Cuda54

Active Member
#5
We all hit a wall on thing every now and then. I too have a problem with the heat plus old age and other things too. Setting the points at just the right spot might fix it. I have seen it be just a little different from one engine to the next before. Could be just a bad plug or wire to kill switch. Did you get gas to the plug yet? I started out on a Mike bike back in the day riding with trail 70s I should have bought a RUPP Roadster. Or added a bigger motor to mine they had more take off than I did.
 
#6
We all hit a wall on thing every now and then. I too have a problem with the heat plus old age and other things too. Setting the points at just the right spot might fix it. I have seen it be just a little different from one engine to the next before. Could be just a bad plug or wire to kill switch. Did you get gas to the plug yet? I started out on a Mike bike back in the day riding with trail 70s I should have bought a RUPP Roadster. Or added a bigger motor to mine they had more take off than I did.
Thanks for the support, means a lot. New key came today, still waiting on head gasket
 
#7
I was able to get my streaker running today, at least. OHh50 stock.
Man I forgot how easy it is to pull over an engine with a mechanical compression release! It was pulling over so easy I thought something was wrong with it lmao
 
#8
So I was hearing a hiss coming from the engine when pulling the rope. Thought it was coming from the breather area hence the reason for this thread. Starter rope was still hard to pull so did not immediately suspect the head gasket.

Turns out that it was the head gasket, replaced that and all is well.
 
#9
I use my fingers right after it fires to feel for a suspected leak. If not, from time to time I have had success using a transmission funnel, backwards as a hearing aid, to search around for a leak. Clean it first.
 
#10
Thanks for the advice, I appreciate it!

I was trying that but the motor never fired.
It was hot as hades here and my fingers were sweaty and dirty and greasy. Thought the leak was from the breather but obviously I was dead wrong an that lol
Def learned my lesson on that one for sure.

To be honest I should have sprayed everything with soapy water like trying to find a leak on a tire.
That might have clued me in, should have thought of that would have saved some headaches.
 
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