Removing governor..adding tach

[Hunter65]

I have a Robin/Subaru OHV 4.5 hp engine that i want to remove the governor on. I have heard that the governor gear on these are ran by the timing chain?? Will this change anything if i take the governor out like mess up the timing? And after i get done i want to add a tachometer to it. I have a few tachs that should work but i just dunno where to hook them up to? Could someone help me out?

 

[solomon]

I dont think this engine has a timing chain. The timing should be a cam gear and crank gear, and thier should be timing marks on them IE a line or dot. The governor should be behind the cam. Most tach's wont work on these engines. If you plan on using a tach use the "Tiny Tach" designed to work on small engines

 

[Russ2251]

Could be Over Head Cam.
Can you provide engine model number?

 

[Hunter65]

I just got it done like 30 minutes ago. And it has a chain of some sort in their that goes to the valves.

 

[solomon]

thats interesting, a chain. Are you going to buy the "tiny tach"

 

[devino246]

I must be an over head cam. I got a lawnmower with one. What does the valve cover say on it?

 

[NJOHC]

Solomon,
Subaru makes a chain driven overhead cam engine. That's what he has apparently. They dont make a 4.5hp without OHC

To the OP. If you take the valve cover off the cam is right under it. That's where the chain was going. When you get the tach hooked up make sure not to go any higher than 6000rpm. Everything will hold up except the flywheel at that rpm. Its not safe to push it past that.

 

[solomon]

I would have a machine shop lighten the flywheel now. Then you will pull a lot more power!

 

[Russ2251]

Everything will hold up except the flywheel at that rpm. Its not safe to push it past that.

Not even the slightest chance.

Valves will float before you even come close to flywheel issues.

The truth.

I would have a machine shop lighten the flywheel now. Then you will pull a lot more power!

Would be better off getting the vertical shaft counter part (if available). Also, no power increase will be realized. A lighter flywheel will decrease response time (gets up to speed faster) and has no appreciable effect on power.

 

[NJOHC]

Email Grant Goracy and ask about that. He helped develop subaru's karting engine and has helped me with all the aftermarket of mine. Subaru has the strongest stock rod in the business. I've never asked about valve float with him, but when I told him I removed the gov. he said over 6k wasnt safe according to his testing. In my mind that meant they could rev that high stock.

 

[Kaptain Krunch]

Email Grant Goracy and ask about that. He helped develop subaru's karting engine and has helped me with all the aftermarket of mine. Subaru has the strongest stock rod in the business. I've never asked about valve float with him, but when I told him I removed the gov. he said over 6k wasnt safe according to his testing. In my mind that meant they could rev that high stock.

Doubt it. Either way a flywheel explosion will not happen if flywheel is torqued to spec and unmolested.

 

[Russ2251]

I wonder how this exploding flywheel thing got started.
I wonder how many times some folks decided against doing any mods because of this unsubstantiated and utterly ridiculous myth.
Would have a much better chance of getting abducted by a leprechaun.

 

[Kaptain Krunch]

I wonder how this exploding flywheel thing got started.
I wonder how many times some folks decided against doing any mods because of this unsubstantiated and utterly ridiculous myth.
Would have a much better chance of getting abducted by a leprechaun.

Im sure flywheel explosions have happened, in-fact i have seen proof. However, none of said flywheels were unmolested, all were either fractured or damaged from dropping/hammering, modified, and/or not properly torqued.

 

[Russ2251]

It has in fact happened to me and was documented a couple of years ago on this forum.
I had to go way out of my way to do it.

 

[freakboy]

It has in fact happened to me and was documented a couple of years ago on this forum.
I had to go way out of my way to do it.

can i get the link?

 

[Russ2251]

I searched for it and cannot find.

 

[freakboy]

i found somewere that you were talking about it that you had em on your bike or something and unloaded weight you had 2 different ones go off?leme find the link here.

http://www.diygokarts.com/vb/showthread.php?t=743

 

[Russ2251]

Yup, that's one of them.
Like I said, I had to go way out of my way to do it.
I thought I got into more specifics. Perhaps not.
I'm a lot smarter now.

 

[anderkart]

I wonder how this exploding flywheel thing got started.

I spent quite awhile researching this and found bobs4cycle forums has several fairly credible sounding reports of stock Briggs 5hp. flywheels exploding, but only when this particular model had been highly modded to spin up into the 10,000 rpm range. As I remember, the only credible sounding death report I ran across was to a spectator that happened to be standing right next to the track when a stock Briggs 5hp flywheel blew at these rpm's.

Several people brought up a good point that most any flywheel could be damaged from improper removal/installation or dropping them. I'm thinking the very few flywheels that have been reported to blow up at very-very high rpm's may have already been damaged/defective in some way.

All I know is what Ive read on the net, and I definitely don't believe all of that. But If you ever want to seriously debate this issue, you'll find some very worthy opponents over there on bobs forum.

I think this whole myth has been greatly overblown by the guys that make money selling racing flywheels, but I do think they're probably a good Idea in at least some full race engine situations.

 

[NJOHC]

I wonder how this exploding flywheel thing got started.
I wonder how many times some folks decided against doing any mods because of this unsubstantiated and utterly ridiculous myth.

I wasnt trying to say it was definitely going to explode. That was the farthest from what I was trying to say. I have heard of flywheel explosions for as long as I've been into karts(not very long but 4 years lol). When It had the tec on it I revved it until the valves floated for days in the summer before it started to lose compression. I knew about the flywheels then but not so much about the crappy rods.

I passed on info from a man who has helped in the engineering and performance of some subaru engines. He has helped me more than anyone with mine. I trust him and his experience. If a guy that does work with Subaru says its not a smart idea you wont find me revving mine any higher than that. Even if the valves dont float.