need shelbyclone or mdb
- Thread starter jesse8931
- Start date
That sounds like a lot of work and won't change the timing one bit. For your information, the points are what trigger the spark. All that "flying magnet" does is build flux in the coil. You need the points to collapse the field so the secondary side of the coil build a high voltage spark. Nice try.
So I pose the question again. How do you advance the timing on a Briggs. Moving the flywheel is only half the problem. Now if you had a Prest-o-lite ignition that would be a different story.
So I pose the question again. How do you advance the timing on a Briggs. Moving the flywheel is only half the problem. Now if you had a Prest-o-lite ignition that would be a different story.
I would say that I dont beileve it... In all that days I have hung around with karters I have never seen a little 3hp Briggs and Stratton engine spin that much.
The only motors I have seen spin that much are outlaw karts running methonal and these were 5hp Briggs. With monster billet cams and off-set ground cranks and such.
Unless you have some special goodies and a HUGE cam and a billet rod and billet flywheel there is NO, and I mean NO way a stock briggs with a cam can spin that much without breaking.
Unless I see some video or pictures or something of prove I say its a bunch of BS!
The only motors I have seen spin that much are outlaw karts running methonal and these were 5hp Briggs. With monster billet cams and off-set ground cranks and such.
Unless you have some special goodies and a HUGE cam and a billet rod and billet flywheel there is NO, and I mean NO way a stock briggs with a cam can spin that much without breaking.
Unless I see some video or pictures or something of prove I say its a bunch of BS!
QUOTE=Taylor;32753]I would say that I dont beileve it... In all that days I have hung around with karters I have never seen a little 3hp Briggs and Stratton engine spin that much.
The only motors I have seen spin that much are outlaw karts running methonal and these were 5hp Briggs. With monster billet cams and off-set ground cranks and such.
Unless you have some special goodies and a HUGE cam and a billet rod and billet flywheel there is NO, and I mean NO way a stock briggs with a cam can spin that much without breaking.
Unless I see some video or pictures or something of prove I say its a bunch of BS![/QUOTE]
I can assure you that what I stated was fact. How do I prove it? Can't really.
But I'll give you some back ground on the set up that produced this. First off I use this tachometer. It is a mechanical tachometer accurate to 1% full scale and good for 12,000 RPM:
[/IMG]
The motor was modified top to bottom:
Cylinder head milled .093"
Hand made dead soft .032" copper head gasket.
Stock aluminum bore with multi-piece Briggs chrome rings (zero gap)
Painted piston crown
connecting rod polished 100% with round journals
"Supertanium" socket head cap screws installed in rod.
Dipper cut down
Lightened piston with custom made hollow wrist pin.
Knife edge counter weights on crank
Maximum port on both intake and exhaust:
Visualized with laminar water flow to maximize inlet swirl
indexed "power tip" spark plug
Back cut valves with narrow seats
Reduced tension intake spring to induce valve float and maximize "open time"
Shimmed exhaust valve spring.
Easy-Spin bump on cam removed and base circle polished
home made bronze valve guides with .001 stem clearance
Carb "helix" removed
Air cleaner mount cut out of carb
flywheel od turned to .0005" run out
magneto "shoe" set to absolute minimum clearance
Points sets to .010" to maximize timing.
Throttle stop modified to yield 90 degree maximum opening
And last but not least:
Home made counter weight to replace rod and piston assembly
during balancing by local industrial shop.
This 9,200 RPM was obtained with the bolted down to the work bench with no load. Two of the biggest problems were oil pumping and spark. I was only able to obtain these RPM with a .010 gap. The oil pumping issue was solved with a partial crank case fill.
Granted the RPM was basically a flash reading. It not like it was held there. But it was good for maybe 3 seconds. Just enough time to kick all the oil right out the spring pocket.
Now these are facts. You can call Bull if you like. Rhovis couldn't give a pinch less because he knows what the facts are.
The only motors I have seen spin that much are outlaw karts running methonal and these were 5hp Briggs. With monster billet cams and off-set ground cranks and such.
Unless you have some special goodies and a HUGE cam and a billet rod and billet flywheel there is NO, and I mean NO way a stock briggs with a cam can spin that much without breaking.
Unless I see some video or pictures or something of prove I say its a bunch of BS![/QUOTE]
I can assure you that what I stated was fact. How do I prove it? Can't really.
But I'll give you some back ground on the set up that produced this. First off I use this tachometer. It is a mechanical tachometer accurate to 1% full scale and good for 12,000 RPM:
The motor was modified top to bottom:
Cylinder head milled .093"
Hand made dead soft .032" copper head gasket.
Stock aluminum bore with multi-piece Briggs chrome rings (zero gap)
Painted piston crown
connecting rod polished 100% with round journals
"Supertanium" socket head cap screws installed in rod.
Dipper cut down
Lightened piston with custom made hollow wrist pin.
Knife edge counter weights on crank
Maximum port on both intake and exhaust:
Visualized with laminar water flow to maximize inlet swirl
indexed "power tip" spark plug
Back cut valves with narrow seats
Reduced tension intake spring to induce valve float and maximize "open time"
Shimmed exhaust valve spring.
Easy-Spin bump on cam removed and base circle polished
home made bronze valve guides with .001 stem clearance
Carb "helix" removed
Air cleaner mount cut out of carb
flywheel od turned to .0005" run out
magneto "shoe" set to absolute minimum clearance
Points sets to .010" to maximize timing.
Throttle stop modified to yield 90 degree maximum opening
And last but not least:
Home made counter weight to replace rod and piston assembly
during balancing by local industrial shop.
This 9,200 RPM was obtained with the bolted down to the work bench with no load. Two of the biggest problems were oil pumping and spark. I was only able to obtain these RPM with a .010 gap. The oil pumping issue was solved with a partial crank case fill.
Granted the RPM was basically a flash reading. It not like it was held there. But it was good for maybe 3 seconds. Just enough time to kick all the oil right out the spring pocket.
Now these are facts. You can call Bull if you like. Rhovis couldn't give a pinch less because he knows what the facts are.
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I can assure you that what I stated was fact. How do I prove it? Can't really.
But I'll give you some back ground on the set up that produced this. First off I use this tachometer. It is a mechanical tachometer accurate to 1% full scale and good for 12,000 RPM:
![](http://www.oldminibikes.com/forum/engines-modifications/<a href="http://s261.photobucket.com/albums/ii55/EllisofRoy/Tachometer/?action=view¤t=Picture012.jpg" target="_blank"><img src="http://i261.photobucket.com/albums/ii55/EllisofRoy/Tachometer/Picture012.jpg" border="0" alt="Photobucket"></a>)
The motor was modified top to bottom:
Cylinder head milled .093"
Hand made dead soft .032" copper head gasket.
Stock aluminum bore with multi-piece Briggs chrome rings (zero gap)
Painted piston crown
connecting rod polished 100% with round journals
"Supertanium" socket head cap screws installed in rod.
Dipper cut down
Lightened piston with custom made hollow wrist pin.
Knife edge counter weights on crank
Maximum port on both intake and exhaust:
Visualized with laminar water flow to maximize inlet swirl
indexed "power tip" spark plug
Back cut valves with narrow seats
Reduced tension intake spring to induce valve float and maximize "open time"
Shimmed exhaust valve spring.
Easy-Spin bump on cam removed and base circle polished
home made bronze valve guides with .001 stem clearance
Carb "helix" removed
Air cleaner mount cut out of carb
flywheel od turned to .0005" run out
magneto "shoe" set to absolute minimum clearance
Points sets to .010" to maximize timing.
Throttle stop modified to yield 90 degree maximum opening
And last but not least:
Home made counter weight to replace rod and piston assembly
during balancing by local industrial shop.
This 9,200 RPM was obtained with the motor bolted down to the work bench with no load. Two of the biggest problems were oil pumping and spark. I was only able to obtain these RPM with a .010 gap. The oil pumping issue was solved with a partial crank case fill.
Granted the RPM was basically a flash reading. It not like it was held there. But it was good for maybe 3 seconds. Just enough time to kick all the oil right out the spring pocket.
Now these are facts. You can call Bull if you like. Rhovis couldn't give a pinch less because he knows what the facts are.
But I'll give you some back ground on the set up that produced this. First off I use this tachometer. It is a mechanical tachometer accurate to 1% full scale and good for 12,000 RPM:
The motor was modified top to bottom:
Cylinder head milled .093"
Hand made dead soft .032" copper head gasket.
Stock aluminum bore with multi-piece Briggs chrome rings (zero gap)
Painted piston crown
connecting rod polished 100% with round journals
"Supertanium" socket head cap screws installed in rod.
Dipper cut down
Lightened piston with custom made hollow wrist pin.
Knife edge counter weights on crank
Maximum port on both intake and exhaust:
Visualized with laminar water flow to maximize inlet swirl
indexed "power tip" spark plug
Back cut valves with narrow seats
Reduced tension intake spring to induce valve float and maximize "open time"
Shimmed exhaust valve spring.
Easy-Spin bump on cam removed and base circle polished
home made bronze valve guides with .001 stem clearance
Carb "helix" removed
Air cleaner mount cut out of carb
flywheel od turned to .0005" run out
magneto "shoe" set to absolute minimum clearance
Points sets to .010" to maximize timing.
Throttle stop modified to yield 90 degree maximum opening
And last but not least:
Home made counter weight to replace rod and piston assembly
during balancing by local industrial shop.
This 9,200 RPM was obtained with the motor bolted down to the work bench with no load. Two of the biggest problems were oil pumping and spark. I was only able to obtain these RPM with a .010 gap. The oil pumping issue was solved with a partial crank case fill.
Granted the RPM was basically a flash reading. It not like it was held there. But it was good for maybe 3 seconds. Just enough time to kick all the oil right out the spring pocket.
Now these are facts. You can call Bull if you like. Rhovis couldn't give a pinch less because he knows what the facts are.
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If you can maintain usable control of the valvetrain, just about any engine is capable of 9000rpm+ without a load....as long as none of the components come apart. Most would hardly make any power at that speed without the airflow to support it, however. It may have been simply luck of the draw that Rhovis's engine didn't come unglued. It could have also been the fact that all of the 3hp components are smaller and lighter than a 5hp. The stock 3hp parts had a better chance of not coming apart than those of a stock 5hp. Try twisting a big 10hp that high with stock parts and it will spill its guts.
Maybe the real question here is, why should you guys even care how I choose to post? Is it that big of a deal how I choose to construct my sentence? The fact is, I have posted some of my experience with Briggs motors and all you guys can do is bitch about the form of my post. So now Rhovis will open your eyes with a few of his observations using the third person form. Like it or bite it.
Rhovis does not care if you "buy it" or not. The facts are, 92 hundred RPM. But then again maybe Rhovis does care because he is actually taking time from many other productive activities to post here for YOUR benefit. First off "don't" is the proper hyphenated form of "do not" and "I" should be capitalized. Rhovis suggests that you spend a little more time on your sentence structure and less time fooling around with motors. If you choose to ignore Rhovis' advise on developing proper use of the English language then he suggest you pay attention to what Rhovis has to say about the technical aspects of internal combustion engines. You just might learn something and that would be rewarding for Rhovis.
And now for Mister "Rude". Super retarded is relative. To imply that Rhovis is super retarded is very close to crossing the line. You sir have no idea who are insulting and Rhovis suggest that you don't take swipes at people you don't know. Just sayin'
Now this statement, even with the lower case "I" is a true demonstration of the wonderful freedoms we as Americans have. And that is the freedom of speech. That Jesse is your opinion and Rhovis will not deny you that right. Rhovis will however attempt to enlighten you as to some technical aspects that might change your mind.
Rhovis does not care if you "buy it" or not. The facts are, 92 hundred RPM. But then again maybe Rhovis does care because he is actually taking time from many other productive activities to post here for YOUR benefit. First off "don't" is the proper hyphenated form of "do not" and "I" should be capitalized. Rhovis suggests that you spend a little more time on your sentence structure and less time fooling around with motors. If you choose to ignore Rhovis' advise on developing proper use of the English language then he suggest you pay attention to what Rhovis has to say about the technical aspects of internal combustion engines. You just might learn something and that would be rewarding for Rhovis.
And now for Mister "Rude". Super retarded is relative. To imply that Rhovis is super retarded is very close to crossing the line. You sir have no idea who are insulting and Rhovis suggest that you don't take swipes at people you don't know. Just sayin'
Now this statement, even with the lower case "I" is a true demonstration of the wonderful freedoms we as Americans have. And that is the freedom of speech. That Jesse is your opinion and Rhovis will not deny you that right. Rhovis will however attempt to enlighten you as to some technical aspects that might change your mind.
Now this is an excellent observation and Rhovis would like to respond if he may.
This is a "flat head" and the air flow actually goes sideways past the valve. Rhovis had two goals in milling the head this much. First off was the "static compression". This being a number generated purely from the geometry of the cylinder as compared to "dynamic compression" that is influenced by the efficiency of the cylinder fill. This dynamic compression is sometimes referred to and is heavily influenced by the "volumetric efficiency". Complicated subject that Rhovis would be glad to address later if permitted.
Rhovis wanted as much cylinder pressure as he could get. That was the main reason for the heavy mill.
The second issue is combustion chamber size. The smaller the chamber the faster the relative burn speed. This higher burn speed allows building pressure early in the stroke. Early pressure build also subjects the piston rings to loading closer to top dead center where the ring has lower face speed and is better able to capture the pressure.
The smaller chamber also has less surface area and thus lower heat loss.
This is a "flat head" and the air flow actually goes sideways past the valve. Rhovis had two goals in milling the head this much. First off was the "static compression". This being a number generated purely from the geometry of the cylinder as compared to "dynamic compression" that is influenced by the efficiency of the cylinder fill. This dynamic compression is sometimes referred to and is heavily influenced by the "volumetric efficiency". Complicated subject that Rhovis would be glad to address later if permitted.
Rhovis wanted as much cylinder pressure as he could get. That was the main reason for the heavy mill.
The second issue is combustion chamber size. The smaller the chamber the faster the relative burn speed. This higher burn speed allows building pressure early in the stroke. Early pressure build also subjects the piston rings to loading closer to top dead center where the ring has lower face speed and is better able to capture the pressure.
The smaller chamber also has less surface area and thus lower heat loss.