720 Big Bore blown head gasket
#71
11-16-2005, 05:11 PM
720 Big Bore blown head gasket
Originally posted by: Bradracer18
15:1 compression on pump gas..........really??? I've never even seen 15:1 compression(on a gas motor)........sounds pretty close to dieseling........
15:1 compression on pump gas..........really??? I've never even seen 15:1 compression(on a gas motor)........sounds pretty close to dieseling........
#72
11-16-2005, 08:47 PM
720 Big Bore blown head gasket
Just because a motor is rated at 15:1 doesn't mean it makes a lot of dynamic compression at low rpm's. A cam with a decent amount of overlap will bleed off a lot of pressure at low rpms by hanging the exhaust valve open long enough. Once you reach a certain rpm the valve overlap will actually use the inertia of the exhaust gas to draw in even more of an intake charge and give you even more compression. I've heard of a 13:1 compression motor running on pump gas. Perhaps with the right cam a 15:1 motor could live on 93 at low rpms.
Well Said....
Stroke plays a good part into what compression you can get away with also..
#73
11-16-2005, 10:13 PM
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720 Big Bore blown head gasket
Originally posted by: MisterHP
The reason an o-ring setup uses copper is so it will crush. The cometic gasket is steel and just sit's on top of the o-ring then when you torque the head down it warps and the cylinder wall distorts up close to TDC causing the piston ring's to loose seal during the compression stroke. I know it will work but its kinda bad for performance and has great potential to leak. I thought you were running a Pami cylinder...why did you o-ring it?
Bigboo, how long did your bike run before it started leaking? Detnation will blow the gasket between the cylinder and water jacket pumping cylinder pressure into the coolant system. An improper sealed head gasket will just leak water outside the motor.
And guy's know what your talking about when you make definate statements about compression and pump gas. I have seen 15:1 compression on pump gas with proper cam timing.
Originally posted by: DuneMe
Interesting. . .
Eric: If the O-rings are recessed too low they won't work as designed? Could you then use the MLS (Cometic) gasket???
My 105.5 jug has an O-ring and I've been running the MLS gasket on it for a couple years now. (Knockin' on wood!) Not sure how recessed the O-ring is. BTW, Gary told me the same thing.
Great info.
I'm guessing mine is probably recessed. . . guess I lucked out [img]i/expressions/face-icon-small-confused.gif[/img]
Great info. Again, Bomb thread has the best info by far.
Interesting. . .
Eric: If the O-rings are recessed too low they won't work as designed? Could you then use the MLS (Cometic) gasket???
My 105.5 jug has an O-ring and I've been running the MLS gasket on it for a couple years now. (Knockin' on wood!) Not sure how recessed the O-ring is. BTW, Gary told me the same thing.
Great info.
I'm guessing mine is probably recessed. . . guess I lucked out [img]i/expressions/face-icon-small-confused.gif[/img]
Great info. Again, Bomb thread has the best info by far.
Bigboo, how long did your bike run before it started leaking? Detnation will blow the gasket between the cylinder and water jacket pumping cylinder pressure into the coolant system. An improper sealed head gasket will just leak water outside the motor.
And guy's know what your talking about when you make definate statements about compression and pump gas. I have seen 15:1 compression on pump gas with proper cam timing.
COME ON ERIC I ONCE SEEN A CHICAGO STREET FIGHTER BEAT HOICE GRACIE!!!!!!! IN HIS FIRST UFC MATCH WHAT WOULD YOU THINK ON THE ODDS AGINST THAT........................[img]i/expressions/face-icon-small-shocked.gif[/img]
PS: HOICE BROKE HIS NECK IN THE SECOND MATCH LUCK HAPPENS NEVER PUT PUMP GAS IN MY 15-1 PLEASE[img]i/expressions/face-icon-small-wink.gif[/img]
#74
11-16-2005, 10:38 PM
720 Big Bore blown head gasket
I have all the respect for ya in the world Eric, but I have to call BS on 15:1 on regular gas. It goes against every motor desighn theory I have ever read. Not saying it wont do it for a few seconds or something but deffinatly not going to run for a extended period of time. And deffinatly not in the same capacity that it would on 110 or simular. The only way I could see it is if the motor was super super beefy built. Things like the connecting rods being built to a point of not stretching, that sort of thing. I will never say never but I bet it will happen about the same time I weigh in at 150lbs.
Psssssst hey AZ, its Royce Gracie [img]i/expressions/face-icon-small-wink.gif[/img]
Psssssst hey AZ, its Royce Gracie [img]i/expressions/face-icon-small-wink.gif[/img]
#75
11-16-2005, 10:55 PM
720 Big Bore blown head gasket
Ok..I have heard a few people om here complaining about head gaskets. Well I have a 2001 ds. I tore down last winter and installed a TVI 720 motor. I am using tvi's race head with web 109 cams, twin 39 carbs ( Thanks Big show ) with MSD. I am also set for NOS.
I have only had one problem with this set up. The MSd was bad would not let me rev over 7200 prm. Other than that. My motor had ran perfect. I do run 110 fuel at all times. My head gasket is copper and the cylinder has an O ring installed in it
Entomer..Just so you know. when i put my ds on the dyno to find out what was wrong with it. I was making 65 hp at 7200 prms. I would call that a very big improvment over stock.
I do need to go back to the dyno and see what i can get now that i shift at 9000.
Ok thats my 2 cents
I have only had one problem with this set up. The MSd was bad would not let me rev over 7200 prm. Other than that. My motor had ran perfect. I do run 110 fuel at all times. My head gasket is copper and the cylinder has an O ring installed in it
Entomer..Just so you know. when i put my ds on the dyno to find out what was wrong with it. I was making 65 hp at 7200 prms. I would call that a very big improvment over stock.
I do need to go back to the dyno and see what i can get now that i shift at 9000.
Ok thats my 2 cents
#76
11-17-2005, 01:21 AM
720 Big Bore blown head gasket
So if I didn't ask about what fuel to run with my 14:1 piston & I didn't get the paper that came with my piston stating what to do or not what to do. What would go first with detanation (wrong fuel) ? would it be the crank bearing, piston/rings or head gasket?
#77
11-17-2005, 10:30 AM
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720 Big Bore blown head gasket
Country, detnation will find the weakest link and thats what goes first.
There was a dyno shoot out a few years back with some major V-8 engine builders and one of the rules was 93 octane pump gas would be run as an equalizer. I was quite amazed at the compression ratio's they were running. So I started studying to find out how they were doing it. I found out cylinder pressure is WAY more effective than static compression. The builders used giant camshafts and ports for high rpm so they could make good horsepower and figured out they were giving up hugh amounts of cylinder pressure because of duration so they started bringing up the compression. Even on pump gas one builder was up to 15:1 compression with no signs of detnation. Most of the other builders were around 12 or 13:1.
Compression is what everybody talks about but cylinder pressure is where the horsepower is at and the way you get it is with porting and camshaft timing. I can make way more cylinder pressure with a good port job than by putting a high compression piston in. Now give me more compression and I can give you better cams that will make power higher in the rpm range. IT'S ALL ABOUT MATCHED COMPONENT'S!
There was a dyno shoot out a few years back with some major V-8 engine builders and one of the rules was 93 octane pump gas would be run as an equalizer. I was quite amazed at the compression ratio's they were running. So I started studying to find out how they were doing it. I found out cylinder pressure is WAY more effective than static compression. The builders used giant camshafts and ports for high rpm so they could make good horsepower and figured out they were giving up hugh amounts of cylinder pressure because of duration so they started bringing up the compression. Even on pump gas one builder was up to 15:1 compression with no signs of detnation. Most of the other builders were around 12 or 13:1.
Compression is what everybody talks about but cylinder pressure is where the horsepower is at and the way you get it is with porting and camshaft timing. I can make way more cylinder pressure with a good port job than by putting a high compression piston in. Now give me more compression and I can give you better cams that will make power higher in the rpm range. IT'S ALL ABOUT MATCHED COMPONENT'S!
#78
11-17-2005, 10:35 AM
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#79
11-17-2005, 11:38 AM
720 Big Bore blown head gasket
Originally posted by: MisterHP
Most of the o-rings I have seen are only about .003-.005 above the sleeve surface which is not enough. Then if the sleeve "drops" all sealing is lost. I remove the o-ring and fill the groove with Devcon plastic-steel epoxy. After it hardens take a light cleanup cut on the deck of the cylinder. I would also take a cleanup cut on the head. I have only fixed three or four but none have leaked after the fix. When you go back with the cometic DO NOT put any sealant or gaskacinch etc on it. The cometic goes on dry. Added sealant also easily gets in the oil passage that feeds the cams timing chain plunger and top end.
Most of the o-rings I have seen are only about .003-.005 above the sleeve surface which is not enough. Then if the sleeve "drops" all sealing is lost. I remove the o-ring and fill the groove with Devcon plastic-steel epoxy. After it hardens take a light cleanup cut on the deck of the cylinder. I would also take a cleanup cut on the head. I have only fixed three or four but none have leaked after the fix. When you go back with the cometic DO NOT put any sealant or gaskacinch etc on it. The cometic goes on dry. Added sealant also easily gets in the oil passage that feeds the cams timing chain plunger and top end.
I know the MLS doesn't need gaskacinch and is good to put on dry but. . . . when Preacher puts her together he always puts it on. As long as it holds I'm happy.
#80
11-17-2005, 12:05 PM
720 Big Bore blown head gasket
Originally posted by: DuneStalker
Ok..I have heard a few people om here complaining about head gaskets. Well I have a 2001 ds. I tore down last winter and installed a TVI 720 motor. I am using tvi's race head with web 109 cams, twin 39 carbs ( Thanks Big show ) with MSD. I am also set for NOS.
I have only had one problem with this set up. The MSd was bad would not let me rev over 7200 prm. Other than that. My motor had ran perfect. I do run 110 fuel at all times. My head gasket is copper and the cylinder has an O ring installed in it
Entomer..Just so you know. when i put my ds on the dyno to find out what was wrong with it. I was making 65 hp at 7200 prms. I would call that a very big improvment over stock.
I do need to go back to the dyno and see what i can get now that i shift at 9000.
Ok thats my 2 cents
Ok..I have heard a few people om here complaining about head gaskets. Well I have a 2001 ds. I tore down last winter and installed a TVI 720 motor. I am using tvi's race head with web 109 cams, twin 39 carbs ( Thanks Big show ) with MSD. I am also set for NOS.
I have only had one problem with this set up. The MSd was bad would not let me rev over 7200 prm. Other than that. My motor had ran perfect. I do run 110 fuel at all times. My head gasket is copper and the cylinder has an O ring installed in it
Entomer..Just so you know. when i put my ds on the dyno to find out what was wrong with it. I was making 65 hp at 7200 prms. I would call that a very big improvment over stock.
I do need to go back to the dyno and see what i can get now that i shift at 9000.
Ok thats my 2 cents