i just bought an aftermarket head. nice pretty thing. westcoast perf products. does anyone know the stock comb chamber size on a stock 650. judging by the number, this is a 31cc dome. i think that is a little too small. 37's and 38's are available, it looks like. pretty cheap too. thanks.
combustion chamber sizes? white 657
- Thread starter derek
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Combustion Chamber size?.....
Never heard that term before, but if your looking for the bore on the 657, stock it's suppose to be 78mm..........
You can bore over twice.......Once to 78.25mm and then to 78.50mm. After that, you need to replace..........
Combustion chamber size...I've never heard bore described quite like that. You learn something new everyday........
Have a good one!........ride hard, live free!:cheers:
Never heard that term before, but if your looking for the bore on the 657, stock it's suppose to be 78mm..........
You can bore over twice.......Once to 78.25mm and then to 78.50mm. After that, you need to replace..........
Combustion chamber size...I've never heard bore described quite like that. You learn something new everyday........
Have a good one!........ride hard, live free!:cheers:
The easy way to check the cc size is to plug the spark plug and use a cc container to fill the chamber. I use to cc my combustions chambers for compressions ratios in my racing days.
Karl
Karl
I get it!....
Oh, now I see what your saying.........your using a graduated cylinder to check the volumetric size.........I don't see the reason behind it, but I see what your doing now.
If you build an engine and want to pump it up, then the crank, bore and stroke seem to be all that's important. I can see using a volumetric test to check the wear. Since the return would be in milliliters, it's the best way to check for even a fraction more wear between cylinders.........
But in the idea of a volumetric measurement of a head....I don't understand the need.
Call me dumb here, but in 30 years of building motors, I've never run across that practice.
Oh, now I see what your saying.........your using a graduated cylinder to check the volumetric size.........I don't see the reason behind it, but I see what your doing now.
If you build an engine and want to pump it up, then the crank, bore and stroke seem to be all that's important. I can see using a volumetric test to check the wear. Since the return would be in milliliters, it's the best way to check for even a fraction more wear between cylinders.........
But in the idea of a volumetric measurement of a head....I don't understand the need.
Call me dumb here, but in 30 years of building motors, I've never run across that practice.
Skatman in reality this practice is just for high performance applications. For a recreational application...waste of time.
Karl
Karl
Dome CC"s
Hi everyone,
I don't know the stock cc's your clylinder head came with from the factory but I'm trying to find out. I do know this....... the less cc's the clylinder dome has the more compression you'll have. Keep in mind when your choosing which cylinder domes to use that 93 octane fuel is only good for up to 175-180 PSI compression. Race fuel will be necessary for any compression that is higher or serious piston damage will occur.
Good Luck, DAWG
Hi everyone,
I don't know the stock cc's your clylinder head came with from the factory but I'm trying to find out. I do know this....... the less cc's the clylinder dome has the more compression you'll have. Keep in mind when your choosing which cylinder domes to use that 93 octane fuel is only good for up to 175-180 PSI compression. Race fuel will be necessary for any compression that is higher or serious piston damage will occur.
Good Luck, DAWG
Stock world?
I guess I've been in a stock world too long, although, I never used a volumetric measurement to decide which heads I had or was going to get when I was building high performace Chevy motors or my motorcycles. So, this type measurement is completly new to me, so the validity of what is being done and for what reason is really interesting to me. Seems if he had a high performance head for the engine, that required a certain type racing piston, it'd be stamped on the head itself.
Dennis, you use the term "cc". Is that by cubic centimeters, like in a standard, metric size of the head pattern? From what I have been understanding, it seems Karl's saying you do a volumetric measurement to determine the head size. Is this what your talking about.
I guess I've been in a stock world too long, although, I never used a volumetric measurement to decide which heads I had or was going to get when I was building high performace Chevy motors or my motorcycles. So, this type measurement is completly new to me, so the validity of what is being done and for what reason is really interesting to me. Seems if he had a high performance head for the engine, that required a certain type racing piston, it'd be stamped on the head itself.
Dennis, you use the term "cc". Is that by cubic centimeters, like in a standard, metric size of the head pattern? From what I have been understanding, it seems Karl's saying you do a volumetric measurement to determine the head size. Is this what your talking about.
Cubic Centimeters
HI SKATMAN,
Long time, no see!!!!
Here"s what I know for sure. I am absolutely no expert.
Aftermarket companies make high performance cylinder heads for skis' and jet boats. These cylinder heads have different "domes" that can be chosen in order to obtain a certain compression and / or performance desired for a persons application. The size of the cylinder head "dome" is dictated by the number of LIQUID cc's (cubic centimeters) of fluid it takes to fill that dome if it is upside and filled up to the flat area of the head( area that mates to cylinder). If it takes 36 cc's of fluid ( most race shops use glycerin) then the cylinder dome is said to be a 36 cc dome. If the 36 cc dome gives you too much or not enough compression then you can install a higher cc dome ( lower compression) or a lesser cc dome ( higher compression ) in order to tune your engine depending on your needs. It's strictly a "race thing" and there is alot more to know about the situation and I'm am NOT the guy to ask advice on the subject.other than what I've just stated.
DAWG
HI SKATMAN,
Long time, no see!!!!
Here"s what I know for sure. I am absolutely no expert.
Aftermarket companies make high performance cylinder heads for skis' and jet boats. These cylinder heads have different "domes" that can be chosen in order to obtain a certain compression and / or performance desired for a persons application. The size of the cylinder head "dome" is dictated by the number of LIQUID cc's (cubic centimeters) of fluid it takes to fill that dome if it is upside and filled up to the flat area of the head( area that mates to cylinder). If it takes 36 cc's of fluid ( most race shops use glycerin) then the cylinder dome is said to be a 36 cc dome. If the 36 cc dome gives you too much or not enough compression then you can install a higher cc dome ( lower compression) or a lesser cc dome ( higher compression ) in order to tune your engine depending on your needs. It's strictly a "race thing" and there is alot more to know about the situation and I'm am NOT the guy to ask advice on the subject.other than what I've just stated.
DAWG
Understood....!
Yes, I was. I thought that was what he was referring to. The dome of his head. Now, it's all clear. With one exception. If I'm not mistaken, because I'm no expert either, the liquid measurement would be in ml's (millimiters) which is a liquid measurement, not cc's (centimeters) which is a unit of measurement by length or area.
But I do see what you mean now.
In the day of removing the standard flat-tops and going with a set of "pop-up" pistons for my 350 cu.in., we changed the connecting rod to change the stroke and create the room needed for the domed pistons...........we never made any liquid measurement of the volume in the cylinder. I guess that's because by the standards of building a 4 cycle V-8, it was already known and additional horsepower pre-calculated as to what you were going to get before you put it together.
But I do see now, what it is that he's trying to accomplish. Makes good sense to do it when working with the 2 stroke, because it doesn't have an intake and exhaust valve to help with lag to build compression by changing the cam shaft duration............
O.K..........thanks DAWG, I got it now.............:cheers:
BTW, I still don't see a need to make these damn engines any hotter than they already are. As many engines as I built, I don't think any of them lasted more than a year with the street racing I did. So, if your gonna make these kind of changes to a PWC, I just can't justify that extra $, unless there was profit in it, like racing...................:cheers:
Yes, I was. I thought that was what he was referring to. The dome of his head. Now, it's all clear. With one exception. If I'm not mistaken, because I'm no expert either, the liquid measurement would be in ml's (millimiters) which is a liquid measurement, not cc's (centimeters) which is a unit of measurement by length or area.
But I do see what you mean now.
In the day of removing the standard flat-tops and going with a set of "pop-up" pistons for my 350 cu.in., we changed the connecting rod to change the stroke and create the room needed for the domed pistons...........we never made any liquid measurement of the volume in the cylinder. I guess that's because by the standards of building a 4 cycle V-8, it was already known and additional horsepower pre-calculated as to what you were going to get before you put it together.
But I do see now, what it is that he's trying to accomplish. Makes good sense to do it when working with the 2 stroke, because it doesn't have an intake and exhaust valve to help with lag to build compression by changing the cam shaft duration............
O.K..........thanks DAWG, I got it now.............:cheers:
BTW, I still don't see a need to make these damn engines any hotter than they already are. As many engines as I built, I don't think any of them lasted more than a year with the street racing I did. So, if your gonna make these kind of changes to a PWC, I just can't justify that extra $, unless there was profit in it, like racing...................:cheers:
i needed a new head anyway. the aftermarket head was cheap and pretty. i found a quik easy way to cc the domes. (cc's are cubic centimeters-the same as a milliliter. there are a thousand cc's and ml in a liter.) anyway, go to a drugstore and buy a 10 ml baby medication syringe. put a CD (compact disc) over the top of your cylinder head dome. (inverted-with spark plug installed.) start squirting water into dome area. i found stock 650 filled at about 38 or 39 cc's. then i found a set of 38 cc domes for $20, so i am good. btw. i have cc'd chambers on 454's and 400 small blocks. i jusst couldn't find my grad cylinder. then i remembered baby med syringes. used them last year to measure hardener for fairly massive fiberglass project replacing gas tanks in my hatteras.
robin savell lloyd
Active Member
I have a rosser head on my 657x engine I do not know any thing about this engine. I do see new gaskets on it. I expect that it was resently rebuilt. When I put my cheap compression guage on it that I got from harbor freight I noticed that the needle goes above 160 psi, when I spin it over, but it it only registers 135 to 140 after guage settles. any thoughts on this? Could this be a rosser built engine? I also have some narlly looking 44 mikuni carbs with a r+d stainless steal exhaust that goes up high instead of low. Any thoughts on this? The only thing I can say is that it hauls a** I seem to hit the rev limiter with a heavy load. Every thing is new! On take of with a full load on boat I have some cavitation. Every thing that could cause cavitation has be replaced with the very best out there available new Inpros concord impeller new wear ring and every thing out there that you could find online. does this engine have so much power that it wants to cavitate? I do not think so :rofl:
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