Engine talk. Rebuild, and cam.

[duneracerweston]

Interesting.. I just measured my EST custom gasket for 85mm bore and I'm getting around 85.25mm (it's are to get real acurate as there is 3 gaskets sandwhiched.. I would have thought wiseco would have sent a build sheet of the spec's. Most manufactures do that.

shoot that would have made my life 10X easier when i was building my motor this fall.

the only thing that comes with the wiseco pistons is stickers and a EXTREAMLY generic ring installment instruction paper witch tells you how to put them on a 2 stroke... not helpful at all.

 

[jasonp]

I think you have to think about how close the tolerances are, there's hardly any room for carbon to build up there. The majority of engines built have a fire ring that's larger than the bore, you're sweating the small stuff if you're worried about that.

Sure there is. If the head is sitting .040-.050" + off the surface of the sleeve by the gasket and you have 3.50mm of clearance past the bore then you will have carbon build up there.

Dude sweating the small stuff is what we are talking about here, that is what I have been trying to say from the first thread... It seperates a great running engine to an ok one.

 

[jasonp]

if you have carbon building up on a 2mm ledge between the head and jug and its causing issues you have bigger problems like were is all that carbon coming from?

if that tiny bit is lowering compression your motor never had it to start with because that is a oem replacement gasket so its ment for a 83mm bore but is big enough to go to .040 which is what it was used for and it did great till the rod bearing and cam bearings died on me. so no running "to big" a gasket wont hurt these tanks.

and if your hunting compression that bad, measure head volume and mill that sucker down to get you your compression your looking for.

just my past experience and .02

This whole post goes off your opinion of what is right or wrong in engine building. Not fact.

 

[beastlywarrior228]

dam now ill have to go tomorrow and check the diameter of my gasket

 

[jasonp]

Yessir, I sure would like to see that if you don't mind. The cam gear is yet another thing on my list to order.

 

[duneracerweston]

now if that ont look confusing idk what is...

and yes that is opinion and past experience i have never had carbon build up there on either of the 3 ive torn apart ive never had carbon there on any motor ive pulled apart ever.

but thats just my .02 if you have a true fact to discredit my opinion i would be happy to hear it and lean something but i have vere heard a reason before why that would be a issue.

 

['00 WO-YA!]

My stock Yamaha engine that had never been cracked open before has a head gasket that measures 84.35mm, that's over a mm out of spec if we're lookin for a dead ringer for cylinder bore diameter. I'm yet to see in all of the engines I've torn apart, a engine that has a fire ring on the gasket that perfectly matches the bore diameter. For example, a typical Small Block Chev, we'll use a 350 for simplicity, has a 4.00 bore, the VAST MAJORITY of head gaskets offered for it come with a fire ring I.D of 4.100 which is 2.25mm oversize. I imagine this allows for some heat expansion.
Now, I hate pissing matches but if there is actuall carbon build up trapped in the oversize area between the sleeve & the fire ring & the deck then in theory carbon has displaced this volume & there is no loss of compression there. Just the same as carbon build up on top of a piston displaces cylinder volume & increases compression minimally. I realize that I'm not a high performance engine builder by trade on a daily basis but please don't mistake me for a dumbass either, I'm familiarizing myself with the availability of parts for numerous quad & motorcycle engines, I don't yet know it like the back of my hand, but again, make no mistake, I'm not a dumbass.

 

[jasonp]

My stock Yamaha engine that had never been cracked open before has a head gasket that measures 84.35mm, that's over a mm out of spec if we're lookin for a dead ringer for cylinder bore diameter. I'm yet to see in all of the engines I've torn apart, a engine that has a fire ring on the gasket that perfectly matches the bore diameter. For example, a typical Small Block Chev, we'll use a 350 for simplicity, has a 4.00 bore, the VAST MAJORITY of head gaskets offered for it come with a fire ring I.D of 4.100 which is 2.25mm oversize. I imagine this allows for some heat expansion.
Now, I hate pissing matches but if there is actuall carbon build up trapped in the oversize area between the sleeve & the fire ring & the deck then in theory carbon has displaced this volume & there is no loss of compression there. Just the same as carbon build up on top of a piston displaces cylinder volume & increases compression minimally. I realize that I'm not a high performance engine builder by trade on a daily basis but please don't mistake me for a dumbass either, I'm familiarizing myself with the availability of parts for numerous quad & motorcycle engines, I don't yet know it like the back of my hand, but again, make no mistake, I'm not a dumbass.

Since the stock head gasket was made for a max bore size of 84mm that makes sense, right? So would it be out of spec at 84mm bore size?

When you bore a stock 350 over what is the max oversize you can go? Like .060" over right? So that 4.100" is looking pretty good esp since most gaskets are not made to custom bore size.

Question should be is that is the factory worried about performance or longevity of the engine? More often then not they are striving for longevity and cost.

I am a dumbass. But I am open minded and willing to read and learn.

If you google head gasket size vs. bore size effects on performance you will come up with some great reads.. In this little of an engine though you most likely won't see a difference. But that is up for you to decide if you want to take the extra step.

You will never see a correctly sized head gasket be the actual bore size of the cylinder... Meaning the head gasket (I believe the spec is .010", going off memory here) has to be larger in bore then the cylinder.

BTW:sorry if I made it seem like I was calling you a dumbass.

 

[duneracerweston]

Since the stock head gasket was made for a max bore size of 84mm that makes sense, right? So would it be out of spec at 84mm bore size?

jw why would it accommodate a 84mm bore when its a 83mm from factory?

jw.

 

['00 WO-YA!]

Since the stock head gasket was made for a max bore size of 84mm that makes sense, right? So would it be out of spec at 84mm bore size?

When you bore a stock 350 over what is the max oversize you can go? Like .060" over right? So that 4.100" is looking pretty good esp since most gaskets are not made to custom bore size.

Question should be is that is the factory worried about performance or longevity of the engine? More often then not they are striving for longevity and cost.

I am a dumbass. But I am open minded and willing to read and learn.

If you google head gasket size vs. bore size effects on performance you will come up with some great reads.. In this little of an engine though you most likely won't see a difference. But that is up for you to decide if you want to take the extra step.

You will never see a correctly sized head gasket be the actual bore size of the cylinder... Meaning the head gasket (I believe the spec is .010", going off memory here) has to be larger in bore then the cylinder.

BTW:sorry if I made it seem like I was calling you a dumbass.

I agree that when the engine is at max bore those specs don't look nearly as bad. I suppose I should have been clearer about the point that to the factory those specs are acceptable @ .100 oversize. If I can find something closer to my bore size that's what I'll get. I'll apologize if I came off frustrated, so often these type threads turn into debate & opinion & it just becomes a worthless pissing match & I usually just dip out of threads like that.

 

[87warrior917]

so often these type threads turn into debate & opinion & it just becomes a worthless pissing match & I usually just dip out of threads like that.

Well put sir, well put

 

[jasonp]

stock warrior head is 36cc.

 

[duneracerweston]

stock warrior head is 36cc.

Before porting ?

 

[beastlywarrior228]

He means the combustion chamber, porting wont have an effect

 

[duneracerweston]

Yes it will you remove material to polish it I just wanted to know which it was a non ported head or ported head

 

[87warrior917]

Yes it will you remove material to polish it I just wanted to know which it was a non ported head or ported head

The combustion chamber? Your thinkin intake and exhaust ports...

 

[beastlywarrior228]

Yes it will you remove material to polish it I just wanted to know which it was a non ported head or ported head

nothing gets polished in the actual combustion chamber so its irrelevant, only intake and exhaust runners

 

[jasonp]

Yes it will you remove material to polish it I just wanted to know which it was a non ported head or ported head

I don't understand what you are talking about.

This was done to a stock warrior combustion chamber. I'm not going to give spec's for my duncan.

Things to effect CC in the chamber is if you do something with the valves ie lower the seats or run a dished valve maybe un shroud the valve also you can have the head machined down.
Porting and polishing the ports will not effect combustion chamer cc's.

 

[beastlywarrior228]

I'm not going to give spec's for my duncan.

awwwww come on why not

 

[87warrior917]

I did notice my +1 black diamond valves had a significant bigger dish than the stock valves before i put the head on hno:. That sucks cause right there is a drop in compression.