tomek Posted December 6, 2019 Author Share Posted December 6, 2019 11 hours ago, superhawk996 said: A thinner gasket will increase compression ratio and squish, milling the head will only increase compression ratio. Basically, squish is the space left in the tightest space between the piston and cylinder head so milling the head won't change that very much if at all, depending on the head and piston shapes. You still don't understand what is considered squish area. It is probably hopeless case with you but once I get back to my garage I'll it color with magic marker and take the picture. Cutting the head wont change it, and is absolutely unrelated to the shape of combustion chamber and the shape of the piston when cut the head go. Btw, this is prime example why I have no patience for you. You post stupid shit , someone corrects you, but you act like you knew very well what you were talking about. And then you post even more retarded shit, and the cycle goes on and on. But you never, ever admit you were wrong and posted knowing dick about the subject. Have a nice day. Quote Link to comment Share on other sites More sharing options...
SwampNut Posted December 6, 2019 Share Posted December 6, 2019 40 minutes ago, tomek said: But you never, ever admit you were wrong and posted knowing dick about the subject. You constantly assume people are making arguments and statements where there are none, and are also an offender of the accusation you made. Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted December 6, 2019 Share Posted December 6, 2019 (edited) Edited December 6, 2019 by blackhawkxx Quote Link to comment Share on other sites More sharing options...
tomek Posted December 6, 2019 Author Share Posted December 6, 2019 (edited) 45 minutes ago, blackhawkxx said: This is NOT how combustion chamber looks on modern high rpm motorcycle engine . Anyway, Ill post pictures, patience please. Edited December 6, 2019 by tomek 1 Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted December 7, 2019 Share Posted December 7, 2019 In the above illustrated combustion chamber milling the head would increase the squish. I think it's more common that the squish area is flat and at the same level that the head gasket sits on, like Tomek's Viffer head appears to be, and with those milling only increases compression ratio. Milling the cylinder block or case or using a thinner head gasket brings that flat part closer to the piston increasing squish...which might sound backwards because you're decreasing the space to increase squish. Playing with the squish is a hit miss thing, but the generic rule is that increasing squish increases performance. Kinda like increasing the compression ratio increases performance and we know that's not a hard set rule and there are limits, but in production engines there's usually room to increase both and gain power. Squish and compression can both have a pretty dramatic influence over performance, efficiency, and emissions so the factory has to do the balancing act. Tomek does know some good shit and he has the motivation to dive in and giterdone, both are admirable. Especially the latter as I always have 57 things I should/could do that get back burnered. I think if he were as confident in his knowledge/abilities as he portrays he would engage and exchange and probably up his game by a fair bit. Whenever I meet someone who already knows it all about any field I find out that they don't and are just protecting themselves. Or maybe it's my lack of confidence that makes me exchange.....I dunno, I aint no sykologyst. 1 Quote Link to comment Share on other sites More sharing options...
tomek Posted December 8, 2019 Author Share Posted December 8, 2019 (edited) You come to my threads and pollute them with blithering nonsense. After reading your posts I'm positive you`ve never ever seen modern head from multi-cylinder ( more then 2 cylinders ) watercooled motorcycle engine, yet it somehow does not stop you from posting over, over and over again . While knowing in real life dick about it. Brilliant. I have a massage you, all heads on engines I just mentioned look like my Viffer, genius like you should know about it. It is dictated by -narrow valve angle -bore to stroke ratio in range of 1.25 to about 1.6 -compression ratio in lower teens. It such a waste of time to have discussion with you, you know the bells are ringing somewhere, but that is about it. You are correct about 20%, the rest is like "wtf is wrong with that guy, why he just does not sftu and save himself from embarrassment". Pictures are coming up next. Edited December 8, 2019 by tomek Quote Link to comment Share on other sites More sharing options...
tomek Posted December 8, 2019 Author Share Posted December 8, 2019 (edited) VFR engine is almost ready to go pics will be from 20 valves r1 engine. But it does not matter, they all pretty much look the same. Edited December 8, 2019 by tomek Quote Link to comment Share on other sites More sharing options...
tomek Posted December 8, 2019 Author Share Posted December 8, 2019 (edited) combustion chamber with cylinder bore marked with marker Edited December 8, 2019 by tomek Quote Link to comment Share on other sites More sharing options...
tomek Posted December 8, 2019 Author Share Posted December 8, 2019 (edited) combustion chamber with squish area marked with marker. Edited December 8, 2019 by tomek Quote Link to comment Share on other sites More sharing options...
tomek Posted December 8, 2019 Author Share Posted December 8, 2019 Piston, essentially it is a flat top with pockets for valves so they wont hit the piston . 1 Quote Link to comment Share on other sites More sharing options...
tomek Posted December 8, 2019 Author Share Posted December 8, 2019 (edited) The same piston view from the top. I tried to mark squish, but with carbon deposits it is impossible to tell on this picture. Edited December 8, 2019 by tomek Quote Link to comment Share on other sites More sharing options...
tomek Posted December 8, 2019 Author Share Posted December 8, 2019 As you can see shaving cylinder head does absolutely nothing to squish on this type of head. Quote Link to comment Share on other sites More sharing options...
John01XX Posted December 8, 2019 Share Posted December 8, 2019 Interesting! I previously had no idea what “squish” was. Had never even heard that term. Trying to wrap my head around the concept when I don’t really understand, but is decreasing squish kind of like reducing the bore in the head only? Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted December 8, 2019 Share Posted December 8, 2019 50 minutes ago, John01XX said: kind of like reducing the bore in the head only? It can be, which would be the illustration Blackhawk posted. The illustration shows the squish at an angle matching an angle on the piston, but they could also be flat. In a 4 stroke you can't effectively do that without impeding the valves so there will be areas around the valves that kinda protrude inward to create squish areas around the valves. Tomek's picture of his head shows pretty typical squish areas, the flat parts that are even with the head gasket surface. The tighter the squish, the space left between the head & piston at TDC, the more effective it is. As the piston nears TDC the air & fuel left in the squish areas is very rapidly pushed toward the center creating lots of turbulence that helps mix the air & fuel, along with a lot of other effects. Generally, an engine with good squish is more efficient and more tolerant of high compression than one without. 1 Quote Link to comment Share on other sites More sharing options...
tomek Posted December 8, 2019 Author Share Posted December 8, 2019 The conrod will stretch at peak rpm. The goal is the set "static" squish so at the redline piston will actually be touching the head, but without nasty side effects like piston pin landing in your belly pan.lol. Universally accepted safe number for Japanese multicylinder with steel rods is 0.7 mm. The piston in picture below is from the engine the was set up tighter , to 0.6 mm. You can see areas were it was touching the head. That's about as good as it gets. It run like a raped ape, I could outmotor anything till bmw1000rr started showing up in large numbers. 1 Quote Link to comment Share on other sites More sharing options...
rhubarbray Posted December 13, 2019 Share Posted December 13, 2019 Wasn't there a case of Suzuki setting the clearance too tight on their GSXR 750 ( I think ) in the mid 90's? Most people never knew but the ones who spent some time at redline had pistons kissing cyl head. Cost Suzuki a lot of labour and thicker head gaskets. Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted December 13, 2019 Share Posted December 13, 2019 I don't know about that situation, but it's a risk when you start tightening up clearances willy-nilly. When you add up expansion and stretch what seemed like a safe clearance can get eaten up quickly. Quote Link to comment Share on other sites More sharing options...
tomek Posted December 13, 2019 Author Share Posted December 13, 2019 12 hours ago, rhubarbray said: Wasn't there a case of Suzuki setting the clearance too tight on their GSXR 750 ( I think ) in the mid 90's? Most people never knew but the ones who spent some time at redline had pistons kissing cyl head. Cost Suzuki a lot of labour and thicker head gaskets. Yes, I remember that. Consequently next production run had thicker head gasket AND less power. If you are getting really close to safe distance squish has to be checked in each cylinder and some parts of piston(s) may have to be machined. OEM can't go that tight on production engines because some piston, rod and cylinder block combinations can end up with squish too small. Quote Link to comment Share on other sites More sharing options...
fizzy Posted December 13, 2019 Share Posted December 13, 2019 Tomek, Interesting thread and I have a question. Let me state first that I don't know squat about squish and that the deepest I have been into an engine is the valve clearance check. I am looking at the pics you posted with the marker showing squish area (thanks for that) and comparing them to the line drawing posted by blackhawkxx. For the sake of simplicity and symmetry let's assume a 4 valve head (which you say is the same). They look the same to me, what am I missing? Quote Link to comment Share on other sites More sharing options...
tomek Posted December 13, 2019 Author Share Posted December 13, 2019 On blackhawkxx pic squish band is at the angle in relation to cylinder head sealing surface. Older designs with wide valve angle would look like that. Milling the head in this particular case would tighten the squish. Cylinder heads on modern multi high rpm bike are different. They have narrow valve angle and squish area on cylinder head is flat and even with its sealing surface. If you mill cylinder head by 0.2 mm you will also remove 0.2 mm from squish area on head like that. Look at those pics closely, you'll understand what Im talking about and why blackhawkxx pic does not apply here. 1 Quote Link to comment Share on other sites More sharing options...
fizzy Posted December 14, 2019 Share Posted December 14, 2019 Ok, looking straight down on these parts its hard to tell the contours, but that makes sense, thanks. Quote Link to comment Share on other sites More sharing options...
tomek Posted December 21, 2019 Author Share Posted December 21, 2019 Progress has been slow lately. It looks like the powerplant should just slide in, although front fork might have to come off. And of course lower fairing. Everything is more time consuming/pita with v4 vs. inline 4. Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted December 21, 2019 Share Posted December 21, 2019 Doesn't it go in the same way that it came out? Quote Link to comment Share on other sites More sharing options...
tomek Posted December 21, 2019 Author Share Posted December 21, 2019 (edited) Not really, you have align mounting holes and slide in the driveshaft. Of course I could remove driveshaft ( extra work ), but I don`t wanna touch that part of the bike since it is on recall. The way I dropped the engine it would not work in reverse, also gravity is not helping when reinstalling the thing. Edited December 22, 2019 by tomek Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted December 22, 2019 Share Posted December 22, 2019 (edited) You'd think so. I wasn't gonna be the one to ask so I'm glad someone did. Edited December 22, 2019 by superhawk996 Quote Link to comment Share on other sites More sharing options...
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