2003LimitedBanshee Posted April 1, 2009 Author Report Share Posted April 1, 2009 for my exhaust ports when i polish them i do it in a way very similar to deckheight. Although i do not use premade sandpaper wheels, mainly cause i dont wanna buy them, :biggrin: . I just take one of my old 1/4" by 6" burrs that is dull and not used for cutting anymore and i wrap it with sandpaper. I start with usually 80 grit then on to 120, 200, 300, 400, and so on until i get the finish desired. Sometimes end at 800. Okay so a question on these pictures, those extra ports above the main transfer, at first I thought they were probably additional transfers. But, the more I look at them, it appears that they are cut into the cylinder and possibly tie into the exhaust? Not that I am actually going to try this, but I am just curious from a technical standpoint how this is done. Heck, even if they are tied into the transfers, same question? EDIT: Do you remember or care to disclose the timing on those transfers? They look HUGE! Thanks! Quote Link to comment Share on other sites More sharing options...
sheerider1026 Posted April 1, 2009 Report Share Posted April 1, 2009 if you look closer, that is a aftermarket mono block cylinder. looks like a trex to me (sleeved).. those extra ports are called tripple exhaust ports, my cub has them also.. i assume it helps with exhaust flow and scavenging.. Quote Link to comment Share on other sites More sharing options...
2003LimitedBanshee Posted April 1, 2009 Author Report Share Posted April 1, 2009 if you look closer, that is a aftermarket mono block cylinder. looks like a trex to me (sleeved).. those extra ports are called tripple exhaust ports, my cub has them also.. i assume it helps with exhaust flow and scavenging.. Ah I see it now... I noticed the outside of the cylinder looked odd and now I see it has a huge thick sleeve in it like you said. I thought it was cut into the exhuast, but the finish on the port looking up through the exhaust was shiny enough I couldn't tell. :cool: Quote Link to comment Share on other sites More sharing options...
trex banshee Posted April 1, 2009 Report Share Posted April 1, 2009 yes those are additional exhaust ports. and yes they are my trex cylinders. they were first ported by someone else for the additional 4mm stroke with a spacer plate, i then got into the porting world a few years ago and ported them more myself. I could do nothing about the big transfer duration because of the way they were ported before, i will tell you though its big, too big for that fact. The triple exhaust is to acheive more exhaust time area without going over your safe exhaust port width. The durations on my cylinders is 202 ex 134 in Quote Link to comment Share on other sites More sharing options...
2003LimitedBanshee Posted April 1, 2009 Author Report Share Posted April 1, 2009 yes those are additional exhaust ports. and yes they are my trex cylinders. they were first ported by someone else for the additional 4mm stroke with a spacer plate, i then got into the porting world a few years ago and ported them more myself. I could do nothing about the big transfer duration because of the way they were ported before, i will tell you though its big, too big for that fact. The triple exhaust is to acheive more exhaust time area without going over your safe exhaust port width. The durations on my cylinders is 202 ex 134 in Thanks! I thought those transfers looked pretty big and the exhaust looked monster also; now I see why at 202*. I can see that I am going to be hooked on porting now and I haven't even finished the other cylinder to get to ride it with my new grind yet! The work is fun (to me at least) but man, the concept and theory and just wondering what this or that will do is the really cool part! Now I'm looking for a set of CPI's because I want to try a little bigger numbers on my stock cylinders that are on the bike now to combo up with a set of CPI's, probably carbs too, or at least have my stockers bored. Actually will probably have the stockers bored to go with these cylinders I'm cutting now and my T5's and then go to different carbs for next cylinders and CPI's. Quote Link to comment Share on other sites More sharing options...
trex banshee Posted April 1, 2009 Report Share Posted April 1, 2009 dont go boring your cylinders just to get displacement, your just wasting the life in them. Porting is very interesting, i got into it a little over 3 years ago and have done quite a few bikes here locally. Its pretty cool on how you can make two run completely different with just a little difference here and there in angles and heights and such. Quote Link to comment Share on other sites More sharing options...
deckheight Posted April 1, 2009 Report Share Posted April 1, 2009 Hey 03LB, there's that pesky time area thingy again... Take a good look at the actual geometry of the main exhaust port, especially the top of the port and corner radius's. Kind of recurring themes for you lately eh? No comment on the port mapping, however that is fine looking porting work IMHO. :cool: yes those are additional exhaust ports. and yes they are my trex cylinders. they were first ported by someone else for the additional 4mm stroke with a spacer plate, i then got into the porting world a few years ago and ported them more myself. I could do nothing about the big transfer duration because of the way they were ported before, i will tell you though its big, too big for that fact. The triple exhaust is to acheive more exhaust time area without going over your safe exhaust port width. The durations on my cylinders is 202 ex 134 in Quote Link to comment Share on other sites More sharing options...
deckheight Posted April 1, 2009 Report Share Posted April 1, 2009 Yup, I would have to agree with you on that. In my experience it doesn't work that way though, but it could have been something in those specific set-ups I was testing at the time... Maybe the tuned exhaust wasn't in sync with what the bust port was doing, who knows? What I found was that it actually disrupted the flow of gases in the combustion chamber resulting in a less efficient burn on those particular engines. But, like I said, it could have been something else in the set-up contributing to it... At any rate the piston wash will tell you what's going on in there. i think he's doing that to help push the old exhaust gas out, before the new large charge of fuel/air comes in thru the main and secondary transfers. Quote Link to comment Share on other sites More sharing options...
2003LimitedBanshee Posted April 1, 2009 Author Report Share Posted April 1, 2009 dont go boring your cylinders just to get displacement, your just wasting the life in them. Porting is very interesting, i got into it a little over 3 years ago and have done quite a few bikes here locally. Its pretty cool on how you can make two run completely different with just a little difference here and there in angles and heights and such. Oh no, I'm sorry, I didn't mean the bore the cylinders. I had heard that the stock carbs could be bored to 28mm for a little bit of added flow with decent results; that was my reference to boring. No, actually I am going to mic my cylinder and see if I can get away with simply honing these cylinders I'm porting right now as opposed to boring them. Haven't actually mic'd them yet. Quote Link to comment Share on other sites More sharing options...
2003LimitedBanshee Posted April 1, 2009 Author Report Share Posted April 1, 2009 Hey 03LB, there's that pesky time area thingy again... Take a good look at the actual geometry of the main exhaust port, especially the top of the port and corner radius's. Kind of recurring themes for you lately eh? No comment on the port mapping, however that is fine looking porting work IMHO. :cool: Yeah, I really need to revisit my port mapping/time area learning from my Jennings write-up before I go trying to determine my own timing configurations. I see that I can definitely change the shape of my exhaust port more along the lines of what you were mentioning. On the port mapping, just visually does it look off or you mean you can't comment because it may or may not work ideally with my combination? Thanks everyone! I'm definitely a student in this area, but I am hoping to do a lot of learning! - Brian Quote Link to comment Share on other sites More sharing options...
trex banshee Posted April 2, 2009 Report Share Posted April 2, 2009 Hey 03LB, there's that pesky time area thingy again... Take a good look at the actual geometry of the main exhaust port, especially the top of the port and corner radius's. Kind of recurring themes for you lately eh? No comment on the port mapping, however that is fine looking porting work IMHO. :cool: thanks for the compliments on the porting, i try and make it look the best as possible. many many hours in my trex cylinders. They suck cutting compared to oem cylinders. Ive yet to touch a cub or anything with nikasil though. Quote Link to comment Share on other sites More sharing options...
deckheight Posted April 2, 2009 Report Share Posted April 2, 2009 My comment about "mapping" was more along the lines of what trex already mentioned regarding the "aggressiveness" of the durations, nothing more. What I was pointing out with the geomentry comment was that in relation to your photo, trex is getting a fairly dramatic increase in time area just with the shape of the roof and corners. In other words trex port geometry will see similar BMEP numbers at a lower rpm. Yeah, I really need to revisit my port mapping/time area learning from my Jennings write-up before I go trying to determine my own timing configurations. I see that I can definitely change the shape of my exhaust port more along the lines of what you were mentioning. On the port mapping, just visually does it look off or you mean you can't comment because it may or may not work ideally with my combination? Thanks everyone! I'm definitely a student in this area, but I am hoping to do a lot of learning! - Brian Quote Link to comment Share on other sites More sharing options...
deckheight Posted April 2, 2009 Report Share Posted April 2, 2009 No problem on the compliment. It really does look good... How so on the cutting part? I hear you about the plated cylinders, given a choice I personally will pass. Tooling cost is a little hard to digest also thanks for the compliments on the porting, i try and make it look the best as possible. many many hours in my trex cylinders. They suck cutting compared to oem cylinders. Ive yet to touch a cub or anything with nikasil though. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted April 2, 2009 Report Share Posted April 2, 2009 I hear you about the plated cylinders, given a choice I personally will pass. Tooling cost is a little hard to digest also oh, come on deckheight....LOL. i did 9 nicasil plated snowmobile cylinders this year and yeah, it sucks. that nicasil is so damn hard, it takes forever to get thru it. Quote Link to comment Share on other sites More sharing options...
blowit Posted April 3, 2009 Report Share Posted April 3, 2009 oh, come on deckheight....LOL. i did 9 nicasil plated snowmobile cylinders this year and yeah, it sucks. that nicasil is so damn hard, it takes forever to get thru it. There is a tricky on that Nicasil stuff :thumbsup: B Quote Link to comment Share on other sites More sharing options...
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