tfaith08 Posted June 11, 2014 Report Share Posted June 11, 2014 Props for going forward with it. You can read and research all you want (which is a necessity imo), but actually doing the work is where you start to find the questions that need to be asked the most. Nobody cares about port geometry before they get into their first cylinder. Keep it up. About boring then porting, I don't like it. If you have angled ports, the height changes and the width and position changes. I mean, it is slight, but it's there. All it takes is a sneeze or a slip of the hand and you're running a carbide across the cylinder, so I'd leave the hone for last. Bore, port, hone. That's what I always do. I'm working on some Banshee cylinders now and the transfers are nerve wracking. I wish they were more like 250R transfers. As for the tunnels, if you want to remove anything, I'd remove material from the outside/front if you're just dying to remove some. I did this to the last set of Banshee jugs and it added a bit more bottom end, but it wasn't drastic. It keeps the charge to the back of the cylinder. Also, I've found that the Boyesen port angle affects power delivery. I've found that those that are angled more downward produce more bottom end response, while those that are angled more toward the mains give a bit more top end pull. Try to think of where the charge flows when it comes in, how long it dwells before it re-directs, and where the majority of the flow has ventured to when the transfers start to pull AFM. Make sure you don't remove the kicker at the main transfers. I've modified some in the past and only did it slightly. I've never really liked the race logic templates, but to each his own. Once I get my 250R port map how I like it, I'm going to map it and put it on a magnet strip to make future jobs easier. I think the next one will be alright, but I'm going to keep porting them until I port one that hauls some major ass and then make that the template. My last one was alright, but this one will be better, I think. If you're thinking of polishing a short side radius to help the AFM adhere to the curve and pull in that direction, it does work, but fuel pools in the polished spots. Not a very good idea IMO. I have a good friend who tried this on a 450R head and then went back and roughened it up a bit. He said he made 2 more HP on the dyno, which he has regular access to. I'll see if he'll send pics. If you look at the porting thread that I posted a while back, there were a few people that chimed in with some good info. Notably, camatv said that getting the air into the cylinder in an orderly fashion was a definite goal (not verbatim). The biggest recommendation that I have is the boost port. The 90 degree edges all around don't help flow too much. If you still have the room for it, I'd round those edges off some. If you only have 1cm or so left, I'd leave it like that. Otherwise, the flow just kind of blobs in the cylinder, rather than flowing in a path. Think venturi nozzle and then adapt a less extreme version of that. It worked pretty well on my wife's Blaster. I didn't recall whether you did it, but I think you mentioned rounding the ports off where they enter the cylinder. I wouldn't recommend that, but that's jsut my thinking; I have no experience/data to back that recommendation up. registered user did have a good point when he said to open the rear of the secondary up at the cylinder. The kick can be improved upon by flattening the rear wall out SOME. Be cognizant of where the rings fall when doing this. I've pondered extending the top of the secondaries to allow the mixture that extra room and to avoid a dead spot. Again, I haven't worked much with Banshee cylinders and haven't applied this yet. However, I have tried it with 250R cylinders and they have done alright with it. It seems to widen the powerband just a bit. I did find that (again, with the 250Rs) the effectiveness of widening the top of the secondaries was largely dependent on the continued shape of the tunnel. Just something to think about. All in all, good job. The workmanship is damn good for a first time job without the right tools. Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted June 13, 2014 Author Report Share Posted June 13, 2014 tfaith08, thank you so much for the input! I'm going to give it a go to do like Russell Wealthall said, and you seconded, to work the outside walls a bit. I'm doing it in an effort to concentrate the flow towards the back of the cylinder. I'm not as concerned about the primaries. To me the primaries are pointed in a good direction, and the choke point there helps direct the flow by creating a low pressure area... like you said, remove material from the front. I'm going to do that to give a contour instead of a straight line up the front of the primaries. My area of concern is the secondaries... I plan to remove the most material from the outside wall closer to the divider. I'm also thinking about about splitting the timing, and raising just the back of port on the boost side. In the area where the flow exits the cylinder is the area where I'm thinking most about adding epoxy. I'm worried about removing too much liner to straighten the kicker. I've been removing material from the back of the divider to reaim the flow back towards the center over the boost port. Between staggering the ports, and reaiming the secondaries, I'm hoping to use the boost port to "kick" the secondary flow around the top of the chamber. Quote Link to comment Share on other sites More sharing options...
tfaith08 Posted June 14, 2014 Report Share Posted June 14, 2014 You're welcome. I'm always for information flow. After all, it is a forum. If you're after increasing flow and velocity out of the secondaries in that manner, I'd look into what Passion Racing has done with their cylinders. They've added a port under the secondaries and in front of the piston ports. I have no details outside of what very rough port map I can visualize. I don't know width, height, aim, curves, nothing. Then, I saw a KX500 cylinder with similar modifications and started thinking on it. At this point, I haven't come to a conclusion on which way they should be aimed nor have I determined contours. I have thoughts, but no test results. Again, that's just something I stumbled upon. I'd leave it alone if it was Passion's claim to fame, but I found it in other stock cylinders. That justifies me tampering with the idea. Also, keep in mind that Boyesen port aiming will have to be re-thought as these extra ports will affect the flow to the secondaries. I'm sure that extra cutouts in the pitons will be beneficial. I'd like to say again that Passion Racing has this down to a science, whereas I've just observed 2 pictures on the matter and thought about it days on end. Don't think that I'm out to take over the world with Passion's design. As for the kick, the design almost makes it a restriction than a kicker. I think that some planned epoxy work here will be the key, but that's another area that I haven't fooled with very much on Banshees. I do it regularly on 250Rs, but they have the casting to allow for such modifications in an easy manner. Also, since you have the extra aluminum added on, I'm sure that you can work with a little more leniency than others. Just to get the mind going, I've seen a guy cut the transfers off of his old Rotax cylinder, reshape them, have them welded back on, and clean the inside of the welds up. Combine that with a blank sleeve like some of the hot saw guys do and imagine the possibilities... Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted June 20, 2014 Author Report Share Posted June 20, 2014 Ok... so this has turned into a complete redo. The frame is getting stipped and powder coated "gun metal grey", the A-Arms and swing arm are getting powder coated silver, and all the brackets are getting coated black. White plastics are on the way. A new long rod crank, and cylinder bore are in the quoting process. There is some more porting to be done, and in addition to the exhaust ports themselves... the pipes have some edges that can be worked. Then there's the transmission... whole new curve in the learning process. Quote Link to comment Share on other sites More sharing options...
turbowrenchhead Posted June 21, 2014 Report Share Posted June 21, 2014 Have you thought about what squish band you want? I've talked to a few builders and they like .040~.050 x 10mil~12mil wide. Quote Link to comment Share on other sites More sharing options...
turbowrenchhead Posted June 21, 2014 Report Share Posted June 21, 2014 I did two sets of DIY ported cylinders. I did this because I didn't have the funds to pay a professional at the time. I did a frame off resto so I spent tons of $ on it as it was. The first set I did I copied pics and vids of the race logic template. I didn't mess with the transfer ports or exhaust port timing. I brought the boost down and the intakes up and left about 3mm between them. They put out 58HP and was ride able on the trails. They lasted one season before the thin spot went missing. The second set I did I left the boost alone and raised the intakes to the roof. Bad idea. Made gobs of top end power but the bottom was horrific. I had a hard time just getting it out of first gear. Now I'm starting over with virgins and sending them to a professional. I'm done with the DIY home port job. Quote Link to comment Share on other sites More sharing options...
tfaith08 Posted June 25, 2014 Report Share Posted June 25, 2014 A long rod will produce different durations for the same port heights. Keep that in mind. Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted June 25, 2014 Report Share Posted June 25, 2014 A long rod will produce different durations for the same port heights. Keep that in mind.^^^^ piston dwell plays in a touch at BBC & TDC with the longer rod Sent from a van down by the river Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted June 25, 2014 Author Report Share Posted June 25, 2014 I'm going with the long rod and buying a new crank. So I'll have to come up with different #s for the port timings. I just read a tread about those new Wiseco ultra stroker pistons, the ones built around the long rod 4mm. Interesting... its got me thinking, but not sure if I like the idea of dropping the pistons that deep in the bore, and what it'll do for the port timings. I imagine it effectively "raises" all the ports, and brings the timings closer to stock. Just don't know how well that will work with the extra stroke. And then if a person drops the port floors to the piston, will it kill velocity with the bigger windows. Quote Link to comment Share on other sites More sharing options...
tfaith08 Posted June 25, 2014 Report Share Posted June 25, 2014 I'd like to work with some of those pistons on a long rod 4mil setup. My first thought would be to deck the cylinder base and get a PD head and run some domes that can take the extra deck height. Pistons that have the pins close to the crown have always been a plus in my book. Also, agreed on dropping the port floors. When at the transfers, an increase in 2mm height will produce much more duration than 2mm added to the exhaust port height. You'd end up with a wide, garbage powerband. Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted August 15, 2014 Author Report Share Posted August 15, 2014 I've been doing a lot of work on the Banshee lately. Powdercoated the frame, new crank, pro-modded trans, etc,etc... finally getting back to the porting. Got the transfer tunnels gasket matched and almost finished with the exception of a little cartridge rolling, and a bead blast. That will happen when I'm done adjusting the port heights and the exhaust. Quote Link to comment Share on other sites More sharing options...
m671054 Posted August 15, 2014 Report Share Posted August 15, 2014 You sure you want the wall finish so smooth? Ive heard otherwise. Look into it before you spend a bunch of time sanding. Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted August 15, 2014 Author Report Share Posted August 15, 2014 I'm using the cartridge roll to round off some sharp edges. The intake and tunnels will be left with a blasted finish. The exhaust might get polished... just depends on how much time I have. Shooting to have it all together by the end of the month. Quote Link to comment Share on other sites More sharing options...
registered user Posted August 16, 2014 Report Share Posted August 16, 2014 ive always liked the idea of a blasted finish. did you use real fine sand or something else ? ive heard of people using walnut shells and other shit like that Quote Link to comment Share on other sites More sharing options...
Atomic Monkey Posted August 16, 2014 Author Report Share Posted August 16, 2014 Ballotini Impact Beads... it's glass blasting media. Quote Link to comment Share on other sites More sharing options...
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