mopar1rules Posted October 27, 2008 Report Share Posted October 27, 2008 i was reading thru my "two-stroke performance tuning" book, by graham bell...and in the chapter on cylinder heads, it says that you want the "dome" of the head, to be as small as possible and to have the spark plug as close to the piston crown as possible. by keeping the "dome" of the head as small as possible, it exposes a smaller portion of the flamefront to the piston's crown, versus if the "dome" was larger...so, with a small "dome", it keeps the piston cooler. now he says the reason for the spark plug being centrally located in the head and as close to the piston crown as possible, it helps the squish band head from deto, because the time for the flamefront to reach the end gases, that are on the cylinder's outter edge, is reduced to a minimum and the end gases don't have the time to heat up and spontaniously ignite/deto. the subject about keeping the "dome" as small as possible, to keep the piston crown as cool as possible, wouldn't that be more oriented towards an air cooled engine than a liquid cooled engine? also, wouldn't having the spark plug as close to the piston's crown as possible, create a hot spot in the center of the piston crown? would you have to drop a heat range on the spark plug then? maybe this topic can turn into a sticky or something, for us tuners to look back on. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted October 27, 2008 Author Report Share Posted October 27, 2008 i am thinking about buying some 2-stroke tuning software. anyone have the TSR stuff? i was thinking of the stuff from BiMotion too. http://www.tsrsoftware.com/ http://www.bimotion.se/ Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted October 27, 2008 Report Share Posted October 27, 2008 You can run a Projected tip spark plug. They stick farter down in the combustion chamber. I have run them before. I didnt really notice a performance gain. They also lasted just as long as a regular set of plugs. You would think with them hanging down farter in the cylinder you would be more apt to foul one. BPR8ES is the NGK projected tip. Get one and see what you think. josh Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted October 27, 2008 Report Share Posted October 27, 2008 I had dave at noss machine make me some custom domes for my black bike with these ideas in mind. It was a bit of a pain to get it tuned to where it wouldn't detonate at the lower rpm range under a load out on the dunes, but once I figured that out its amazing how my setup runs with some domes that I had him cut quite a bit different than normal squish domes. Experiment around and try stuff in real life. Its interesting what you will find runs good compared to what books will tell you runs good or doesn't. Most people who heard what my squish was and how it was shaped told me it wouldn't work. Turns out it works pretty dang good, and with almost 0 degrees timing advance. :biggrin: - Jared http://s70.photobucket.com/albums/i94/powe...llshooting2.flv Running rich, it still pulls plenty hard with the setup I have. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted October 27, 2008 Author Report Share Posted October 27, 2008 (edited) You can run a Projected tip spark plug. They stick farter down in the combustion chamber. I have run them before. I didnt really notice a performance gain. They also lasted just as long as a regular set of plugs. You would think with them hanging down farter in the cylinder you would be more apt to foul one. BPR8ES is the NGK projected tip. Get one and see what you think. josh josh, i'm not looking into running a different plug, as i have no issues what so ever with the b8es plugs. i'm looking for any info on the software and or/tips or tricks on coming up with head profiles and of things to keep in mind/know about head mods etc. bigred, i went to your photobucket link, and your shee sounds killer. what pipes are those and what did you do to the heads? Edited October 27, 2008 by mopar1rules Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted October 28, 2008 Report Share Posted October 28, 2008 The banshee cool head design is going to be the best thing out there for these bikes. After that, the time spent dinking around and decking a head, the rechambering domes is not worth the gain you will get. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted October 28, 2008 Report Share Posted October 28, 2008 josh, i'm not looking into running a different plug, as i have no issues what so ever with the b8es plugs. i'm looking for any info on the software and or/tips or tricks on coming up with head profiles and of things to keep in mind/know about head mods etc. I was just saying it would help you get the spark plug a little closer to the top of the piston. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted October 28, 2008 Author Report Share Posted October 28, 2008 I was just saying it would help you get the spark plug a little closer to the top of the piston. that's what i figured, but i think the book wants you to bring the spark plug closer to the piston crown by bringing the entire "dome" profile down towards the piston crown. if a guy just ran the projected tip spark plug, wouldn't you have the threaded end of the spark plug, sticking way down into the dome? then, wouldn't the fuel mixture thats being stuffed up into the "dome" of the head, collide into the side (threads) of the spark plug? if the end of the spark plug ends flush with the top of the dome, then the fuel mixture that's being compressed/stuffed up into the dome, would sweep right into the electrode (instead of the side of the plug or threads), where it would be burned. do you know what i'm trying to say? Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted October 29, 2008 Author Report Share Posted October 29, 2008 The banshee cool head design is going to be the best thing out there for these bikes. After that, the time spent dinking around and decking a head, the rechambering domes is not worth the gain you will get. now snop....its got to be worth the time to learn how/what to mod on the head, to make our shees faster....lol. remember those fellows, that said its not worth porting our engines ourselves? well, you and i both know that it was worth it. look at how much faster our shees are, and what more we learned from that. i don't mind investing the time. i would just like a few pointers on head modding. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted October 29, 2008 Report Share Posted October 29, 2008 that's what i figured, but i think the book wants you to bring the spark plug closer to the piston crown by bringing the entire "dome" profile down towards the piston crown. if a guy just ran the projected tip spark plug, wouldn't you have the threaded end of the spark plug, sticking way down into the dome? then, wouldn't the fuel mixture thats being stuffed up into the "dome" of the head, collide into the side (threads) of the spark plug? if the end of the spark plug ends flush with the top of the dome, then the fuel mixture that's being compressed/stuffed up into the dome, would sweep right into the electrode (instead of the side of the plug or threads), where it would be burned. do you know what i'm trying to say? Yea I see what your saying. On a BPR8ES the thread length is the same. The tip of the spark plug hangs down in to the combustion chaber a little farter instead of being flush with the top of the combustion chamber. Standard BR8ES BR8ES Spark Plugs LINK Projected tip BPR8ES BPR8ES LINK Standard tip Iridum Plug BR8EIX LINK Projected ip Iridum Plug BPR8EIX LINK $35 Denso Iridium Racing Plug IW01-24 LINK Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted October 29, 2008 Report Share Posted October 29, 2008 It doesn't make since to do it with a head though. We can mill it, and get the squish and compression right, but I dont have a cnc or a lathe. I definitely dont see the need to recut my chambers to tighten the squish band up. Pro design got it close enough for me. I would rather just buy a cool head and slap it on. They already did all the work for me. As long as I have the right base gasket on my bike, the squish is good so no need to mess with it more than that. There isn't much to improve on with the cool head design. I know Bell said to spend the time just bringing up the motor to par, but slapping on a head does that for you as long as your cylinder deck heights are close. I can also buy pre cut stroker domes for $80 if I ever go to a 4 mill crank since I run the cool head. Quote Link to comment Share on other sites More sharing options...
dlnoss Posted October 30, 2008 Report Share Posted October 30, 2008 There are of course some limiting factors for the spark plug height; volume required, squish area width desired, etc.. If the piston doesn't hit the squish area, it won't hit the spark plug if the plug is flush with the inside of the bowl. I interpret the book to mean you don't want the bowl to be any deeper than it has to to get the proper volume. The wider the squish area, the deeper the bowl will be. I have made some domes with flatter, shallower bowls (keeping the spark plug closer to the piston) by stepping from the squish area 'up' into the bowl area instead of making the bowl area a constant radius. -David Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted October 30, 2008 Author Report Share Posted October 30, 2008 I interpret the book to mean you don't want the bowl to be any deeper than it has to to get the proper volume. The wider the squish area, the deeper the bowl will be. I have made some domes with flatter, shallower bowls (keeping the spark plug closer to the piston) by stepping from the squish area 'up' into the bowl area instead of making the bowl area a constant radius. -David what would this give a guy...more bottom end power? my buddies 19cc dome for his pro design head, looks kinda like this. it doesn't look like a true radius. Quote Link to comment Share on other sites More sharing options...
dlnoss Posted October 31, 2008 Report Share Posted October 31, 2008 It's a little hard to say for sure with someone else's dome design. If you have a specific volume you are shooting for, and a specific squish width (say 40%), you have some choice on the bowl shape, mainly how it transitions from the squish to the bowl. I prefer flatter bowls but they take a little longer to design because dome software doesn't usually calculate for multiple radii in the dome shape. I guess I'm not really answering the question, because the answer isn't really the same in all circumstances with the variables of porting, fuel, etc. -David Quote Link to comment Share on other sites More sharing options...
grizzly700 Posted November 2, 2008 Report Share Posted November 2, 2008 (edited) if u r really serious about this subject u could maybe get a set of E3 plugs custom made for ur bike that way the spark is fired directly into the fuel and that would prolly be the best of both worlds. i dont know much about the heads on the shees yet cause i just got mine but that seems like a good idea to me:/ i tried to get E3's for my shee but they dont make em. for the right price u might be ablt to get a custom set. or u could patent it.lol Edited November 2, 2008 by grizzly700 Quote Link to comment Share on other sites More sharing options...
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