okbeast Posted August 29, 2006 Report Share Posted August 29, 2006 I'm fixing to get a '98 banshee and want to put some cool-heads on it. I'm wondering what dome size to run? I live in Oklahoma so we're about 1500 ft. above sea level. It's a stock bore and stroke motor, stock compression piston too. What determines what dome size to get? And does a different size make a difference in power? Quote Link to comment Share on other sites More sharing options...
okbeast Posted August 29, 2006 Author Report Share Posted August 29, 2006 Anyone? Quote Link to comment Share on other sites More sharing options...
cRaZyShee8 Posted August 29, 2006 Report Share Posted August 29, 2006 I am not sure how much of a gain you will get. I have repowered outboard motors at work with larger bore higher compression pistons (Large displacement V6 2 strokers), and the power gains are minimal. On these larger engines, a bore and compression change are lucky to net 30-40 horse. And that is on a much larger scale to start with. And if you think about it on a smaller scale like our tiny twin two strokers, you may gain a few (4-6) with a larger bore and compression bump. As far as what CC dome to run for different elevations, I am not too sure. I would have to guess at it, where as I am sure someone else can chime in that knows for sure. Once again, all the motors I work on are ON sea level, so the only jetting/compression changes I have are for weather changes, not elevation. Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted August 29, 2006 Report Share Posted August 29, 2006 the differant dome sizes will determine your compression which will then determine your gas octane needed to prevent detonation. as for the out board motors they dont get as large of gain as a smaller motor will by adding suddle changes. the banshhe and any other small motor for that matter makes major gain by performing the smallest bolt on or machined modification do to the displacmetn these motor have. back to the main topic if your running a stock bore stock stroke motor then in my opinion there is no reason to put a cool head on your bike spned the money else where and get new reeds or porting , if your stuck on the coolhead then 22cc domes will run a stock bike fine on 91 octane but like i said what the point? Quote Link to comment Share on other sites More sharing options...
dajogejr Posted August 29, 2006 Report Share Posted August 29, 2006 At 1500 ft of elevation, you could use 21cc domes and probably run pump gas safely all day long. 20cc domes would put you at the risk of MAYBE having to run 50/50 mix of pump and race gas. They do a few things: Cool better Look better Seal better and will give you a boost in bottom end with a little more compression PM DLNOSS here on HQ. He can answer any questions you may have... 1 Quote Link to comment Share on other sites More sharing options...
dlnoss Posted August 30, 2006 Report Share Posted August 30, 2006 I' also in Oklahoma. If you run good fresh 93 octane, your timing isn't advanced, and you are riding at 1500' (plus or minus a couple hundred), 20cc domes will be okay. If there is doubt about any of the above, I'd say 21cc domes. Quote Link to comment Share on other sites More sharing options...
okbeast Posted August 30, 2006 Author Report Share Posted August 30, 2006 I had actually planned on advancing the timing, probably 4 degrees to start. Does the dome size change what the compression is and that's why the octane matters? Quote Link to comment Share on other sites More sharing options...
dlnoss Posted August 30, 2006 Report Share Posted August 30, 2006 Advancing the timing increases the risk of detonation as does higher compression so more octane is needed to reduce the detonation risk. With the +4, 21cc domes would be safer. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted August 30, 2006 Report Share Posted August 30, 2006 Hey noss, what about with my 16cc domes and 9 Quote Link to comment Share on other sites More sharing options...
okbeast Posted August 30, 2006 Author Report Share Posted August 30, 2006 Thanks for the info guys. DLNOSS, where you located in Oklahoma? Did I read somewhere that you're a coolhead retailer? Quote Link to comment Share on other sites More sharing options...
knight_ripper Posted August 30, 2006 Report Share Posted August 30, 2006 DLNoss is the owner and maker of noss cool heads. awesome product IMO. give him a call...nice guy....excellent customer service. Quote Link to comment Share on other sites More sharing options...
okbeast Posted August 30, 2006 Author Report Share Posted August 30, 2006 So if I decide to run smaller domes and use race gas will I really notice much difference just from that? I'm assuming I would since the compression would be higher. Quote Link to comment Share on other sites More sharing options...
dlnoss Posted August 30, 2006 Report Share Posted August 30, 2006 I would probably run 20cc domes and 93 octane pump gas if you aren't competing. It's a good size for recreational riding at Little Sahara. On the other hand, I like race gas and Avgas because of it's shelf life. It doesn't turn to goo like pump gas does after a couple of months. I run 19cc domes and race gas but might put 20cc domes back in next time I have the head off. I'd still probably run at least Avgas to keep the carbs clean. ($3.85 a gallon at Sand Springs last weekend) My deal is I sometimes let my toys sit for months without riding them and regular gas goes bad....I hate rebuilding carbs. I'm North of Cleveland, Oklahoma,,,out in the sticks. Quote Link to comment Share on other sites More sharing options...
okbeast Posted August 30, 2006 Author Report Share Posted August 30, 2006 Yep that's the sticks! LOL. I wouldn't mind running half 100 and half 93 if I had to. My quad would also sit for awhile so this might be a good idea. If i wanted to run 100 or 110 could I go to a 20cc dome or would you still recommend the 21cc? You got a # or website or something that I could get in contact with you for prices and stuff? Thanks Quote Link to comment Share on other sites More sharing options...
dlnoss Posted August 31, 2006 Report Share Posted August 31, 2006 You would be fine with that mix and 20cc domes. The web site is www.nossmachine.com and the phone is 918-358-3804 A silver head with domes is $234.00 + shipping. Blue, Black, or Red with domes is $247.50 + shipping. Those prices are with the BHQ discount, of course. -David Quote Link to comment Share on other sites More sharing options...
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