blueshee Posted February 6, 2007 Report Share Posted February 6, 2007 I just had my head milled .030" and am wondering what size that puts my combustion chambers at. Also my cylinders are out being ported, so I was wondering if Im going to need to run race fuel or a mix. If I can get some opinions, It would be appreciated. Here is a rundown on what the bike will have done. 65mm pistons, .030 off the head, full port job, t-5s, vforce 3s. Im also thinking of advancing the timing, but if that is the deciding factor btwn pump and race gas, ill leave it alone. Thanks for any help Quote Link to comment Share on other sites More sharing options...
yamaha04 Posted February 6, 2007 Report Share Posted February 6, 2007 first you need to find out what evelation above sea level you ride at, then if you can find out what cc domes your are now someone should be able to hook you up with the noos machine chart that give an estimat campression. or you could wait until you get your motor back and do a compression test. if your over 160 i would run a 50/50 race/pump mix. if your lower then you should be alright. also you can advance your timeing 4 degrees. thats where most people start. Quote Link to comment Share on other sites More sharing options...
HotCarl Posted February 6, 2007 Report Share Posted February 6, 2007 Stock heads are about 22-23cc so my guess would be that .030 off would put it around a 20cc dome. the only way you are going to tell forsure is to do a compresson test. Quote Link to comment Share on other sites More sharing options...
bigdaddy69 Posted February 6, 2007 Report Share Posted February 6, 2007 Doing a compression test when you get it all together will be your most accurate source. heres a link to give you and idea of what your lookin at, scroll to the bottom. compression chart Quote Link to comment Share on other sites More sharing options...
Crazy05 Posted February 6, 2007 Report Share Posted February 6, 2007 Fully ported cylinders should lower your compression. Milling the head will bring it back up. Check the compression when its all done. Timing efects octane. If you bump the timing you will need to bump the octane. I have a motor similar to yours and read on here if your 150 or less on compression you can run pump gas. I lost my motor trying to be cheap. Sometime people trying to help that dont know shit can hurt you. If you turn your timing down so you can run cheap gas then you will be leaving a lot of HP at the pump. The gas isnt what makes it fast. High octane actually burns slower, igniting the mixture later, (+4 or mor timing) needs a slower burning fuel. (higher octane). Why it makes more power is the air and fuel mixture are also part of your timing. Having a lower octane fuel witch ignites quicker on top of advanced timing could cause the shit to ignite all the way before the piston reaches TDC top dead center. Idealy you want the bang to happen at TDC and the full force pushing the piston down. If it happens before the piston gets to the top, the bang will try to stop the piston and its called detonation. Very bad for motor. I would say run at least 100 octane and +4 on the timing. 2.5 gallons of 91 and 2.5 gallons of 110= 101. This will keep you safe. Talk to the guy doing the porting for timing and octane FIRST also. Example. A new GT mustang with a chip can give you a tune for either 87 octane or 91 octane. The timing is what the chip changes. The chip doesnt change your compression. So you guys telling people they can run pump gas on 150 or less compression are very wrong. You need to know everything about the setup before giving advice. You probably shouldnt give advice. You should advise them to get advise from a motor builder or someone who knows. Also you cant really hear mild detonation in a 2 stroke so play it safe. A good dyno tune is highly reccommended. Its pricey but so is rebuilding your motor several times till you get it sorted out. Quote Link to comment Share on other sites More sharing options...
Banchetta Posted February 6, 2007 Report Share Posted February 6, 2007 Agreed, although some people on here have shaved their head w/o any problems, but my buddy shaved his and blew the motor up 3 times in one year from detonation using 93 octane....I'd just get a head from dlnoss..Its not worth the headaches some people will run into. Regardless of compression numbers, shaving a head affects the dome shape. Quote Link to comment Share on other sites More sharing options...
headsup Posted February 7, 2007 Report Share Posted February 7, 2007 I just had my head milled .030" and am wondering what size that puts my combustion chambers at. Also my cylinders are out being ported, so I was wondering if Im going to need to run race fuel or a mix. If I can get some opinions, It would be appreciated. Here is a rundown on what the bike will have done. 65mm pistons, .030 off the head, full port job, t-5s, vforce 3s. Im also thinking of advancing the timing, but if that is the deciding factor btwn pump and race gas, ill leave it alone. Thanks for any help you need to run at least 50/50..but full race is better, runs cooler also. Quote Link to comment Share on other sites More sharing options...
dante Posted February 7, 2007 Report Share Posted February 7, 2007 I just had my head milled .030" and am wondering what size that puts my combustion chambers at. Also my cylinders are out being ported, so I was wondering if Im going to need to run race fuel or a mix. If I can get some opinions, It would be appreciated. Here is a rundown on what the bike will have done. 65mm pistons, .030 off the head, full port job, t-5s, vforce 3s. Im also thinking of advancing the timing, but if that is the deciding factor btwn pump and race gas, ill leave it alone. Thanks for any help Thats what my trail bike runs with 93 octane only and +3 on the timing advance; +5 gives me detionation so +3 is safe. The difference between the bikes is the porting job though. Compression testing will help out alot, my other bike has 185 compression -9 retard and a colder plug and runs like hell. And will smoke my trail bike any distance off pump gas. When I go to the track I advance the timing +10 and 115 octane (red gas) new plugs and can beat any body - oh It looks all stock. Tune and tune again is my advice. Quote Link to comment Share on other sites More sharing options...
csrmel Posted February 7, 2007 Report Share Posted February 7, 2007 if you need to measure the dome size cut a piece of plexi to fit on the cylinder head. apply a light coating of grease to the head and snug the plexi down with a few bolts. then fill the dome up using a medical syringe filled with fluid, oil works good for this. most syringe have the cc's labeled on the outside, so keep filling untill the cylinder is full right up to the spark plug threads. keep track of how much fluid you used, this will be youre head cc's. this is a quick, cheap and dirty way to get the cc's. its pressy accurite though. Quote Link to comment Share on other sites More sharing options...
yule16met Posted February 8, 2007 Report Share Posted February 8, 2007 Would you recomend this for a stock engine? I am a machinist, and I could shave 30thou off on my lunch break.no sweat. But i just dont know the motor problems I might get from it. please advise me Quote Link to comment Share on other sites More sharing options...
blueshee Posted February 8, 2007 Author Report Share Posted February 8, 2007 Thank you all for your input. I just got my cylinders back last night and the port job looks bitchen. My pistons arrived today so ill pick them up tomorrow. Hopefully Ill get it all put back together tomorrow night so I can check what my compression ends up at. And this weekend go break her in. :biggrin: I hope it rips, I think I should notice a difference since before this the motor was stock other than pipes, filter and vforce. Ill be sure to post the outcome Quote Link to comment Share on other sites More sharing options...
csrmel Posted February 8, 2007 Report Share Posted February 8, 2007 hell yeah i recomend it for a stock banshee. stock banshees should of came from the factory with 22-21cc domes (depend on elevation) and a stator plate thats 4 degrees advanced. you machinist guy that can shave on youre lunch break, do youre head and also slot youre stator plate so you can advance the ignition timing by 4 degrees. man i tell you i did both mods and i think the timing advance was a bigger kick in the pants than the high compression head or aftermarket air filters. best part is you still get to run premium fuel. Quote Link to comment Share on other sites More sharing options...
yule16met Posted February 8, 2007 Report Share Posted February 8, 2007 hell yeah i recomend it for a stock banshee. stock banshees should of came from the factory with 22-21cc domes (depend on elevation) and a stator plate thats 4 degrees advanced. you machinist guy that can shave on youre lunch break, do youre head and also slot youre stator plate so you can advance the ignition timing by 4 degrees. man i tell you i did both mods and i think the timing advance was a bigger kick in the pants than the high compression head or aftermarket air filters. best part is you still get to run premium fuel. COOL thanks and will do Quote Link to comment Share on other sites More sharing options...
blueshee Posted February 10, 2007 Author Report Share Posted February 10, 2007 I got the engine together last night but it was too late to rip it around the street. So when I got home tonite I ripped it around the block. I am very happy with it, the thing scoots. I ended up at dead nuts 160 psi on a snap-on guage, so I guess ill have to mix with race gas? after ripping it around a bit I pulled the plugs, they started to whiten. I have 350 mains in there now and 30 pilots, air screw 1 turn out. Any suggestions on what I should jump the jets up to? I am at 1000 above sea level. Most the riding I do is at Glamis and Gordons Wells. Also The left pipe is getting hotter than the right when I fire it up and idle/rev it while sitting. But after ripping it around I cant tell because their both really f-ing hot. Any Ideas? Oh yeah, I just went from uni/airbox to k&n pods so add that to the list of my mods. Quote Link to comment Share on other sites More sharing options...
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