AKheathen Posted June 27, 2009 Report Share Posted June 27, 2009 I don't think I was clear on what bike I'm thinking about the head for. I want to put a cool head on my wifes bike which is .80 over, stock porting and timing and put the head off of her bike which is shaved .20 onto mine when I get the jugs back from being ported oh, just go to the noss site, and check with your elevation. probably 20's. 155-165 psi, depending on how much wear on the rings. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted June 27, 2009 Report Share Posted June 27, 2009 Yall can do what u want but 145-150 is about the limit on pump any builder will tell u that as far as the porting goes it wont change it a whole bunch about 5psi at the most is what i seen. And if you are going to run it long especilly at high compression welding the crank is a must they are known to come apart. I would say 140-145 with 4 degress on the timing is about all I would go on pump. I may be wrong but if i remember right the stockers are 24cc and u gain about 10psi for each cc you drop. the stock chambers range between 22 and 25, not all the same, and cranking compression increases @ a slope. for example, you should gain alot more pressure jumping between 16-15cc, than you would jumping from 22-21cc's. it would be nice if a more experienced builder like blowit or daj would chime in :biggrin: Quote Link to comment Share on other sites More sharing options...
Maul Posted June 27, 2009 Author Report Share Posted June 27, 2009 (edited) Noss site says 156 psi at sea level with 21cc domes. From what I have read that might be ok with pump gas but may be a little hard on the crank. Sounds like unless I want to get my crank welded and run higher octane (which is in the books just not right now) I should just save some and shave my head .10 or .20 and keep my comp around 140 - 150 BTW this bike is running 140 psi at 3500 feet so I wonder what I'm running at sea level Edited June 27, 2009 by Maul Quote Link to comment Share on other sites More sharing options...
RILS Posted June 27, 2009 Report Share Posted June 27, 2009 Noss site says 156 psi at sea level with 21cc domes. From what I have read that might be ok with pump gas but may be a little hard on the crank. Sounds like unless I want to get my crank welded and run higher octane (which is in the books just not right now) I should just save some and shave my head .10 or .20 and keep my comp around 140 - 150 BTW this bike is running 140 psi at 3500 feet so I wonder what I'm running at sea level I had to recheck my self here after raeding a bit it looks like the 165 is about the cutoff. I do know where I got that 145 number though I built a couple of outboard boat motors and thats as high as we set them on pump but they only have one gear which causes a lugging situation on start and that makes them detonate. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted June 27, 2009 Report Share Posted June 27, 2009 I had to recheck my self here after raeding a bit it looks like the 165 is about the cutoff. I do know where I got that 145 number though I built a couple of outboard boat motors and thats as high as we set them on pump but they only have one gear which causes a lugging situation on start and that makes them detonate. it's because the compression ratio is the deciding factor. stock stroke and porting allows us to use cranking compression as the basis for the banshee Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted June 27, 2009 Report Share Posted June 27, 2009 maul, just have your stock head shaved for a total of .030" off, so another .010" in your case. your squish should be right @ .050" and the comp is just fine on pump gas. i use 93 octane w/no problems. Quote Link to comment Share on other sites More sharing options...
Maul Posted June 28, 2009 Author Report Share Posted June 28, 2009 maul, just have your stock head shaved for a total of .030" off, so another .010" in your case. your squish should be right @ .050" and the comp is just fine on pump gas. i use 93 octane w/no problems. Sounds like a plan and cheaper than a cool head. Thanks for all the info quys Quote Link to comment Share on other sites More sharing options...
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