Fastassbanshee96 Posted August 25, 2011 Report Share Posted August 25, 2011 How should I set up my 4 mil serval. I'm running 35mm a/s on pump, cool head with 22cc domes, open k&n filters, +4 timing. I don't remember what jets are in it but it's what Jeff told me to put in it. Where should the clip be, it's in the middle now. How should I do the fuel screw? Any other tips. I'm just now getting ready to start it for the first time. I've been building this thing for the last year now and really want to hear it run. Oh and I'm running R2 pipes and live in Michigan. I think about 500ft. Quote Link to comment Share on other sites More sharing options...
No Limit Powersports Posted August 25, 2011 Report Share Posted August 25, 2011 You might want to check your compression if your at 500ft thats going to be pushing it with 22cc and pump gas Quote Link to comment Share on other sites More sharing options...
05stroker Posted August 25, 2011 Report Share Posted August 25, 2011 Yes, check your compression multiple times. I checked mine after a couple heat cycles with the 22cc domes and it was at 155 psi. After it fully broke in I found out the hard way that it had gone up to about 173. It detonated, backed out the plugs and started to melt the o-rings in the head. Quote Link to comment Share on other sites More sharing options...
gangstahic Posted August 25, 2011 Report Share Posted August 25, 2011 whered u get ur domes from? that culd b the problem right ther Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted August 26, 2011 Report Share Posted August 26, 2011 I run 24cc domes and kick over 158psi. I also run R2s and I have found they like a lean pilot jet. Also, the jetting specs Jeff gave you were a starting point. Do a plug chop and fine tune that. As I sit now (with the mods in sig) I have a 45 pilot with air screw one turn out, 158 main jet, and CEL needles clipped on 4th notch down. I am not saying "run what I run" but I would bet you'd be real close to this. Soon here, I will run a 160 main jet as the cooler autumn air starts to blow in. To answer your specific questions, the "fuel screw" you mentioned is actually an air screw on the Keihins. Turn it clockwise to richen the idle and CCW to introduce more air and leaning idle. This is used to further dial in the air/fuel ratio after the proper pilot jet has been selected. If you find it idles/runs best with the air screw turned less than one turn out, you need the next richer pilot. If more than three turns out, you need a leaner pilot. The needle clip position is more of a preference/feel type of tuning for me. Where the main jet, for instance, can be tuned using a test (plug chop) the needle clip is more of a feel for throttle response and power delivery in partial throttle range. All in all, the engine will tell you if it is rich or lean. It will tell you it has too much compression or ignition. Problem is, it won't say what it wants in english. Once you learn the language tuning carbs is a breeze. And remember, always sync your carbs to each other when you get done tinkering. Pulling the carbs off may un-sync them and that'll have you chasing your tail. lol Quote Link to comment Share on other sites More sharing options...
SuperMex Posted August 26, 2011 Report Share Posted August 26, 2011 What altitude are you at GoFast? Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted August 26, 2011 Report Share Posted August 26, 2011 Just west of fastassbanshee96 in Wisconsin. Roughly 600' Quote Link to comment Share on other sites More sharing options...
dirtydownunder Posted August 26, 2011 Report Share Posted August 26, 2011 im running 24's asl and kicking 150psi. Quote Link to comment Share on other sites More sharing options...
coryv4 Posted August 26, 2011 Report Share Posted August 26, 2011 How should I set up my 4 mil serval. I'm running 35mm a/s on pump, cool head with 22cc domes, open k&n filters, +4 timing. I don't remember what jets are in it but it's what Jeff told me to put in it. Where should the clip be, it's in the middle now. How should I do the fuel screw? Any other tips. I'm just now getting ready to start it for the first time. I've been building this thing for the last year now and really want to hear it run. Oh and I'm running R2 pipes and live in Michigan. I think about 500ft. dont run pump with the 22cc domes i am also from mi and i am about 500ft and my comp is at 148 with 24cc domes Quote Link to comment Share on other sites More sharing options...
CFH87 Posted August 26, 2011 Report Share Posted August 26, 2011 Why would 22cc domes not be pump gas domes? This is makein me worry about the 21cc domes for my 350... Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted August 26, 2011 Report Share Posted August 26, 2011 Why would 22cc domes not be pump gas domes? This is makein me worry about the 21cc domes for my 350... Different beast I would think, apples and oranges. Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted August 26, 2011 Report Share Posted August 26, 2011 Do you understand how internal combustion engines work? A larger volume squeezed into "X" space will be compressed more than a smaller volume in the same "X" space. X is our control. If X = 21cc, and you try to squeeze 421cc of air into 21cc (forget that there are ports all over the cylinder for now) you will have more pressure than if you squeezed 350cc into 21cc chamber. Now, port timings affect this a lot more. A lower exhaust port will show more kicking psi than a higher port because at that slow of piston speed the higher port will allow more trapped air to escape before the piston fully covers it. What happens at 9000rpm though? In over-simplified terms the higher port timing (along with matched exhaust chamber) will draw in more air-which most escapes out the exhaust like when you kick it over slowly-but all that air is forced back into the cylinder before the piston covers it up. The result? More compression during the powerband than a lower exhaust port. This makes sense in my head, lol. Anyway, combine this with a load of other factors will tell you exactly what fuel you need. Set your ignition at a modest point and run the 21cc domes with pump fuel. If you notice any signs of detonation then step up the octane. I'm guessing you'll be more than fine with a good quality pump fuel say 91 or better. Quote Link to comment Share on other sites More sharing options...
CFH87 Posted August 26, 2011 Report Share Posted August 26, 2011 This is why I ask 1000's of questions lol Quote Link to comment Share on other sites More sharing options...
Fastassbanshee96 Posted August 26, 2011 Author Report Share Posted August 26, 2011 Damn now you guys have got me kinda worried. Jeff at fast built and setup the motor for pump. I will be deffinetly doing the compression test before starting. Quote Link to comment Share on other sites More sharing options...
gangstahic Posted August 26, 2011 Report Share Posted August 26, 2011 its the builders or ur builder cutting ur domes...mne ppl had this problem of servals detonating bc of the science fast explained u gotta ffind a proven head/dome builder to do ur domes or ur engine is shit to bricks...k and t supposedly makes the best domes out there my 2 cents Quote Link to comment Share on other sites More sharing options...
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