Checkmate Posted January 1, 2004 Report Share Posted January 1, 2004 i just went through 2 motors due to detonation. You guys informed me i needed race fuel. Now i just put it all back together, and took compression tests. i am at 200 lbs. at sea level. i have the adjustable timing plate, but backed it off for now...will probably advance it after break in. I just bought some VP C12 (108 octane). Do i need to run this VP fuel straight or can i mix with 94?? Will this change my mix ratio? i run Motul 40:1 now. i have FMF's, Vito's Power Pistons, Vito's Needles, Ported reed cages and Torque reeds, Cool Head with 20cc domes. I WAS running 300 mains, 30 pilots. I also just installed a dial-a-jet kit on the stock carbs, and moved to 310 mains. Dial a jet tells you to go down 1 or 2 sizes on the Mains. Do you guys think this is a good place to start with the Jetting? I don't feel like building another motor. Oh yea...when i turned the gas valve ON, both carbs were pouring out of the overflow. What are the chances that both floats are stuck????? Quote Link to comment Share on other sites More sharing options...
. Posted January 1, 2004 Report Share Posted January 1, 2004 with that much compression I'd definitely be running straight race gas. Is your crank welded? Thats a lot of compression. Quote Link to comment Share on other sites More sharing options...
Dragg-on Posted January 1, 2004 Report Share Posted January 1, 2004 200psi and 20cc domes sounds odd. NE ways, hell ya you better run full vp gas. I d back off the compression if I were you, maybe run 21 or 22 cc domes, I dont see a reason to have so much compression and worry about your crank all the time. my buddy runs 330 w/ stock porting and fmf pipes. Quote Link to comment Share on other sites More sharing options...
Meat Posted January 1, 2004 Report Share Posted January 1, 2004 with that much compression I'd definitely be running straight race gas. Is your crank welded? Thats a lot of compression. Agreed. I havent heard much about the dial-a-jets on this forum. If it was me, I would get the engine broke in, jetted correctly and running good, then Id slap in the dial-a-jets. Quote Link to comment Share on other sites More sharing options...
Checkmate Posted January 1, 2004 Author Report Share Posted January 1, 2004 200psi and 20cc domes sounds odd. NE ways, hell ya you better run full vp gas. I d back off the compression if I were you, maybe run 21 or 22 cc domes, I dont see a reason to have so much compression and worry about your crank all the time. my buddy runs 330 w/ stock porting and fmf pipes. i didn't think the compression would be that high either.... i switched from the vitos Super Stock (Exhaust timing pistons) to the Vito's Power Pistons. I guess the Power pistons raised the compression even more. If i am at 200 LBS. now, what would 21cc bring me down to? and what would 22cc bring me down to?? I would rather be reliable at this point.....i'm gettin pissed with the 2 stroke when all my boys are running thumpers and have NO PROBLEMS. But when my chit runs it whoops ass. But i am having too much trouble keeping it together. i have an aftermarket hodrod crank. i don't think it is welded. What compression is safe for an unwelded crank?? i have already installed the DIAL-A-JET, and it took drilling into the carbs, so there is no going back. Quote Link to comment Share on other sites More sharing options...
Toomey Banshee Posted January 1, 2004 Report Share Posted January 1, 2004 I would guess each size you go up on the domes will bring your compression down by about 15 lbs. I wouldnt run much over 170 and with this I would run straight race gas just to be on the safe side. For comparasions sake I have a stock bore/port motor and with 20cc domes I have 169 lbs of compression. I run 3 gallons of race a 2 gallons of super and no problems. Quote Link to comment Share on other sites More sharing options...
fixitrod Posted January 1, 2004 Report Share Posted January 1, 2004 When you take that head off, measure from the top of the cylinder to the top of the exhaust port. I'm curious what that is. Maybe they are lower than they are suppose to be. Man, that compression seems way high. Quote Link to comment Share on other sites More sharing options...
Checkmate Posted January 2, 2004 Author Report Share Posted January 2, 2004 My bore size is .040 over. how much more compression is that worth? (if any). Does anyone know how much compression increase the power pistons give you? i am still looking for the answer to the fuel questions. Can i mix with 94, and do i need to change my ratio? only reason i want to mix is because i am getting wacked for almost $8.00 per gallon for the VP. Quote Link to comment Share on other sites More sharing options...
239banshee Posted January 2, 2004 Report Share Posted January 2, 2004 lower your compression down alot more and you wont have to use it Quote Link to comment Share on other sites More sharing options...
txblueshee Posted January 2, 2004 Report Share Posted January 2, 2004 HOT DAMD!!! That's a lot of compression there jackson! That's definately full race gas... I would leave your timing backed off. Matter of fact if it was my bike I would remove it, even w/ the hot rod crank(un-welded) that 200psi will eventually bust it apart. Mike Quote Link to comment Share on other sites More sharing options...
bigtreads Posted January 2, 2004 Report Share Posted January 2, 2004 not saying you did anything wrong but how did you take your comp. readings. I screwed mine up the first time I did mine by not holding the throttle wide open which gave me inconsistent readings. I have 21cc domes at about 1000 feet above sea level and got 162lbs both sides. What level are you at ? I also run Motul -seems to be providing a excellent wear rate Quote Link to comment Share on other sites More sharing options...
Checkmate Posted January 2, 2004 Author Report Share Posted January 2, 2004 not saying you did anything wrong but how did you take your comp. readings. I screwed mine up the first time I did mine by not holding the throttle wide open which gave me inconsistent readings. I have 21cc domes at about 1000 feet above sea level and got 162lbs both sides. What level are you at ? I also run Motul -seems to be providing a excellent wear rate I did hold the throttle wide open during the test. and i am at sea level. a buddy just asked me if i ran the motor before i did the comp. test. i didn't. he said that the oil i used to lube everything during the install would give me a higher reading. he also said that running it will take any sharp edges off the rings that could give you a higher reading. i am going to go do another check. i'll let you know the results. Quote Link to comment Share on other sites More sharing options...
Leadfoot350 Posted January 2, 2004 Report Share Posted January 2, 2004 Can you start it? I would run straight 108 or higher. Run it like it is for a tank or more and then measure it again. If it is still that high then put the stock head back on and see what that one says. Quote Link to comment Share on other sites More sharing options...
Checkmate Posted January 5, 2004 Author Report Share Posted January 5, 2004 ok...got my carbs straightened out, and ran the bike. checked compression again, and i am now at 180. must have been the oil i used during assembly. so now with 180 lbs at sea level. should i run the 108 straight, ar can i mix? how much does everyone pay for thier race fuel?? Quote Link to comment Share on other sites More sharing options...
txblueshee Posted January 5, 2004 Report Share Posted January 5, 2004 I would still run 108 octane w/ 180psi. I "think" the going rate is between 4-6.50$ a gallon for race fuel. Mike Quote Link to comment Share on other sites More sharing options...
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