ryskie22 Posted August 20, 2008 Report Share Posted August 20, 2008 i have had mixed input on fuel and on how to check the compression, i have 19cc domes in a prodesign cool head on a 350 with a hotrod crank, advanced 4 degrees, 33 keihn pwk carbs jetted at 165 mains and 48 pilots, also the tops of the jugs were surfaced due to imprefections, t4 pipes, now my queston is that should i be running straight 110 or 50/50 mix with pump or straight pump gas? ive checked compression many different ways, i really dont know what the proper way is but here it goes, i first kicked the shit out of it and it never got over 155,now if i check one cylinder while the other is running it has 180 to185 idleing of course, and the cylinders are even and this is a fresh topend. so what is the proper way is it that i cant kick it fast enough? from the info ive found this should have 180, oh and i am at sea leval to 500 feet, thanks for everyones help on this its been a question ive had for a long time. also just recently did a plug shop and ran it up hill into 4th gear and held it wide open warmed up and a new set of plugs, found after cutting the plug open to see the base that the porcelin was white and at the bottom was a aprox 2 millimeter of a golden brown ring with the mods shown above, what do you guys think maybe a little lean right on the edge? Quote Link to comment Share on other sites More sharing options...
BURRITO Posted August 20, 2008 Report Share Posted August 20, 2008 Dave (Dave Moore Racing) had me just check mine while kicking the bike over....He never had me run on one cylinder...??? Anybody else??? Dave also doesn't recommend pump gas for any bike...Due to the fact "its shit". Too much crap getting through for sales these days. Quote Link to comment Share on other sites More sharing options...
TeamRealtreeHD Posted August 20, 2008 Report Share Posted August 20, 2008 Please... don't run the bike and try to do this. THAT IS THE WRONG WAY. I don't even know how you accomplished that in the first place... 180 is wrong. 155 is about right. 180 is not right! Only 19cc domes my friend. With your elevation, that is correct. The jugs are not ported either. That is right where you need to be. So you can relax... 155 PSI is good. Run pump gas if you want... run race gas mixed 50/50 or straight race gas if you want. You will be wasting your money if you do. It won't run better. The correct way to check compression: 1. unscrew the spark plug on one side... flip a coin to choose. It doesn't matter what one first. 2. Screw the gauge threads in. 3. hold throttle wide open 4. Start kicking.... doesn't have to be as fast as hell... the guage hold pressure and won't leave it out. So take your jolly old time if you want 5. When it stops climbing, that is your reading. 6. Unscrew guage, put plug back in 7. Repat on other side. Quote Link to comment Share on other sites More sharing options...
TeamRealtreeHD Posted August 20, 2008 Report Share Posted August 20, 2008 Throw one size bigger main in and call it a day Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted August 20, 2008 Report Share Posted August 20, 2008 There is no way we can tell you what your compression should on those domes without knowing what pistons, base gaskets, exh. port duration and machine work has been done to the head. The right way to check compression is run the bike and get it warm. Pull both plugs and hook up the tester. Kick over the bike 10-15 times as fast as you can with the throttle wide open and the kill switch to off. The result is your compression reading. You also need to check squish. I run 18cc domes at 184 psi compression. However a standard exhaust port duration 350 will make almost 200 psi with 18cc domes. Please do a search next time, this topic has been covered more times than I have taken a shit in my life. Quote Link to comment Share on other sites More sharing options...
TeamRealtreeHD Posted August 20, 2008 Report Share Posted August 20, 2008 Please do a search next time, this topic has been covered more times than I have taken a shit in my life. :yelrotflmao: Quote Link to comment Share on other sites More sharing options...
mdhc500 Posted August 20, 2008 Report Share Posted August 20, 2008 There is no way we can tell you what your compression should on those domes without knowing what pistons, base gaskets, exh. port duration and machine work has been done to the head. The right way to check compression is run the bike and get it warm. Pull both plugs and hook up the tester. Kick over the bike 10-15 times as fast as you can with the throttle wide open and the kill switch to off. The result is your compression reading. You also need to check squish. I run 18cc domes at 184 psi compression. However a standard exhaust port duration 350 will make almost 200 psi with 18cc domes. Please do a search next time, this topic has been covered more times than I have taken a shit in my life. Lets just assume that since he didnt mention any custom pistons, port duration, etc... That his mods are what he says they are. And the bottom line is, his compression is what it is... With 19cc domes the 150psi ballpark is pretty close. Oh, sorry, but you do a compression check on a cold wet cylinder. The numbers will obviously be higher when the sleeves, pistons, and rings are warm. I think your numbers seem pretty close, and on the plug chop, you want to see a 2mm chocolate colored ring at the base. Just my .02 take it with a grain of salt... Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted August 20, 2008 Report Share Posted August 20, 2008 (edited) Lets just assume that since he didnt mention any custom pistons, port duration, etc... That his mods are what he says they are. And the bottom line is, his compression is what it is... With 19cc domes the 150psi ballpark is pretty close. Oh, sorry, but you do a compression check on a cold wet cylinder. The numbers will obviously be higher when the sleeves, pistons, and rings are warm. I think your numbers seem pretty close, and on the plug chop, you want to see a 2mm chocolate colored ring at the base. Just my .02 take it with a grain of salt... The thing is porting will change compression numbers hugely. 150 psi is not really close to where I would assume they would be, unless he is running too much squish clearance and has a 1mm or so higher exhaust port. Hence, I need to know and dont like to make assumptions. There are too many times when people on here just want to shoot something off and dont really worry about what the real answer could be or should be. You have to ask questions, get facts, and then formulate an answer based on that. In example: Sunday I am chilling on the couch watching some tv. The neighbor guys come over and say the little kia sephia commuter car one of them owns broke down. The clutch apparently doesn't disengage and allow you to shift gears. I go through everything and tell them it sounds like the clutch slave cylinder or the clutch master cylinder went out. However, I ask some questions and tell them to see if there is anything that looks like shredded fiberglass in the trans bell housing. They come back and say yeah. I say ok, well your clutch disc is probably toast also. So the one guy takes the car in and has the repair shop put a clutch master, and a clutch slave cylinder on it. Never tells them the clutch is bad, or what I told him. They do the repairs at the tune of $300 and give him the car back, car drives like shit and will now pop out of gear and do crazy lurching stuff while it is running down the road. The moral of the story is, ask questions, get the right answers, listen to them, and life is then cheaper and easier. So do the compression test right, ask your builder some questions, and check your squish. Edited August 20, 2008 by Snopczynski Quote Link to comment Share on other sites More sharing options...
ryskie22 Posted August 20, 2008 Author Report Share Posted August 20, 2008 The thing is porting will change compression numbers hugely. 150 psi is not really close to where I would assume they would be, unless he is running too much squish clearance and has a 1mm or so higher exhaust port. Hence, I need to know and dont like to make assumptions. There are too many times when people on here just want to shoot something off and dont really worry about what the real answer could be or should be. You have to ask questions, get facts, and then formulate an answer based on that. In example: Sunday I am chilling on the couch watching some tv. The neighbor guys come over and say the little kia sephia commuter car one of them owns broke down. The clutch apparently doesn't disengage and allow you to shift gears. I go through everything and tell them it sounds like the clutch slave cylinder or the clutch master cylinder went out. However, I ask some questions and tell them to see if there is anything that looks like shredded fiberglass in the trans bell housing. They come back and say yeah. I say ok, well your clutch disc is probably toast also. So the one guy takes the car in and has the repair shop put a clutch master, and a clutch slave cylinder on it. Never tells them the clutch is bad, or what I told him. They do the repairs at the tune of $300 and give him the car back, car drives like shit and will now pop out of gear and do crazy lurching stuff while it is running down the road. The moral of the story is, ask questions, get the right answers, listen to them, and life is then cheaper and easier. So do the compression test right, ask your builder some questions, and check your squish. its not ported that crazy and dont know who ported it butt it was done by someone that knows what there doing just cant remember the name,also have campared it to stock jugs and the exhaust is not even 1mm higher from the top of the jug(head surface) to the top of the exhaust port,and it has wiseco pistons in it,i know if you rase the exhaust port you will loose compression, i understand that,thats why i checked it this time before reinstalling the cylinders, as far as squish, didint check that but i use yamaha gaskets,if that helps. the transfer ports on the side are opened up alot though and the intake side is a lot bigger but not huge. the only reason i checked the running compression was to see if there was a difference becouse there always is just how much. i am a auto mechanic and do this every day for a a living, when i do this test with a engine with valves it does make a differnce and a automobile engie spins over much faster or even a 4 stroke quad than you could ever kick a banshee with that short ass kicker that they have. its easy just pull one plug screw in tester and fire it up on one cylinder and see what you get at idle that would be close to having a starter in my mind, but its a two stroke, if it dont have valves im not that educated on this, thats why im asking Quote Link to comment Share on other sites More sharing options...
mdhc500 Posted August 20, 2008 Report Share Posted August 20, 2008 its not ported that crazy and dont know who ported it butt it was done by someone that knows what there doing just cant remember the name,also have campared it to stock jugs and the exhaust is not even 1mm higher from the top of the jug(head surface) to the top of the exhaust port,and it has wiseco pistons in it,i know if you rase the exhaust port you will loose compression, i understand that,thats why i checked it this time before reinstalling the cylinders, as far as squish, didint check that but i use yamaha gaskets,if that helps. the transfer ports on the side are opened up alot though and the intake side is a lot bigger but not huge. the only reason i checked the running compression was to see if there was a difference becouse there always is just how much. i am a auto mechanic and do this every day for a a living, when i do this test with a engine with valves it does make a differnce and a automobile engie spins over much faster or even a 4 stroke quad than you could ever kick a banshee with that short ass kicker that they have. its easy just pull one plug screw in tester and fire it up on one cylinder and see what you get at idle that would be close to having a starter in my mind, but its a two stroke, if it dont have valves im not that educated on this, thats why im asking There is nothing wrong with asking... Quote Link to comment Share on other sites More sharing options...
TeamRealtreeHD Posted August 20, 2008 Report Share Posted August 20, 2008 So this bike is ported too? You didn't tell us that in the original post... Quote Link to comment Share on other sites More sharing options...
ryskie22 Posted August 20, 2008 Author Report Share Posted August 20, 2008 So this bike is ported too? You didn't tell us that in the original post... i know and im sorry for that, i forgot about it, so yes it is ported Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted August 21, 2008 Report Share Posted August 21, 2008 So this bike is ported too? You didn't tell us that in the original post... Thats why you pay attention, gather info, and give an educated answer. I noticed it was a 4mm long rod motor, to be done right it would need the port floors moved down 2mm. If your in there doing that, it was more than likely ported at the same time. Since it is a 4mm long rod all the things like what pistons he used, spacer plate, machined domes, base gasket thickness, and crank manufacturer can ultimately effect final compression and squish. Also, moving the port in increments of thousands or decimals of a millimeter will change compression. It doesn't just change if you move it a whole millimeter. Quote Link to comment Share on other sites More sharing options...
vortechblown306 Posted August 22, 2008 Report Share Posted August 22, 2008 (edited) Wow just run 110 :: lol Edited August 22, 2008 by vortechblown306 Quote Link to comment Share on other sites More sharing options...
TeamRealtreeHD Posted August 22, 2008 Report Share Posted August 22, 2008 Yes... how 'bout it. If you do a compression test, and it shows a number, but you won't believe it because you still think it should be higher, then run race gas. Problem solved Quote Link to comment Share on other sites More sharing options...
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