Ieat4strokes Posted July 3, 2009 Report Share Posted July 3, 2009 Recently put together a 4 mill Fast drag ported motor. Crank was in exellent condition tho used. As well as cylinders and pistons all with less than 10 hrs on em. Pistons and everything looked great. Fired first couple kicks idled fine. Let it warm up. Ran it around the yard a few times and it felt really strong almost scary strong. Ran it wide open down the road and it did fine until on the way back and started missing. Pulled it under carport and both plugs were backed out. It couldve been cuz I didn't tighten them down enough I don't know. But there is a noticable tick coming from the motor. I put new plugs in compression was at 150psi with my o reillys auto parts guage. I'm running 19cc 4 mill Gas domes cut by Noss and I'm at sea level. It read the same 150psi with my 18cc domes in a fresh build. I'm scared I'm way higher and it's detonating. Could that be the noise I'm hearing? It gets faster with motor speed but not louder. I'm runnin 35 pwks 50 pilots and 160 mains needle on second clip from top. Like I said it ran strong toted the wheels through all gears but has a tick sound comin from head area almost like pistons are hittin domes. Quote Link to comment Share on other sites More sharing options...
bonbon Posted July 3, 2009 Report Share Posted July 3, 2009 Recently put together a 4 mill Fast drag ported motor. Crank was in exellent condition tho used. As well as cylinders and pistons all with less than 10 hrs on em. Pistons and everything looked great. Fired first couple kicks idled fine. Let it warm up. Ran it around the yard a few times and it felt really strong almost scary strong. Ran it wide open down the road and it did fine until on the way back and started missing. Pulled it under carport and both plugs were backed out. It couldve been cuz I didn't tighten them down enough I don't know. But there is a noticable tick coming from the motor. I put new plugs in compression was at 150psi with my o reillys auto parts guage. I'm running 19cc 4 mill Gas domes cut by Noss and I'm at sea level. It read the same 150psi with my 18cc domes in a fresh build. I'm scared I'm way higher and it's detonating. Could that be the noise I'm hearing? It gets faster with motor speed but not louder. I'm runnin 35 pwks 50 pilots and 160 mains needle on second clip from top. Like I said it ran strong toted the wheels through all gears but has a tick sound comin from head area almost like pistons are hittin domes. Plugs backing out is usually going to be detonation. With those 19 cc domes at sea level I would be a little concerned that detonation is the problem. Are you running 91 or 93 pump gas? Does your compression tester fitting screw into the dome as far as your plug does? If not you won't get an accurate reading. I don't have the correct adapter for mine but figured it to make ~1cc difference. i.e. a 19cc dome would actually be reading like it was a 20cc dome. About the ticking I'm not sure. My motor from stock, to cub, now to a fully rebuilt (bearings crank clutch everything) cheetah still makes a ticking noise I have yet to figure out. Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted July 3, 2009 Author Report Share Posted July 3, 2009 i just wanna clear up that I put new plugs in with the intention of running it again, but im to worried about the ticking and if its detonation i dont wanna toast my motor. So im gonna wait on you guys! Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 3, 2009 Report Share Posted July 3, 2009 What is the squish clearance? What did the plugs look like? Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted July 3, 2009 Author Report Share Posted July 3, 2009 Plugs backing out is usually going to be detonation. With those 19 cc domes at sea level I would be a little concerned that detonation is the problem. Are you running 91 or 93 pump gas? Does your compression tester fitting screw into the dome as far as your plug does? If not you won't get an accurate reading. I don't have the correct adapter for mine but figured it to make ~1cc difference. i.e. a 19cc dome would actually be reading like it was a 20cc dome. About the ticking I'm not sure. My motor from stock, to cub, now to a fully rebuilt (bearings crank clutch everything) cheetah still makes a ticking noise I have yet to figure out. Its got 93 in it now, Timing at +5, i mean i took my time with the build, oiled everything during assembly, pistons, bearings cylinder walls, new seals in it etc.... it feels like its got a ton of compression, spun motor over several times by hand fully assembled before I dropped it in and everything felt and sounded fine, not like the pistons were hitting or nothing, but it almost sounds like the tick is coming from inside the pipe on the left side and from the head.....im not sure, i guess ill need to check squish clearance? Also its pitch black out and reving it a few tims th white porcelin on the plugs was lighting up....never seen that before but it is pitch black out here......The compression guage has a adapter with o-rings and its the exact length as the plug threads, i checked it with one plug out and throttle wide open..... Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted July 3, 2009 Author Report Share Posted July 3, 2009 What is the squish clearance? What did the plugs look like? I need to get some thinner solder, all i have is this thick heavy duty shyt and it wouldnt even flatten it out....plugs werent new, they were from my other motor, I have new plugs in it now and wanna run it, do you think it would be ok? Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 3, 2009 Report Share Posted July 3, 2009 I was just wondering if they had a grey ash look to them. You might look at them with a magnifying glass looking for specks of aluminum. Quote Link to comment Share on other sites More sharing options...
badland banshee Posted July 3, 2009 Report Share Posted July 3, 2009 I wud run it with the new spark plugs and run it through all the gears then hold 5th gear pinned and then pull in the clutch and kill it then check your plugs and see what they look like Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 3, 2009 Report Share Posted July 3, 2009 I wud run it with the new spark plugs and run it through all the gears then hold 5th gear pinned and then pull in the clutch and kill it then check your plugs and see what they look like I wasn't having him look at the plugs to check his jetting. I was having him look at them for signs of detonation. I would probably wait to start it back up until I checked the squish. I would probably want around .040. If you get a good squish I wouid then drain the fuel and try running straight race fuel. See if the sound still exists and if the plugs back out. Using a guage to determine what octane to run can only get you so far. The pipes also affect compression. You will have more than 150 psi of compression when your banshee is in the powerband and the port timing and pipes are working together. Quote Link to comment Share on other sites More sharing options...
PassionRE Posted July 3, 2009 Report Share Posted July 3, 2009 If your cylinders are set up the way I suspect they are, your actual static compression is higher than you think it is. I suspect your closer to 180+psi static= 109octane fuel at sea level...possible gauge discrepency...Jim Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted July 3, 2009 Author Report Share Posted July 3, 2009 If your cylinders are set up the way I suspect they are, your actual static compression is higher than you think it is. I suspect your closer to 180+psi static= 109octane fuel at sea level...possible gauge discrepency...Jim I'm thinking the same. It's noticibly harder to kick over than my previous build. Both were showing 150psi. My old motor was a fresh build 18cc domes and showing 150. This one is harder to kick and shows 150 with 19cc domes. Don't make since. Am I doin the check right? One plug out, wde open throttle , kick till the needle stops? If so then my guage is inaccurate. Would running low octane cause the tick I'm hearing?? Ima grab me some c12 tomorrow and see if that's the culprit. Also Ima try this squish thing out. I've never worried about it before on a stock motor but now is different. With the 4 mill squish is a issue due to clearences etc and I'd I got the right domes. I got some 115 laying around not much but enough to see I'f that's it. Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted July 3, 2009 Report Share Posted July 3, 2009 You need to check squish before you run it anymore. You should have checked it before you even started it. Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted July 3, 2009 Author Report Share Posted July 3, 2009 (edited) I got betwen .045 and .050 on both cylinders on both sides of the plug, not even sure if i did it right or if the solder was too thick to smash completly etc....calipers are accurate to .0001, and I used 3/32" solder and also got some wire solder thats measured out to b .036 and it wouldnt even crush it, so i suppose thats good...... What next fellas? .053 was my highest reading Edited July 3, 2009 by Ieat4strokes Quote Link to comment Share on other sites More sharing options...
AWR Posted July 3, 2009 Report Share Posted July 3, 2009 pull the head just to be safe and to make sure no ring lands are broken.don't base your octane requirements on static compression alone(i had a 115 lb# compression motor that would detonate without race gas)i would bet detonation is backing out your plugs......peace Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted July 3, 2009 Report Share Posted July 3, 2009 Did you originally check the compression with the motor warmed up, and the throttle wide open while kicking? Quote Link to comment Share on other sites More sharing options...
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