stroking Posted July 11, 2012 Report Posted July 11, 2012 anyone know what would keep causing the plugs gap to close after making a full pass 1/8mile gap is completely closed after run,and i have to regap it to 18 again plug looks pretty wet too when i pull it out Quote
03crawldaddy Posted July 11, 2012 Report Posted July 11, 2012 How is it running if it's completely closed? Quote
stroking Posted July 11, 2012 Author Report Posted July 11, 2012 How is it running if it's completely closed? it shuts off Quote
03crawldaddy Posted July 11, 2012 Report Posted July 11, 2012 I know with some of our four strokes we had, the plugs would do weird stuff when they got hot or lean. Maybe try a cooler plug, or check out the jetting. But that doesn't explain them being wet when you pull them unless they are getting soaked after they lose fire. I'm just getting into banshees... I'm probably way off... Quote
Bkm2006 Posted July 11, 2012 Report Posted July 11, 2012 deto? too tight of a squish gap? maybe a pro will follow up.. id deff pop the head and see whats going on... Quote
CarvedArt Posted July 11, 2012 Report Posted July 11, 2012 A couple things could cause them to close. The most obvious would be the piston is hitting the electrode. Carbon build-up on the piston top from running too much oil. Or an overheat/detonation condition. You could place a washer on the spark plug to raise it a little just to see if it's hitting or overheating. If it's hitting try cleaning the carbon off of the piston top, you can use a spray bottle with just water, warm-up the motor, take the air filter(s) off, and lightly mist the inlets while keeping the RPMs up. Water does not burn, but steam does compress so don't get too crazy; you should see a lot more smoke than usual. When it's done steam cleaning the black smoke will subside. Or it could be running too rich. You might also consider altering your premix ratio (less oil). Other things to think about why it could be hitting: Is the head shaved too far? Are you missing a head gasket? Are the plugs too long? Are the piston domes too tall? Is the stroke to long? Etc. If it's running lean that's a meltdown on it's way. Quote
BigRed350x Posted July 11, 2012 Report Posted July 11, 2012 anyone know what would keep causing the plugs gap to close after making a full pass 1/8mile gap is completely closed after run,and i have to regap it to 18 again plug looks pretty wet too when i pull it out What kind of motor setup do you have? What fuel? Who cut your domes? What is your static compression and computed dynamic compression ratio? What pistons are you running? If I had to wager a guess I would say deto is closing them up and when you lose spark they are getting wet. OR... you have so much fuel going in on the big end it is hydrolic'ing and compressing the strap on the plug. Quote
Wheelman Chassis Posted July 11, 2012 Report Posted July 11, 2012 Its lean causing it to glow the ground strap red hot making it weak and it closes the gap. only other cause ive ever seen is to much timming. This will also make strap run red hot. Normally deto will happen on the outside edges not effecting the plug unless already way hot.... other than possible breaking the porcilin (sp) Chris Quote
stroking Posted July 13, 2012 Author Report Posted July 13, 2012 (edited) i think big reds got it....it was way rich i cause put it a new set of plugs and make a pass and the plugs still look brand new when i put them squish is .040 180 psi alky 7mil cub dump tube 123 60 pilot main 126 power jets wide open pulled the head and pistons look brand new also Edited July 13, 2012 by stroking Quote
Wheelman Chassis Posted July 13, 2012 Report Posted July 13, 2012 i think big reds got it....it was way rich i cause put it a new set of plugs and make a pass and the plugs still look brand new when i put them squish is .040 180 psi alky 7mil cub dump tube 123 main 126 power jets wide open pulled the head and pistons look brand new also Timming? Im new to how the hydrolics of fuel in the cylinder could push closed the strap..Thought the fluid would be all around the strap equalizing pressure around is resulting in no directional force. Hydrolocked motors normally have head o ring blowouts or bend rods.. big red i know your very good can i get some info on this? Chris Quote
RadarRacing Posted July 13, 2012 Report Posted July 13, 2012 I lean more towards what Wheelman said. Why would you run a bigger mainjet than dumptube? I would add more fuel asap. I would pull the head and check the outer edge of the piston for pitting as well. When the cylinder shuts off it will of course get a wet plug very quickly. Quote
stroking Posted July 13, 2012 Author Report Posted July 13, 2012 I lean more towards what Wheelman said. Why would you run a bigger mainjet than dumptube? I would add more fuel asap. I would pull the head and check the outer edge of the piston for pitting as well. When the cylinder shuts off it will of course get a wet plug very quickly. piston and plug looks like it just came out the box........definitely not lean timing on +7.5 Quote
BigRed350x Posted July 13, 2012 Report Posted July 13, 2012 .123 dump and .126 main seems huge to me. I've only ever seen them that big on huge setups. I'm at higher elevations, so I know its a little different up here... we run .118 dumps with .116 mains in the 10mil. Try and open your squish up to .052-.055 that tight a squish with that much compression is a lot for the crank to work to compress... With the tighter squish you might be building too much heat and getting the strap red-hot like wheelman said. - Jared Quote
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