Id like to raise compression but the spark plug will hit the top of the piston. I imagine using another washer or two might work if i mill the head some more.
Id like to raise compression but the spark plug will hit the top of the piston. I imagine using another washer or two might work if i mill the head some more.
no, the spark plug will heat up and fire super advanced like.
Fir more compression, loose thehead gasket or mill the head
Ehh.. let me make it more clear.
My head is milled to the max right now. But, I was thinking, could you mill the head some more, and put in another washer so the spark plug doesnt make contact with the extra milling?
your head is just going to shoot off like a cannon one day.
Not sure about mopeds, but some racers do this on cars. It's to "index" the plug. Meaning to get the plug gap pointed directly at the intake valve helping to fire the mixture. but like I said I don't know if it's ok an a moped
i run B5ES ngk plugs, witch are longer put 3-5 washers on it, so it doesent touch the piston raises compression for sure, but its not that obvious.
I did it, and it worked. But if it got hot for whatever reason, the plug would fail from heat.
I'm running a flatted crush washer and a normal crush washer together to index my sparkplug towards the center, no more sputtering at max speed.
I am not sure what moped you are working with, but you would be best served with a true high compression head. If you look at a high compression head, you will see there is a squish band like a bell curve not a dome. The bell curve like squish increases the compression more than milling your head ever could.
Moving the position of the sparkplug from the designed location in the head will likely make your performance worse, because it is not firing at the optimal part of the dome.
Yeah and why would you "index" your spark plug towards the "center"? The center of what? There is no intake valve to point to.
Also, NGK makes plugs with no projection whatsoever, though I forget the letter designation off hand.
you don't want exposed threads in your head or on your sparkplug inside the combustion chamber.
The only reason for a spark plug washer that i am aware of is to concentrate the spark in a certain direction. For example point the sparkplug towards the exhaust port or valve to make the engine run a little cooler or point it towards the intake port or valve to make a little more power and make the engine run hotter. And on a four stroke flat head point it towards the piston. Thats why they have all these new wacky spark plugs like E3 because they concentrate the spark directly down towards the piston therefore making more power. But anyway i wouldn't recommend putting your sparkplug any closer to the piston than it already is to raise compression because u risk burning a hole in your piston. Just buy a hi comp head and use a head gasket because getting a good seal is key in raising compression. Most likely you are not getting a seal now and milling the head more isnt going to raise the compression more if your not getting a seal. You will also loose high end tremendously without a proper squish band so like i said before just buy a high comp head and save yourself the trouble
Will high comp heads run higher compression than a milled stock head?
my yamaha's sparkplug hole is a little above center and no matter which head of mine I tried the plug always used to face up towards the intake/steep side of the dome. So I put the flattened washer on the plug first then the normal crush washer, now it faces the less steep side and runs a lot better.
go get a short spark plug.l how high of compression are you going for?
Go buy the INDEX washers, not because they index the spark plug, doesn't matter here in this application,.
It is beacause they are washers designed to be used on spark plugs without negative impacts.
If your plug comes in at an angle, it could help a little to facus it toward the center.
have this same challenge, someone just told me the other day I could possibly grind the area of the piston where it is compacting the plug's electrodes together. Don't want to do that really though.
was just looking for washers last night, then today I saw this ngk pdf:
http://www.ngksparkplugs.com/docs/tech/partnumberkey.pdf
after looking at it, it seems for my application (stock newport cylinder with a Treats Hi Comp head) I would want to use a NGK BP6SS. the first S being the thread reach which S indicates 9.5mm or 3/8ths.
scoured the net thursday, an found "autolite 295" it has the 9.5mm thread reach, 14mm width, and it's heat range is 5. not sure what 5 means in autolite terms or the site I used to cross reference, but it works well. should be pretty common plugs.
also, the washer and the tip come in the box, and not already on them, or at least the set I got didn't.
Couldn't find any NGK plugs with the 9.5mm thread reach and 14mm width.
simple solution ive done and it works perfect, get 2 spark plugs, wrastle off the washer on one and put it on the other no leaks no problems
/end thread
gay.
no extra washers. set your squish right and make sure you have the right Spark plug
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