head kit & spark trouble

[racer182]

hi guys i thought i'd let ya know about my bike
and get you thoughts and comments...

i bought a 3D ported headkit and engine.. fitted it up
to my bike and it ran fantastic for a good 6 months
until the spark plug kept coming out..
i got the dome re threaded (helicoil)
worked great after that.. till i put in a ngk spark plug...
the bike ran for about five minutes and then would not
want to run.. it was acting like the jet was blocked
so i cleaned out the carb and tried again..
still did not work.. went over the whole bike including
the coil and anything it could be...
the last thing i tried was the plug again.. i took it out and
realised the plug tip was bent down and getting a very poor
spark...
i put back in the chinese plug that came with the kit.. and
the bike ran great again...
in the end i realised the ngk plug thread must have been a
slight bit longer as it looked like the plug was hitting the piston
and bending the plug tip...i have come to the conclusion that
when they did the helicoil they must put in a touch lower that
the original thread so it looks like that i can only run the chinese
plug or maybe put the ngk plug in with 2 spring washers from the plug...

what do you guys think ?

[RD RACING]

all you need to do to run the ngk plug is to add another plug washer, this will give enough clearance between the piston crown top and the sparkplug bar.

[Glen]

ill check the type of plug i have but i run a special type in one of my bikes where the electrode is flush with the spark plug end - maybe this will solve the problem also? it was like $27 if i recall. but it throws a huge spark.

[racer182]

cheers glen.. if you could check it out for me... and let me know
what brand it is and stuff..
thankyou heaps mate.. hey could you take a picture of it
and post it in here.. that would help me too.. if ya cant.. no worries.

cheers for the info RD...

[Glen]

yeah ill check it out - i had to get it for the Gp3 because of a "special" setup on the head/barrell. i think its NGK from ozminimoto (the CH7??) but cant remember. give me a few hours and ill whack a picture of it up.

[mac90]

inspect the plug number they may have given you a R type or resistor type plug
they have a slightly longer electrode that protrudes further into the cylinder

here is a example with the standard plugs for stock heads

[racer182]

nice pic mate.... thankyou heaps..
next time i get plugs i'll get the BM6A
cheers

[mac90]

the bm6a are a stock plug they wont fit the headkits its just a example of electrode difference on the standard & resistor type plugs

[racer182]

oh ok mate..
so what would the best plug be that fits a head kit
that is similar to the BM6A
cheers

[bennyboy213]

a c7hsa?? is wot im thinkin will run in ur head kit?? dont u have the number of the spark on ur ngk plug?? to help us out..

have u set the squish properly???
try increasing and see what happens.. if u increase the clearance it shouldnt hit the plug.. and the spark should be alright..
give it a go and see what happens