Quick question Taking the CBR250RR which seems to have a relatively low/safe compression ratio would it be advisable to use plugs that take up more room in the chamber to increase compression for more ponies? Also what is people's thoughts on the side gaping theory? Thanks.
how would you like a piston or 4 with holes punched in them by plugs if they are longer?how much room between valves for an extra plug?how much money do you have to modify the heads?on bikes this year i have spent in the ballpark of 20k. i have anthony,s mc22 to do up and have parts but not energy.i WANT 1` of each 4 cylinder bikes from the late 80,s. what i need is different. the head idea is in the latter category- not impossible but damn expensive.
IMHO, No to longer plugs. If the piston or a valve don't hit the end, the exposed threads will build up with carbon and you will never get the plug out again. Have never noticed any difference with the side gap on plugs. You may be able to get a measurable gain on a dyno with indexing of your plugs, but I have never noticed any different in any of the racing engines I have built on the track.
I don't mean dual plugs as installing a second plug, I mean those silly dual fire plugs that have 2 prongs off the one plug to take up more room in the chamber. As for carbon build up maybe just change them once every 4 months? It cant be the worst idea in the world.
Your idea is ok as far as getting higher combustion pressures, but the practicalities of fitting the plug in the combustion chamber (piston/valve clearance) will be the limiting factor. I tried the dual fire plugs once and noticed no difference (note that my engines were still running Avgas at 11.1 to 1 ratio) in performance. They looked a good idea, and have been used in aero engines (for reliability) for donkeys years, but without the aero engine magneto to give them a really hot spark (magnetos make more amps the faster you rev them (Top Fuel dragsters run twin 44amp mags which burn the ends off the plugs by half track, 200me and have to be replaced before the engine can be started again)) I didn't see any advantage for the extra expense.
You can get some plugs that are better quality (eg iridium) but "quality" is not really in the functionality of the spark plug, just how many KMS they are supposed to last before replacement. Just in my experience anyway. If you want more ponies the simplest way I can think of is to take the valves out and lap/polish.
Well to tell the truth I haven't even got the bike yet, it gets dropped off this Friday. There is a good chance I will be more than happy with the power but I guess its just in a bikers nature to seek an advantage where ever he can.
Weve raced the, not only twin electrode plugs but even the triple ones & guess what, no difference. Longer plugs, well you'll never notice any difference, wouldn't even show up on a dyno. Go for it if your racing & looking for a few tenths a lap but you'll have to have a whole lot of other performance enhancers to accompany it. It's a good thing to hear your looking & listening to what makes a difference. You'll get more from squaring up the carbs & valve clearances etc Be careful mucking around with the combustion chamber, could have a sad ending. Remember the Engineers that design these things do it for a reason, cutting the electrode back to let the spark shoot out further looks detrimental to the piston crown to me. If she's your transport don't risk it, if she's a disposable wreck then go for it & let us know your findings, I'm interested.
