good explaination Digs. Just for curiosity did the tests say what the highest compression ratio that 86 - 93 pump octane fuel would be sufficent for? Just wondering.

 

It all depends. Aluminum heads disapate(sp.?) heat better than iron heads. Heat adds to the diesel effect. Water cooled engines also can run more compression because they run cooler. I would run high test in an air-cooled engine because they run hotter, this is why cars ping more in the summer. I would say you might get away with close to 10:1 ratio on 93 octane iron head water cooled max. Aluminum heads add about 1pt. to ratio. Air cooled probably 9:1 or so on 93 with iron heads. Keep in mind these are appoximates and other variables come into play slightly that I wont get into such as shape of the combustion chamber, camshaft size...bigger cams bleed off cylinder pressure due to overlap(exhaust and intake open slightly at same time) and so on. I personally run the next higher octane rating in the summer due to extra heat. Best thing to do is test it and see if you hear any pinging go up to the next octane rating.

 

Digs just noticed your from middle Tn. Is that Murfreesboro.?

 

Yep, South side.

 

You guys, the Raptor DOES NOT have tiatanium valves. It is that simple.

 

raptor 720 dont be stupid ok read some literiture alright the raptor has titanium vales go on the frikking site and look it up beleive me its titanium

 

Just read some official literature. No titanium vlaves. the 426 YZF does, but not the Raptor. Straight from Yamaha's website...they never mention the word titanium in the whole Raptor page.

 

Well, you have all the answers. To be accurate, the web site that mentions titanium valves in the Raptor is wrong. I build this motors daily and I have yet to see one with Ti valves.
So, when you call someone stupid, look more near your home town.

By the way, does Ti give off orange sparks when put under a grinding wheel?? Duh, NO.