Yamaha BIG BORE

bryanupdike

196bryan
DOES ANYONE KNOW IF THERE IS A BIG BORE OR THE 660 THAT OFFERS STOCK OR CLOSE TO STOCK COMPRESSION. I THINK I HAVE A HEAD GASKET ISSUE AND WOULD LIKE A LIL MORE PERF. BUT AM NOT INTERESTED IN RUNNING ANYTHING OTHER THAN PREMIUM GASS?
 
The question is what makes you think you have a head gasket issue?

A stock replacement offers stock compression ratio with options up to a 1mm oversize if I remember correctly but, I believe weather it be stock bore or oversize aftermarket pistons will bump the compression.

How much?

A quick search at Wiseco, CP, and J&E pistons can answer your questions in regards to compression ratio.

Im running a CP 11:1 CR in my wifes 686 w/ no trouble and she is not easy on it...or maybe its me, I forget.
 
I GUESS I WORDED THAT WRONG. THE REASON I FEEL I MIGHT HAVE AN ISSUE IS BECAUSE IT OVERHEATS VERY RANDOMLY. IF I RUN A DISTANCE AT WIDE OPEN THROTTLE I WILL LOOSE COOLANT ON THE FLOOR. I KNOW IM NOT LEAN, I HAVE AFTERMARKET FAN RAD AND SHROUD ON A SWITCH THAT ALWAYS RUNS. WHAT I WAS ACTUALLY ASKING IS WITH A BIG BORE IS THE GAIN IN POWER MOSTLY FROM THE COMPRESSION JUMP OR THE CC DIFFERENCE. IM NOT TOO INTERESTED IN HAVING TO RUN ANY OCTANE HIGHER THAN 91. I KNOW IN A CAR SOMETIMES YOU CAN GET BY ON 91 WITH 11.1. WHAT DO YOU RUN? I ALSO DONT WANT TO DEAL WITH RELIABILITY PROBLEMS AND I DONT WANT TO BUILD A COMPLETE NEW ENGINE {BOTTOM END WORK TO MAINTAIN INTEGRITY}.
 
I run 11:1 for a very long time on premium gas and raced it that way also for many rounds, no cooling issues, you have another prob, like you stated,

also you may need to recheck the AFR about 13.1 max is good
 
Lets take this apart, my .02 from the consumer per Joeys request.

I GUESS I WORDED THAT WRONG. THE REASON I FEEL I MIGHT HAVE AN ISSUE IS BECAUSE IT OVERHEATS VERY RANDOMLY. IF I RUN A DISTANCE AT WIDE OPEN THROTTLE I WILL LOOSE COOLANT ON THE FLOOR.

From? The overflow bottle? Head gasket? Water pump?

I KNOW IM NOT LEAN

You checked how? Just curious.

I HAVE AFTERMARKET FAN RAD AND SHROUD ON A SWITCH THAT ALWAYS RUNS.

Good, do you have a bash guard blocking the radiator too? Chit can it if so, i feel bash guards in front of the radiator contribute to hot air re-circulating around the radiator.

Do you have a gauge too?

WHAT I WAS ACTUALLY ASKING IS WITH A BIG BORE IS THE GAIN IN POWER MOSTLY FROM THE COMPRESSION JUMP OR THE CC DIFFERENCE.

Both contribute, more from compression but they both enhance each other.

Compression makes more cylinder pressure during the compression & power stroke = more power.

Displacement make for more surface are for the combustion process to push against = more power.

IM NOT TOO INTERESTED IN HAVING TO RUN ANY OCTANE HIGHER THAN 91

Myself included.

I KNOW IN A CAR SOMETIMES YOU CAN GET BY ON 91 WITH 11.1. WHAT DO YOU RUN?

11:1 w/ 91 pump. I do also add Lucas Oils octane booster to guard against detonation, its cheap insurance. Some may disagree that octane boosters work but Ive done enough personal testing to satisfy myself and use it.

I ALSO DONT WANT TO DEAL WITH RELIABILITY PROBLEMS AND I DONT WANT TO BUILD A COMPLETE NEW ENGINE {BOTTOM END WORK TO MAINTAIN INTEGRITY}.

The crank is not the weak link in your bottom end (although it should be welded if you open up the cases), the middle drive gear support is. Anyone who mods their engine, drives hard, has long travel (see drives hard) is driving on borrowed time.

Also, the wrist pin has more potential for failure than the crank since it is splash lubricated, never run low on oil.

Bottom line, if your unsure of where to turn next or are tired of playing the guessing game there are a couple of real talented engine builders out there that can help (or help you) solve your problems, one is in Phoenix but since your in La Mesa theres this guy in Ramona thats pretty good with Rhinos, a phone call & 30 minute trailer tow away.

If your out a Superstition this weekend swing by, south side of Wheeler @ MM 2.5. Look for the trailers with the fists on them.
 
Hit up john at the pro shop ....... he has a killer affordable pump gas kit.

The Pro Shop 714-892-1300

Here is a link to his car going up china wall ....

[ame=http://www.youtube.com/watch?v=gizH7PRLy1o]YouTube - Glamis Pro Shop Rhino climbs China Wall[/ame]
 

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