You don't ride hard enough for anything to happen
This melt down just might have me stumped..
- Thread starter Roseand
- Start date
Mark44
Katie's Boss
- Location
- 100% one place
before you tune again go to Watcon and purchase a PET tach. Do not tune by ear or feel its not close enough. IMO
BrightE's
Paul
- Location
- Seattle, WA
If not tuning by max rpm, what does a tach buy you in tuning?
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Sent from my VS980 4G
No body has done it yet, probably because of water jackets, but ideally you should tune off of egt's along with piston wash and plug reading. I agree, tach tuning gets you the best performance at wot when in reality your going to need a much richer setup down low, otherwise like said earlier you'll end up with a stumble or weak midrange and screaming top end
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Mark44
Katie's Boss
- Location
- 100% one place
I have always found peaK rpm tuning to be spot on with no hesitation.
its usually wonderful if racing. but sit at just of idle for a minute then pin it and i have a feeling it will be loaded up. theres too many transfers in a mikuni carb to tune off one adjustment screw.
VXSXH20
Sionis Industries
- Location
- Mid-Atlantic
Just tuning in here.. I didn't see where this was asked upfront. But " Were these new replacement pistons?" installed after porting? Or are they the same pistons as of last season when you rebuilt it the first go around?
Same pistons used last season
VXSXH20
Sionis Industries
- Location
- Mid-Atlantic
I rest my case.. I think a lot of the head scratching can stop and just live and let live as " A learning experience " Just a few months ago I remember you posting something about cylinder scoring or piston marks. I was curious if you put them back in the same cylinder sleeves after a hone job. I would venture to say that there was a flaw with them before. now under more compression and heat/expansion they reached their limitations
http://www.x-h2o.com/index.php?thre...n-whats-considered-a-normal-safe-mark.160846/
http://www.x-h2o.com/index.php?thre...n-whats-considered-a-normal-safe-mark.160846/
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
WOW. Yeah. You had something going on there............. If it makes you feel any better I just did a full rebuild. New Bore, Pistons and Crank. Lasted 10 minutes before it shut down at speed..........
A little side note about that situation: A very very reputable engine builder message me about that thread and shared his theory on the marks, and due to that one mark not being deep at all, it very much likely confirmed his suspicion. But he didn't want to post on the thread due to people disagreeing.
His theory, especially since it was on the intake side, is that those marks are very normal from when water is ingested since skis constantly get small amounts of oil through them. He said he's noticed it with certain oils. There was a few rides where I was running cheap wally world oil, and there's a possibility that that's when that happened. Just what a builder told me... Was told not to worry about it due to the compression being perfect.
His theory, especially since it was on the intake side, is that those marks are very normal from when water is ingested since skis constantly get small amounts of oil through them. He said he's noticed it with certain oils. There was a few rides where I was running cheap wally world oil, and there's a possibility that that's when that happened. Just what a builder told me... Was told not to worry about it due to the compression being perfect.
Ouch dude that blows... No pun intended :l
Peak rpm without hesitation requires a very rich pilot pop off setting. If part throttle is somewhat clean you will develop a hesitation before the main circuit reaches peak rpm. You should start carb tuning well rich of peak power.
Egt tuning is no good unless you already know what they should be. Best power mixture occurs below max temp. We have the ability to measure power with a tach, the temps don't matter.
you often have to go higher than that. I went from 135 main on a 44 to a 150 main on a 46 and it was still a bit lean.