Always makes me laugh when people assume less oil=more power and they are proud to announce some weak ratio they run. Yamaha studied this subject in outboards. I cant remember specifically but i think it was ratios from 150:1 all the way down to 10:1. Basically finding an increase in power evertime oil was added to the ratio. Food for thought.
This melt down just might have me stumped..
- Thread starter Roseand
- Start date
I see where you're coming from. I might go back to 40:1. Just gotta add 2 more oz to the rest of my 5 gal cans.
Anyways, my ski was running extremely well. Plenty of people can verify it was loaded with power. I'd say it has a decent amount more pull with 61x cases and a single 44 than a limited 61x/62t dual carb motor with the same mods unported. Both @Lumpy and @brightees and a few others can verify.
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- Location
- seattle area, Wa
I like how so many people have given you GREAT ideas and tips, but you always come back with a position attempting to negate what they suggest.
Really makes people want to help out.
My advice? Reread the whole thread, follow some of these tips from the highly experienced posters, and reassemble and tune it correctly. Its a 700cc jet ski motor, not a formula one car engine..
Really makes people want to help out.
My advice? Reread the whole thread, follow some of these tips from the highly experienced posters, and reassemble and tune it correctly. Its a 700cc jet ski motor, not a formula one car engine..
Jeesh dude, I appreciate every single response and have been thinking through all of the different scenarios and have been soaking up as much information as possible, and trying to piece together what exactly went wrong. It's in my nature to think about every possible situation from each perspective to try and decipher what went on, since there obviously isn't a clearly seen cause for the damage. Can't blame me for being curious and thoroughly thinking through the situation.
Yes. I have been given some awesome tips. The only thing I haven't checked is the piston to wall clearance. I'll admit I'm not a know it all, but I'd like to know it all. I've reread it multiple times, and I'm not stupid either. You can't tell me I haven't covered most of the bases that could be the issue. So before you rag on me, please understand where I'm coming from. This whole thread I've been as respectful as possible.
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speedysprocket
Alex
- Location
- Chesapeake, VA
How's the saying go? They always run best just before they blow...?
Yeah that's usually the case lol.. But it's been the same since I started it up this season. If anything it felt like I still could do some fine tuning with the pipe and such to get it snappier.. But hey. Maybe you're right
speedysprocket
Alex
- Location
- Chesapeake, VA
Fine tuning as in richer...
Mark44
Katie's Boss
- Location
- 100% one place
Did you use a tach. when tuning the carbs, did you tune for peak RPM's?
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
That does sound like a small N&S.
- Location
- Charlotte NC
The smallest needle and seat will flow more fuel then it will ever need. Quote from the mikuni book.
great in theory, not so much in real world.
Why aren't we all running 1.5s?
Why do they make 2.0s and 2.5s?
- Location
- Charlotte NC
to achieve correct pop off.
Only reason I thought this was because the plugs were uniform dark gray. First thought was blown top end, even before you took the head off. I've blown motors before and the plugs looked just like your one, except missing the metal pieces, which you prob lucked out on. All I can say is try to think real hard if those plugs came from the holes you thought they did. Everyone gets mixed up from time to time. To me, it would make more sense as to what happened
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Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
Mikuni book is based of stock motors. If it is all about the correct pop off, then the 4 different springs would achieve this. The different size N&S is there to work in conjunction with different jetting options needed to make each of how many different hundreds of variables of engine packages be able to achieve proper tuning. Ever looked at all the different jetting specs used just for Stock Class SXR Carbs? At one time Farthing, Jetworld, Jazz Motorsports, ZForce, JSU/Kommander all had different jetting packages for the SXR. They were all widely different and all worked really well. It's all about the tuning.
A 1.5 NS may work perfectly for Rosie if all the other jetting variables are in line. Or, it may not be enough and cause him to lean out on top at WOT runs.
- Location
- Charlotte NC
the four different springs with a 1.5 needle and seat will only give you around 30 psi at the lowest. 30psi is still too high for an aftermarket flame arrestors. Im almost certain that the 1.5 needle and seat is not the cause of the failure. Ed sends his full spec carbs with a 1.8 needle and seat, these carbs are run on huge motors.......
- Location
- Charlotte NC
maybe you mean 65..... dull and shiny silver are very hard to tell apart
- Location
- Charlotte NC
http://www.mikuni.com/pdf/sbn_manual.pdf
Check the link and you will see the chart at the bottom...... shows where each circuit comes into play
Check the link and you will see the chart at the bottom...... shows where each circuit comes into play