My yamaha WRIII has been a nightmare Craigslist rebuild, but I am certain I am at the last thing to fix:
First, the ski is converted to pre mix. The entire fuel system has been replaced (lines, filter, check valves, NEW CARB, etc) New spark plugs, etc.
The ski has ~140 PSI compression on each cylinder.
And now I realized something: The previous owner never had the "Flame Arrestor Element" , or the stock metal screen inside the plastic box. I just now connected the dots and realized that with out the restriction in the intake tract, the manifold pressures will be off, and essentially make it difficult for the carb to draw the fuel in through the small, stock jets and needle/seat etc.
My Questions:
1)
Would this metal screen cause a problem if it's missing? Not from the flame arresting capabilities, but for carbeuration? The ski has basically no power past 1/4 throttle and seems to always run lean. It seems that with a much freer air flow, the vaccum pressures would be lower, and would thus have a harder time drawing fuel through the small stock jets etc.
2)
Should I increase the jetting size, Needle/seat, spring to accomodate the less restrictive air flow? How do I know what sizes are necessary? Currently, the ski has the stock plastic box but NOT the metal screen. I don't want to deal with rejetting if this is going to be a difficult guess and check process for figuring out the springs/jets/needle/seats.
3)
Should I purchase a stock flame arrestor from eBay for ~$65, or purchase an after market flame arrestor for around the same price? Is it necessary to rejet with an after market arrestor?
I would like to either:
A) Purchase a flame arrestor (stock or after market) that will work with the current stock jets in the carb
OR
B) Purchase new jets that will work with the stock air box without the metal screen.
I do not want to purchase an aftermarket arrestor and still have to re-jet!
First, the ski is converted to pre mix. The entire fuel system has been replaced (lines, filter, check valves, NEW CARB, etc) New spark plugs, etc.
The ski has ~140 PSI compression on each cylinder.
And now I realized something: The previous owner never had the "Flame Arrestor Element" , or the stock metal screen inside the plastic box. I just now connected the dots and realized that with out the restriction in the intake tract, the manifold pressures will be off, and essentially make it difficult for the carb to draw the fuel in through the small, stock jets and needle/seat etc.
My Questions:
1)
Would this metal screen cause a problem if it's missing? Not from the flame arresting capabilities, but for carbeuration? The ski has basically no power past 1/4 throttle and seems to always run lean. It seems that with a much freer air flow, the vaccum pressures would be lower, and would thus have a harder time drawing fuel through the small stock jets etc.
2)
Should I increase the jetting size, Needle/seat, spring to accomodate the less restrictive air flow? How do I know what sizes are necessary? Currently, the ski has the stock plastic box but NOT the metal screen. I don't want to deal with rejetting if this is going to be a difficult guess and check process for figuring out the springs/jets/needle/seats.
3)
Should I purchase a stock flame arrestor from eBay for ~$65, or purchase an after market flame arrestor for around the same price? Is it necessary to rejet with an after market arrestor?
I would like to either:
A) Purchase a flame arrestor (stock or after market) that will work with the current stock jets in the carb
OR
B) Purchase new jets that will work with the stock air box without the metal screen.
I do not want to purchase an aftermarket arrestor and still have to re-jet!