Modded Yamaha

[Ballistic]

I found better airflow through the "square" carbs.
Also, depending on level of porting, I ran 90 carbs. Biggest limiting factor I found on the 50's were the reeds! I ended up modding the intake and fitted 6 petal reed block instead of the stock 4 petal! Made HUGE difference! Bare in mind there were many more mods required!!

Hi Karl,

Dit you get this 6 petal reed cage off a different motor or did you create it yourself?

Wouldnt making a 2 petal reed cage be more efficient?

[byrdsperformance@tds.net]

Hi' Joe
A 70 front can be fitted to a 40 .
If you decide to enlarge 40 cage's be carefull.
To much matiral removed an reed collapse can happen:

[OUTBOARDER]

I found better airflow through the "square" carbs.
Also, depending on level of porting, I ran 90 carbs. Biggest limiting factor I found on the 50's were the reeds! I ended up modding the intake and fitted 6 petal reed block instead of the stock 4 petal! Made HUGE difference! Bare in mind there were many more mods required!!

Was going to prep a Yamaha or Tohatsu 42.6 but rules were restrictive at the time.
HAVE THE RULES FOR THE YAMAHA 42 TRIP CHANGED ?

After going thru a Yami and Tohatsu 42 to measure stuff it became apparent that
the intake system as a whole was the bottle neck to competing with a larger engine.Compared to a 49.7 omc intake system it's not even close.

That engine in the video sounds like it is dialed in on the money! Especially when you squeeze it. Bet it turns a lot bigger prop, Big question is how much punch will you have to give up to swing a 90mph wheel????

[Karl Kretzmann]

Hi Karl,

Dit you get this 6 petal reed cage off a different motor or did you create it yourself?

Wouldnt making a 2 petal reed cage be more efficient?

Hi Ballistic,

2 petal would be more efficient if you could find one much bigger than stock. for me it was easier to take the reed blocks off the from end of an 85 or 90 Yam, and weld it onto the case of the 50. I cut off the whole lot, carbs and all!
the best i could get out of the std 2 petal with max mods was around 85 BMEP. stock 85 intake gave me 125 BMEP ( going on memory here so don't take exact figures as fact)
this basically means that with the 3 petal reeds and larger intake..... you could go crazy wild on the porting!

[Karl Kretzmann]

Hi' Joe
A 70 front can be fitted to a 40 .
If you decide to enlarge 40 cage's be carefull.
To much matiral removed an reed collapse can happen:

removing material from the reed seat is a risky one. many failed attempts to find the limit!
also many sets of reeds!.... rather expensive!

[Ballistic]

Hi Ballistic,

2 petal would be more efficient if you could find one much bigger than stock. for me it was easier to take the reed blocks off the from end of an 85 or 90 Yam, and weld it onto the case of the 50. I cut off the whole lot, carbs and all!
the best i could get out of the std 2 petal with max mods was around 85 BMEP. stock 85 intake gave me 125 BMEP ( going on memory here so don't take exact figures as fact)
this basically means that with the 3 petal reeds and larger intake..... you could go crazy wild on the porting!

Thanks for the info.

But i mean a 2 petal reedcage in total. just 2 big reeds. One on the left and one on the right.Wouldnt that be more effecient?

Which parts do you take from a 85/90? The plate the carbs bolt on to? the reed cages? Or something else because i don't see how you can put any bigger reedcages in the 50 block. Its rather small. I over-bent the reedstops a bit and i almost couldnt get the reedcage back into the motor.

[byrdsperformance@tds.net]

If you are still use stock reed's they must go.
A broken steel reed can wipe your nice engine out.
You will find different type's of composite reed's.
Single, dual , carbon or glass ect. An many various opinion's
With a wide single or dual type reed you can remove center diveder's,
an some more from the stock cage's Some even cut out side's an,
mount a reed,s ? As far as a 3 peddle front all the 40 runner's, cage's,
mount flange an ove course reed to carb adpator plate are replaced,
Machine 40 frt. runner's off weld 3v runner's on .

[Karl Kretzmann]

Thanks for the info.

But i mean a 2 petal reedcage in total. just 2 big reeds. One on the left and one on the right.Wouldnt that be more effecient?

Which parts do you take from a 85/90? The plate the carbs bolt on to? the reed cages? Or something else because i don't see how you can put any bigger reedcages in the 50 block. Its rather small. I over-bent the reedstops a bit and i almost couldnt get the reedcage back into the motor.

If you could find a reed cage with no resistance to flow... that would be best! but that doesn't exist!

i chopped the reed block off the 50 case, and welded on the 85hp's! then used all the 85 hp's plates, reeds, carbs etc.

[Ballistic]

This is what i mean:
http://www.thunderproducts.com/Banshee%20reed.htm

I think im gonna give this a go because i am currently running a 50horse with 70 carbs and i think the reedcages are a big restriction.

[byrdsperformance@tds.net]

Ballisic,
This is quite simular to cage mod's i do.
As the center's are removed i leave apx. 1/8" of runner at top of cage's.

To help guard against reed collapse.