What is this bore doing?

[will941s]

Re: What is this bore doing?

There is a Bosch plant here (Charleston, South Carolina), like 2 miles from my house.

 

[Ostsideend]

Re: What is this bore doing?

There is a Bosch plant here (Charleston, South Carolina), like 2 miles from my house.

It's a small world !

 

[Ostsideend]

Re: What is this bore doing?

Update:


Got a different CDI and put it in.

Trials with NOS volume, it's too much:

http://www.youtube.com/watch?v=uMr2nqZgrsg

Reduced max Volume:

http://www.youtube.com/watch?v=e0GUljr9Q88

Temperature Check:

http://www.youtube.com/watch?v=FzlH0-7PVdk

Still not at the end. The max rpm without NOS does not satisfy me.

Best regards
Oliver

 

[Arkman]

Re: What is this bore doing?

boy i can't wait to see this in action

 

[Ostsideend]

Re: What is this bore doing?

boy i can't wait to see this in action

Hi arkman, can't wait to realize if the thing gets into aqua plane or not.

Found some torque hiden in the tiny Yamaha....

http://www.youtube.com/watch?v=7NSJ80zSsxE

Oliver

 

[wbeaton]

Re: What is this bore doing?

I just love what you are doing. How long until the water tests? Do you have GPS data of the motor on your boat before you began tuning it?

 

[Ostsideend]

Re: What is this bore doing?

Hi Wayne,
no i don't.

But today i did the test. Without NOS the tinY Yamaha don't get the short rubber boat into plaining.

With NOS it's an amazing "rocket" and it takes a second to get it planing.

I am obset. It has got a lot more of torque, but up to a rpm border it stops accelerating. I have to have some more rpm. Don't like to win the race yust with a larger bottle of NOS.

 

[Ostsideend]

Re: What is this bore doing?

I did some more work. The carb got an intake "trompet" nozzle and i moved the ignition in direction of 8' before upper Dead Point. Got more rpm... Moving this Week end the ignition Point to 12' and then check a fixer point at 30' .i'll See what Happens. Idle rpm was a lot more with 2' plus.

Ordered a 5 lbs nos bottle As well )

 

[wbeaton]

Re: What is this bore doing?

Have you also looked into re-propping the motor? A little adjustment in pitch might give you better performance.

 

[Ostsideend]

Re: What is this bore doing?

Won the Race, but with the Second 3 hp Malta. The tuned startet einging the bells.... Don't Know Why. But i will get him Fine during Winter time.

Nos in a 2lbs bottle helps a Lot)
Pics and Video After comming Home....

 

[Willyclay]

Re: What is this bore doing?

The outcome was never in doubt! Congratulations, enjoy the beer while we enjoy the pix and video.

 

[wbeaton]

Re: What is this bore doing?

Congratulations. I am a little unclear, though. Did you will with the modified motor or a second stock motor running NO2? Can't wait for the photos/video.

 

[Ostsideend]

Re: What is this bore doing?

The the tuned sound became "unsafe" it was the Stock with the cfk Membran and tuned intake, closed decompression bore and a Little more pre ignition Timing. But i had some luck....

 

[Ostsideend]

Re: What is this bore doing?

after a while of not beeing here...

Still gamebling with my yamaha malta.

The bore does not have a decompression function!

It is done to get oil and or fuel (mostly oil) which can be collected in the crankcase burned and not let it directly drained into the water via the exhaust.

I am willing to make a self made dyno test up tp 6HP max this winter.

Its based on a rotary brake disk to manually hold a constant rpm and an electronic pressure gauge which will be mounted between the brake piston housing an the backstop on the outboard shaft.

This thing will show me Nm and with having the rpm according tho the Nm reading it is easy to calculate HP.

Setup idea:




Sketch for the rotary adapter arrangement:



I found that a twin malta (2 x 3 HP) will let the dinghi plane. So i do have to reach approx. 6 HP on a single...



It moves:



In motion:

Yamaha Malta offshore schlauchi.wmv - YouTube

The problem is based on to get a 2 meter rubberboat to plain with a 70ccm motor only

 

[Ostsideend]

Long time ago, but still a fan of these nice tiny 2 stroke outboards.
A new race will take place and this time i will do everthing 100% right.

I did build a DIY Dyno for the 3HP Yamaha, which i pre tested today. (Just for fun, nothing else)
Larger Carb is already on and an inner rotor digital ignition is mounted.

Hydraulic gear pump based dyno-system pre tested with a power drill...

Vid about the pre test:
https://www.youtube.com/watch?v=W6F1K8IYDhM


Vid about a first step with the digital PVL ignition:
https://www.youtube.com/watch?v=oDeb2dz8I0A

Is there anybody who can explain, or show me a page where it will be explained, how the function of the exhaust works? I am fully aware about tuned 2 stroke exhausts, but her on outboards we do have an open end pipe which ends in a non conical chamber...?!?

 

[Sea Rider]

Just leave the engine standard, prop it right with a induction tach to run towards full wot rpm factory stated, throw away what's not needed out of the boat, if you happen to be a feather champ boater and your opponent a fat one, will have an oustanding weight advantage

Sitting engine at the sweet transom height along a correct prop maximization usually towards one less pitch will do the trick..

Happy Boating

 

[Ostsideend]

Hi Sea Rider and many thanks to your reply. It is a 1,95 meter rubber boat (about 6 feet in lenght) There is nothing i could throw away exept myself or the motor ;-)

To prop it right is also a problem. There are two props available. The smaller one is on and the larger one works worse.

The hight position is something i will work on. I plan to cut the shaft, take approx 100mm out and weld it togehter again (incl. dirve shaft-, gearshift-, and water supply pipe shortening) due to that the "short" Malta is sitting still way to deep in the small rubberboat. (Think i"ll do a setback and a kind pf jack plate as well for adjusting the motor to an optimal hight and position to hepl to get on plane.

By the way the idea to cut 100mm out of the shaft leeds me to fully understand if the volume or the shaft lenghts matters or if it is the length of the exhaust pipe (open end pipe) matters only.

If i can get no answer to this, i have to do it and see what my DIY dyno tells by comparing between the power curve before and after.

Its all for fun

 

[Willyclay]

To prop it right is also a problem.

Welcome back! Could a prop repair shop modify a stock prop after all your other planned mods are complete?

 

[Ostsideend]

Hi Willyclay,
thanks!
Good idea! There is one professional prop-shop in Cologne city which is not to fare away. I will show them one and ask what they can do.
it will be good to know the max rpm as Sea Rider said, before they squeeze it down...

 

[Ostsideend]

Did a lot of things... and it went not so bad!

7.4 HP @ 5.300 rpm out of the 70cc 3HP Yamaha Malta

https://www.youtube.com/watch?v=XAemR-L8sUc

Power curve: