Build 77cc Minarelli, next step ?

[plea]

Hello from Bulgaria ! My name is Peter and I am new to this forum. Anyway
Basically. We decided to increase the power of the Yamaha Aerox YQ50 2005 Minarelli horizontal.
And it started with the purchases. Crankshaft Malossi MHR 12mm, Cylinder Airsal Extreme 77cc, Exhaust Yasuni C30, variator Malossi MHR, carburetor China PWK 24mm ( main jet 115, low 39) , valves VL14. We successfully build and start up. The result is not very satisfactory, but the noise created by this setup with a simple sports filter is extremely loud. We are now work on custimise the original filter box, hopefully it will reduse noise. By the way, we have purchased and should install Tork pulleys Malossi OverRange and a Malossi long belt .

I have a few questions for you.
How to achieve good low and medium RPMs? Carb, jets, exhaust ? 
What would you advise me for tuning the electronics, for the moment everything is standard there? Should we put rotor electronics or just sport coil and CDI. At the moment, working with NGK BR10 spark ( advice if need other one ? )  

This setup produces over 13k RPM, but I can't say exactly how much.


Best Regard Peter  

[aeroxbud]

Welcome to the forum Peter.
I think you have the wrong sort of cylinder for low to mid range power. This thing needs to rev high to be in the power band.
The best you can do is fit a clutch that can be set-up for a high RPM take off. At least then you still be getting near the power band.
With this setup you could really do with an inner rotor ignition.

[plea]

Thanks for the welcome aeroxbud! Currently, the clutch is a MALOSSI sport with white small springs and a red central. Will I bet on red smalls or yellows? If I replace the clutch with the delta version of Malossi, will the difference be noticeable?

What rotor electronics would you recommend?

I read, that the low and mid rpm also occur with quality Japanese carburetors with good tuning, or is that a myth.



Thanks for answers in advance !

[aeroxbud]

If you look at this dyno chart as an example. It shows you how much power different Yasuni exhaust systems make. The power is not so important. But you can see your pipe doesn't really make much bottom end power.
You need to set up the transmission to work in the range with the best possible spread of power. www.pedparts.co.uk/c/asset/yasuni-power-graphs.png

[808ministroke]

Sept 30, 2023 12:08:11 GMT -5 plea said:

Thanks for the welcome aeroxbud! Currently, the clutch is a MALOSSI sport with white small springs and a red central. Will I bet on red smalls or yellows? If I replace the clutch with the delta version of Malossi, will the difference be noticeable?

What rotor electronics would you recommend?

I read, that the low and mid rpm also occur with quality Japanese carburetors with good tuning, or is that a myth.



Thanks for answers in advance !

welcome to the forum!

I am running the same mallosi fly clutch with red springs and they are great for these kind of set ups, had orange or kid clutch (small) springs at first and the upgrade made huge difference.

[Philipp]

Welcome

[plea]

Thanks, i will try and post. What do you think about rotor electronics? For or against? Does it wear out the cylinder and piston faster. Can i give advance with standard ignition and how. Sorry for my bad English.

[808ministroke]

You can start out simply by putting in a Woodruff key that advances the Ignition time you you'll notice that differences however if you want to get the full potential of the kit and safely rev above 12000 RPM you you should look into an inner rotor. Not only does it give you the ability to grab higher and safety of doing so but it also has So great capabilities that you will definitely notice a lot more than just advancing it having different curves and such. I started with AMVTD19 which was fine at all but really when I switch to the melosi teeth I noticed that the quality in the performance was a lot better so keeps out in mind.

[fabster]

Oct 5, 2023 12:59:19 GMT -5 808ministroke said:

You can start out simply by putting in a Woodruff key that advances the Ignition time you you'll notice that differences however if you want to get the full potential of the kit and safely rev above 12000 RPM you you should look into an inner rotor. Not only does it give you the ability to grab higher and safety of doing so but it also has So great capabilities that you will definitely notice a lot more than just advancing it having different curves and such. I started with AMVTD19 which was fine at all but really when I switch to the melosi teeth I noticed that the quality in the performance was a lot better so keeps out in mind.

As you said, complete inner ignition is way better than a woodruff key.
The woodruff solves the low rpm issue, but gives to much timing at high rpm.
Variable ignition are the way to go on that king of setup.
You really need the advance timing at low rpm to get off the line.

OP, you'll mostly have much to gain by raising the exhaust port on that cylinder. You should measure your port timing, but I'm pretty sure it would be like TPR77 and 86. A few degrees go a long way. The Yasuni C30 likes to revs high also.

High strength clutch springs are probably a necessity.