For those of you that have been on the forum from the beginning you are aware of my testing of performance parts on the MSX. I have tried many combinations of throttle bodies, cams, big bore kits, ECUs etc... Which now are in a pile collecting dust. With the first kit i didn't have good results, which i posted and gained a lot of attention. Ill admit i wasn't too happy, but Reggy later contacted me and replaced the parts for free that were defective. Because at the time there were no options on the market for tuning the AF mixture, the results were marginal. Last winter while Reggy was here in Europe he stopped by and we installed some new parts on my bike and he provided me with a programmer for the original fuel tuner yuminashi had developed. Afterward i couldn't seem to get the fueling quite right with the temperature and elevation here. I then started providing feedback and assisting with some R&D. At that point Yuminashi went back to the drawing board and began working on its current kit. In the meantime i got a Bazzaz and was able to get some fairly decent results with the crower cam, but i wanted what most everyone wants, a kit that just works. About two weeks ago i received the new 160cc kit, complete with fuel tuner and everything. Its been a long time coming, but i think we now have a great tuning kit for the grom/msx. I am happy to say i am now, finally satisfied with the results of countless hours of work.
I started with a reasonable goal which was to reach around 14hp from my MSX that i bought last year on may 4th 2013. This goal was based upon the yx150 i had making 15hp. Since then I've had the engine apart so many times i lost count. During the last dyno run i hit 12.7bhp, not too shabby, but i knew there was more to be had. During that run my setup was with the 150cc bore, 1st gen yuminashi cam, stock exhaust with faddybike header, 25 tooth 4th gear and stock sprockets.
Today i went to the dyno with my laptop and a buddy to help me. After about 3 hours (i don't have a data logger) of working on the fueling i finally have a pretty decent map that works well. Its not perfect, but pretty close to. My main concern is making sure im not too lean anywhere. I got the map so the bike runs between 12.4:1 and 13.4:1, but in most areas its around 12.7:1 to 13.1:1. Its interesting that in a few specific places it was running either really lean or way rich. Maybe it has something to do with gas backwaves or resonant frequencies within the intake runner or reversion in the exhaust. At any rate its pretty decent and safely drivable without fear of running too hot. I believe oil engine oil temps stayed between 170~180 degrees so it looks like an ok operating temperature.
My current engine setup:
Yuminashi 160cc big bore kit
Stand-alone ECU
New yuminashi cam
Big bore injector
Longer valves and dual valve springs
33 tooth rear sprocket, stock front
25 tooth fourth gear(inside transmission)
Yoshimura RS9 full exhaust system
k&N r1100 air filter
Stock throttle body
Stiffer clutch springs
During tuning i really pushed the engine hard and i was a bit nervous revving to 12000rpm, but it held up fine. The stiffer clutch springs are also great. I am getting absolutely 0 clutch slippage. This alone is a great upgrade.
I was really shocked to see the engine make 16.9PS (16.7bhp), i was definitely was not expecting that. It also made 10.10ft lbs of torque. This is a huge improvement over my first run.
The black line is the run in january, the red is todays result in metric horsepower, but it is pretty close to the same as HP. Keep in mind i had a stock 34 tooth sprocket on with the first line and 33 with the red.
![Text Line Diagram Parallel Design]()
Torque comparison in Newton meters
![Text Line Design Parallel Paper]()
The bottom line is I'm really happy with it so far. While the crower cam was ok i was not really happy about the valve noise. Im looking forward to putting some miles on to see how the durability is now. I also don't recommend lightening the flywheel and oil spinner. With a higher lift and duration cam it also doesn't idle quite as smoothly, its not too bad, but keeping the mass on the crank should allow the engine to idle better.
Ill have the fuel map file available soon for the stand alone ECU, so please feel free to use it and improve upon it. I tried to interpolate the whole map, but it ended up being way off. Like i said its not perfect as one can see the curves are not completely without chop, but it got me close in all areas and is quite useable.
If you purchase a kit please provide Yuminashi with feedback so they can continue to improve on what is a promising product.
Thanks for reading and once the rain stops ill get my top speed and road riding impressions posted. I did ride in the parking lot before i left the motorcycle dealership and it was really easy to pull a wheelie without using the clutch.
Sent from my iPad using HondaGrom.net
I started with a reasonable goal which was to reach around 14hp from my MSX that i bought last year on may 4th 2013. This goal was based upon the yx150 i had making 15hp. Since then I've had the engine apart so many times i lost count. During the last dyno run i hit 12.7bhp, not too shabby, but i knew there was more to be had. During that run my setup was with the 150cc bore, 1st gen yuminashi cam, stock exhaust with faddybike header, 25 tooth 4th gear and stock sprockets.
Today i went to the dyno with my laptop and a buddy to help me. After about 3 hours (i don't have a data logger) of working on the fueling i finally have a pretty decent map that works well. Its not perfect, but pretty close to. My main concern is making sure im not too lean anywhere. I got the map so the bike runs between 12.4:1 and 13.4:1, but in most areas its around 12.7:1 to 13.1:1. Its interesting that in a few specific places it was running either really lean or way rich. Maybe it has something to do with gas backwaves or resonant frequencies within the intake runner or reversion in the exhaust. At any rate its pretty decent and safely drivable without fear of running too hot. I believe oil engine oil temps stayed between 170~180 degrees so it looks like an ok operating temperature.
My current engine setup:
Yuminashi 160cc big bore kit
Stand-alone ECU
New yuminashi cam
Big bore injector
Longer valves and dual valve springs
33 tooth rear sprocket, stock front
25 tooth fourth gear(inside transmission)
Yoshimura RS9 full exhaust system
k&N r1100 air filter
Stock throttle body
Stiffer clutch springs
During tuning i really pushed the engine hard and i was a bit nervous revving to 12000rpm, but it held up fine. The stiffer clutch springs are also great. I am getting absolutely 0 clutch slippage. This alone is a great upgrade.
I was really shocked to see the engine make 16.9PS (16.7bhp), i was definitely was not expecting that. It also made 10.10ft lbs of torque. This is a huge improvement over my first run.
The black line is the run in january, the red is todays result in metric horsepower, but it is pretty close to the same as HP. Keep in mind i had a stock 34 tooth sprocket on with the first line and 33 with the red.
Torque comparison in Newton meters
The bottom line is I'm really happy with it so far. While the crower cam was ok i was not really happy about the valve noise. Im looking forward to putting some miles on to see how the durability is now. I also don't recommend lightening the flywheel and oil spinner. With a higher lift and duration cam it also doesn't idle quite as smoothly, its not too bad, but keeping the mass on the crank should allow the engine to idle better.
Ill have the fuel map file available soon for the stand alone ECU, so please feel free to use it and improve upon it. I tried to interpolate the whole map, but it ended up being way off. Like i said its not perfect as one can see the curves are not completely without chop, but it got me close in all areas and is quite useable.
If you purchase a kit please provide Yuminashi with feedback so they can continue to improve on what is a promising product.
Thanks for reading and once the rain stops ill get my top speed and road riding impressions posted. I did ride in the parking lot before i left the motorcycle dealership and it was really easy to pull a wheelie without using the clutch.
Sent from my iPad using HondaGrom.net
