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Discussion Starter #1
Although many of the parts are in stock we are waiting on a couple still from Yuminashi. Within the next two weeks I expect to have all of the parts and will be taking pictures of the engine disassembly and installation of the parts on my msx125 for all of you to enjoy.

Yesterday i paid for the following parts from a Yuminashi distributor in the netherlands.

150cc light bore kit
sx30 head (same diameter valves as the tb v2 head)
Yuminashi camshaft
High performance injector

total price: $1130 with tax and shipping.

i currently have 840km on my msx.
 

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Discussion Starter #4
Ive already got a stainless steel down pipe on the bike with the stock muffler for now. I am aware of the many different exhausts available, but haven't decided on one yet. Im leaning toward a Yoshimura. Eventually i will also be getting a fuel controller. The only intake mod for now will be match porting if it needs it.
 

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Good stuff! Will be watching this with interest.

May I ask why the 150 kit? With the head and the injector would that not give you the scope to go to 180?
 

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Although many of the parts are in stock we are waiting on a couple still from Yuminashi. Within the next two weeks I expect to have all of the parts and will be taking pictures of the engine disassembly and installation of the parts on my msx125 for all of you to enjoy.

Yesterday i paid for the following parts from a Yuminashi distributor in the netherlands.

150cc light bore kit
sx30 head (same diameter valves as the tb v2 head)
Yuminashi camshaft
High performance injector

total price: $1130 with tax and shipping.

i currently have 840km on my msx.
Patiently waiting!:thumbsup:
 

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Discussion Starter #9 (Edited)
I went with the 150 for three main reasons. If i went with the 180 kit i would need the 31mm throttle body which would be around another $350-$400. I may do this later on, but for now the 150 should be fine. Second reason is, i want to maintain a balance of power vs reliability. The bigger the bore/piston the more mass and crank angle the engine will be subject to meaning more stress. Finally, the 150cc kit is powder coated black. During the safety inspection it won't be as obvious that the engine has been modded if the cylinder is the same color as the case and hopefully therefore, they wont bother to look. I have a yx 150 on my pitster pro lxr with a bench flowed 4 valve head. It has a lot more power than the msx125/ grom. Same with my '76 monkey with a yx engine, 146 TB BBK and a z40 cam. Im hoping to achieve similar or better power results. If the head is designed well im hoping for around 15-16hp. This should be plenty for what I'm doing. The roads around my area are very twisty and hilly, which are perfect for the msx125/grom, but id like to be able to maintain 65mph up hills without the engine bogging down so much to 50mph.
 

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Something you could look into, from what ive read a PCX uses a 30mm throttle body standard, while I haven't seen an MSX tb off the bike there's a good chance they're the same just larger than one another.. Here in the states you can buy a complete pcx tb from honda with the sensors attached for less than $120
 

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Well, part of the fun of this bike for me will be pushing it to the limit all the time. That is a lot easier to do on a 125 than it is on a 1200. As the engine gets bigger and faster it is harder to push it to the limit. For example, it is easy to ride a stock Ruckus at full throttle all over town, but pretty much impossible with a full on sport bike. The roads just are not long enough and there is too much traffic etc... Anyway, this is something I will think about long and hard before I go too crazy with the engine. I will probably focus on the suspension first and then just work on stretching out that throttle cable.
 

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Discussion Starter #12
Something you could look into, from what ive read a PCX uses a 30mm throttle body standard, while I haven't seen an MSX tb off the bike there's a good chance they're the same just larger than one another.. Here in the states you can buy a complete pcx tb from honda with the sensors attached for less than $120
Interesting i might have to look into that. Might be worth an email to yuminashi.
 

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Yeah I'm debating between the 180 and 150... decisions, decisions.
 

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Discussion Starter #14
Once the 150cc is worn out I'll probably bore up at that point and get the cylinder Nicasil coated and a new piston

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Discussion Starter #15
I bet Tb will come out with BBKs, heads, cams and all sorts of stuff that will be reasonably priced for this engine,. They may copy like they did takegawa with the +r head.

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I foresee Two Brothers and BBR Motorsports coming out with a ton of parts for these bikes.
 

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The roads around my area are very twisty and hilly, which are perfect for the msx125/grom, but id like to be able to maintain 65mph up hills without the engine bogging down so much to 50mph.
Exactly what I am thinking. Hills and full tanks of fuel are the devil! :furious:
 

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Once the 150cc is worn out I'll probably bore up at that point and get the cylinder Nicasil coated and a new piston

Sent from my XT890 using Tapatalk 4 Beta
How many miles or hrs. do you think the top end will last compared to say the stock setup? Doesn't seem to be much more stress with this conversion. What do you think will wear? Bearings, rings, guides, or just the piston skirts? Curious.:encouragement:
 

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Discussion Starter #19 (Edited)
It depends, I am not sure if the new cylinder is Nicasil coated, if it is it could last years, if not maybe a few years. It all depends on how much you ride it, but it shouldn't be as often as a dirt bike. The piston rings and bore would wear the most. Lugging the engine does the most damaged as it squeezes the oil layer out between the bearing surface and crank journal. This can cause metal on metal and can wear off some of the layers of the bearing surface. Some Connecting rod and crank bearings have several layers of metal to include steel, copper and tin. The top layer is softer and allows small particles of metal shavings to embed in its surface so as not to score the journals. This why it's so important to change the oil early during the break in to minimize this. On many motorcycles they have just roller bearings or needle, but still are susceptible to wear.

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Finally, the 150cc kit is powder coated black. During the safety inspection it won't be as obvious that the engine has been modded if the cylinder is the same color as the case and hopefully therefore, they wont bother to look.
Relocate to NJ where we have neither motorcycle inspection nor emission inspections for motorcycles! Put whatever you want on that sucker!
 
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