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Discussion Starter · #1 ·
Hello there.

It's my first time here on this forum. I was redirected from the other forum :p

My bike Honda NSR had two major repairs. First, it was a new cylinder and a new piston. Alain helped me with all of it, without his help I wouldn't know what to do. Then the rod seized...it was lacking lubrication and just seized. The "circle" turned into an egg. After that, my mechanic said to ditch the oil pump and run premix. So right now I'm mixing ipone 2t samourai racing 50:1, but was recommended to switch to 32:1 (high revving 125cc bike) and that's what I'm gonna do.

After the repair, the bike has problems with stuttering and shaking. At about 7k rpm with WOT it stutters, it shakes, and it struggles to go past 7k. After a few seconds, it finally manages to do that and pulls nicely until the redline. What I did is increased the amount of fuel by raising the needle. It helped a little, but now there is a lot of spooge and it seems it's not the way. I educated myself some more about carbs and I think I am on the right track? Right now I am running stock jets 138 main, 42 idle, and 65 power. What would you change here? I should probably increase the main jest size to 140, or even 142? What do you think?
 

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High revving - high power nsr?
Thats a new thing:)

Joking aside heres a post from few days ago and use that information... Beong new on a forum you shoold have read a little back at least... Its actually the very first post before yours...


Ps no need to run 32:1 on a road bike using such oil....

Dont forget. Oil changes the viscosity of the fuel and change of oil type or ratio will effect jetting!!
 
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Discussion Starter · #3 ·
High revving - high power nsr?
Thats a new thing:)

Joking aside heres a post from few days ago and use that information... Beong new on a forum you shoold have read a little back at least... Its actually the very first post before yours...


Ps no need to run 32:1 on a road bike using such oil....

Dont forget. Oil changes the viscosity of the fuel and change of oil type or ratio will effect jetting!!
High revving, not high power :)

I've read all those previous posts, and they don't help at all. I spoke a few times with Alains, my carb is stock and was running fine before. Just asking if someone had a similar situation (since you guys specialize in NSR), and maybe if my bike's behavior signals that it's too lean on WOT (main jet) yet too rich on 1/4/-3/4 throttle (needle). I did stumble on all of the jetting articles (the one linked in a previous thread) and I'm a little confused.

Yeah, I am aware of that, more oil = leaner mix. Everything would suggest that the main jet is too small. That is the first thing that I'm gonna experiment with.
 

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The thing is that nobody can point you correctly. That is why I dont give a straight advice as to "go for a bigger MJ"

More oil=displaced amount of fuel and also more viscose fuel. Makind it leaner

Alcohol in fuel, needs more fuel for stoich ratio. Ie for E10 or E5 fuel you need more fuel, ie normal one becomes lean and you need a bigger MJ....
But you have to remember. Needle position is also effecting the MJ/WOT and MJ is effecting yhe the needle/part throttle even on idle. And you can feel it even at ¼..

Be careful with whatever you do.
 
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Discussion Starter · #5 ·
The thing is that nobody can point you correctly. That is why I dont give a straight advice as to "go for a bigger MJ"

More oil=displaced amount of fuel and also more viscose fuel. Makind it leaner

Alcohol in fuel, needs more fuel for stoich ratio. Ie for E10 or E5 fuel you need more fuel, ie normal one becomes lean and you need a bigger MJ....
But you have to remember. Needle position is also effecting the MJ/WOT and MJ is effecting yhe the needle/part throttle even on idle. And you can feel it even at ¼..

Be careful with whatever you do.
I understand that and I appreciate all the input you can give. I know, there are so many variables that the answer can't be so easy. I am really thankful. I've read a lot about two-stroke jetting over the past few days and I have learned a lot more thanks to people like you.

In terms of fuel, I am using our European (Poland) Euro 95. According to our gov info, it is the E5 variant. Euro 95 and Euro 98 are both E5 in Poland.

I will remember that. I've seen the graph that shows the jets that take over when cracking open the throttle. For now I have marked my throttle position 1/4,1/2,3/4 etc. and I will try to jet it correctly starting with idle, then the needle, and then main jet. Overall I think I am running rich on the lower throttle positions because I still have a lot of spooge even after 20 kilometers. I will however test that and try to make it better...and not to kill my motor.
 

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Be careful with thise graphs. They show where one is mostly effective. Not where they are not effective. Main jet influences the idle, and vise versa. There is no single circuit that is not active all of the time. They are just more or less effective (the "more" part being shown on those graphs)
 
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Discussion Starter · #7 ·
Be careful with thise graphs. They show where one is mostly effective. Not where they are not effective. Main jet influences the idle, and vise versa. There is no single circuit that is not active all of the time. They are just more or less effective (the "more" part being shown on those graphs)
Thank you for the top Remy, I will keep that in mind.
I'm actually leaning back to the idea of going back to the oil injection. I would then use stock settings for this carb and have peace of mind.
But then why the connecting rod seized...
 

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The stock size is also wrong as you dont use the fuel it was designed for.

What oil did you use in oil injection
 

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Discussion Starter · #9 ·
The stock size is also wrong as you dont use the fuel it was designed for.

What oil did you use in oil injection
Hmm you may be right. It's getting more and more complex with this bike.

I was using Motul 710 with the oil injection. Right now I use Ipone 2t Samourai. I think both are suitable for oil injection.
 

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Discussion Starter · #11 ·
Ok so I came back to oil injection, so far so good, everything works fine. The bike still struggles and a new thing just showed up...

I'm dripping transmission oil AGAIN on the left side (magneto/coil). All of the engine seals were changed and are brand new, and yet the oil is dripping again. It just sips on the starter...

I'm so sick of this seriously...now waiting for my mechanic to retake a look at it. A faulty seal on the left side (as far as I'm aware) will cause lean condition due to air being sucked into the crank chamber. Last time it was leaking as well, and maybe THIS was the reason connecting rod seized yet the cylinder/piston was in good shape.
 
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