Last week I got my new mc18 but had some issues and here are the details: http://nsr250.net/forums/viewtopic.php?t=15043.

So one of the problems we found was that the idle rpm is around 1200 which is suggested by factory menu, but the bike died a couple times at low rpm idle without throttle, so we want to bump up idle to 1500 with a new pilot jet. The current pilot jet is a size 38 and we think it should be one size smaller.

So any place that we can get a new pilot jet?

Another problem we found was that the choke was kind of always on...fixed now.

Since you resolved the choke issue, have you done much mileage?

I'd consider new plugs if it doesn't already have them, and just give it run. As others have said, basics for now - sounds to me like this choke would be the issue.

Whenever I have an issue with the carb and its cleanliness related, I like to strip them completely, check all the jets are clear and look sharp when held up to the light, record needle positions (check needles are stock size and shape!) count screw turns, and then reset to standard if possible and applicable (airbox, exhaust, port mods etc all change this) - I'm no expert on NSR's as I don't have mine yet but its worked for me on everything else, and I find it better both mentally and physically to to just do it once, and do it right, and then have the peace of mind knowing its done, and if the problem persists, confidently move along to the next potential issue. Once you know you've got your air and fuel right, having presumably checked the basic electrical already, I'd then be checking beyond plug condition, is the core in the HT corroded, are the caps in good nick, swap the coils, does the problem swap to the other cylinder etc..

As Russ says, make sure the basics are right before you start chasing that problem with jet sizes etc...otherwise you can end up running down the wrong lines all the time, you'll go crazy!

As the choke is now clear, give the bike a good run on new plugs and then see about the tick over issue...lumpy tick over is often caused by air leaks (i.e. choke issues). I think it may be fixed already it may just need a good ride out!!

Russ_B wrote:Since you resolved the choke issue, have you done much mileage?

I'd consider new plugs if it doesn't already have them, and just give it run. As others have said, basics for now - sounds to me like this choke would be the issue.

Whenever I have an issue with the carb and its cleanliness related, I like to strip them completely, check all the jets are clear and look sharp when held up to the light, record needle positions (check needles are stock size and shape!) count screw turns, and then reset to standard if possible and applicable (airbox, exhaust, port mods etc all change this) - I'm no expert on NSR's as I don't have mine yet but its worked for me on everything else, and I find it better both mentally and physically to to just do it once, and do it right, and then have the peace of mind knowing its done, and if the problem persists, confidently move along to the next potential issue. Once you know you've got your air and fuel right, having presumably checked the basic electrical already, I'd then be checking beyond plug condition, is the core in the HT corroded, are the caps in good nick, swap the coils, does the problem swap to the other cylinder etc..

I've done 50 miles regular riding, and 10-20 miles high rpm(10000+) riding. No big issue found. Carb was cleaned. It was just that the mechanics suggested another pilot jet to increase the idle rpm...

Max wrote:As Russ says, make sure the basics are right before you start chasing that problem with jet sizes etc...otherwise you can end up running down the wrong lines all the time, you'll go crazy!

As the choke is now clear, give the bike a good run on new plugs and then see about the tick over issue...lumpy tick over is often caused by air leaks (i.e. choke issues). I think it may be fixed already it may just need a good ride out!!

The plugs looked fine actually. I took a look and it just got some carbon build up on it(mechanics said it was from the pilot jets being slightly to larger). Like my previous comment above to Russ, I gave it a really good run, no issue found. I was suggested to keep revving the bike while waiting for a red light because the idle is low.

Btw anyone know where to get the manual of the bike?

eBay or Jauce
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kangranwang wrote:
I've done 50 miles regular riding, and 10-20 miles high rpm(10000+) riding. No big issue found. Carb was cleaned. It was just that the mechanics suggested another pilot jet to increase the idle rpm...

https://tech.nsr-world.com/nsr250/all-nsr250/nsr250-stock-carb-settings.php

Stock pilot jet is #38 across the board. We've actually found we've often needed to go up a size on the pilots with the latest fuels.
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Andy.
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Andy wrote:

kangranwang wrote:
I've done 50 miles regular riding, and 10-20 miles high rpm(10000+) riding. No big issue found. Carb was cleaned. It was just that the mechanics suggested another pilot jet to increase the idle rpm...

https://tech.nsr-world.com/nsr250/all-nsr250/nsr250-stock-carb-settings.php

Stock pilot jet is #38 across the board. We've actually found we've often needed to go up a size on the pilots with the latest fuels.

My mechanic guy mentioned size 38 as well but he thought it should go 1 size smaller in order to reduce the carbon build up in the plugs. What do you think?

I think you should get a new mechanic!
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Andy.
NSR-WORLD.COM

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Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

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Andy wrote:I think you should get a new mechanic!

Lol. Can you provide the reason like why the fuel nowadays leads to bigger jet? I want to discuss this with my mechanic...

Another thing that I’m trying to solve is that this bike starts with one kick when it’s cold, but can take 20 kicks when it’s warm and has been resting for like 10 minutes. I think it has to be something with the carb...