NSR guys a little help? Very low Smoke, normal?

[Heretic]

I noticed my NS50 wasn't make much smoke this year.

I didn't ride it last year (which is why I'm worried), but the summer before it would smoke quite a bit on a cold start up.  And also a noticeable but faint smoke trail when full pin.     I'm not sure what was in the injector tank for brand that summer.  But now there is Amsoil HP Injector in there, and it doesn't make near the smoke on cold startup.  You can't even really see any smoke.  At full pin it doesn't seem to leave any smoke trail.  Is it just that Amsoil smokes very little?  (Is HP Injector the right stuff for these, it was that or Amsoil Interceptor on the shelf)

I can sometimes see a little mist of smoke, if I let it idle for a minute or two, then rev it out.  I also reached in there and manually pulled the injection pump open when it was idling on the driveway.  I got a little bit of noticeable smoke after about 15 seconds or so.  So is it safe to assume it's working?  I just don't want to melt it down. 

[Hawker]

The amount of smoke that you get does depend on the brand and quality of 2-stroke oil that you are using.

If you are worried about how much oil is coming from the pump, you could just unhook the line and turn the motor over by hand.  I would just keep an eye on the consumption from the injector tank.  If it goes down as fast as always, everything is probably ok.

Or, you could just do away with the injection system entirely and run pre-mix.  That little motor would benefit from not wasting power on turning a pump.

[Heretic]

Is the NSR50 premix?

I could do that, but I'm under the impression a re-jet is required.    I wonder if anybody makes a block off plate for it, or if I would be on my own to fabricate one.

[Hawker]

Yep, the NSR is a pre-mix machine.  Going to premix will technically lean out the mixture (less octane per unit volume of fuel), but not by very much, I'd wager.  Besides, these bikes come so rich from the factory that a little leaning out could be a good thing.  Of course, someone else may have rejetted it already.  In any case, reading the plug would be a good idea.

Team Calamari Racing has dealt with these bikes, and I'd bet that they'd have a block off plate and/or other performance goodies for it.

http://www.teamcalamari.com

[Heretic]

Well it was an SGI trainer bike, so I don't think it's ever been re-jetted.

I was just looking at a CF Posh Super Battle Racing CDI for it.   Apparently it removes the rev limiter found on street version NS50's  (I guess the NSR don't have the rev limiter?), and adds some more aggressive timing advance.  Not sure if it's worthwhile or not, but sounds like a good idea.?  Not really planning on too much else in the area of mods for this year.  I might remove that injection stuff now, and go pre-mix too, just for piece of mind.  I agree leaning it out a smidge, could only help.

Thanks.

[T-bar]

I thought the SSC trainers were NS50s, not NSRs?

[Hawker]

I thought the SSC trainers were NS50s, not NSRs?

Yes, they were.  The NS50 and NSR50 have motors that are almost identical.  The NSR is stripped down and set up for racing - no lighting coil, injector pump, rev limiter, kickstarter, etc, since it was never sold as a street legal machine.

The best mod for any small displacement road going two stroke is an aftermarket expansion chamber and a pod filter in place of the airbox.  For some reason, the manufacturers choke these bikes off with restrictive exhausts and intakes.  Doing this will require extensive rejetting, but it will pay off in spades.  That racing CDI sounds like a great idea too, especially combined with improvements to the exhaust and intake.  It will feel like a different bike.

The next step would be a bigger carb, porting, and squish band modification of the head.  Of course, once you get the motor sorted you are going to want to do something about the suspension, which is probably soft and has next to no damping.

The list can go on and on.