Hey guys, I just picked up a stock MC28. Only mod done to it is the HRC030 card. I was wondering if I need to rejet the bike or should I be ok running it for a month or two as is until I get some new pipes. The bike is running at sea level if that makes a difference

Also, this is my first two stroke street bike. Does any company sell a workshop book (ie hanes)? I want to change the two stroke oil thats in the bike. Should I just pour out whats in the oil reservior and refill it with the new oil (going to run Motul 600)?

Thanks
Pete

I can't stress this enough, and if you read up on the main Site, you'll find words to the effect of the following all over the place...

** Always check the jetting after ANY modification. **

As for the 2-stroke oil, yeah, just drain out what's in there, and refil with your desired brand.

As long as you don't try mixing synthetic/mineral with castor oils, then you won't have any problems.
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Andy.
NSR-WORLD.COM

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big pete wrote:Only mod done to it is the HRC030 card.................The bike is running at sea level if that makes a difference

Just??? Oh, is that all?

And you're at sea level

So timing moved forward from mc28 40bhp silly setting up to mc21+HRC box and loom, all speed restriction removed, rev limiter removed (or moved so far round I can't find it) and just for a little bonus extra oil at cold start removed too. Believe you me the only thing stopping your bike dying right now is the huge restriction in the exhaust. Remove that and you'll be able to join in on all the rebuild threads.

Seriously I did a similar thing (run a modded '28 without checking the jetting) and paid a heavy price. Read all about it here, ignore monkey and I bitching, it's all in fun (I hope) and see all the carnage here.
Ok the bike was a bit of a lemon and needed loads doing, it'd been down hard enough to bend the gear shaft, it looked like neither the oil nor the front sprocket had ever been changed etc.
But the engine still had to come out, the crank was full of bits and the bill could have been £700 or so lighter if I'd just took it steady for a few days and followed the tuning section.

Fantastic bike now though, well, not right now, I don't regret it for a second.
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thanks guys

hey fontyyy, do you still have a 400?
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1994 NSR250SE

Hey Pete,

Welcome to NSR-WORLD.com.

Now dont bring that many BARF'rs with ya

The 030 card is going to change some of the mapping, but I don't think it will do so much that you will need to rejet the bike when the rest of the bike is 100% stock. With no changes to the airbox, intake, or exhaust you should be fine with the stock jetting.

I ran my NSR all over the bay area with stock jetting (with a derestricted MC21) and had no issues. Once I went to a Jha air box, and started messing with the intake/exhaust was when I started getting into the jetting.

Problem with our area is that we can go from a nice warm 85 degree day in San Jose at near sea level, then get up into the hills where it may be 55 foggy as anything and be 3000 feet above sea level. I know when i got into jetting my bike it sucked cause there was never a perfect middle ground (except for the stock setting with stock airbox).

Good luck, and I think you will be happy keeping the NSR instead of selling it like you were thinking.
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Charles Gallant

thanks Charles for answering all my pm's. Dont worry...there will be more questions coming your way if you dont mind . It'll take me a little time to get up to par with 2strokes.

As far as jetting, hotter day and/or higher altitude = up the jetting?
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1994 NSR250SE

High temp needs leaner jetting
Low temp needs richer jetting
High altitude needs leaner jetting and higher compression
sea level needs richer jetting and lower compression

It all about relative air density. Which basically means how much oxygen there is in a given volume of air. Cold air is dense so contains more oxygen than hot (less dense) air. More oxygen needs more petrol for an efficient, controlled burn so richer jetting is required.

big pete wrote:hey fontyyy, do you still have a 400?

Yes mate http://www.aoof13.dsl.pipex.com/MyBikes/index.htm
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Please do not PM me technical questions, if you can't find it on the Forum start a thread