Just got my mc21 in manila and i noticed my front cylinder doesnt do much but blow cold air till i rev it. the other cylinder idles nice and hot. when i do rev it the front cylinder feels strong and gets hot. Is this normal?

no it's not. check your coil is fine, spark plug and connections are fine. Next I would check your reeds and carbies.

hrm, their just isnt pressure coming from the exhaust until i rev it then it sounds great. connections checked will look at the carbs.

searching for my feeler gauge but noticed that the rear cylinder seems to be firing steady while the front isnt as steady.

It could be a failed crank seal on the front cylinder side. The engine is basically an air pump, so if the seal integrity is lost on one side it won't pump air as effectively / strongly as the other side.

Don't panic just yet, check the basics / obvious parts first - ignition / carbs etc. Then check the piston rings, make sure you have decent compression. If all that checks out, think about doing a crankcase pressure leak-down test.

Do also search the discussion forum for these topics, all have been covered before.

Good luck.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

thanks for the input, i wasnt sure if that was a problem or not. will have to look deeper tomorrow.

check your coil resistance too, I'm sure it has been mentioned here before if you do a search in the forum.

started checking the coil wiring and found some corrosion along with what seemed to be weak connections. runs alot better now, as its firing evenly. That aid i can tell i need to adjust the carb! one pipe is super hot at idle (rear) the other is only warm.

Not that it's always the case, but I've seen some shocking examples of poorly maintained NSRs (and import bikes in general) in SE Asia... probably due mainly to a lack of knowledge and spares for them.

It's quite possible it's been stood around a while, so get the carbs off and check the jets are clear, specifically the slow jets. If you are lucky it will just be a dodgy slow jet.
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Andy.
NSR-WORLD.COM

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I bet you a pound to a pinch of sh!te it`s just your carbs need balancing.
You do it by adjusting the spring loaded screw between the carbs on the throttle linkage. You need to synchronise, or balance the throttle slides so they open simultaniously.
I had the same issue long ago.
It`s a bit of a pain if you have the stock airbox fitted, is also easier to do with the tank removed and an auxillary tank fitted temporarily. You can extend the fuel line from the standard tank and sit it on the bench as an alternative.
I got fed up trying to synch the slides by eye and did it by ear and eye instead in the end. Whatever works for you.
Once they`re set you should be able to adjust the tickover quite easily and have both exhausts getting warm on idle.

Another kababayan(countrymen) nsr lover Hope everything is well for your bike.

the carbs are next. i went to the tuning section and realized that booster hose was gone and that all the hoses off the carb were blocked off. remedied that and now it starts with ease, unlike before. but i still have the sense the jetting or adjustment is off as the rear cylinder is blowing very hot and the front is just warm. at idle i am used to warm air coming out and the hot exaust and 1100 rpm makes me nervous. Since i bought the bike last month i havent had a real chance to ride it. THe pgm was missing the cover and suffered from water failure the second ride! since then it has sat while i went through it going WTF is this and why is this like that.

Here in the philippines it is hard to get quality items and exactly what you are looking for. i spent 3 days looking for fork oil, and i am still looking for stainless bolts since mine are all rusted. every part purchase is an up hill battle, why i dont know!

By the way i am running open carbs do to the fact the K&N it came with were rotted out and rusted. no luck as of yet finding a a replacement or foam filters. I have a tig welder so i might end up making a housing for a filter i can get.