hi

got my mc21 recently, but starting to experience problems with the plugs either fouling / no fuel delivery / no spark.

the previous owner told me the bike is stock, with no wire splice (which i need to check) although when changing spark plugs the other day, i noticed the airbox lid mod has been done.

rode the bike for little over a week as its my bike into work, a 60km round trip, everything seemed fine, parked it when i got home, turned switch off, turned fuel off. next morning bike was a no go, wouldnt start with the choke on, usually it would start with just the one kick. tried to push start it, still nothing, gives the sound you get when you just hit reserve.

bike sat for 2 days till i got plugs from a good friend over the weekend, whacked em in, started fine, rode fine. back home parked it again, fuel switch off, kill switch off. monday morning no go again, got plugs last night so i changed them over this morning, just in case something will foul them overnight. wouldnt even kick over, tried push starting again and the same thing happened. fuel in the tank, switched it to reserve just in case, tried kicking it over to no avail.

the last owner said bike hasnt been ridden in a while. so when i got it my mate helped me out with a battery and oil. finishing early today, so im planning to strip the carb off and clean it, and try to inspect. couldnt find a post on how to clean carbs, and all i could find in the tuning section was this

"Now the carb's are off, take the opportunity to clean the exterior surfaces until they are spotless. You are now ready to start installing the kit."

what sort of cleaning agent should i use? would a spray type of carby cleaner be good?

i also noticed that when the key is in the ignition section and i switch on the kill switch, my RC valves dont move.. could this be a problem?

forgot to mention when i removed the plugs they are an oily black, and when the bike is just sitting there it reeks of fuel. doesnt appear to have any leaks anywhere though.

sorry for the long post, but any help appreciated.

found this post by maxim,

is it that straight forward?

It's quite a straightforward job on the 21. Remove the seat unit and tank, followed by the airbox if you have one. Make sure you get a good mate with the airbox seal screws, using a good Philips driver as they are made of soft blue cheese and can round off very easily...

Once these are out of the way, access to the carbs is easy. You will need to remove most of the connections to take them off, although you can usually leave the throttle and choke assemblys in situ. The thing to try first is to clean up everything in the float bowl, which is at the base of the carb and held in place with 4 screws. Have a PU container ready to catch the fuel contained in them as you turn the carbs upside down. Once you have the bowls off, you will see some brass jets. Have a look at the float bowl and check to see if there is any build up of a residue. The jets can be taken out gently, using an 8mm spanner for the mainjet holder, and a small flat head/slot driver for the main jet and slow jet.

Clean all of the bits using a good carb cleaner and a toothbrush and re-assemble. At this point you can also check the float height, which are the black plastic pieces in the float bowl, 2 per carb. Holding the carb upsidedown, they should rest with 13mm showing from the base of the carb.

If that doesn't help then we can look at other bits. Wink

It really is that easy.

Have you taken a plug out as soon as you finish riding to check the colour?

Black / oily plugs indicate the mixture is too rich. Is the air filter clean?

What voltage is the battery at when the engine is off / idling / at 4000 rpm? It does hint at weak spark, and the NSR is very suseptable to low voltage preventing it starting.

The power valves will not move if they were in the park position when the engine stopped (which they will be if it was at tickover).

Havea look at that lot and get back to us.
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

thanks dave, turns out to be a spark problem, mate is having a look at the coils for me

just wondering what are replacement screws for the float bowls as i've nearly rounded two, they are extremely soft, and a bit on the rusty side

voltage of the battery tho is 12v, the coil leads are .36v, when i kick over the bike there is no voltage spike

bike doesnt run at the moment, but see how it goes

well finally got the bike started, now im having an idling problem.

if the RC valves are not adjusted properly do they cause poor idle till the motor cuts off?

i've tried adjusting the rev screw but that doesnt work, i might have stuffed that up when i took the carb off so i'll need to check that again

but the RC valves are a thing of concern, following the adjustment steps in the tuning page when i have the switch set to on, and turn the ignition on, RC valves dont move at all... i'll need to check the wiring i guess and see how that goes

but does it cause the motor to idle poorly and die?

Very unlikely. Unless it's because the cables are too tight and the servo motor is straining and upseting the PGM!

The servo motor will not run at switch on if the bike was idling when shut down - the valves will be in their 'parked' position. Rotate them by hand away from park with the ignition off, then switch on and they should return to parked.

Does the motor run ok at anything other than idle?
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

thanks dave, tried what you said about adjusting the valves and they do move back when i switch on the ignition switch.

only just realised what you were trying to say in the other post about them not moving when the bike is in idle.

rc valve cables have some slack in them.

only rode it in first gear, down the street seemed to be normal, only when it tries to idle it dies.

i did have a play around with the carbs though, so i might have stuffed something up..

Blocked idle jet, wrongly set mixture screw, wrongly set idle / throttle cables...
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

i sorta opened up the carbs... but i didnt touch anything i just cleaned it with some carby cleaner.

going to try and check my idle screw later today, if that doesnt work i might as well open it up again.. is there a link on how to set up the float height, or procedures to overhaul a carb?

thanks

A search for "float height" perhaps?

Took me all of 15 seconds!

There's plenty of threads covering cleaning of carbs and components, and information on base settings (both HRC and OEM Honda) on the Site.
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Andy.
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i looked through the tuning pages and did do a search, must of overlooked that thread.

i remembered seeing it somewhere, than through that link you gave remembered tyga had it on their site too

http://tyga-performance.com/site/index.php?cPath=369_379

thanks tho andy

Workshop Manual: Float height setting.
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Andy.
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bike started yesterday though and took it for a short ride

idled okay but seems to have developed a flat spot, i have a spare mc28 carb for me to overhaul though which i think i'll use

thanks for the help dave and andy

Very different jetting and needles on the MC28 carbs, and also different air corrector plumbing. You will most definitely be on your own if you go that route as I have no idea how it will all mix'n'match with the MC21 electronics/pipes/plumbing etc!
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Andy.
NSR-WORLD.COM

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thanks for the heads up, guess i wont be going down that route