NSR 2002

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

ive just phoned the local mechanic to ask how much it would be to have my nsr taken in and diagnosed with the starting issue. he has just told me that it is £50 an hour labour and it could take him a couple of hours to find why its not starting. he said there is a procedure that he follows i.e. he tries something and if it doesnt work then he tries the next step to eliminate the good bits. does anybody have any clue how i can do this myself by trying different things? its def got a spark and if i pour petrol down the intake to the carb it also starts but when it does it revs at 10k then cuts out.

Marci · Brolly Dolly Joined: 01 Sep 2005 Karma :

The problem isn't at the engine then... strip reeds, carb manifold, carb, air intake manifold and airbox. Ensure all rubbers are ok - not perished with cracks in. Strip carb and clean all jets etc. Clean airfilter.

If it starts and revs up with fuel directly in cylinder, problem can only be in the fuel delivery system... all easy stuff to remove, strip, clean and put back on.
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FAB-Racing MiniMotoSidecars - Back with a vengeance - F1 Class 2011...
CBR170 engine, custom chassis - www.minimotoscene.co.uk

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

yeah ive had the carb out the other day and checked again and its all clean also there is new gaskets on the reed etc its totally baffling me as to why it would be revving so high then dying after a couple of seconds. i thought it was the fuel system the other day but would that make the engine rev high then die?

Marci · Brolly Dolly Joined: 01 Sep 2005 Karma :

It's revving high due to the amount of fuel your pouring into the cylinder at a guess.
____________________
FAB-Racing MiniMotoSidecars - Back with a vengeance - F1 Class 2011...
CBR170 engine, custom chassis - www.minimotoscene.co.uk

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

what i done a few months ago because it just wouldnt start was me and dad bumped it outside and eventually after nearly passing out it fired and it actually ran and didnt cut out but again it was red lining it all the way and we had to kill the engine befor that did lol

Marci · Brolly Dolly Joined: 01 Sep 2005 Karma :

That can only be massive airleak and/or carb problem. It won't rev to 10k unless it has enough fuel to rev to 10k... are you SURE the carb is assembled correctly - slide properly inserted correct way round, correct size jets, float valve sealing properly etc etc...?
____________________
FAB-Racing MiniMotoSidecars - Back with a vengeance - F1 Class 2011...
CBR170 engine, custom chassis - www.minimotoscene.co.uk

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

well my mate rebuilt the carb for me ages ago and cleaned all the jets out etc. when we opened up the carb the other day to check the float because thats what i thought it was the pin that secures this in place stuck out the end slightly is this normal and does this have to go in a certain way round? what normally causes an air leak ? the guy at the shop said that theres possibly an air leak

Marci · Brolly Dolly Joined: 01 Sep 2005 Karma :

Cracks in the rubbers between carb and engine and carb and airbox... lack of gasket on carb float bowl...

If floats / float valve was a problem you'd have fuel dripping out of the carb breather nipple on the base of the float bowl.
____________________
FAB-Racing MiniMotoSidecars - Back with a vengeance - F1 Class 2011...
CBR170 engine, custom chassis - www.minimotoscene.co.uk

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

urrm there is no gasket on my float chamber lol should there be ? also ive got the screw done up all the way on the side of the chamber because if i dont then petrol leaks out. does this seem right.

Marci · Brolly Dolly Joined: 01 Sep 2005 Karma :

Screws on the SIDE of the carb are to set idle air:fuel mixture, and idle speed. They should be set according to the manual, not "to stop fuel pissing out".

There should be a rubber ring that sits in a lip around the edge of the float bowl which provides an airtight seal.
____________________
FAB-Racing MiniMotoSidecars - Back with a vengeance - F1 Class 2011...
CBR170 engine, custom chassis - www.minimotoscene.co.uk

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

right im guna go and order a gasket for the float chamber and the mixture and idle screws are at the top this one im on about is on the bottom of the float chamber. would the fact that ive not got a gasket on there stop the bike from not starting and when it does over revving?

Marci · Brolly Dolly Joined: 01 Sep 2005 Karma :

Apparently it's a PHBH28 carb or similar. There should be a big bolt on the bottom, that should be done up tight - it's what holds the floatbowl on and also should have the main jet fitted to the middle on the other end of it.

On the side are two screws. A Large sprung screw, and a smaller one.

Turn the smaller one ALL the way in til it nips gently, then wind it out 2 and a half turns.

Get the bike running then turn the Large sprung screw to set idle revs... one way will increase revs, the other way decrease revs. You want it set to idle around 1200rpm ish.
____________________
FAB-Racing MiniMotoSidecars - Back with a vengeance - F1 Class 2011...
CBR170 engine, custom chassis - www.minimotoscene.co.uk

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

yeah ive got the side screws set up but this damn bike is annoying me now big time lol ive just had the float chamber off and there is a small rubber seal on it which i didnt even realise was there lol the manual which i have got doesnt actually tell you much about the carb and pipe locations and the float etc.

Marci · Brolly Dolly Joined: 01 Sep 2005 Karma :

Have you checked that the throttle slide and needle are all correctly seated etc so that when throttle is closed the slide is in the fully-down position (look up the carb air inlet)?
____________________
FAB-Racing MiniMotoSidecars - Back with a vengeance - F1 Class 2011...
CBR170 engine, custom chassis - www.minimotoscene.co.uk

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

the way that i tested this was i took the throttle bit off the top of the carb then poured a bit of petrol in the air intake then started it and it revved up just as bad. i did the same procedure with the choke and the exact same thing happened again. the throttle and the choke havent had any adjustment made on them at all on the rebuild. the throttle barrel thing is seated in the carb properly aswell.

Marci · Brolly Dolly Joined: 01 Sep 2005 Karma :

That's not testing anything. That's you GIVING it fuel, and it'll rev as high as the amount of fuel you've given it. Stop pouring fuel in holes. We already know fuel is getting to the engine, that much is clear. What we don't know is HOW MUCH fuel the carb is giving it, and the only way to test that is to let the carb do the delivery, not by you feeding it thru a hole...

If you're hundred percent certain that the throttle slide and needle etc are all seating correctly, and returning fully to the closed position when throttle is shut (ie: no cable snags / cable too short once fitted so holds the slide open slightly), there's no further advice I can give.
____________________
FAB-Racing MiniMotoSidecars - Back with a vengeance - F1 Class 2011...
CBR170 engine, custom chassis - www.minimotoscene.co.uk

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

i think its time to ring a mechanic and get it booked in lol its guna be so much eaiser to do it that way and a heel of a lot less stressfull lol

nsr_rory · Renault 5 Driver Joined: 21 Jan 2007 Karma :

thanks for all of your help mate much appreciated ! got the bike booked in now for next wednesday mechanic is going to have a couple of hours to find the problem.