fuel filter and pump

[hoppy41]

hi, just got my superfour 1993 nc31. The owners manual states there should be a fuel filter and fuel pump? My bike doesnt seem to have this. The fuel tap is directly plugged into carbs?

Can anyone please shed some light on this? Do some bikes comes with fuel pumps?

many thanks

dave

[tomigun]

The NC31 has vacuum tank and no fuel pump.If you try to lift up the gas tank (at the back side near seat cowl)you will see 2 hoses.The right hose (as you seat at the bike)is for the air input to the gas tank.If this hose is stuffed no fuel is gonna travel to carbs.
There is this fuel valve under the fuel tank,at the left side (as you seat at the moto).
http://www.ebay.co.uk/itm/Gas-Tank-Valv ... 1070909413
There are two hoses,one comes from the cilynder to the valve that gives air and makes the membrane pulse, giving fuel to the other hose that goes from the valve to the carbs.
In the upper side of this valve there is a fuel filter already.Some owners(not me) put on a paper filter in the hose between the valve and the carbs,but i have heard that this makes fuel issues especially in high speeds.

[hoppy41]

thanks Tomi, making sense now.

The filter thats in the petcock can it be changed? Whats the little bowl for that unscrews at the bottom?

thanks dave

[tomigun]

thanks Tomi, making sense now.

The filter thats in the petcock can it be changed? Whats the little bowl for that unscrews at the bottom?

thanks dave

Info direct from the parts manual.If your NC31 is FiiN(1993) then your filters part number is 16952-MA4-771 or
16952-MY9-000.
If your NC31 is FiiR(1994),FiiS,FiiT,FiiV,FiiiS(1995)FiiiT(1996)FiiiV(1997)then your filter part number is 16952-MY9-305
Here a link for the first filter:
http://www.cmsnl.com/honda-nas750m-rc39 ... 952ma4771/
Look at this part and you will understand what is inside that bowl at the bottom.I can only tell you that if that membrane have a crack or small hole then you have fuel issues:
http://www.cmsnl.com/honda-nas750m-rc39 ... 953me5005/
I hope that i help.
PS:I believe the reason of using paper filter between fuel valve and carbs is that it is too difficult to find only the filter.Here in Greece a member of Superfour club asked for an oem fuel filter and they told him that he must buy all the petcock.Paper filter is a chip solution but with that way you can not protect the fuel membrane inside the petcock from dirt +rust that comes from the gas tank.

[hoppy41]

hi, my petcock filter screen is missing. Its a 1993 nc31. So theres no way of just buying that? part number?

Looks like ill have to buy a inline filter.

Im in UK, ill check with Honda too.

thanks Tomigun :-)

[tomigun]

Dave you have pm.

[hoppy41]

Hi. Put new petcock on. Still having issues. Runs ok on full tank of gas. Then when about 6 litres and especially at speed stutters and loses power. I think the breather tubes are blocked somehow. The wider one is ok. The narrow one whats this for ? Why are there two. ??? Dave

[Irishbiker]

Hi. Put new petcock on. Still having issues. Runs ok on full tank of gas. Then when about 6 litres and especially at speed stutters and loses power. I think the breather tubes are blocked somehow. The wider one is ok. The narrow one whats this for ? Why are there two. ??? Dave

Does it cut out when it starts losing power? Possible blocked tank vent? Take a spin on the bike with the cap cracked open, had a similar problem and that turned out to be the cause.