NC30 possible carb air leak locations

[krisztian_andre]

I made a video of the idle and it isn't too bad but it becomes worse when the bike gets hot in city traffic:

http://www.youtube.com/watch?v=xWPNfLjx ... page#t=93s

What do you think?

[bikemonkey]

Sounds a little like mine, but much more noticeable.

I however know my valve clearances need doing (I know it needs doing, winter time won't be long knowing England...)
Plus my carb restrictors for my 33bhp license and the fact I haven't re-jetted to suit might be a contributing factor.

How long ago were yours done?

[krisztian_andre]

Sounds a little like mine, but much more noticeable.

I however know my valve clearances need doing (I know it needs doing, winter time won't be long knowing England...)
Plus my carb restrictors for my 33bhp license and the fact I haven't re-jetted to suit might be a contributing factor.

How long ago were yours done?

A week ago.

[J.B.]

Kris,

I still think the most likely cause of the air leak is the O rings in the mixture adjustment. The ones I sourced locally are: 1 mm CS X 3.00 mm i.d. This is slightly smaller CS and slightly larger i.d. than OEM. So, they're a loose fit on the slow jets, too loose IMO and being a tad thinner CS I suspect they do not seal as well.

I suggest you either:

1/ pay the big money and get the OEM NC30 gasket sets (I already know you're not gonna go this route LOL)

2/ check if the OEM O rings from some of the pre-FI local 100 cc Hondas are a direct replacement (i.e. '08 Click, Wave etc). They all use Keihin carbies so there's a high likelihood of an exact match.

3/ try and source Nitrile O rings in the exact OEM size: many, many to choose from here:

http://www.rubberstore.com/catalog/as56 ... 39_43.html

Hopefully someone who knows the exact dimensions of the OEM o rings will chime in and assist.

Cheers,

Jimmy

[Neosophist]

Since you dont know you have an air-leak then i`d forget about the airleak idea for now.

It could be an air leak but sort the electrical out first.

Hanging revs can also be caused by a lean mixture, try backing the pilot screws out another turn and see how that affects the return to idle.

[J.B.]

He doesn't know he has an electrical problem either.

[krisztian_andre]

Kris,

I still think the most likely cause of the air leak is the O rings in the mixture adjustment. The ones I sourced locally are: 1 mm CS X 3.00 mm i.d. This is slightly smaller CS and slightly larger i.d. than OEM. So, they're a loose fit on the slow jets, too loose IMO and being a tad thinner CS I suspect they do not seal as well.

I suggest you either:

1/ pay the big money and get the OEM NC30 gasket sets (I already know you're not gonna go this route LOL)

2/ check if the OEM O rings from some of the pre-FI local 100 cc Hondas are a direct replacement (i.e. '08 Click, Wave etc). They all use Keihin carbies so there's a high likelihood of an exact match.

3/ try and source Nitrile O rings in the exact OEM size: many, many to choose from here:

http://www.rubberstore.com/catalog/as56 ... 39_43.html

Hopefully someone who knows the exact dimensions of the OEM o rings will chime in and assist.

Cheers,

Jimmy

The idea is that if I find the o-ring measurements then nobody will ever have to pay 60 or 80 GBP just to get four new o-rings for their pilot screws.

Keihin part number: 16075-KG8-9010 pilot screw o-ring CS1.2mm ID2.7mm
fits the description.

JB, I lost the paper with the washer's dimension, do you still have it?

[J.B.]

That is pretty much exactly what I measured the OEM o rings to be, yes.

The washers ... I don't have any anymore because all my spares are now in your carburetors but Rick O told me he measured them at: 5 mm o.d. x 3 mm i.d. x .5 mm thick.

JB

Kris,

I still think the most likely cause of the air leak is the O rings in the mixture adjustment. The ones I sourced locally are: 1 mm CS X 3.00 mm i.d. This is slightly smaller CS and slightly larger i.d. than OEM. So, they're a loose fit on the slow jets, too loose IMO and being a tad thinner CS I suspect they do not seal as well.

I suggest you either:

1/ pay the big money and get the OEM NC30 gasket sets (I already know you're not gonna go this route LOL)

2/ check if the OEM O rings from some of the pre-FI local 100 cc Hondas are a direct replacement (i.e. '08 Click, Wave etc). They all use Keihin carbies so there's a high likelihood of an exact match.

3/ try and source Nitrile O rings in the exact OEM size: many, many to choose from here:

http://www.rubberstore.com/catalog/as56 ... 39_43.html

Hopefully someone who knows the exact dimensions of the OEM o rings will chime in and assist.

Cheers,

Jimmy

The idea is that if I find the o-ring measurements then nobody will ever have to pay 60 or 80 GBP just to get four new o-rings for their pilot screws.

Keihin part number: 16075-KG8-9010 pilot screw o-ring CS1.2mm ID2.7mm
fits the description.

JB, I lost the paper with the washer's dimension, do you still have it?