Needle and seat testing

[bazwell]

Is blowing through the fuel line with your mouth a good test of a needle and seat, or am I just being a dumb-ass?

I seemed to me that my no 4 needle and seat was acting all funky. Seeing as how it's heading towards the end of riding season, I thought that I would be better off ordering a stack of parts and doing a proper rebuild on the carbs.
I'm still tooling around trying to work out what to buy and how I'm going to do it. And the weather is still nice. So i decided to try and see if it was really in need of new parts.

The needle seemed OK, and when I tested it by blowing through the fuel line, it cut off pretty good, at the right level.

So I put a new fuel filter on, put the carbs back on, and tested it out. Eventually fuel just floods out of the needle jet tube thingey, where the needle on the slidey thing pokes in and out.

The weather is so perfect, and I ain't got the parts. Woe is me. :bang head:

ps. sorry about all that technical jargon :biglaugh:

 

[dannymax]

Re: eedle and seat testing

Sounds like the float may be hanging up....was it moving freely up & down when you had the cover off, maybe the mounting post is bent causing it to rub or bind.

 

[naughtyG]

Re: eedle and seat testing

The weather is so perfect, and I ain't got the parts. Woe is me. :bang head:

Well what do you know, I've got all the parts (even my new larger tank arrived) but still got NO BIKE !!!!

And yes the weather could not be better.. :damn angry::damn angry::damn angry:

 

[bazwell]

Re: eedle and seat testing

Sounds like the float may be hanging up....was it moving freely up & down when you had the cover off, maybe the mounting post is bent causing it to rub or bind.

Checked that one out. No joy unfortunately, seems perfect.
Thanks for that one though Danny, it was worth having a look! :biglaugh:

 

[tugla]

Re: eedle and seat testing

got a pic of the needle, is the tip worn out or damaged??

 

[bazwell]

Re: eedle and seat testing

Went out and gave it a go with my phone.
I'm surprised it isn't working for me.

 

[dannymax]

Re: eedle and seat testing

Almost looks like some rub marks at the bottom of the ridges, when you blow on the fuel line and tip the carb upside down does the needle seat or can you continue to blow air thru?

That's an odd place for the needle to bind....if it is. :ummm:

Did you try a Q-tip on a hand drill with very mild abrasive medium....I use 'cleaner/whitener' toothpaste, it rises well with water....to polish the seat?

 

[tugla]

Re: eedle and seat testing

if when you blow air and lightly push the needle towards closed does it stop the air and then let it go air starts up again? if so sounds like a worn needle or seat....... doesnt look new the needle anyways.

 

[dannymax]

Re: eedle and seat testing

if when you blow air and lightly push the needle towards closed does it stop the air and then let it go air starts up again? if so sounds like a worn needle or seat....... doesnt look new the needle anyways.

There's that 'great minds' thing again Rov!! :biglaugh:

 

[tugla]

Re: eedle and seat testing

There's that 'great minds' thing again Rov!! :biglaugh:

mmm well must be the exposure to brc.......missed the long weekend, will have to make up for that one....

 

[bazwell]

Re: eedle and seat testing

Almost looks like some rub marks at the bottom of the ridges, when you blow on the fuel line and tip the carb upside down does the needle seat or can you continue to blow air thru?

That's an odd place for the needle to bind....if it is. :ummm:

Did you try a Q-tip on a hand drill with very mild abrasive medium....I use 'cleaner/whitener' toothpaste, it rises well with water....to polish the seat?

If I blow thru the fuel line is seals perfectly when I tip the carb over. Every time! That's what confuses me.
I haven't polished the seat, but I've been over it with a fine tooth magnifying glass often enough to be sick of the sight of it! I'll just change the needle and seat and stop pfaffing around. They are probably just suffering from being 27 years old.

I want to give the carbys a fulll strip and clean anyway.

Cheers! :biglaugh:

 

[tugla]

Re: eedle and seat testing

sounds like its fine......you have to tip it and if it seals with gravity effecting the needle should be good. not the same as 4-6psi of fuel or what ever the vmax is at but close. so trying to clean it up might help if for sure thats the issue your having.