Quote from: Toner on April 25, 2018, 05:55:15 PM

Quote from: The Buddha on April 25, 2018, 04:40:22 PM

Quote from: Darkstar on April 24, 2018, 06:10:01 PM
buy jets and allen head bolts from The Buddha, then get o-rings from thisoldtractor,

and drill out the brass plug covering the pilot mixture screw, as it allows you to dial that circuit in nicely, plus you'll look cool doing it when you stop for coffee on the group rides   

I also have the O rings. If I can find em now - well that's the question.
Cool.
Buddha.

If I can get it all from you, that would be great. Do you have the one-sized-up jets Alpo is talking about? 
If you have the boots too, even better.
Let me know, Cheers Buddha.

I don't have boots. I have jets - you need 40/125 I believe, yes I have those. O rings I need to find em. I am not even sure if I can but will know by the weekend.
Cool.
Buddha.

Quote from: Toner on April 24, 2018, 10:20:13 PM
measure the butterfly height with digital calipers?
I've seen people sticking needles in to gauge the gap but cannot picture being able to use calipers.

You can get calipers which are able to 'inverse measure', mine can. They just have some bits that stick out the other side of the caliper which you would put there instead.

Dial and digital calipers have a rod that extends out of the shaft as the jaws are opened. That rod provides the "inverse measurement", which is identical to the distance the jaws are open. I set the end of the shaft on the mouth of the carbs and used the rod to measure the butterfly openings.

Quote from: The Buddha on April 26, 2018, 05:38:19 AM
I don't have boots. I have jets - you need 40/125 I believe, yes I have those. O rings I need to find em. I am not even sure if I can but will know by the weekend.
Cool.
Buddha.

Thanks Buddha, Darkstar said you might have allen head bolts too. I'll get some of them too if you do.

Here's  the most detailed instructions yet on actually building the manometer. I wondered how the bridging tube was filled but in fact it's ridiculously easy. https://youtu.be/7D_f05_a74Y

Quote from: The Buddha on April 24, 2018, 02:18:43 AM
You don't need either to synch the carbs. Look to a bright spot and adjust the idle screw to set the crescent of light as thin as possible, and then adjust the butterflies to be equal. That's a lot easier if you have the carbs off, which you would when installing a rebuild kit.
Cool.
Buddha.

This makes sense, and it's what I did on my bike as I don't have a sync tool.

But can the case be made that vacuum synching on a running motor is a significantly more accurate test?  Assuming no clogged jets or intake boot cracks / leaks, would there be enough variability in the engine pistons / rings / valves etc that a dynamic test would give much different results?  Or is the simpler static mechanical test pretty much adequate?

Yes, I recently installed a new set of carbs and I used the eyeball method to sync them, they feel good but I am curious to know how they really are. Will be checking next service.

I was reading the "Haynes Carburettor manual" that I picked up at a yard sale and they make an interesting point regarding the fact that on our carbs the "slide" is dependent on the butterfly opening, the diaphragm resistance, spring strength etc. The last ones can only be verified when running. I guess they are saying you can get close without gauges but it probably won't be perfect. Here is what they say (note that they use the terms CD for our carbs = "constant depression")

"On twin-cylinder, twin-carburettor installations, it will be
necessary to attend to the problems of synchronisation, or
balancing carburettors which are out of balance will result in
surprisingly rough running, and it is vitally important to ensure
that this is correct. Where CD carburettors are employed, it is
not really sufficient just to check that the two butterfly valves
open together, as this does not necessarily mean that the
piston/valve arrangements will do likewise. For this reason, it is
recommended that vacuum gauges are used to check the
depression in each inlet passage. For owners who wish to
attempt adjustment by feel, the following procedure should be
followed. "
Cheers

Hello hereennow!

You've been posting some really good info.

Would you mind posting the next section that follows:
"For owners who wish to attempt adjustment by feel, the following procedure should be followed. "
What's that procedure?

Hi Endopotential, sorry - missed your query. It's a few pages with some pictures, PM me with your email and I'll send you the material.

If Buddha isn't able to find the parts, do you think this set will work if I request a 125 main jet and a 40 pilot jet?

https://www.discountbikespares.co.uk/ourshop/prod_5449514-CARBURETTOR-REPAIR-KIT-GS500-K-Y.html

I would have to inventory all of those o rings but at first blush it looks like it would work.

Many of those hard parts you won't have to replace because you usually don't even remove the parts when doing a carb cleaning. The rest, might as well put in new parts (including that pilot needle).

Quote from: Toner on May 01, 2018, 01:48:50 AM
If Buddha isn't able to find the parts, do you think this set will work if I request a 125 main jet and a 40 pilot jet?

https://www.discountbikespares.co.uk/ourshop/prod_5449514-CARBURETTOR-REPAIR-KIT-GS500-K-Y.html

Going to have to make a purchase soon so I'm going to go ahead and buy two of these kits if I don't hear of any other option in the next day.

Something you need to consider. It's not mentioned in the Wiki and it is always overlooked by the 'carb experts' in here.

Because of the slight differences in the make up of fuel UK and other European bikes were jetted differently from USA bikes in the factory.

So while the advice given may work fine for 'full fat' gasoline it could well be a different story when it comes to our lead-free petrol.

This place will well you everything you need and give you reliable advice

http://www.nrp-carbs.co.uk/contact_us.htm

Quote from: sledge on May 06, 2018, 06:28:27 AM
Something you need to consider. It's not mentioned in the Wiki and it is always overlooked by the 'carb experts' in here.

Because of the slight differences in the make up of fuel UK and other European bikes were jetted differently from USA bikes in the factory.

So while the advice given may work fine for 'full fat' gasoline it could well be a different story when it comes to our lead-free petrol.

This place will well you everything you need and give you reliable advice

http://www.nrp-carbs.co.uk/contact_us.htm

Didn't think of that. Glad I hadn't ordered yet.
This site does say that I may need a #115 main jet for the EY model. I was going to get a #125.
https://www.discountbikespares.co.uk/ourshop/prod_5449514-CARBURETTOR-REPAIR-KIT-GS500-K-Y.html
It only says may need though. How would I know...

Quote from: sledge on May 06, 2018, 06:28:27 AM
Something you need to consider. It's not mentioned in the Wiki and it is always overlooked by the 'carb experts' in here.

Because of the slight differences in the make up of fuel UK and other European bikes were jetted differently from USA bikes in the factory.

So while the advice given may work fine for 'full fat' gasoline it could well be a different story when it comes to our lead-free petrol.

This place will well you everything you need and give you reliable advice

http://www.nrp-carbs.co.uk/contact_us.htm

Also noticed shape of their o-ring for the 2000 model is different to the shape in the discountbikespares store. 
Wonder which is the one I need.



http://www.nrp-carbs.co.uk/shop/index.php?route=product/product&keyword=gs500&product_id=2853

My suggestion: Look at the parts fiche for your carb. In the US the float bowl gasket changed from the complicated one (13258-44B00) to the more simple one (13258-04F00) in 2001.  Pulling the bowls on yours will tell you exactly which one you need.

I no longer bother overhauling carbs myself.

I send them to a specialist who completely strips and inspects them before cleaning them ultrasonicaly and rebuilding them with the required seals and gaskets. He is an ex professional race bike tech, is very very good at what he does and has an excellent reputation in the circles and can do a far better job than me.

He did a pair of 24 year old GS5 carbs for me a couple of months ago, £85, yes......£85!
They came back looking and performing like they did when they left the factory and parts that NEVER get mentioned in the write ups you read in here were inspected, example fuel inlet barbs, choke plunger seals and throttle shaft seals.

For that money it's not worth getting your hands dirty.

Ask for Matt.

http://m.harpers-ultrasonic.com

Quote from: sledge on May 07, 2018, 12:58:55 AM
I no longer bother overhauling carbs myself.

I send them to a specialist who completely strips and inspects them before cleaning them ultrasonicaly and rebuilding them with the required seals and gaskets. He is an ex professional race bike tech, is very very good at what he does and has an excellent reputation in the circles and can do a far better job than me.

He did a pair of 24 year old GS5 carbs for me a couple of months ago, £85, yes......£85!
They came back looking and performing like they did when they left the factory and parts that NEVER get mentioned in the write ups you read in her were inspected, example fuel inlet barbs, choke slider seals and throttle shaft seals.

For that money it's not worth getting your hands dirty.

Ask for Matt.

http://m.harpers-ultrasonic.com

That looks like it would be cheaper and less fuss alright all things added up. 
I did want to do it myself so as to learn but I'm getting stressed out about it now. 
Lots of differing complicated info around and then there are missing pictures in the threads that explain it etc because of that crappy photobucket site everyone use to use.

Don't fall for the hype' 

Changing the bowl gasket and a few o-rings is NOT a rebuild and it's certainly no guarantee the carb will be free of issues, fully serviceable or perform correctly afterwards.

And........if you are going to start altering the jetting its pointless unless the carb is in good order beforehand.