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Main Area => Projects / Builds, Racing and Tech => Topic started by: Bhealy on May 19, 2017, 11:00:23 PM

Title: Kind at my wits end on this one any one have a clue
Post by: Bhealy on May 19, 2017, 11:00:23 PM
Not sure if i am in the right place but i am gonna post it neway

So i got this 93 gs 500e from my brother in law for a box of beer rode it 250 miles to my house it was rough shape so i decided to tear it down before i did took it on one last ride about 63 miles had no problems  stripped it of its multi colors and had it pro painted still not totally done  but i got it back together a year later ( looks awsome btw) couldnt get her to start replaced spark plugs took some doing got it going but will not idle ne where below 3000 and super hard to gnet going cleaned the carbs they r like new i sart it on prime the switch it to on
Title: Re: Kind at my wits end on this one any one have a clue
Post by: J_Walker on May 20, 2017, 12:04:43 AM
sounds like a carb adjustment issue to me..
Title: Re: Kind at my wits end on this one any one have a clue
Post by: 1018cc on May 20, 2017, 01:32:26 AM
If you tore it apart and it took a year to put back together I'd dump the fuel and put some fresh stuff in before pulling it all to bits again - you don't specifically mention if the fuel is fresh. If it is, I'd say you've done something incorrectly with the carbs during disassembly / reassembly / rebuild if it was fine before.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: ShowBizWolf on May 20, 2017, 09:32:15 AM
Very simple but have to ask, have you turned the idle adjust screw and it still won't drop below 3000?

That's all I got cuz I have zero experience with my carbs. Praise Jesus they've been good to me <3

Hope the others on this site can help ya get the problem fixed!  :cheers:
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Bhealy on May 20, 2017, 10:23:16 AM
The fuel is about a week old now.   If i adjust the idle down below 3000 she dies... and very real possability i reassembled the carbs wrong.  Are the adjustment screws under the brass plugs on the botton next to the idle screw and if so how do i get those off
Title: Re: Kind at my wits end on this one any one have a clue
Post by: 1018cc on May 20, 2017, 12:10:22 PM
I wouldn't go pulling the brass plugs off of the adjustment screws. It rode fine before you pulled it apart for a rebuild. Something else is obviously wrong with the carbs if now it won't run correctly - why go changing more stuff to make it more difficult to fix?

I'd start by checking for any vacuum leaks anywhere near the boots / carbs in case something isn't seated correctly or you are missing o-rings in the carbs etc. Does it sound like it is running on only one cylinder? Did you change the balance screw between the carbs? (i.e. do the throttle plates open the same amount?)
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Bhealy on May 20, 2017, 06:50:10 PM
I agree why change it if it was fine before.  I willhave to check the vacuum... it does have pods for the air filter it doesnt have the stock air box.  Is there an easy way to check  vacuum?
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Big Rich on May 20, 2017, 08:06:33 PM
Just going out on a limb here: did you jet the carbs for the pod filters?
Title: Re: Kind at my wits end on this one any one have a clue
Post by: 1018cc on May 20, 2017, 10:59:18 PM
It might be easiest to tell us what you've changed about the carbs / done to the carbs since it last rode fine. Have you put some aftermarket kit in it to make it faster or have you disassembled everything and put them back together only?

To check for vacuum leaks, get some water in a spray bottle and spray it around the intake boots and around the carbs etc. If there is an intake leak, you will hear the revs change when you spray the water and then change back to the way they were once the water has cleared. Another favourite of mine is just to get a long-ish length of hose and put one end to my ear and move the other end around the carbs - it allows you to pin point and hear a vacuum leak really easily if you can get access with the hose.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Bhealy on May 20, 2017, 11:19:48 PM
No the carbs are stock i took them apart cleaned the bowls, floats and cheched the vacuum diaphrams then put them back together. I will deffinatly do the soapy water trick. How do i know which jets r right... 
Title: Re: Kind at my wits end on this one any one have a clue
Post by: 1018cc on May 21, 2017, 12:24:56 AM
Your stock jets will probably be a bit lean with an aftermarket lunchbox filter. If your '93 still has the early style carbs on it (the ones with two jets rather than three like the later ones) there should be posts by Buddah on here that lists around what they should be - but if you've recently changed the airbox and the jets, you'll need to adjust the idle mixture screws which are under the brass plugs on the bottom of the carbs.

If you cleaned the floats - did you change the float level for some reason?

In order for the carbs to work really well, the valve clearances need to be within spec, they need to have no vacuum leaks, be balanced air-flow wise and have the same combination of jets / needles in each of them. How you go about doing all of this is down to the individual but I have my methods (my bike is stock jetting but I've got ZX6R carbs on my 1981 Toyota pickup that I custom built both inlet and exhaust manifolds for and it runs sweet). After checking the valve clearances to see they are in spec, I balance the air flow through the carbs to make sure each one is pulling the same amount of air as the other using a manometer (note I have one carb hooked up to two each so the two gauges on the left are the left carb and the two on the right are the right carb - note how the needles all point to pretty much the same spot - the needle type tend to bounce around more than the water / mercury type):
(http://imagizer.imageshack.us/v2/xq90/924/kpWvQJ.jpg)

Next I use a Colortune to set the idle mixture the same on both carbs (get a nice blue colour and you'll also hear the firing pattern even up until it is really smooth - generally) It is a see through spark plug. The colour of the combustion in the cylinder indicates how rich / lean it is - some people hate them but I find mine very useful for dialling in idle mixture for multi-carb setups:

(https://i.ytimg.com/vi/l31fbUCxu6o/maxresdefault.jpg)

I built a portable wideband to verify settings. This is my bike at idle with no choke - little rich but about where it needs to be for carbs for smoothness and easy starting. My carbs / bike is entirely stock. I hit the starter button and it starts easily from cold or hot:
(http://imagizer.imageshack.us/v2/xq90/924/8hta0q.jpg)
(http://imagizer.imageshack.us/v2/xq90/923/R0UIDE.jpg)

After you run through all of this and have everything dialled in they should be sweet. You really can't have any vacuum leaks though (which is what I suspect you have). The vacuum leak might be bad enough that you need the slides open @ 3,000rpm to allow in enough fuel to run (slide will pull up, which is connected to the needle to allow additional fuel through from the main jet. Any lower and the mixture is so lean it won't sustain an idle - at least that is my guess at this stage. Hard to move forward with carb tuning / adjustment with vacuum leaks.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Bhealy on May 21, 2017, 12:20:47 PM
So huge improvement today. Made a manometer tuned the cabs runs amazing.  Tooke her for a spin around town, four blocks later at a stop sign she dies. Start her back up, she wont rev up.  Call my wife for a tow home, on the way i start her up samething, wont rev, put her in gear and gradually she comes back.  We stop she idles send the woman on her way.  Take her four more blocks bring home, idles high mess withe idle screw it idles down. Then i notice smoke or maybe steam comming our of the valve cover breather hose.  What could cause that... didnt smell like smoke...oils fine..checked it before test run one and after still a good honey color... good fuel... idk
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Suzi Q on May 21, 2017, 04:09:45 PM
While not GS specific, here's a link with some basic info on mikuni carb theory. I'm adding this (for the proverbial "next guy") because this is turning into a really good thread, and I have a feeling it will end up in search results often.

http://www.iwt.com.au/mikunicarb.htm
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Bhealy on May 22, 2017, 09:29:38 AM
So turns out the "smoke" is actually steam, ideduced thos by putting a glass over the valve cover breather hose then sealed it and let the steam cool it left condensation on the inside of the jar so steam. Is that normal. Are valves hard to shim?
Title: Re: Kind at my wits end on this one any one have a clue
Post by: mr72 on May 22, 2017, 09:46:18 AM
for it to be steam, there has to be water in the fuel.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: gsJack on May 22, 2017, 11:05:59 AM
Water is a natural byproduct of internal combustion.  Water vapor coming out of the crankcase vent in an excessive amount would indicate worn rings.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Suzi Q on May 22, 2017, 06:11:57 PM
Quote from: Bhealy on May 22, 2017, 09:29:38 AMAre valves hard to shim?

Inherently, no. It takes a special tool (or homemade equivalent,) a pick, a flathead and a retractable magnet. Also, feeler gauges so you know what size you need, and the appropriate replacements. Best price I can find new was from here:  https://www.z1enterprises.com/catalogsearch/result/?cat=&q=valve+shim+29.5

Additionally, there are a few members here that are more than willing to trade shims via the classifieds.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Bhealy on May 23, 2017, 01:23:29 AM
Wow i just want to say that i am impressed with every thing that you guys have taught me i have her running preemo now the steam has stopped after about a three hour ride around town thank you all for the help i will try and contribute in the near future
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Random00 on May 23, 2017, 12:30:14 PM
Quote from: 1018cc on May 21, 2017, 12:24:56 AM
I built a portable wideband to verify settings. This is my bike at idle with no choke - little rich but about where it needs to be for carbs for smoothness and easy starting. My carbs / bike is entirely stock. I hit the starter button and it starts easily from cold or hot:
(http://imagizer.imageshack.us/v2/xq90/924/8hta0q.jpg)
(http://imagizer.imageshack.us/v2/xq90/923/R0UIDE.jpg)
Do you have a post somewhere on your portable wide band setup?  I would love to learn more!
Title: Re: Kind at my wits end on this one any one have a clue
Post by: 1018cc on May 23, 2017, 12:56:47 PM
Quote from: Random00 on May 23, 2017, 12:30:14 PM
Quote from: 1018cc on May 21, 2017, 12:24:56 AM
I built a portable wideband to verify settings. This is my bike at idle with no choke - little rich but about where it needs to be for carbs for smoothness and easy starting. My carbs / bike is entirely stock. I hit the starter button and it starts easily from cold or hot:
(http://imagizer.imageshack.us/v2/xq90/924/8hta0q.jpg)
(http://imagizer.imageshack.us/v2/xq90/923/R0UIDE.jpg)
Do you have a post somewhere on your portable wide band setup?  I would love to learn more!
I don't have a post anywhere on it but I can do one up for you and I'll show you the inner workings. Will probably happen later in the week.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Endopotential on May 23, 2017, 01:12:53 PM
1018 - Sir, you get my vote for badass mechanical guru of the month!!!  :cheers:

Most of us shadetree wrenchers have a few primitive homemade tools.  But building your own wideband sensor?  That's just next level coolness
Title: Re: Kind at my wits end on this one any one have a clue
Post by: gregjet on May 23, 2017, 03:04:24 PM
+1 for the wide band meter construction.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: The Buddha on May 23, 2017, 06:56:30 PM
Actually you can get a O2 sensor from an older car - I used a 1992 chevy cavalier one and weld its thread boss into the exhaust.
Then you can read it with a digital milli volt meter velcroed to the tank or dash. The road is your dyno. You can jet it to the perfect spot.

That's how I made up my jetting formula.

Cool.
Buddha.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Random00 on May 25, 2017, 11:10:21 AM
Quote from: The Buddha on May 23, 2017, 06:56:30 PM
Actually you can get a O2 sensor from an older car - I used a 1992 chevy cavalier one and weld its thread boss into the exhaust.
The problem with that is that most stock O2 sensors (cars and motorcycles) are narrow band right around 14.7:1, once you're outside of their range, they really stop reporting any useful data.

That's what makes wide band 02's so useful!
https://www.enginebasics.com/EFI%20Tuning/AF%20Ratio%20Basics.html

Title: Re: Kind at my wits end on this one any one have a clue
Post by: 1018cc on May 27, 2017, 02:22:37 AM
I don't want to take over this thread anymore than I already have but I have uploaded a heap of photos of my portable AFR gauge here: http://gstwins.com/gsboard/index.php?topic=71642.0 (http://gstwins.com/gsboard/index.php?topic=71642.0) for those of you who are interested and didn't notice it in GD.
Title: Re: Kind at my wits end on this one any one have a clue
Post by: Suzi Q on June 02, 2017, 07:27:09 PM
Kickass, thanks 1018!