Carb sync made things worse...

[spray____]

TL,DR;
I tried to sync my carbs and after I got to what I thought was balanced, the engine is running rough and the idle dropped from 1200 to 1000.

FULL
Hey guys, hoping to get some possibilities on what might be going on here.

A few weeks back I was generously given a home-made manometer. Last weekend I finally got around to doing a carb sync on my 06 GS500F. I followed this video http://www.youtube.com/watch?v=NYt33GRHzww and got everything apart, with the only issue being I had to remove the airbox + carbs to get at the left side vacuum source. Once the manometer was attached, I put the carb + airbox back together. I noticed some hoses had detached from the airbox when I removed it, so I hooked them back up and started syncing the carbs.

I played with the carb sync screw for a while, and managed to find a spot where the fluid was staying even, so I started putting everything back together. When it came to put the fuel tank vent hose back on, I relized it needed to get routed between the carbs + airbox and fought with it for a bit before getting it attached properly.

When everything was assembled and I started the bike, I noticed it was idling a little low. It had previously idled between 1200 cold and 1500 warm, but it was now hovering around 1000. I figured maybe I accidentally changed the adjustment when I was fighting with the tank vent hose, so I adjusted it back up to 1200.

The problem I'm having now is the bike seems to be running rough. I'm not sure what's going on, but the vibrations from the engine seem to be stronger than they were before I started tinkering. I can feel it the most with my hands down through the bars. So right now I'm thinking there are a few possibilities:

- I messed something up with the hoses. I'm 90% sure I've got everything back where it was, but maybe there is something wrong here
- I didn't have a good seal between the manomter/vacuum source, and it was reading balanced while I actually made it worse
- This is all in my head
- Something totally unrelated to his

I'm planning to take everything apart and try again when I get a chance. If anyone has ideas about likely causes, things I should look for, ect, I would greatly appreciate it. I'd also be open to going for a cruise (around Toronto) if anyone who has a lot of experience is open to having a quick look. I'm not suggesting doing the work for me - just confirming that this is not all in my head and having a look + listen.

[yamahonkawazuki]

check the butterflies and hose routing.

[spray____]

check the butterflies and hose routing.

Thanks. As far as butterflies, are there common issues I should look for that would make an engine run rough? I'm fairly new to this sort of tinkering, so I'm not sure I know what to look for.

[Snake2715]

Check the wiki for the hose routing you probably hooked up something incorrectly or wrong. It may have a leak.

What year of bike? How many miles?

I had a 98 and it had just 7250 miles.. The fuel line was junk at the barb when I went to remove the tank and kind of cracked or ripped very easy.

So its possible it is nothing other than a bad line as well.


Few links:

http://wiki.gstwins.com/index.php?n=Main.Troubleshooting


Hose routing:

http://wiki.gstwins.com/index.php?n=Main.HoseRouting

good luck and keep us posted.

[spray____]

Thanks for the info.

I've been talking on another forum with someone who suggests I should have done more work before syncing the carbs, and it's not surprising I'm having problems. I'm a newbie when it comes to this stuff, and I've never cleaned the carbs, adjusted the mixture, ect, and that is likely the cause of the problems.

I'm going to try and get some help from someone in the area that has the tools and know how to get it done right. At this stage, I'm worried that I'm only wasting my time and making things worse.

[Snake2715]

Thanks for the info.

I've been talking on another forum with someone who suggests I should have done more work before syncing the carbs, and it's not surprising I'm having problems. I'm a newbie when it comes to this stuff, and I've never cleaned the carbs, adjusted the mixture, ect, and that is likely the cause of the problems.

I'm going to try and get some help from someone in the area that has the tools and know how to get it done right. At this stage, I'm worried that I'm only wasting my time and making things worse.

A couple of notes.

What area may that be? There may be a GS'er nearby.

Also dont assume that a "motorcycle mechanic" knows the GS that great, or is all knowledgable in all things. The one I bought the bike from had the carb bowls on backwards, among other things. And this holds true from other stories talked about and posted here among other forums.

Not sure of your knowledge but this forum and its members are a great resource, you can probably tackle this yourself (rebuilding carbs). I would suggest having access to an air compressor to really blow crud out of the lines (once disassembled) but other than that you should have most tools at home in a basic kit.

[spray____]

Area is Toronto, ON.

I know what you're saying. After thinking about it for a while I'm reconsidering attempting this myself. As scary as the thought sometimes is, I might attempt to pull apart the carbs and clean them out, adjust the mixture, and do whatever else needs to be done once I find out exactly what that is.

In the meantime I'm going to keep searching for some articles and videos to get a better understanding of what exactly it is I should be doing, and how it's done.

[Snake2715]

One thing of note.

Take pictures as you pull it apart. This site is great (as are others or google) but nothing is better than pictures as you take it apart, different angles, etc.

Put screws/bolts back in the holes they came from or with the parts they attached.

Mark cables on the carb with a black marker or white out dabber.

Write down how many turns out your mixture screws are for each carb, before you start to take them apart. There typically is no reason to separate the carbs so leave the two attached to each other.

I use a stainless steel dog bowl to put my part in to soak. I have seen people use the caps that come on the carb cleaner spray.

There are lots of posts, and videos on youtube and I think even GS specific ones if I recall correctly.

Get the stock measurements and provided you get in there to find stock jets, needle, etc then reset the bike to stock settings when re assembling (the one mixture screw) on each carb is the only setting other than the sync/throttle plate screw between the carbs.

Thats some info for you. I think if you take your time almost anyone can do this no problem.

There are exploded diagrams of the carbs on say rockymountainatv.com or bikebandit.com etc. That will show you what all goes where. Again pictures are best in my opinion.


The last thing is once the carbs are off you can adjust the sync screw to line up both butterfly/throttle plates again (bench sync). That will give you a base.

Last weekend I was riding and one of the guys bikes started to run poorly. Back at home we checked a few things and finally dropped the bowl to see that his main jet had literally fallen out. It was apparently not properly tightened down last year (!) when the carbs were apart. (not a GS an enduro). Point being once you get in there you will most likely find the issue.

[spray____]

Thanks, great advice.

Pictures are definitely something I'm planning on doing, just need to find a way to not get my camera dirty, and not have to wash my hands ever 3 minutes

[yamahonkawazuki]

the gallon can of carb cleaner ALMOST fits the 2 carbs together. soak one side for 24 hrs then the other. BUT remove the rubber orings inside. otherwise youll have issues with them down the road

[Snake2715]

the gallon can of carb cleaner ALMOST fits the 2 carbs together. soak one side for 24 hrs then the other. BUT remove the rubber orings inside. otherwise youll have issues with them down the road

wouldnt the rubber T's be effected by this?

[spray____]

Wow, I don't think I do enough carb cleaning to justify buying and using an entire gallon, lol.

It's a great idea for someone who does this frequently though. How many times could you reuse the same gallon?

[spray____]

Update for those who are interested.

Got around to ripping things apart again on Sunday. I've been studying diagrams of the airbox, carbs, and all the associated hoses since my last attempt. Had more confidence this time, and figured if I'm going to take it all apart again, I might as well open the carbs and clean them out. Got lucky, and everything went back together without any leftover pieces.

Ripped out the brass caps covering the idle mixture screws. They came out fairly easily. One thing I found was that one was 2 turns out, the other was 3 1/4. Seems strange that they would be so different from the factory. They spin fairly easily, so maybe one had loosened over the last 6 years under the cover? Anyway, I set them back to the baseline 2 turns.

Bike seems to be running a bit better now, and seems to have a bit more power, although that could be the placebo effect. I still want to do some fine tuning (adjust idle mixture and try the manometer again) but in general I feel a lot better about things now.

My guess as to what went wrong was a bad fitting somewhere, probably the seal between the airbox + carb, or carb + head. Didn't see any problems while taking it apart, but I wasn't really looking. It was however a bit of a pain to get back together, so I could have easily had a bad seal there.

Seems to have a bit more power now, although that could be the placebo effect.

Only problem I ran into was when reassembling, my reserve fuel line broke right off at the tank petcock. Lost about 1/4 tank of gas before I managed to pinch it off and yell at my wife to come out and close the petcock.

[Snake2715]

Grab some new line quick:

http://www.mcmaster.com/#catalog/118/124/=n50kr1

1/4 Do not do 5/16th.

Regular fuel line will work, Tygon is known to be the best or on the upper tier of quality.

4-5 ft is  enough. Do use zip ties or something on the line still. A bit fo fuel on the line will allow it to slip on, some use 2 cycle oil (very lightly)

I personally also grabbed this heat resistant mesh to cover the yellow line.

http://www.mcmaster.com/#catalog/119/815/=n50ljt

Sweet deal its working better. Know get back out there and try the carb sync when you get time. Keep the idle where it needs to be (12-1500if I recall), no higher.