First I'd like to introduce myself. I'm new to the forum and just got my '93 gs500 a few months ago and Ive been slowly getting her up to speed. I've already done a lot of work. Fork seals, new handlebars, cleaned chain, changed oil, new rear signals and probably more im forgetting. Replaced and cleaned all the jets and orings on the carbs (lots of mess ups on the way!). It started out with a 145 main jet, so I'm thinking the previous owner had a lunchbox or something on it. Exhaust seems stock. I'm now running the stock airbox with a new OEM filter and 125 mains and 40 pilots, 3 turns out.
Everything is running, but sometimes the idle hangs a bit. Also when I choke the bike, it goes up to 3k rpm or so, but then drops right back down to about 1.2k. Shouldn't it stay at higher RPM? I haven't properly checked the valve clearances yet...could tight clearances cause this? I checked for a vacuum leak with some WD40 on the seals with the bike running, didn't seem to make a difference in RPM so I don't think there is a vacuum issue. Thoughts?
In another unrelated thought...I'm also only able to run on the RES setting on the frame mounted petcock. Ive heard this a common issue with the GS so I'm planning on going to the Honda 250 petcock that was suggested somewhere else on the forum. It will be nice to eliminate the vacuum system to the petcock and be able to have an accessible shut off to avoid flooding in the case of my needle valves sticking.
Plenty more work to do on the bike, looking forward to being part of the community. The cold here in Illinois is killing me! I finally have the bike working enough to ride!
There are a going to be a ton of suggestions to address your issues, because they may be caused by a variety of things:
Definitely replace the petcock.
Make sure you have caps on all the vacuum ports at the carbs, and make sure you have o-rings under the plastic caps on top of the carbs.
Check valve clearances. GS500 valves become tighter as they wear.
Did you synchronize the carbs after you cleaned and rejetted them?
Did you check for any air leaks around the exhaust headers?
You hear there are lots of problems with the petcock because those with a problem are very vocal about it - almost like a religion.
If you can only run in reserve, check the fuel lines. The fact it runs in reserve means the petcock IS WORKING. The lever you turn simply controls whether fuel cones from the main or reserve line.
Probably a pinched fuel line. Or, do you have gas in your tank? About 20% of your tank is reserve. People have reported your problem, then they put gas in the tank and all was OK.
Taking off the tank and then putting it back on, or even lifting it a bit, could see you with a pinched fuel line, as Addy mentioned. If the main is pinched you'll run out trying to run with it, then switching to res will work. Isn't necessarily the fault of the frame mounted petcock. BTW, just bobbing your head down for a quick look won't tell you if you have a pinched fuel line.
Michael
Sounds like you got a nice project finishing up there!
What did you put on for turn signals?
Orings on the vacuum ports on top of the carb are ok as they were replaced with new. Pretty sure the exhaust headers are as well. I retightened them to the torque spec a while ago.
On the petcock, I wes rearranging the tank to do my vacuum testing and I noticed the main could have been pinched. Regardless, I would like to replace the original petcock with on that doesn't use the vacuum line. I like the ability to shut the fuel to the carbs off without having to lift the tank. Fewer issues if my needle valves decide to hang.
I eyeball synced the carbs after cleaning. Still need to make a homemade manometer. I need to figure out how the one with the aquarium valve is put together. The links to the pics an videos are all dead.
I think the next step is the valve clearances. I attempted to measure the clearances once before an they seemed tight, but then again I might not of known what I was doing.
I got my turn signals on eBay. I'll post a link when I get a chance.
Right now the tins and plastics are off the bike waiting for paint. (No more purple decal!!)
Here's the missing diagram for you :)
(http://i815.photobucket.com/albums/zz72/mitchc_1/Bike/carbbalancer.png)
Awesome. Thanks for that! I'll be doing that right after my valve shims.
http://www.ebay.com/itm/Set-Four-Black-Amber-MOTORCYCLE-TURN-SIGNALS-/390369994818?pt=Motorcycles_Parts_Accessories&vxp=
These are the signals I'm using. I'm only using 2 of the 4 for the rear. They are very similar to stock in the style, just smaller And shorter. The work great plug n play.
Quote from: bombsquad83 on December 03, 2011, 06:40:56 PM
I need to figure out how the one with the aquarium valve is put together. The links to the pics an videos are all dead.
Which place with "the links"?
we have a wiki: wiki.gstwins.com
I semi-recently made sure that particular thing had a valid pic, I thought.
Hmm . well, it wasnt nicely done, since that was before I knew how to edit properly.
Updated http://wiki.gstwins.com/index.php?n=Maintenance.5CarbSync so it's more nicely "in-line" now.
Just measured my valve clearances. .13 mm on right exhaust, .05 on left exhaust. Tighter than my smallest feeler gauge of 0.04 mm on both intakes, but the shims will move in the seat.
I couldn't get a shim out to measure it without the shim tool. I tried with a couple screwdrivers and got it halfway out, but it got caught between the cam and the bucket. I got it back in place and I'll have to get or make the appropriate tools.
Ended up pulling the camshafts to get at the shims. It was a more painful process than it should have been. First of all I need a new camchain tensioner gasket (probably to be expected when you pull something that old). Then I dropped a shim down into the crankcase...doh!!! Luckily I was able to get it out with a quick trip to autozone for a telescopicing magnet. Then getting the camshafts back on in the right place was a chore. At least 3 tries later I had it.
So the verdict? 2.72 shim in the right exhaust and 2.75 in the left. 2.65 in both intakes.
Quote from: bombsquad83 on December 04, 2011, 07:49:41 PM
Ended up pulling the camshafts to get at the shims. It was a more painful process than it should have been. First of all I need a new camchain tensioner gasket (probably to be expected when you pull something that old). Then I dropped a shim down into the crankcase...doh!!! Luckily I was able to get it out with a quick trip to autozone for a telescopicing magnet. Then getting the camshafts back on in the right place was a chore. At least 3 tries later I had it.
So the verdict? 2.72 shim in the right exhaust and 2.75 in the left. 2.65 in both intakes.
Ouch!!!!
Maybe spring for the motion pro tool? Only a coule of $$$....and put a rag or paper towel in there so you don't drop shims into crankcase...
Seems like all your clearances were in spec...so why take everything apart...?
Cookie
Well.. I'm an idiot. Broke off a bolt that holds the cam journal down by over torquing. Didn't think I could put that much torque on it with a 5 in socket wrench. Sigh... Not sure what to do now. Machine shop I guess.
To be fair. I bought the bike to learn how to work on small engines and stuff like this...so...success? I'm definitely learning what to do and what not to do.
Also, I know the shims were close to spec, but they were above or below it, so I wanted to learn how to do the job.
Now to the issue at hand. I read somewhere that a left hand drill bit can help get the broken bolt out. I might order one of these and give it a shot. I don't think I can hurt it anymore, cuz the machine shop is going to have to drill it out if I can't. I'm going to have to either drop the engine or take off the top end to get to it though since it's on the exhaust valve side :( . Any suggestions?
I got some left-handed bits and the smallest size screw extractor (ez out) from Mcmaster Carr. Hopefully I'll be able to get the broken end out! I will update when the attempt is made. Just snowed a bit here, so not in a rush to get it done. I also got a small torque wrench...so I won't break another one off!
I'm going to go ahead and necro my own post here for an update.
The left handed drill bits worked great! My freind and I dropped the engine to get an angle on drilling into the bolt. Drilled a pilot hole with a 1/16" left-handed bit. Then moved up to a 3/32" bit and it spun out without even needing to use the ez-out.
Now...back to the task at hand. I have ordered the parts I need to get her back together, along with some 2.60 mm valve shims for my intakes that were a little tight. Wish me luck!
So I've pretty much decided the tightening bolts is not my strong point. I stripped out the threads on the middle back valve cover You win!. More fun time learning how to fix stripped threads now (First trying a tap, then helicoil here I come!)
I got my valve shims in and adjusted now though. Probably should have gone with one size lower for one of my intakes, as it ended up at .04mm clearance. Still in spec so I'm happy.
Still cold enough in Illinois that I'm not that disappointed that this process is going longer than it should. Once I'm done getting the valve cover in order I'll be able to give everything a good degreasing with the engine out of the frame.
EDIT:
I tested my old petcock after I replaced it with the Honda CRF250X petcock. Couldn't blow air through the "on" side even when it was on prime. So it looks like there is a problem with the petcock after all. Glad I got the replacement so I don't have to deal with the vacuum system anymore too. I just capped off the vacuum with the same part number that is used to cap off the carb sync ports. Looks like it will work well.
Quote from: bombsquad83 on February 03, 2012, 06:13:33 PM
So I've pretty much decided the tightening bolts is not my strong point. I stripped out the threads on the middle back valve cover You win!. More fun time learning how to fix stripped threads now (First trying a tap, then helicoil here I come!)
Good judgement comes from experience. Experience comes from bad judgement!
Quote from: Paulcet on February 03, 2012, 07:17:39 PM
Quote from: bombsquad83 on February 03, 2012, 06:13:33 PM
So I've pretty much decided the tightening bolts is not my strong point. I stripped out the threads on the middle back valve cover You win!. More fun time learning how to fix stripped threads now (First trying a tap, then helicoil here I come!)
Good judgement comes from experience. Experience comes from bad judgement!
^^^haha...yup. if you are gonna wrench on your bike, get a service manual and a torque wrench! They are the two best purchases, period!
My problem is patience. I had a torque wrench but not an adaptor to fit to my hex bits. I should have just waited...not the first time thats happened. So true about where good judgement comes from. Oh well, more learning and new tools to come.
A useful trick for bolts that are impossible to get to with the torque wrench is to torque another easy to get to bolt to the spec you need, then do the same bolt with a regular wrench (or allen key) and get the same feel for how tight is needs to be at that certain torque spec. the two allen bolts on the cam cover are nearly impossible to get to with a torque wrench.
Threads successfully repaired with a Helicoil. Waiting for the right adaptor for my torque wrench so I can properly tighten those valve cover bolts this time. Plenty of M7.0x1 helicoils left in the pack that I got. If anyone else needs one let me know and we can work something out for cheap!
Next step is to put the engine back in the bike and put on the new chain and front sprocket. Then it's on to paint!
See my new build thread. Pics!
http://gstwins.com/gsboard/index.php?topic=59113.0