So I had gotten the bike to start now. But it seems as if it will only start with the choke and even with the choke on the bike will go back and forth from 5k rpm to 1k and will steadily go back to 4K. Then it just slowly dies out. It had an issue with the idle screw but I'm new to this whole bike scene so I'm not sure on any of it
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What year is the bike? How long have you had it? How long did it sit before your tried to start it? Do you have an aftermarket airbox or exhaust? Have you pulled the plugs to make sure both cylinders are firing and that the plugs are a nice toasted marshmallow brown (not ashy white or oily black).
Needing choke to start is normal. The rest sounds like a carburetor issue. Is the bike new to you? As with any carbureted bike that isn't running perfectly when you get it, you should probably pull the carbs, fully disassemble them and clean all metal parts in carb cleaner (I recommend the carb dip you can buy at auto part stores) and replace all o-rings. Also check the carb jet sizes to make sure no previous owner did any weird rejetting. If the bike has sat for 3+ months with fuel in the carbs it likely needs a full carb clean.
Also check the vacuum lines, airbox-carb boots, intake boots and o-rings for flexibility and dry rot. These bikes are all getting old so most of the rubber parts are due for replacement. When they are stiff or cracked they can cause vacuum leaks.
Quote from: Bluesmudge on March 15, 2022, 11:18:49 AM
What year is the bike? How long have you had it? How long did it sit before your tried to start it? Do you have an aftermarket airbox or exhaust? Have you pulled the plugs to make sure both cylinders are firing and that the plugs are a nice toasted marshmallow brown (not ashy white or oily black).
Needing choke to start is normal. The rest sounds like a carburetor issue. Is the bike new to you? As with any carbureted bike that isn't running perfectly when you get it, you should probably pull the carbs, fully disassemble them and clean all metal parts in carb cleaner (I recommend the carb dip you can buy at auto part stores) and replace all o-rings. Also check the carb jet sizes to make sure no previous owner did any weird rejetting. If the bike has sat for 3+ months with fuel in the carbs it likely needs a full carb clean.
Also check the vacuum lines, airbox-carb boots, intake boots and o-rings for flexibility and dry rot. These bikes are all getting old so most of the rubber parts are due for replacement. When they are stiff or cracked they can cause vacuum leaks.
The bike is a week old to me. 06 gs500. The dude had it running just fine. Rode it to me and showed me it running as well. Nothing seemed to have an issue but I bring it home and it hasn't acted right at all. He said he fixed the idle screw saying it wasn't idling right but it also smells kind of rich to me but maybe that's normal with the choke on
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Smelling rich is normal with the choke on. The choke adds fuel (or chokes air) to make the mixture more rich for cold starts.
It kind of sounds like the previous owner bumped up the idle speed to mask another carb issue. Maybe the pilot jet is clogged in one of the carbs but not the other. Unless you are saying the rpms bounce like that when the bike is cold with full choke, that sounds more like maybe a vacuum leak. The previous owner may still have been masking it because the bike will be less effected by carb issues when its fully warmed up. This is why its important when buying a used bike to always make sure a bike is dead cold before starting it for the first time. Feel the headers to be sure the previous owner hasn't warmed it up before you get there. A lot of issues are only noticeable during the warm-up period. That said, the GS500 is cold blooded, especially with factory jetting. With stock jetting it should require full choke for a minute or two when cold. Even if the ambient temperature is high. The entire GS series is that way. My GS1000 will never start cold without full choke.
You will need to start doing some diagnostic work. Its a 16 year old carbureted bike with an unknown history, so you are going to have to get comfortable working on carburetors and replacing rubber parts related to fuel and air. It could be a combination of issues which is difficult to diagnose (like old fuel or rust in tank plus vacuum leak). My strategy when I buy an old carbureted bike is to pull the carbs and replace everything rubber related to fuel and air and make sure all the jetting and carb settings are stock or +1 from stock if the bike is known to be lean from the factory like the GS500. Then adjust the valves. Then vacuum sync the carburetors. I throw is fresh spark plugs for good measure. That combination should get any bike with good compression running great. If the valves are out of spec and the carbs aren't in sync, that's hard to diagnose. Best to just do all these routine maintenance items all at once to set the bike back to "new."
Quote from: Bluesmudge on March 16, 2022, 09:21:05 AM
Smelling rich is normal with the choke on. The choke adds fuel (or chokes air) to make the mixture more rich for cold starts.
It kind of sounds like the previous owner bumped up the idle speed to mask another carb issue. Maybe the pilot jet is clogged in one of the carbs but not the other. Unless you are saying the rpms bounce like that when the bike is cold with full choke, that sounds more like maybe a vacuum leak. The previous owner may still have been masking it because the bike will be less effected by carb issues when its fully warmed up. This is why its important when buying a used bike to always make sure a bike is dead cold before starting it for the first time. Feel the headers to be sure the previous owner hasn't warmed it up before you get there. A lot of issues are only noticeable during the warm-up period. That said, the GS500 is cold blooded, especially with factory jetting. With stock jetting it should require full choke for a minute or two when cold. Even if the ambient temperature is high. The entire GS series is that way. My GS1000 will never start cold without full choke.
You will need to start doing some diagnostic work. Its a 16 year old carbureted bike with an unknown history, so you are going to have to get comfortable working on carburetors and replacing rubber parts related to fuel and air. It could be a combination of issues which is difficult to diagnose (like old fuel or rust in tank plus vacuum leak). My strategy when I buy an old carbureted bike is to pull the carbs and replace everything rubber related to fuel and air and make sure all the jetting and carb settings are stock or +1 from stock if the bike is known to be lean from the factory like the GS500. Then adjust the valves. Then vacuum sync the carburetors. I throw is fresh spark plugs for good measure. That combination should get any bike with good compression running great. If the valves are out of spec and the carbs aren't in sync, that's hard to diagnose. Best to just do all these routine maintenance items all at once to set the bike back to "new."
Thanks man. I'll get on it
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A quick diagnostic is to check the temperature of the exhaust headers, as they warm-up from a cold start.
I've done this many times on 4 cylinders, where the bike runs, but poorly. So in that case you have 2 or 3 cylinders
carrying the weak one(s); with a twin it would likely stall without constant throttle tweaking.
If you find this is the case, it's often a bad coil. It can show a spark in testing, but under compression
you get intermittent firing. Otherwise as Bluesmudge, said, it's a probably a plugged pilot jet.
If it is a pilot, you should be able to keep it running, by holding the throttle open enough to engage
the next fuel circuit, and the pipe will heat up too. If it's the coil the weak side will heat a little, but
there will remain a significant difference like 35-40 degrees or more.
Spit on a thumb works ok, but one of those (cheap is ok for this) laser thermometers is the Voodoo :)
**edit**the 1-4k cycling you described, does sound like a vacuum leak at the carb boots to me.
But it wouldn't hurt to do the header-temp test anyway.
Quote from: chris900f on March 18, 2022, 11:01:20 PM
A quick diagnostic is to check the temperature of the exhaust headers, as they warm-up from a cold start.
I've done this many times on 4 cylinders, where the bike runs, but poorly. So in that case you have 2 or 3 cylinders
carrying the weak one(s); with a twin it would likely stall without constant throttle tweaking.
If you find this is the case, it's often a bad coil. It can show a spark in testing, but under compression
you get intermittent firing. Otherwise as Bluesmudge, said, it's a probably a plugged pilot jet.
If it is a pilot, you should be able to keep it running, by holding the throttle open enough to engage
the next fuel circuit, and the pipe will heat up too. If it's the coil the weak side will heat a little, but
there will remain a significant difference like 35-40 degrees or more.
Spit on a thumb works ok, but one of those (cheap is ok for this) laser thermometers is the Voodoo :)
**edit**the 1-4k cycling you described, does sound like a vacuum leak at the carb boots to me.
But it wouldn't hurt to do the header-temp test anyway.
So get this man. 40 degrees yesterday and I get it running on choke. Went up to 3k right away moved a little down then went to 4K all the way to 5.5k so I moved the choke a bit off and it died. So I start it again runs like it was and lower the choke and it struggles just a bit but I blip them throttle and is was working. So I decided to try and ride it and it freaking rides. Once I got it moved without shutting off for once it seemed to be idling just fine when warm and had no issues shifting or anything. But I feel like something is definitely off still
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That sounds like normal startup behavior for a cold engine with stock jetting. You usually have to let the bike run at full choke for at least 30 seconds (4 - 5k rpm) before you can start removing some choke.
Quote from: Bluesmudge on March 21, 2022, 08:11:47 AM
That sounds like normal startup behavior for a cold engine with stock jetting. You usually have to let the bike run at full choke for at least 30 seconds (4 - 5k rpm) before you can start removing some choke.
Yes but even when it was 60 it acts the same. But if I as much as touch the joke after it's been sitting at 4-5 k for a couple minutes it struggles to stay alive I have to use throttle
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seriously, just read the post in my signature.
"Choke" normally makes it "idle" at 5k-6k rpm. That's normal. It's on purpose. This helps it warm up faster.
Turning off the "choke" before it's fully warmed up will make it try to idle at like 400 rpm and it'll stall. That's normal.
If you ride it on the road, going through gears, whole thing, for like 20 minutes, then it will be fully warmed up, then you can set the idle speed to 1100-1200.
Having to keep a little choke on for the first few minutes you ride is totally normal.
You don't seem to really get how the choke works and how hard it is to warm up an air cooled motorcycle.
BTW 30F vs 60F ambient is not meaningful to an engine that's trying to get the cylinder head over 300F. We're talking 30 seconds more warmup time. Out of like 20 minutes.
TL,DR: it's working like it's supposed to. You need to adjust your habits.
Or TL,DR: you really should read more, it's not too long.
Quote from: mr72 on March 21, 2022, 02:06:11 PM
seriously, just read the post in my signature.
"Choke" normally makes it "idle" at 5k-6k rpm. That's normal. It's on purpose. This helps it warm up faster.
Turning off the "choke" before it's fully warmed up will make it try to idle at like 400 rpm and it'll stall. That's normal.
If you ride it on the road, going through gears, whole thing, for like 20 minutes, then it will be fully warmed up, then you can set the idle speed to 1100-1200.
Having to keep a little choke on for the first few minutes you ride is totally normal.
You don't seem to really get how the choke works and how hard it is to warm up an air cooled motorcycle.
BTW 30F vs 60F ambient is not meaningful to an engine that's trying to get the cylinder head over 300F. We're talking 30 seconds more warmup time. Out of like 20 minutes.
TL,DR: it's working like it's supposed to. You need to adjust your habits.
Or TL,DR: you really should read more, it's not too long.
I get how the choke works buddy. But when it's warm out it shouldn't die for no reason on choke or start in the cold at 4K. Go be an ass somewhere else
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This is a case where a quick video would really help. It can be difficult to describe these issues as many problems have overlapping symptoms.
Your 2006 bike has an air-inlet-solenoid valve on the carbs. It is triggered by ECU at start-up. After the engine starts and runs a few cycles the
ECU opens the solenoid and causes the RPM to go WAY up,( it startled me at first too). Since there is no sensor to provide feedback the ECU
just counts a prescribed number of engine cycles and then closes the valve.
On your next cold start, just let her roar at 4k or whatever it hits; it should drop back down to a normal, high-idle after a bit.
Then you can reduce the choke as the engine warms up.
Quote from: anesbitt267 on March 21, 2022, 02:29:01 PM
I get how the choke works buddy. But when it's warm out it shouldn't die for no reason on choke or start in the cold at 4K. Go be an ass somewhere else
I didn't realize you were already an expert.
Good luck, you'll need it. Welcome to my ignore list.