Newly Revived 2000 GS500E hangs at 5000rpm after any throttle

[struckjm]

https://youtu.be/RP3eCeoiQX0

Video demonstrates what I mean too.

Bought this bike a couple months ago and I've been trying to get it to start up ever since.
It had no compression and the valve clearances were way out of spec after I fix up the valve clearances I was able to get 80 and 90 PSI. So with that I reassemble the bike and started it up. It was a little rough at first it needed starter fluid to really get going but after a few starts in a little bit of a warm-up it will now start on time without any other help. The issue now is if I apply any throttle it rises up to about 5000 RPM and just hangs there you can see in the video that I release the throttle but the RPMs do not come back down.
you can see in the video that I release the throttle but the RPMs do not come back down

To save you guys some time the carbs been sitting for a year or two and hasn't been properly rebuilt I believe they are stock jets. the stock airbox is improperly mounted. I'm sure all you guys can appreciate how in a rush to just see if the thing would start up I was not willing to go through the pain and effort of getting the airbox gaskets around the air intake on the carb perfectly but it's pretty damn close enough.
I'm really new to motorcycle repair and honestly validating the camshaft timing and replacing all the valve shims is the most mechanically complex thing I have ever done so forgive me if I haven't checked the throttle cable yet.

Can you beautiful people help me troubleshoot my throttle fuel carb problem?

Where should I be looking first?

[Sporty]

https://youtu.be/RP3eCeoiQX0

Video demonstrates what I mean too.

Bought this bike a couple months ago and I've been trying to get it to start up ever since.
It had no compression and the valve clearances were way out of spec after I fix up the valve clearances I was able to get 80 and 90 PSI. So with that I reassemble the bike and started it up. It was a little rough at first it needed starter fluid to really get going but after a few starts in a little bit of a warm-up it will now start on time without any other help. The issue now is if I apply any throttle it rises up to about 5000 RPM and just hangs there you can see in the video that I release the throttle but the RPMs do not come back down.
you can see in the video that I release the throttle but the RPMs do not come back down

To save you guys some time the carbs been sitting for a year or two and hasn't been properly rebuilt I believe they are stock jets. the stock airbox is improperly mounted. I'm sure all you guys can appreciate how in a rush to just see if the thing would start up I was not willing to go through the pain and effort of getting the airbox gaskets around the air intake on the carb perfectly but it's pretty damn close enough.
I'm really new to motorcycle repair and honestly validating the camshaft timing and replacing all the valve shims is the most mechanically complex thing I have ever done so forgive me if I haven't checked the throttle cable yet.

Can you beautiful people help me troubleshoot my throttle fuel carb problem?

Where should I be looking first?

I thought I had the issue, but my idle was just too high. The bike was still warming up and if you revved it, the rpms hung.  Once it warmed up and the idle was lowered... no more problem.

There is the thumbwheel screw for idle. Then look to see if the linkage is coming back against the end of it.


I still hear one cylinder cutting in and out.

Possible vacuum leak. Check the orings between the intake boots and the head.

I'd go through and clean the carbs... they are pretty simple.

A lot of exhaust smoke. I wonder if you have st up rings or scored cylinder walls/pistons. Do you have an inspection camera that can go in the spark plug hole (cheap Bluetooth for smartphone)

[struckjm]

I am going to re-summarize...

So. I think each cylinder may only have about 80PSI.

It starts up on it's own most of the time. With the choke on it rises to 4500-6000RPM. Stays there. Smokes a bit.

I've never let it run like that more than say 30-45 seconds.

Without the choke it dies. Adding throttle it either dies or climbs a little and hangs.

It sat for 18 months. The valve clearances were wildly off.

Where should I start my next step of troubleshooting?

[Sporty]

I am going to re-summarize...

So. I think each cylinder may only have about 80PSI.

It starts up on it's own most of the time. With the choke on it rises to 4500-6000RPM. Stays there. Smokes a bit.

I've never let it run like that more than say 30-45 seconds.

Without the choke it dies. Adding throttle it either dies or climbs a little and hangs.

It sat for 18 months. The valve clearances were wildly off.

Where should I start my next step of troubleshooting?

Too bad that so few of forum members who have owned and worked on these bikes for many years, answer these questions...

Anyway,

I think you have more than one problem.

It very likely that you have carburetor issues... almost impossible not to have clogged up carbs with the ethanol in the gas these days.

Possible intake leak, the bikes are known for hard, leaky and broken O-rings,  mine were bad. .

Then there is the question of engine condition. I would look at that first.


Can you give some clarification on the compression test?

Test method should be:

Engine warm, both plugs out, throttle held wide open, fully charged battery, 6-7 puffs (compression strokes) until the gauge stops climbing.

Where is the location of the Schrader valve on your compression tester? 
Is it in the very end of the hose? (The part the screws into the cylinder)
The location makes a BIG difference, especially on a motorcycle!

[struckjm]

I am going to re-summarize...

Can you give some clarification on the compression test?

Test method should be:

Engine warm, both plugs out, throttle held wide open, fully charged battery, 6-7 puffs (compression strokes) until the gauge stops climbing.

Where is the location of the Schrader valve on your compression tester? 
Is it in the very end of the hose? (The part the screws into the cylinder)
The location makes a BIG difference, especially on a motorcycle!

yesterday was my first time doing it warm. I let it turn 5-10 times until it stops climbing. Full throttle. Shorai battery has high CCA. The schrader valve is at the very end (that goes in spark hole). It might not be fully warmed up, because I really just let it run for about 45 seconds until it started to smoke some and I cut it off at the swich.

[mr72]

idle is set too high. Simple as that. Low compression may cause it to refuse to idle.

[Sporty]

yesterday was my first time doing it warm. I let it turn 5-10 times until it stops climbing. Full throttle. Shorai battery has high CCA. The schrader valve is at the very end (that goes in spark hole). It might not be fully warmed up, because I really just let it run for about 45 seconds until it started to smoke some and I cut it off at the swich.

Your test technique is good!

75-80 PSI cranking compression is enough to fire a cylinder, but it's not going to run well and will be hard to start in cold weather.

So now the source of low compression. Is it leaking past the rings or valves?

I prefer the compressed air into the cylinder method.

There is the old school method of squirting some oil in the cylinder and re- testing. If the compression goes up, it's poor ring seal.

However... the oil is not going to seal up scuffed cylinders, broken rings, etc...

[struckjm]

Your test technique is good!

75-80 PSI cranking compression is enough to fire a cylinder, but it's not going to run well and will be hard to start in cold weather.

So now the source of low compression. Is it leaking past the rings or valves?

I prefer the compressed air into the cylinder method.

There is the old school method of squirting some oil in the cylinder and re- testing. If the compression goes up, it's poor ring seal.

However... the oil is not going to seal up scuffed cylinders, broken rings, etc...

It may be ring related. I did do the oil test, and it got the compression to go from 0.0 up to about 9PSI by doing that.

[mr72]

It might not be fully warmed up, because I really just let it run for about 45 seconds until it started to smoke some and I cut it off at the swich.

yeah you'll have to deal with misinterpreting warmed up once you get the compression sorted. Takes 15-20 minutes of actual riding on the road under load and going through the gears to warm up a GS500.

Your compression problem sounds like rings to me but could be a blown head gasket or a dozen other things. With these numbers I'd jump straight to a top end rebuild. Don't waste time hoping for better outcome. There's nothing like new rings, honed bores, and a valve job to wake up an old GS.

[Sporty]

Your test technique is good!

75-80 PSI cranking compression is enough to fire a cylinder, but it's not going to run well and will be hard to start in cold weather.

So now the source of low compression. Is it leaking past the rings or valves?

I prefer the compressed air into the cylinder method.

There is the old school method of squirting some oil in the cylinder and re- testing. If the compression goes up, it's poor ring seal.

However... the oil is not going to seal up scuffed cylinders, broken rings, etc...

It may be ring related. I did do the oil test, and it got the compression to go from 0.0 up to about 9PSI by doing that.

Do it again, now that you have 80 PSI.

IMHO, it's always good to have an idea what the problem is before diving into a repair.

[struckjm]

OIL TEST RESULTS

Starting with 80 PSI, add oil to spark plug hole, get 105 PSI.

[Sporty]

OIL TEST RESULTS

Starting with 80 PSI, add oil to spark plug hole, get 105 PSI.

25 PSI is a major increase. It would indicate significant ring seal/ cylinder wear issues.

If it were the valves, it would show no increase.

I'm going to theorize that the bike had low compression and power. Someone tried to adjust the valves, put the wrong shims in and it never ran again.

I guess you have to decide if it's worth fixing.

People speak well of these videos. Take a look and see if you are willing to tackle the repair

She has the engine on the bench, but you can do the work in frame too.

[struckjm]

Whether or not a top end rebuild is possible in frame would have been one of my next questions.
I've watched those vids. A LOT of specialized tools I don't have.

Legit question: bought the bike for $750. Have put another $200-300 in parts and tools in to it.

How expensive and time consuming is a top end rebuild?

I could probably buy a well kept, running GS500e in my market for about $1500. Sad to give up on this one, but is it really worth it?

[aconti2]

I think all the parts/gaskets for my top end job came out to around 200. Ended up having to buy an ebay cylinder head for another 50 bucks.

Your best bet would be doing almost all the work yourself and brining in the cylinder head and pistons for the new rings/hone and fit job at a shop. Its not a lot of work and they shouldn't charge much, call around for an estimate?

Everything can be done in frame and its a really fun and rewarding job.

[struckjm]

Thanks. I appreciate that perspective.

I am considering that.

I am also considering purchasing a UGLY but RUNNING bike soon. I found a few for ~$1200. I can use the two bikes to complement each other partswise, and take my time restoring things (like do a paint job on the parts bike parts while I continue to ride the ugly runner).

Long term, I'd like to chop the tail off, jet the carbs with pods/lunchbox, maybe make the wheels a little 'scrambly' and re-paint it with something modern looking pallette wise. It'd be nice to do one thing at a time without de-commissioning the daily rider while doing so.

[Sporty]

Thanks. I appreciate that perspective.

I am considering that.

I am also considering purchasing a UGLY but RUNNING bike soon. I found a few for ~$1200. I can use the two bikes to complement each other partswise, and take my time restoring things (like do a paint job on the parts bike parts while I continue to ride the ugly runner).

Long term, I'd like to chop the tail off, jet the carbs with pods/lunchbox, maybe make the wheels a little 'scrambly' and re-paint it with something modern looking pallette wise. It'd be nice to do one thing at a time without de-commissioning the daily rider while doing so.

Anywhere near Detroit  Michigan?

http://gstwins.com/gsboard/index.php/topic,73519.0.html

[struckjm]

I am in Richmond, VA.

[struckjm]

RESURRECTION

Fun update.

I bought a second bike, and tested my compression gauge on that bike. Turns out that perfectly running Ducati Monster ALSO read 80PSI.

So I am calling BS on the gauge, and getting back in to making this GS RUN!

So, I've decided the next easiest step would be to rebuild and properly install the carbs and a lunchbox.

I am getting the K&N lunchbox, a 40 pilot and 150 main (x2) and 2 rebuild kits sent to the house. Shopping for an ultrasonic cleaner, b/c hey why not?

I might choose to by OEM/New rubber for the manifolds between carbs and valves, and carbs and air source, because both are really stiff and hard to work on properly, and I want to make sure there's no dumb air leaks.

ANYTHING ELSE I NEED TO KNOW?

[mr72]

I would strongly suggest you get it running with the airbox and stock air filter (assuming you have that stuff) FIRST, so you are not trying to solve more than one problem at one time. If everything is in decent shape you KNOW it can be made to run with stock jets, stock carbs, stock airbox, air filter, you name it. You don't know it can be made to run with your mods.

Again, the reason it was hanging 5K returning to idle is because the idle speed was set way too high. The reason the idle is set too high is either simple operator error (whoever set up the carbs did it wrong) or trying to overcome some other issue causing it to not idle at all, among those issues might be legit 80psi compression.

The lunchbox and big jets may eventually work but getting it to idle right is not going to be a plug and play affair. Also you will accelerate wear on the rings a lot by fitting a k&n air "filter". Not a great plan IMHO, especially if you already have low compression due to worn rings, but it's your bike and do what you want.

[struckjm]

Just to wrap this thread up:

Actual compression when 'kinda' warm is about 147 and 152 left and right.