81 gs550T wont start after valve adjustment... very confused

[Guest]

Hi everyone, couldn't get my bike to start today so here's some background in case anyone has any ideas...

Over my school's winter break this past winter I took the carbs off my 81 GS550T, dipped them in carb cleaner, spray cleaned thru all the ports and jets were replaced for a 4to1 pipe. I couldn't get it to run and had to get back to school, so the bike sat for a few months. I came back home for quarantine and I decided to replace the jets (now for pod filters as well), I shimmed the needles, and put in a cycle o-rings kit. I also replaced the oil and took out all the old gas from the tank. The bike wouldn't start and I suspected it was getting no fuel, so I checked the petcock. on prime the fuel flows slowly, not as fast as I'd like, but in the 'on' setting fuel flows beautifully when I apply a vacuum. So, I hooked up the fuel line to the carbs and sucked on the vacuum line to prime the bowls with fuel. I then replaced the spark plugs and she fired up!

I drove the bike for a short 15 minute test run and she ran pretty bad - couldn't get above 40mph and had barely any power getting to the engine. Before trying to figure out the jetting issue, I knew it was time to do a valve check. Ended up changing 4 shims, and now all clearances are in spec. I also cleaned up an old, melted gasket and a ton of gasket sealant from the valve cover, replaced with a new OEM valve cover gasket, put everything back together.

Now the bike won't turn over! At first I heard a hissing sound coming from the engine when trying to turn over and realized one spark plug wasn't fully screwed in. Fixed that, no hissing, charged up the battery fully, checked spark on all plugs, and tried again - starter engine cranks but still the bike won't turn over.

Thinking about taking off the carbs tomorrow to see if anything wrong sticks out and also to replace the carb boot o-rings. When the bike ran last week, I sprayed carb cleaner around the carb intake boots to check for a vacuum leak and didn't find any. note, it would backfire when turning over and idle a little high at 1500rpm. Pulling the spark plugs after my short test run showed a lean condition, which I suspected.

My choke mechanism also seems little tight... when I pull the choke to fully extended it springs back down to about halfway pulled and will stay there. Since the choke mechanism starts my engine when it's cold, as far as I understand, I wonder if this has anything to do with it?

Any ideas or help will be greatly appreciated!

 

[1948man]

It would seem a carb issue wouldn't keep the engine from turning over. Is the battery strong? Sounds like the starter isn't engaging. If it was, and the engine wouldn't turn over, the starter probably wouldn't spin either. Also, is there any chance fuel has leaked into your crankcase creating resistance to turnover?

 

[Guest]

I assume the starter engine is engaging because it is making that loud clicking over and over and I hear it turning. Is this what you mean? I recently had to fix the wiring for the solenoid so I know 12V of current is getting to the starter engine and the sound I hear makes me think it is firing. I could be wrong though.

To answer your question, I wouldn't exactly call the battery strong - it doesn't hold a charge very well and replacing the r/r and testing the charging system is next on the to do list for the bike. in response to the fuel in the crankcase, I'm not sure. How would fuel get in there and is there any way to check for it?

In the past when the bike wouldn't start, ie the starter was firing very slowly, once I charged the battery fully it would turn over. Today, I charged it to full charge and could hear a drastic quickening in the starter engine compared to earlier in the day when the battery was weak. so I assume it had enough power to turn the engine over...

Maybe I need to get a new battery and ensure that's not the culprit?

 

[1948man]

If the petcock is left on prime, fuel will flow to the carbs and unless the needle jets (fuel inlet valve) are strong, gas will seep by and eventually flow through the intakes and past the pistons down into the crankcase. If there is too much fluid (gas and oil) in the system, the pistons can't turn over (hydra-lock I think it's called.). With your description, it seems more likely the starter is spinning but it's teeth are not engaging with the flywheel (?) to spin the engine. If there was gas in the oil it's more likely you would just have a very slow, labored attempt to turn over. Also, if you take off the oil filler cap and sniff, you should be able to smell gas in the crankcase. You can also check the oil level in the sight glass with the bike on the centerstand. I'm not sure if a stronger battery is the remedy for the starter not meshing with the flywheel or if there could be other issues.

 

[1948man]

https://mechanics.stackexchange.com...g-but-not-engaging-flywheel-what-is-the-issue

 

[Guest]

thanks for the help 1948man, here's a video of me trying to start it up so you can hear as well:

https://imgur.com/a/eBKwf29

Looking at that post you linked, it seems like my starter is spinning but not engaging, and making a grinding sound? If you listen closely to my video, right after the 1st and 2nd starting attempt I hear a slight grinding sound coming to a halt. If this is the case, according to this GSforum (https://www.thegsresources.com/_forum/showthread.php?192352-Starter-spins-but-not-engagin/page4&highlight=starter+not+engaging+freewheel) it seems like the starter clutch is not engaging.

This thread recommends draining the oil and removing the left engine cover and seeing if the starter clutch ring gear is spinning the crank. If it's not, then its the starter clutch that's the issue. (post#8).

I have no experience working with the starter, this seems little out of my depths but I'm willing to do some investigating... let me know what you think.

ALSO, in the picture I linked, you can see there's a gap between the casings right next to the hex bolt on the top of the starter cover. This was how I got the bike from the PO, so I'm wondering if a previous impact might have caused the starter to get jostled and not be engaging the starter clutch?

Wondering if I should remove the starter cover first and take a look in there before I take off the left engine side cover... and if that's the case what do I look for? I'm a newbie mechanic so really don't know what I'm getting myself into but willing to (carefully) put in the time to learn.

 

[Grimly]

That video sure sounds like it's turning the engine over.
Put a thumb over a spark plug hole and feel the pressure popping your thumb out the way.

 

[Gorminrider]

yes, it sure does... grimly's instruction will set you right...and you can check for spark too....

Tip? generally, when starting a recalcitrant bike, I like to use a car battery so I know the bike is getting all the current it wants for spark and headlight too,if you haven't unplugged it or its fuse already.

 

[Guest]

Tip? generally, when starting a recalcitrant bike, I like to use a car battery so I know the bike is getting all the current it wants for spark and headlight too,if you haven't unplugged it or its fuse already.

do I run the risk of putting too much charge thru the solenoid? Or is it ok for a test jump start?

also, if it does sound like it?s engaging the flywheel and turning the engine over, and the pressure from the spark plug hole confirms this, then it means it is a fuel/air/spark/compression issue, correct?

 

[Guest]

jump started with a 12V car battery and still nothing... confirmed I have spark in all 4 plugs, and did the test that grimly recommended and there's definitely pressure pushing out of the plug holes. At least now I know the starter is engaging the engine.

so it must be a fuel/air issue in the carbs? I'm confused n surprised by this bc I did a carb rebuild so recently and in the past once the bike actually started (although I still had issues with a long and slow turn over/backfiring) it would idle ok at about 1500. Which I assume would mean fuel and air were indeed getting to the engine...

so is it my choke circuit in the carbs? Just trying to figure out next steps do diagnose the problem. Thanks in advance.

 

[Big T]

Are your spark plugs getting wet when you try to start it?
Did you let it sit for months with fuel in the carbs?

 

[Guest]

Spark plugs aren?t wet no. It sat for about 3 months because I couldn?t get it started, but when I took the carbs off in the beginning of this month to change the jets and shim the needles there wasn?t any fuel in the bowls. That?s why I originally suspected a lack of fuel. Petcock was rebuilt about 6 months ago and hasn?t seen regular riding since, but fuel doesn?t flow super freely on prime, is a little sluggish. On the ?on? position the vacuum lets fuel flow very well.

 

[1948man]

Definitely sounds like it is turning over strong. Are the plugs bone white which would indicate lean (lack of fuel)? You could spray a little starter fluid in the intake just to see if you could get it to fire although many don't like to use that. I will use it judiciously occasionally. If it's not lack of fuel and you've confirmed spark, is it possible you erred in the valve adjustment and it has so little compression it doesn't want to start? 550T, is that a 16 valve engine or shim and bucket?
EDIT... okay, I see its shim and bucket.

 

[Guest]

Heres some photos of the plugs. https://imgur.com/a/Ee5M1mf

#1and#2 show a lean condition, although #1 has more carbon(?) deposits around the ring. #3 and #4 look almost like clean metal... not sure what this would indicate. Plugs are new and were in there while the bike was running for no more than 25 minutes before I did valve adjustment.

Regarding the valve clearances, I'm positive all are in spec, everything is within .05-.08mm

I'd rather not throw starter fluid in there but will if its a last resort.

 

[Guest]

Has it run at all since the valve adjustment? It could be the cams are out of time.

 

[Guest]

Has it run at all since the valve adjustment? It could be the cams are out of time.

nope, it hasn't. how could I identify bad cam timing? When I was hand turning the engine for the valve adjust it didn't turn smooth at all points, had a lot of drag and resistance sometimes. not sure if this relates?

 

[1948man]

nope, it hasn't. how could I identify bad cam timing? When I was hand turning the engine for the valve adjust it didn't turn smooth at all points, had a lot of drag and resistance sometimes. not sure if this relates?

You should start a new fresh thread about the drag encountered when advancing the engine. That's not a good sign. Put the new thread in the 4 Cylinder Engine Section. If the chain somehow jumped and the cams got out of time, it could cause piston to valve contact or other problems as well as ill-timed compression. Maybe carbon buildup could also cause problems with the valves closing.

 

[Guest]

thanks for the tip, I've started a new thread.