1982 GS450 mystery rattle

[Will8837]

Hi. I have a 1982 GS450. I just bought and restored an '82 GS450T. Got everything painted, sealed, lubed and back together, and now I have engine noise. I need help. Here are the symptoms...
1. Won't start on a charged battery, only on a car battery.
2. Backfires really loud, but only when starting.
3. Will not run unless choke is full on.
4. Will idle fine (with choke on).
5. If any throttle more than just a hair, the motor will not rev above 2000 rpm, and the motor bangs around and will stop with a jerk. I'll start it again and it will purr like a kitten until I give it gas.

I have checked the timing chain, and it has not jumped a tooth. the spark plugs seem fine.

Do I have a floating valve? Is the cam chain messed up somehow?

Thank you for any advise!

Will.

[BassCliff]

Greetings and Salutations!

Hi Mr. Will8837,

Did your restoration include new carb intake boots and O-rings? Carb disassembly, clean and rebuild? Valve clearance adjustment? Carb sync? Ignition timing? Let me roll out the welcome mat for you. I hope you find a lot of useful information on it....

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.


Thank you for your indulgence,

BassCliff

[aquamon]

carb float bowl (sump) has a jet in it, make sure this is clear!!!
Most people overlook the sump when cleaning carbs as it is removed first and put aside.
THIS IS WHERE the VARNISH settles!

Engine noise is another problem in itself.
Maybe the starter "bendix".

[Will8837]

Thanks for your quick and knowledgeable responses. I guess this opens up more questions.
How do you set or check the valve clearance on this engine?
How do you check or set ignition timing?
The plate in the signal generator can be slid back and forth to some degree, but this did not solve the problem.
I thought it might be the starter drive gear, but it seems this is not meant to disengage.
I did go over the carbs. I disassembled them and cleaned all jets, perhaps I missed one. A re-cleaning is on the to do list.
I'll let you all know how it goes. Thanks again for the help.

[BassCliff]

Hi Mr. Will8837,

Do you have a manual yet? Have you checked out everything, including all the links, on my website? There really is a lot of stuff there that will answer a lot of your questions. If it's not on my site, follow the links to other websites with even more information. Rather than type out complicated procedures (which have been covered in this forum - use the Search), it's much easier to point you toward resources that already exit.

For example, by searching the Technical section's titles for things like "points" and "timing" I found this:

http://www.thegsresources.com/_forum/showthread.php?t=136832&highlight=points+timing

http://www.thegsresources.com/_forum/showthread.php?t=134893&highlight=points+timing

http://www.thegsresources.com/_forum/showthread.php?t=134893&highlight=timing

The '82 should have electronic ignition and not really need much adjustment other than lining up the timing marks. Now roll up your sleeves, do some research and reading, and ask questions when you get stuck. Let us know how you fare.

From my website:

Valve Adjustments (8 Valve) - It's for a 4 cylinder, but the concept is the same.

On my site you'll also find this in the "Odds and Ends" section:

Valve Adjustment Video

Kerry Burton, from the GSTwins.com forum shows us how to adjust the valves on the "shim-over-bucket" two valve per cylinder GS motors. His bike is a later model (twin cylinder) GS500, but the concept is the same.

http://video.google.com/videoplay?docid=-2015554469142545363

Thank you for your indulgence,

BassCliff

"Give a man a fish and you feed him for a day. Teach a man to fish and he'll sit in a boat drinking beer all day."

[Will8837]

Wow! Thanks for the info. I didn't realize how much stuff we have to share on this site. I checked the valves, and they all seem pretty tight except the number 2 intake that maxed out at .073 mm. Would this cause the banging around and the backfiring? I will try to locate shims from the parts links on your page. Worst case scenario, can I grind them down?

Thank you so much...I might have it running by st. patrick's day!

Will

[aquamon]

Wow! Thanks for the info. I didn't realize how much stuff we have to share on this site. I checked the valves, and they all seem pretty tight except the number 2 intake that maxed out at .073 mm. Would this cause the banging around and the backfiring? I will try to locate shims from the parts links on your page. Worst case scenario, can I grind them down?

Thank you so much...I might have it running by st. patrick's day!

Will

Yes, you may grind the valve stem head down, not much, per clymer manual=no less than 4mm from middle of lock groove to top of valve.

page 68 (9.)
"If the valve seats in the cylinder head have ever been reconditioned, the ends of the valve stems can be refaced if necessary, however, the end of the valve must not be less than 4.0mm..."

NOTE: this is for valves with little clearance.
For valves with too much clearance, try re-lapping.

The jet that needs to be cleaned is in the carb. sump by the drain plug.

[BassCliff]

Hi Mr. Will8837,

Grinding valves seems like too much trouble. Just do a valve clearance check, make notes of the clearances and the shim sizes you have. Then order the shims you need from Z1. They have the best prices on shims. Be sure to get the Suzuki style 29.5mm diameter shims. Here's the link.

http://www.z1enterprises.com/catalog.aspx?pid=GS450EZ-1982-EN1

Steve has a spreadsheet that's handy for keeping track of your shims, clearances, and other maintenance. Send him an email.

Thank you for your indulgence,

BassCliff

[aquamon]

Hi Mr. Will8837,

Grinding valves seems like too much trouble.
BassCliff

Some people live in remote areas and shipping is really not an option...

[blo]

Hi Mr. Will8837.
Does your bike have the mechanical timing advance?
My -81 GS450 have a mechanical timing advance under the ignition cover on the right hand side of the motor. After last years winter storage the bike displayed much of the same symptoms as yours, and a close examination revealed it to be the advance that was "frozen".
This led to horribly wrong timing on anything but idle. Giving throttle would make it bang and stutter like mad.

Just my experience.
-blo

[lexx2525]

Hi Will8837, I have 81 gs450l and one day it developed the same kind off symptoms. After checking curbs and petcock it turn out to be one of the spark plug caps was bad. It was easy fix, just got one from some other motorcycle that was sitting around local junkyard until I get a new one. I hope it helps.

[Will8837]

I can't believe I overlooked the coils and wires. Sure enough one of the caps was toasted, and upon closer inspection one of the coils was cracked. I took the coils off a parts bike tried it out, and it started within 2 compressions without backfiring. After about 2 minutes of running, it started back to the previously mentioned symptoms.

I guess I will be getting shims in the mail and coils, wires, and caps from the shop.

Blo,
How did you fix your advance? How did you tell it was frozen? I can turn mine with my hand, is that loose enough?

Thank ya'll.
Will

[Will8837]

Oh Yeah...spark plugs too!!

[Will8837]

Ok, so I feel a little dumb at the moment. I went to get those new coils. I put them on, and the problem was not fixed. I determined through touching the crankcase when it was banging around, that it was either coming from the starter clutch or the clutch. I took off both side covers, farted around a bit on the starter side. I couldn't get anything off on that side except for the little idler gear. I removed, inspected and replaced the entire clutch. I noticed a little endplay in the crank. Is that normal? When I put everything back together...problem solved!!! Sounds like a fully functioning motor now.


I need my turn signals, insurance and a tag, and I'll be on the road.

Thank you all so much. When I joined this site, I was about 5 days from putting the bike on craigslist as a partially completed project. Thank you all so much for giving me ideas of things to try. It really kept me moving on the bike the past couple of weeks.

YOU GUYS ROCK!!!