Ignition Timing

[Guest]

Hello All,
My 1st time here, and I have performed a search for this info, but have been unable to find the specifics.
I recently purchased a 1981 GS850G(L?), got it kinda cheap, and for very good reason! I've done a lot to it already, but can't find timing information. I DL'd the PDF repair manual, but it only addresses "contact point" ignition. I have the electronic ignition with mechanical advance.
I had to purchase a parts bike because of extensive problems. I pulled the trigger from the other bike, as well as the advance and all other ignition components.
I cannot find the procedure for timing the trigger. I have a timing light, I can make a simple degree wheel, I just need to know how to time the ignition.

Any help would earn my Undying Gratitude! As soon as I'm finished with all the parts I need from the Donor Bike, I will offer them up for sale. It's a 1981 GS750L. I have the title as well. The top end was disassembled a few years ago, long before I saw it. The ARE 3 sets of carbs, as well as an fuel tank. The original tank was removed new and stored, it's pristine. I wish I could use.

Thanks for reading!

Scott

[Crankthat]

Do not know if this will help you?
CLICK

[tom203]

I'd worry about camshaft to crank timing first (this is clearly marked so easy to check) - the electronic ignitor setup does not have much adjustment as to spark timing. The ignitors are slighty different- make sure you keep the signal coils that went with the ignitor you plan to use.

[trippivot]

F is for fire

1 and 4 "F" mark is used to set the ignition timing at idle or at least under 2000 rpm. - 2 and 3 sometimes only have a "T" on the advancer -- good to check both pairs.


have a tricky digital timing light? set it at zero to get "F" to line up OR set to 11~13 btdc and get the "T" to line up

T is for T.D.C. and F is ignition firing -- do you have the thin metal pointer plate that has a line on it?

[AirCooled]

I'd worry about camshaft to crank timing first (this is clearly marked so easy to check) - the electronic ignitor setup does not have much adjustment as to spark timing. The ignitors are slighty different- make sure you keep the signal coils that went with the ignitor you plan to use.

The bike was running and engine timing seems fine. I used ALL ignition components from the donor ie: Coils, Trigger, Ignitor, AND Complete wiring harness. I double checked all parts numbers to verify they are the same with the online fiche..........
Now, to be certain, the cylinder heads IS weeping a bit of oil, but I'm not prepared to pull the head right now. When THAT happens, I will do a complete rebuild, valves, guides, seats, check cams, and make sure the surface is flat.
Right now I'm trying to verify procedure for IGNITION timing. So far, it appears there is none for this ignition system.
I followed "Crankthat's" link, and will see how it goes.

Thanks for the input!

[tom203]

The bike was running and engine timing seems fine. ...

Ok, but you said
"The top end was disassembled a few years ago, long before I saw it."

Doesn't take much to pull camcover off and verify "fine" - best to be suspicious of previous efforts.

[AirCooled]

Ok, but you said
"The top end was disassembled a few years ago, long before I saw it."

Doesn't take much to pull camcover off and verify "fine" - best to be suspicious of previous efforts.

Hey Tom,

The engine on the DONOR BIKE had been disassembled, not MY ride. That bike is a 1981 GS750L and has 4 valves per cylinder and is CHAIN drive. The bike I'm resurrecting is a 1981 GS850G, and by all indications an LX. It's basically an assembled basket case, lots of wires chopped, twisted, and taped. I'm certain there's at least $100. worth of Zip Ties on this thing! Wrong tank, wrong side covers, airbox, etc....... I took it right up the Ole Chute!
So I bought the disassembled bike for parts. I took the whole ignition system, wiring harness, headlight assy, turn signals, front brake M/C, and various and sundry items from the donor. Hence my Ignition Timing question. I may be New HERE, but I am NOT new!

Sorry for the confusion, Sir!

Again, Thanks for all of the input from everybody!

[AirCooled]

Doesn't take much to pull camcover off and verify "fine" - best to be suspicious of previous efforts.[/QUOTE]

By the way, I do intend to pull the cover soon and check Valve Lash, compression test shows good, and I'm suspicious of EVERYONE else's Previous Efforts! Words I live by: "Always Check the Evidence"!

[trippivot]

another way to see the timed ignition event

remove the plug wire going to #4 spark plug and install a testing spark plug into the wire end so you can see it flash.

turn on the key and with a 19mm wrench turn the crankshaft clockwise from the ignition signal generator side. You can see and hear when the spark plug gets the signal.

it should spark when the 1-4 "F" mark and the backing plate marking line align. if not ask another question.

spark ? no spark? spark at the wrong time?

most all these parts are dimensionally identical and interchange - but there are exceptions between a mechanical advancer system and a transistorized advance system. either system type will bolt up to your engine. The bigger coils under the tank don't care which is which - it will spark when told to..

but the advance unit, signal generator plate, and brain box combo matter - they have to match each other. don't forget the safety circuit if there is no spark at all.

[AirCooled]

remove the plug wire going to #4 spark plug and install a testing spark plug into the wire end so you can see it flash.

turn on the key and with a 19mm wrench turn the crankshaft clockwise from the ignition signal generator side. You can see and hear when the spark plug gets the signal.

it should spark when the 1-4 "F" mark and the backing plate marking line align. if not ask another question.

spark ? no spark? spark at the wrong time?

most all these parts are dimensionally identical and interchange - but there are exceptions between a mechanical advancer system and a transistorized advance system. either system type will bolt up to your engine. The bigger coils under the tank don't care which is which - it will spark when told to..

but the advance unit, signal generator plate, and brain box combo matter - they have to match each other. don't forget the safety circuit if there is no spark at all.

Got it.
No, no Digital Timing Light, just an old school Chrome Craftsman. Got spark, changed ALL Ignition Components from Donor bike, because frankly, everything looked new, with the exception of the coils. Used those as well, better plug wires and no cut off connectors and twisted and taped.
So........ I put my light on it, dialed it in to spec. I will say, the method from "Crankthat" seems to be right, since it definitely runs better advanced! That's where I'm leaving it!

Couple more things to button up tomorrow, I should be rubber to the pavement tomorrow! If it only it weren't SO COLD! It's only gonna' hit 73 degrees tomorrow! Come on Summer!!!!!

Again, thanks for all the help and input!

[earlfor]

Right now I'm trying to verify procedure for IGNITION timing. So far, it appears there is none for this ignition system.
I followed "Crankthat's" link, and will see how it goes.

Thanks for the input!

You are correct. The stock ignition timing system is non adjustable.

[Steve]

You know, usually, even I will trust you guys, but seriously, ... "non-adjustable"?
"crank it hard counter clockwise and lock it down"?

And this is coming from guys who build engines and race bikes.

At the top of page 16-11 of the factory manual, you will see this:




Yes, it is adjustable, and should at least be checked to make sure that it's in the ballpark before going very far.

Granted, once it is set, you will not have to adjust it again, but let's face it ... this is a different timing plate than what came with this bike from the factory, IT SHOULD BE CHECKED. There was someone who has posted somewhat recently that said "I'm suspicious of EVERYONE else's Previous Efforts! Words I live by: "Always Check the Evidence"! "

.

[AirCooled]

You know, usually, even I will trust you guys, but seriously, ... "non-adjustable"?
"crank it hard counter clockwise and lock it down"?

And this is coming from guys who build engines and race bikes.

At the top of page 16-11 of the factory manual, you will see this:




Yes, it is adjustable, and should at least be checked to make sure that it's in the ballpark before going very far.

Granted, once it is set, you will not have to adjust it again, but let's face it ... this is a different timing plate than what came with this bike from the factory, IT SHOULD BE CHECKED. There was someone who has posted somewhat recently that said "I'm suspicious of EVERYONE else's Previous Efforts! Words I live by: "Always Check the Evidence"! "

.

Well.......... I had a really nice response all ready to post, and BAM! My POS Android tablet just locked the hell up!
Anyway, I'll try again. I used my Inductive Timing Light on #4 cylinder, set it to the "F" mark and the bike ran decent. I then followed previous advice, and rotated the the trigger fully counterclockwise, which is obviously advanced, and the engine smoothed out even more. Especially at idle. All of the donor parts I used were identical in appearance and markings. The factory part numbers were the same, using the online fiche from CycleSpringsOnline.
After 30 years of working on everything from cars, motorcycles, boats, small engines, and EVEN the 8" Self-Propelled Howitzer, I'm actually pretty familiar with all things mechanical.Years in the Industrial Diesel business, as well as being a Marine Mechanic have served me well when it comes to working on ANYTHING.
Now, to be certain, this is my FIRST SUZUKI. So I'm learning, not a bad thing in itself. The bike itself was in essence a Basket Case, which happened to be assembled, very, very poorly. The airbox is incorrect. Airbox to Carb boots do not fit the carbs. The fuel tank is incorrect for this bike. The wiring harness was butchered, and instead of butt splices, most connections were bare wire twisted together and taped. I then purchased a Donor bike, GS750L, with title, that had the cylinder head removed. This is the bike I removed the ignition components from, as well as the entire wiring harness. 99% of the connection are identical. So far, I'm very happy with how it's turned out. Of course the donor had the K&N Pods, which I was forced to use on my bike, due to not having the correct airbox. I performed the "Strip & Dip"of the carbs, and ignorantly bought the K&L carb kits. I did verify the needle, and jet numbers that came with the kit to factory numbers. So far so good, with the exception of those Dreaded Pods. What I've learned about this engine.......... It absolutely HATES Air! I had to TAPE OFF 95% of the Pods surface area JUST to get the bike to run on throttle. It would only start and rev using the Choke Circuit. As soon as TOUCHING the throttle, it would die! Lesson learned! So.......... definitely in the market for a Factory Airbox. I'm considering fabricating one as well. I am NOT interested in re-jetting, as I'm comfortable with the power and speed available at factory settings. This has been quite the learning experience, not sure I was in the market for that, but there it is! I realize that most of this monologue is probably a mis-post, but I'll try to get back on track.
Steve, as for your quote about "Suspicion and Evidence" that was me!
Unfortunately, due to a successful scuba and spearfishing expedition, with blood in the water, I became one of many victims of a shark bite. My fellow diver said it was a 10-12 foot Bull Shark. Lucky for me, the hard plastic of my swim fin must have hurt his gums(maybe he had Gingivitis?)because he spit out my foot without severing it. Still dealing with a nasty infection, and amputation is a very real prospect, at about 65% as of today. SSI Disability does NOT pay well, the work on the bike, as well as everything else in my life, is on a strict budget!

[78suzidave]

If you used the timimg components from a 4valve motor the F mark would be 12 degrees, if the 750-4V is the same as the 1100e. Most 2 valve Suzuki's run about 5 degrees advanced from 4valves. So advancing it would make it run better, but that has it's limits.