1981 Suzuki GS450L - Cruiser to Scrambler

Northish

If you know what you're doing, you're not learning
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Wanted to get these slightly fancier shots of the bike added to the thread for completeness.

It really is a fun bike on the gravel! I think I will forever have a soft spot for air-cooled, light and simple 2 cylinder bikes.

_Northish
 

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Northish

If you know what you're doing, you're not learning
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NoRiders said:
Such a good looking bike, like it should've left the factory like it, if you get what I mean.
I definitely get what you mean! I'm glad you think so as that was my hope for this bike.

djmaynard said:
Those were great shots! Beauty!
Thanks djmaynard!

And thanks to all who got out and voted for October's BOTM. It's easy to do and can mean so much to the community.
 

sacruickshank

New Member
Northish ... i"m sure this has already been said in the thread, but thank you for documenting this. I recently snagged an '83 GS450L and will borrow from your thread shamelessly as I bring this bike back to respectability. The PO painted the tank and fenders a decent white, but the engine is a sketchy mix of the original metal and inconsistent black spray with no masking.
 

Northish

If you know what you're doing, you're not learning
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sacruickshank said:
Northish ... i"m sure this has already been said in the thread, but thank you for documenting this. I recently snagged an '83 GS450L and will borrow from your thread shamelessly as I bring this bike back to respectability. The PO painted the tank and fenders a decent white, but the engine is a sketchy mix of the original metal and inconsistent black spray with no masking.
Hey sacruickshank - Glad you found the build info helpful; also glad to hear someone else is turning a GS450 into something they can be proud of! No shame in not reinventing the wheel; I'm sure you'll be adding your own ideas and flair. Let me know if something I did was unclear or lacking in detail and I'll try to add some detail. Best of luck and have fun with it!
 

Northish

If you know what you're doing, you're not learning
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While waiting patiently for warmer weather to reach the north, I've made a few more purchases to take care of a few things I wanted to do last year but ran out of time for.

First things are new fork springs and oil. The front end was a bit soft and I was bottoming out on moderate bumps. I went with 10W oil and set the level at 140 mm (from the top of the forks with springs out and forks compressed.)

When I pulled the original springs out I was surprised to see that they already had a progressive wind to them, so maybe they were an aftermarket spring already? The new Progressive springs I put in seemed to be made with thicker metal so I'm hoping they are firmer than what was in there. I'll be curious to see. I may need to do some work with the preload spacer and oil level depending on how they feel. More to come on this once I can get out and ride.

I also got a Koso narrow-band A/F ratio meter that was on sale. I'm hoping to use that to make sure my carb tuning is in fact good. I'll be wiring that in at some point and welding in the sensor port. I'll post an update once it's installed.
 

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ApriliaBill

Yeah...I'm old school.
Northish said:
Wanted to get these slightly fancier shots of the bike added to the thread for completeness.

It really is a fun bike on the gravel! I think I will forever have a soft spot for air-cooled, light and simple 2 cylinder bikes.

_Northish
You took a horrible looking bike (never a fan a the L models) and turned it into something anybody would be proud to own. Great job....
 

troyholder437

New Member
Northish said:
Glad you like that gauge - It's pretty awesome. It can learn gear position and I've got a cylinder head temp. sensor feeding into it. Since I've messed with the wheels and diameters it gives me a lot flexibility. It's pretty compact which was my biggest draw. I've mounted it with a modified aluminum cell phone mount which worked out great.

And you are correct, I got that tail light from DCC. You can find it a fair bit cheaper elsewhere but I like to support the U.S. retailers.
If you don't mind, where's you pick that up? And how much mulllllaaaaa?

Sent from my K88 using DO THE TON mobile app
 

troyholder437

New Member
Northish said:
Glad you like that gauge - It's pretty awesome. It can learn gear position and I've got a cylinder head temp. sensor feeding into it. Since I've messed with the wheels and diameters it gives me a lot flexibility. It's pretty compact which was my biggest draw. I've mounted it with a modified aluminum cell phone mount which worked out great.

And you are correct, I got that tail light from DCC. You can find it a fair bit cheaper elsewhere but I like to support the U.S. retailers.
I should read it before I reply nvm

Sent from my K88 using DO THE TON mobile app
 

Northish

If you know what you're doing, you're not learning
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ApriliaBill said:
You took a horrible looking bike (never a fan a the L models) and turned it into something anybody would be proud to own. Great job....
locul said:
Nice work.
Thanks guys, I appreciate that. Even though it was my first build I knew that I'd have to try pretty hard to make it look worse than it already did ;) Can't wait for the weather to warm up so I can get it out and get the air/fuel ratio gauge going to optimize the tuning.
 

Northish

If you know what you're doing, you're not learning
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Was able to get the O2 sensor bung welded into the exhaust without too much trouble. The probe is a narrowband but the unit will read 12.2 - 17.2 so I think that will be fine. The unit is a Koso Mini 3 Narrowband A/R Meter if interested.

My worries are this, however. The instructions call for the probe to be installed ~20 cm from the exhaust port, but I wasn't real excited about having an O2 probe sticking out in the open right behind the front tire and on only one of the headers. So, it currently will be mounted about 50 cm from the exhaust ports where the two headers join up. I'm assuming the 20 cm recommendation is because the probe isn't heated, so will need the heat of the exhaust gases to get up to operating temp. My hope is that it will still get hot enough further down the pipes, just may take longer to get up to temp.

Next I'll need to take the tank off and get back into the loom I made to wire it up. Waiting for warmer weather to do that :)
 

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trek97

Active Member
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Im interested to see how your O2 setup works out.
Mine are wideband Lambda units which are heated. Installed about the halfway point, on a 2x2 exhaust set up on 76 CB360. Thus completely isolated from one another. Unlike your 2x1 system mixing gases.
Wondering how much that will affect the reading.
I think the biggest concern to watch for is leaks in the exhaust system. If it can get any fresh air in at all will give false results.

I love mine. I couldnt have tuned her as easily/accurately without it.

Keep up the good work.
 

trek97

Active Member
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Also, I had the single sensor setup and just grew tired of swapping it from side to side, to check performance of each carb. Thats why I went a picked up the duel sensor unit.

Now considering installing the old single sensor unit on my bmw triple w 3x1 exhaust.

OH am most importantly, its a bunch of fun to watch the gauge as you ride...keep your eyes on the road!!!
 

Northish

If you know what you're doing, you're not learning
DTT BOTM WINNER
trek97 said:
Also, I had the single sensor setup and just grew tired of swapping it from side to side, to check performance of each carb.
Hey trek97 - Thanks for passing on your experiences with AF measurements. After reading your exhaust leak comment I went back and re-tightened the headers to make sure they were well seated.

Would you mind telling me how much of a difference you found between your two carbs? I'm trying to gauge how much of a risk I'm taking by not reading both carbs individually. My thoughts were that the carbs have been rebuilt with new o-rings and all jets and settings to be identical, and then they were synchronized at idle and high throttle. And I should be able to tell with plug readings if there are any major problems between the two carbs.

Currently, my AF system is just about fully installed. The O2 sensor is installed and the unit has been wired into the bike's loom. Now I need to rebuild the carbs again to clean out last year's gas that seems to have plugged something up as I'm getting pretty bad rev hang at part throttle. A bummer, and probably should have just drained everything before parking it, but I tried going with fuel stabilizer. Still learning...
 

trek97

Active Member
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I have no idea about Suzuki carbs. Only the bastards that come stock on 360s.

The only reason for checking both carbs individually is setting up A/F mix at idle. (for fastest idle speed) So you know both carbs are performing at their peak. Basically making the most power along w best fuel economy. Without going too lean. Air cooled engines require a bit richer mix, the richness helps to keep the engine from overheating during extended idling periods. Stuck at railroad crossings etc...

I found on my bike 12.8 to 1 gives me the best performance at idle.

So, I shoot for 12.8 as the minimum throughout the rpm range while cruising. I would like to see mid 13's to 1 on WOT. But cant hit that due to limitations of needle size availability. And I dont have the proper equipment to make my own needles. Otherwise I would try.

If I do jet her to accelerate leaner. I find she occasionally wants to die during deceleration from higher rpm to a complete stop.

You will find, when rolling off throttle this closes the butterflies and she cant get any fuel through high rpm jets, making it crazy lean. Mine gets upwards of a 21 to 1 mix.

thus if I could make a leaner needle for WOT I could install richer low rpm jetting and she would be able to recover quicker.

This is what causes the exhaust "popping" during decel. Its a lean condition.

AND, you would be a very lucky dude if your carbs were able to simply match A/F mix adjustment and have them both running the same mix at idle. They are crazy touchy adjustments on my bike. As little as a 16th of a turn can be enough to make a big difference between set up properly or not. I have a sickness, a lot of guys dont need that type of accuracy to be perfectly happy w a decent running machine. ;D As a lot of guys know its hard to keep a 360 running period.

You may find your A/F idle mix adjusters land in different spots. (number of turns in or out) as long as both are giving the max idle speed. It dont matter if they match turns. Its performance your looking for. And a difference may be that the PO had tuned one in too hard, messing up the seat a bit. Therefore it would allow for more or less air or fuel at the same # of turns as the other carb.

At this time I have no idea the number of turns my A/F mix adj needles are set. I just know they are both operating at perfect 12.8 to 1 mix.

I hope this helps a bit and keep me posted on your results.
 

trek97

Active Member
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Also dont make any adjustment unless your machine is at full operating temp. If you cant ride it, it will need like 10-15 full minutes idling. Atleast.

The head and carb manifolds must be hot for fuel to atomize properly. Otherwise, atomized fuel will re-condense to back liquid state between carbs and cylinders. Screwing up your readings and adjustments.

I also park it on the center stand and shove a 2x4 under front tire to level the thing.

AND make sure your float levels are matching dead nuts perfect.

LOL is my sickness showing yet? ::)
 

trek97

Active Member
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And one more thing.

You will find that even the air temp/weather and altitude will affect the A/F mix adjustments.

This is the reason the engineers made the A/F mix adj external for quick and easy tuning on the go.

If you leave home at 5am and temp is 65f. Mix can change that same afternoon when its 90f. So, you can adj for that.

I dont mess w all that. I made my system easily removable and just check it a couple times a season to make sure everything is healthy.
 
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