1981 GS450SX - Bringing it back from the dead

[Guest]

Hi guys, I wanted to start a thread for my GS450. This bike needs basically everything done to it. I got it basically for free and I knew it wouldn't be a cost or time efficient project, but I got it to learn the ins and outs of bikes and I think when I'm done I'll be damn proud.

What I've Done So Far:

• Removed rust and lined tank with Por-15
• Stripped paint off tank
• Replaced reg/rec with a mosfet
• Replaced battery with a lithium iron
• Replaced spark plugs and caps
• Semi cleaned the carbs

I had no idea if it ran when I got it. The guy who sold it to me didn't even know what model it was. He said it was a GS400 and all it needed was a stator (lol).

The electricals miraculously all worked still, even the gauges. It shifts gears. The oil that was already in it looks great, looks like it was changed recently. I'll still change it along with the filter.

My brother came over and we had a mission to get it started. After having our brains fall out of our noses looking at wiring diagrams we somehow got the mess of wires all wired up and grounded correctly. And lo and behold... she started!!! She even idled for about 2 minutes before dying. There's no air box and who knows what shape the carbs are in so I didn't expect much. We were feeding fuel through a funnel. I just wanted to make sure the engine wasn't seized before tearing it down and getting to work.

So that's where I'm at now. The forks are in good shape, no rusting or pitting. Rear shocks.. who knows, might replace. The frame has some rust eaten through on the top, previous owner tried to repair it with JB Weld. I plan on cutting that section out and replacing with the same size tubing and plugs, which I already have.


Next Steps

Right now I'm working on getting the engine out. It's a bitch so I'm gonna take the head off and should be able to get it out relatively easy like that. I'm gonna tear it down and rebuild, replacing gaskets and seals. Will fix valve clearances and then rebuild the carbs. I'll be using pods (I know) so carb tuning and re-jetting will be in order.

Somewhere in there I'm going to strip everything off the frame, repair it and either paint or get it powder coated. I know frame repair can be controversial but what choice do I have beside find another frame. I keep my eyes peeled but it's kind of hard to find a 40-year-old frame, let alone one in good shape. I have faith in my ability to replace and weld so that it will be structurally sound. If I put some nice long and solid plugs in there I think it'll be good. I might even weld on some tubing underneath, running parallel, to give it some support.

The brakes and wheels need work as well. Probably rebuilding the caliper and replacing the shoes and pads. Wheels will need new bearings.

Once all that's done I'm putting all new wiring and electrical components on, using an M-unit. As well as new brake, throttle and clutch cables.

I've got a long road ahead of me but I'm having a blast and I enjoy a good challenge.

I look forward to your advice and I'll keep this thread updated periodically. In case anybody was interested in a color scheme, I was thinking a copper/bronze and black theme, similar to this:

 

[tobar]

looks a good start...there's a red one in internet land that runs a gs500 front end and back wheel..looks smart..talking of gs500, how about pistons n barrel (jugs) on ya 450?

 

[GSXR7ED]

Welcome and thanks for posting all the repairs you intend on completing. You have some skills to be able to replace a section of the frame tubing that is JB welded.

Those shocks have definitely gone past their life. The exhaust pipe looks to be in decent condition. Original airbox searches are in your future.

Lots to do and plenty of time to do it.

Ed

****

 

[Guest]

looks a good start...there's a red one in internet land that runs a gs500 front end and back wheel..looks smart..talking of gs500, how about pistons n barrel (jugs) on ya 450?

Sorry I don't know understand what your question is.

 

[Guest]

Welcome and thanks for posting all the repairs you intend on completing. You have some skills to be able to replace a section of the frame tubing that is JB welded.

Those shocks have definitely gone past their life. The exhaust pipe looks to be in decent condition. Original airbox searches are in your future.

Lots to do and plenty of time to do it.

Ed

****

I figured the shocks were bad. The exhaust is just fine, yep. I'm going to try my best to get it running well on pods. If not, yea sure I'll look for an airbox.

 

[Guest]

Quick question guys.. manual tells me to remove the head nuts in sequence. It?s supposed to be stamped on near the nuts but it?s either worn off or never was there. Anybody know the sequence?

 

[Rich82GS750TZ]

Are you saying there's no numbers cast into the head near where the arrows point to in the Factory Service Manual?

 

[Rich82GS750TZ]

this figure a few pages later shows the tightening sequence. So you want to loosen them in descending order from 8-1

 

[Rich82GS750TZ]

If you're wondering, the images above are from the Factory Service Manual available for free download on BikeCliff's website

 

[Guest]

Hell yea brother thanks!!!

 

[Guest]

If you're wondering, the images above are from the Factory Service Manual available for free download on BikeCliff's website

Yeah I have that manual, I got it from his site. I actually got it printed and spiral bound at Fedex. Pretty nice. I didn't think to check the tightening sequence

Anyway, got the head off. Now I gotta figure out how to take the engine out by myself......... Wish me luck

 

[Rich82GS750TZ]

It’s a wee 450 twin. Man up! Lol

 

[Guest]

Anyway, got the head off. Now I gotta figure out how to take the engine out by myself......... Wish me luck[/QUOTE]

I'd make sure the countershaft sprocket nut is loose or off while you have the chain on to hold it before taking the motor out. Sometimes they're almost falling off and other times you need serious force.

I've always had help for install/removal but there may be a way you could devise to do it solo. The last time I installed one I cut two pieces of 1/2" copper pipe and used head nuts to keep the cylinders from lifting. Then I used a two screw hole type pipe hanger to hold a 3/4 pipe to the cam chain tensioner location. This gives you a purchase near the balance point of the block and one guy each side can up and out really easy. A long pipe means you don't run out of shuffle room. You might replace the helper with a support box or whatever and jack the block up, well you get it.

Let us know how you did it.

 

[Gorminrider]

tip the bike over onto padding and tactical 2x4s.

 

[Guest]

I'd make sure the countershaft sprocket nut is loose or off while you have the chain on to hold it before taking the motor out. Sometimes they're almost falling off and other times you need serious force.

I've always had help for install/removal but there may be a way you could devise to do it solo. The last time I installed one I cut two pieces of 1/2" copper pipe and used head nuts to keep the cylinders from lifting. Then I used a two screw hole type pipe hanger to hold a 3/4 pipe to the cam chain tensioner location. This gives you a purchase near the balance point of the block and one guy each side can up and out really easy. A long pipe means you don't run out of shuffle room. You might replace the helper with a support box or whatever and jack the block up, well you get it.

Let us know how you did it.

I understood half of that! Not sure where the countershaft sprocket nut is. I have the chain hanging on with some wire.

I'll probably get my brother to help but I don't know if I can wait till weekend. Tipping is an option but I don't love it. I think I can probably get it off alone, can't weigh much more than 100 lbs right? I'll probably put something level with it and throw some board down and just kinda shimmy it out.

Oh quick question...

That rod doesn't come out and the engine slides off, right?

 

[Rich82GS750TZ]

Not sure where the countershaft sprocket nut is. I have the chain hanging on with some wire.

Simply, the front sprocket. (Drive Chain, not cam chain) If your drive chain is still on the bike and on both the front and rear sprockets, it's often much easier to loosen the big nut (I know I have a socket, can't remember the size, it's a biggun.) Bike in gear, someone standing on the brake pedal, to get that nut loose. There should probably be a washer with a tab folded over keeping it from loosening on its own. Just peen it back flat. Some L models do not have this washer, not sure about your bike.

 

[Guest]

Simply, the front sprocket. (Drive Chain, not cam chain) If your drive chain is still on the bike and on both the front and rear sprockets, it's often much easier to loosen the big nut (I know I have a socket, can't remember the size, it's a biggun.) Bike in gear, someone standing on the brake pedal, to get that nut loose. There should probably be a washer with a tab folded over keeping it from loosening on its own. Just peen it back flat. Some L models do not have this washer, not sure about your bike.

Ah I see, good to know. It's in neutral and the clutch cable and rear brake are already off but I can stick em back on.

Oil question!! According to a website about motorcycle oils:

Remember, 10w-40 oils contain a lot of VIIs which tend to shear in your transmission, so I believe 10w-40 oils should be avoided. You can't use 10w-30 because of the friction modifiers. This doesn't leave much. Commercial 15w-40 oils are a good choice, because they have relatively few VIIs which are the more expensive shear-stable sort. Synthetics typically don't contain much of a VII package, so shear is not as big an issue with them.

My bike calls for 10w-40. Why would it call for 10w-40 if it was harmful to my transmission? I notice Shell Rotella 15w-40 and even 5w-40 recommended a lot. Any harm in using one of those? Where I live it never gets cold.

 

[Rich82GS750TZ]

Sprocket: bend back the locking tab first before you go through all that bother. You may get lucky. My nut was only on there finger-tight.

Oil Opinion: 10w-40 is fine but be sure to get motorcycle formula for wet clutches. JASO MA2