81 GS450S Build

[pete]

Ok, little confused on that advice but Steve does know his stuff

Maybe things are different on the US carbs? Personally I'd try it as is with just adding the shim first and going from there.

[jmaresca]

I got everything hooked up. I'm running 145 mains and the stock 17.5 pilot jets. I shimmed the needles with a few washers. It still won't kick over. I'm backfiring flames out of the pipes. I'm getting spark from the plugs. 12.4v from the battery. Anyone have any ideas?

[Sci85]

Hmm, I'm not an expert but the only time that's happened to me turned out to be the timing was way off. Might want to check your timing plate. Maybe it moved or wasn't set correctly?

[pete]

Yeah that sounds like timing to me too! I can't recall if you've had to have your camshafts out or not but if you have then it's worthwhile making sure it's right.

Also, if you've had your camchain tensioner out, it's possible that the cam chain has jumped a tooth or two on the cams which will also put the timing out.

If it's too far out it can cause the pistons to hit the valves which ain't pretty...

[jmaresca]

Hmm, I'm not an expert but the only time that's happened to me turned out to be the timing was way off. Might want to check your timing plate. Maybe it moved or wasn't set correctly?

Yeah that sounds like timing to me too! I can't recall if you've had to have your camshafts out or not but if you have then it's worthwhile making sure it's right.

Also, if you've had your camchain tensioner out, it's possible that the cam chain has jumped a tooth or two on the cams which will also put the timing out.

If it's too far out it can cause the pistons to hit the valves which ain't pretty...

I actually did have my tensioner out, so that makes sense. Looking at the manual, I removed it without locking the tensioner pushrod. Although I don't remember seeing one.

Is there anything special I need to do to my tensioner?
Which direction on the tensioner tightens the cam chain?
Is there a certain order I need to go in when checking/adjusting my timing? Tensioner off, Adjust timing, Tensioner back on? etc?

[Sci85]

Don't forget to also check the ignition timing. That is what was causing my backfiring once. I had the timing plate way off cause I removed it and forgot to mark it and didn't have a timing light.

[pete]

Nothing special you need to do with the tensioner to *check* the timing, but if it's off then you may need to remove it again so you can adjust it be moving the chain over some teeth on one or both of the cam shafts.

And yes, definitely check your ignition timing too as Sci says.

Given that it's in the situation it is now with not firing, I'd be covering off cam timing first.

[jmaresca]

Nothing special you need to do with the tensioner to *check* the timing, but if it's off then you may need to remove it again so you can adjust it be moving the chain over some teeth on one or both of the cam shafts.

And yes, definitely check your ignition timing too as Sci says.

Given that it's in the situation it is now with not firing, I'd be covering off cam timing first.

I tried swapping my coils but that didn't work. I actually started getting backfiring coming from my carb as well as my exhaust once I swapped the coils. Also, when I turn it by the bolt, a certain part of it is harder to turn than other parts. Is this normal?

When I hook everything back up, does the TDC need to be in any specific location to sync correctly with the plugs firing?

From what I've read, my model doesn't have ignition timing. I just checked my cam timing and it looks right. What do you guys think?

[pete]

I always get confused with the ignition timing marks but I think that's right...

As for cam timing, that looks like your exhaust cam is in the right spot, but did you count the links back to the mark on the inlet cam to make sure the chain hasn't jumped a tooth or two? From memory the 18th pin is on the number 2 mark on the inlet cam, but definitely check the manual to confirm as it's been about 2 years since I last looked at mine...

Also, I just remembered there is one way to get your ignition timing 180 degrees out of whack.

If you have had your advance mechanism out and disassembled, the ignition rotor can go on 180 degrees out of alignment which will put your timing out. The photo below shows the magnets that are on one lobe of the rotor and these are used to align it correctly. When putting the rotor back in, make sure the "R" side of the advance plate is pointing up, then put the rotor back on so the magnets are facing to the right.

[jmaresca]

I'm all out of ideas. I tried turning the magentic ignition rotor to the right while the timing plate R was pointed up, but that didn't work. Should the ignition rotor spin freely while the bolt stays still? Also, while I crank the engine with a wrench, there's a rough spot that's harder to turn than the rest. Is this indicative of something wrong in the motor?

I broke one of the bottom caps of the carbs by over-tightening it

I can't catch a break.

[jmaresca]

I'm getting closer. I redid my cam chain and it turns a lot smoother now. It must have been off a link. It's still not starting, but it sounds like it wants to. Since my carb is busted, I'm trying starting fluid, but that's not working. I also keep blowing fuses so I need to figure out why.

[pete]

When I'm talking about the rotor facing right with R up, I'm meaning when you have the rotor removed from the advance mechanism and that's the way to reassemble it... just in case I wasn't clear there

Once it's reinstalled, you should be able to rotate the rotor easily to full advance and the springs should return it to no advance nice and smoothly and quickly.

[jmaresca]

When I'm talking about the rotor facing right with R up, I'm meaning when you have the rotor removed from the advance mechanism and that's the way to reassemble it... just in case I wasn't clear there

Once it's reinstalled, you should be able to rotate the rotor easily to full advance and the springs should return it to no advance nice and smoothly and quickly.

I've actually found someone with possibly the same problem here:

http://www.thegsresources.com/_forum/showthread.php?t=174493&highlight=advance+mechanism&page=8

The metal part that spins inside the signal generator (pictured above), is that supposed to be able to spin without the advance mechanism spinning? The notches/springs/arms on the advance mechanism make me think not. Either way, mine does. I can spin it by hand while my advance mechanism is stationary. Maybe that's it.

[pete]

That doesn't sound right at all! The rotor should spin to the limit of what the advance springs allow and no further. Take note in the pic's below that I have a Dynatek rotor on instead of the stock rotor, but otherwise everything should be the same as yours.

Here's my advance unit dismantled:



Here it is assembled:



When putting it together, the flat washer should have a bit of engine oil on it and sit over the shaft on the bottom first.

The arms sit on the pivots and the springs slot through them and around the other posts. The rotor has two slots in the bottom which locate on the arms also. The E clips secure the arms to the posts.

A bit of a crappy description but I hope it helps.

I would pull the advance mechanism out and see what you've got... pic's will help us for sure.

Use a 19mm socket to hold the crankshaft still with the big nut as shown in the photo below, and a 12mm?? to get the rotor bolt out (could be 10mm can't remember).

[jmaresca]

That's got to be it:






Mine will just spin by hand. The notches on the arms must have ground down. You can tell because the metal where the magnet is is ground down. What's the best way to fix this? Dyna system? Which dyna system should I use? Can I use my existing coils? Or will I need to replace those too?