New to an '82 GS450 L

[free99]

Hello everyone, glad to have found a site for fellow GS motorcyclists.

I recently bought my first moto, an '82 GS450L for $300 which wasn't running well. I've done some work, but am a bit nervous to rip into the engine to check valve clearance, and I haven't done a compression test.

I want to improve my understanding, as well as have a better performing machine, but... I'm kinda broke right now.

So, the questions:

1. Where can I get a cheap (but reasonably accurate) compression tester?
2. Is there anything I should watch out for when I try to check the valves, as I've never played with a valve-train?
3. The cap for the stock airbox is missing, how important is it?
4. Would any of the above be a reason for the engine struggling to get past 5k RPM while on the center-stand?

Idle seems OK, though there's a dead spot going from 1500 -> 2500 RPM before the engine suddenly perks up.
I've cleaned the carbs using an idle ultrasonic cleaner at work and replaced the O-rings from cycleorings.com.
The petcock looks OK (no leaks overnight), and so does the intake boot, with new O-rings for the boot too. I checked for air leaks using a dash of starter fluid here and there while idling, very minimal change.

Any help or suggestions for going forward are much appreciated. Thank you!

[sam000lee]

Hey and congrats on the new bike. For the valve clearances, I say just jump into it. You're probably going to have it apart for several days the first time you do it but if you have as much as you can on hand, the downtime should be minimal.

1. You should be able to buy or rent one for free from your local Advanced Auto Parts or Autozone. My buddy bought this one. It's the one I use and seems to work just fine. https://www.amazon.com/BlueDriver-Co...JNH76YWD8MEWZ5

2. Definitely buy a new OEM valve cover gasket and replace it (partsoutlaw.com or somewhere similar). If the previous owners had neglected to do this for a while, there's a good chance you'll be scraping some old gasket off which requires a little patience. You'll also need either the suzuki valve compression tool or if you search "zip tie valve adjustment", you'll find some posts that use zip ties in the cylinder to hold the valves open. You also might find that the valve shim markings are either hard to read or gone completely so I'll typically have calipers on hand to measure the thickness of the shims.

3. The missing airbox cap is almost definitely going to cause a lean mixture. I have an extra I can mail you if you send me a private message. In fact, I have tons of extra GS450 parts I need to get rid of so let me know what else you need

4. The airbox cap could definitely cause that. I'd set the valve clearances first to make sure everything's all set there before troubleshooting the idle.

Somebody else is going to bring it up so I'll just do it - When you cleaned the carbs, did you completely disassemble, remove all jets, etc. before putting them in the ultrasonic and did you spray all the internal passages out with carb cleaner followed by compressed air afterwards? If not, you might have to do it again. There's a GS450 carb cleaning tutorial as well as tons of other useful info about your bike here:

http://gsarchive.bwringer.com/

[LAB3]

I'll agree with sam000lee, valve clearances are pretty easy to do and the zip tie method is simple. Also agree on borrowing or renting a compression gauge if you plan on being a shade tree mechanic. It's not something you need very often unless you plan on doing a lot more work on other engines in the future.

[free99]

Hey LAB3 & sam000lee, sorry for replying so much later than the original post. I really appreciate your help. I bought an air cover and the bike responds a lot better, no more plateau at the low end.

I dove in and removed the cover. The old gasket shattered almost like glass after gently lifting the over. (Thanks sam000lee for the prescience to get me to order a replacement gasket).

So, some questions:
My feeler gauge only goes down to 0.004mm. When I set each cam lobe to be perpendicular to the cylinder head, I could just barely fit the gauge into the gap between each spacer and cam lobe, and for two of the cylinders I could not fit the gauge in at all. Does this mean any are out of spec, ready for replacement?

Secondly, how should I remove stuck-on old gasket stuff without damaging the aluminum mating surfaces? I'd like to avoid getting grit into the engine too.

Thank you

[free99]

Ah, I see that the clearance between the shim and the cam lobe actually decreases, not increases over time. I'll look into the Shim club(TM) as well.

The clymer manual mentions that there is a notch to help with popping the shims out in the shim bucket, but I didn't see one. How do I actually remove the shims?

[Steve]

My feeler gauge only goes down to 0.004mm.

Where did you find one that goes THAT thin???
Most feeler sets are good to go down to .04mm, sometimes you can find one that goes to .03, but I have never seen one that is one tenth that thin.

I'll bet that you are either adding a zero or looking at the INCH measurements. If you are looking at INCH, you need new feelers, you need to have them in the .0015 to .003 range.

When I set each cam lobe to be perpendicular to the cylinder head, I could just barely fit the gauge into the gap between each spacer and cam lobe, and for two of the cylinders I could not fit the gauge in at all. Does this mean any are out of spec, ready for replacement?

I have not looked in the manual for a 450. Are you sure you are supposed to have the lobe perpendicular to the head?

Before we answer questions about whether your feelers fit (or not), we will have to determine what feelers you have. The one you described above simply does not exist, so we don't know what we are dealing with.

.

[LAB3]

Yes, the lobe needs to be perpendicular to the head when measuring. Same thing happened to me when checking mine the first time, two of them where.too tight to get a feeler gauge into. In that case I ordered a shim that was two sizes smaller than the ones that where in there then rechecked the clearance. Note that the shims have the thickness size etched into the bottom (bucket side) of the shim.

[John Park]

Yes, the lobe needs to be perpendicular to the head when measuring. Same thing happened to me when checking mine the first time, two of them where.too tight to get a feeler gauge into. In that case I ordered a shim that was two sizes smaller than the ones that where in there then rechecked the clearance. Note that the shims have the thickness size etched into the bottom (bucket side) of the shim.

Do you mean perpendicular to the valve cover part line - horizontal - or to the shim surface? 'The head' seems a bit arbitrary.

[LAB3]

Do you mean perpendicular to the valve cover part line - horizontal - or to the shim surface? 'The head' seems a bit arbitrary.

It might do well to download the manual and look it over, it doesn't cost anything and the pictures show it quite well.

http://members.dslextreme.com/users/bikecliff/