1998 Suzuki Quadrunner LT-F500F 4x4

[1954JF]

I'm looking for someone with knowledge about the Suzuki 500 'automatic de-compression' system when starting. It may be the same on many others in design, I do not know. It stopped working and one comment I got suggested I needed a new battery then use the electric starter. My starter is fine and works fine. But I know enough to realize decompression while starting allows for these tiny starters and batteries to be used instead of larger ones like on a car or truck. Over working the starter or punishing the battery is not the way to go. I guess it was my fault for putting it the way I did. 'Very hard to pull the rope because decompression is not working'. Does anyone have a diagram of the head and internal parts. 1998-2002 Suzuki 500 ATV's. I see nothing outward on this head for a decompression lever or linkage. Old dogs never die? or maybe they do from pulling that rope starter.

thanks for any help 

[Mech]

Parts diagrams are normally helpful, but not this time.. https://www.partzilla.com/catalog/suzuki/atv/1998/quadrunner-4wd-lt-f500f/cam-shaft-valve

The service manual doesn't tell us anything. It looks very simple and similar to other one's I've seen. At start revs the weight falls down towards the cam shaft, and once it starts spinning faster the weight flies out. When it's in there will, I think, be a steel pin bumping the rocker up, lifting the valve.

It looks like you might be able to poke a screwdriver in through the valve adjuster holes and flick the weight.. 

output.pdf

[Mech]

Ok..  arctic cat but the same engine I think..

output.pdf

[1954JF]

Next up, I pull the covers and see if I can see inside.

I should mention this decompression worked fine until one day I had a fuel issue that slogged the combustion chamber full. Leak through caused hydraulic lock. I pulled the fuel line and plugged off the tank then pulled the spark plug and then pulled the rope and it had gas spewing forth like a fountain out the spark plug hole for a moment. After this episode I was replacing bad fuel system components and when I finished that work, the decompression has no longer worked. I don't see any correlation there. Something stopped working inside on or by the cam.    

thank you

[Mech]

You wouldn't think the flooding etc would cause a problem. I'm pretty sure that the decompressor will operate like most do and not force the valve open, but only hold it open after the cam has opened it. Hard to see how that could damage anything.

Good luck in there. They are good to work on. I'd recommend you get some "loctite master gasket" to reseal the top up..  Brilliant stuff.. Way better than silicon or anything else on the market. Clean, economic, doesn't block selves or filters, never leaks, doesn't harden till the parts are clamped together so you don't need to rush, and if you have it apart again the old stuff is easy to get off.

[1954JF]

That sounds like great stuff, I've tried many products. Loctite is usually good. 

[Mech]

Ha.. You're the first fellah that's heard of the company..

They sell it in different packaging but i always get the syringe, it's about thirty or fifty mills, but goes a long way. It's said to fill gaps up to 0.013'. I'd believe it.

[Gwbarm]

I agree Loctite is the best, been using in for 20+ years. Although i cannot find the Master Gasket loctite locally that you mentioned Mech, maybe its just packing differences. The same number it just doesnt say master gasket on the package.

[Mech]

If it's the 518 it will be the stuff Gw. They sell other "master gasket", products with different numbers, and there are other brands as well but the others aren't always as heatproof.

 

[Gwbarm]

Thanks Mech! I need to get some so i will look for 518, i think thats what i have been using , but i will have to double check.

[Mech]

If you buy the syringe, the actual plastic syringe not the squeeze tube they describe as a syringe, then the number's in smallish print just above the Master Gasket on the label. 

[Gwbarm]

Thanks! I have not seen it in a syringe, thats would be good, i will look for that. What i get comes in a little squeeze bottle about 2 inches long.

[Mech]

Hmm.. When I do a google of "loctite master gasket", it comes up straight away with pictures of the syringe, and the squeezy, but I notice they are all kiwi sites. So I checked the legendary Walmart, Loctite.com, and one other company, and they all only had the squeezy, and a gun cartridge, and big and small amounts in all sorts of containers and dispensers, but no actual syringe.

Another really great feature of Loctite Master Gasket though is... it never hardens in the tube. I've had old part tubes for literally years, that I use to lock nuts these days because it's thickened some, but it would still be just fine for an engine.

So buying a big pot is perhaps cheaper...

[Mech]

Hmm.. So I hate a mystery and so I did some more searches and the only place that had it in a syringe (Hisco.com), described it as 518 flange sealant, but the blurb didn't mention it being high temp or anything much at all, and it's label was different.

If you google loctite master gasket, with or without 518, and, add nz to the search, you will see the syringes we've always got over here.. 

Some only stand temps of about 118 C or so but the stuff I get does about 150 C.