When you buy a GS what should you do?

[SVSooke]

Unusual bike for Canada,imported from the US is my thought.Had a couple of 400's and just picked up this one:

for my wifes first bike.Soon as my 750 projects done I'm going to dig into it.Welcome to GSR,nice to have another BC member.

[oldrupert]

I have run into some problems.

The left cylinder wasn't firing. The right one would fire up no problem but nothing on the left. Checked for a spark out of the plug and it was fine and strong, so I did a compression check. At first there was no compression then all of a sudden it fired up to 150psi with three strokes. I pulled out the comp. checker and put the plug back in and fired it up. Both cylinders fired and ran smooth for 30 sec and then the left one died. tried a couple more times and the same thing happened, compression then no compression, compression then no compression.

Are my piston rings fried?

I suppose the valve timing couldn't be off or the right cylinder would do the same, and I would probably have other problems.

Maybe the valves are semi fried in some strange way.

any Ideas would be helpful before I start to pull the engine apart.

[pete]

Somewhere I have seen how to test to see if it's your rings or valves, but for the life of me I can't remember.

Aside from doing a search here for compression testing, there will be something either in the garage section of the main www.thegsresources.com website or on BassCliff's page.

Either way, you need to check the valves, but of course if rings need doing you need to take the cylinders and head off anyway...

[Redneck]

Nice find but I think that in answer to your post question no one mentioned the most important thing,

1.Pray to God for forgiveness for the sins you will commit.

2.You will curse and swear more times than you care to count, it will either be the broken bolt, lack of parts, or funds, usually the latter or why will this not go back in the way it came out. Think you get the picture.

3.Then once you are done sinning, and you have it up and running you can thank God for the good thing he has given to you.

4. One week later, return to step one and repeat.

Gratz again on the find and welcome to the sight hopefully the wonderful wealth of knowledge here will keep step 2 to minimum.

Paul

[spyug]

Welcome aboard. Nice bike. You will have lots of fun once its ironed out.

I'm trying to read between the lines here and I suspect you are not performing the compression check correctly. I haven't quite figured out what you're doing wrong but its highly unusual to go comprssion, then no comprsssion and back and forth with adding something to the equation.

Usually when you find an engine with low compression, you would add a few teaspoons of oil to the cylinder and that will allow the compression to come up and gives you the diagnosis of bad rings. If you add the oil and it doesn't change then it is likely valve related. This back and forth is just too weird.

I think you should make sure your valves are correctly adjusted before you try the compression test again as this may well have something to do with it. So don't freak on your rings until then.

The not firing is less likely to be rings or valves and more likely to be a carb issue in that the cylinder is not getting any/enough juice. So a carb rebuild is definitely a priority. Don't rush in to pod filters right away either. Pods need to be dialled in with 'fatter" jets (larger orificed jets that allow for a richer gas mix) to compensate for their freer flowing abilities. It can be tricky getting them right and impossible if the bike is not running right to begin with.

Once you know the carbs are clean and with fresh o-rings and the valves are adjusted have at it again. I'm betting it will fire right up and a compresssion test will show plenty of compression in each cylinder.

Its nice to find an oldie that fires right up and runs like a Swiss watch but that is not common in any bike that sits for more than a few months. Cleaning and adusting is all part and parcel of the game but if you take your time and do a thorough job you will soon have it running like that proverbial watch from the land of cheese and chocolate.......mmmm fondue!

Keep us informed of how it goes and lots of pics on the way too please.

Cheers,
Spyug

[Strycker]

Hey OldRupert, I'm about to undertake the exact same bike, down to the paint job too! Mine was a little worse off than yours, but I got it cheap too. 7,150 miles and only used 2 years. Good luck with your project! My carbs are sitting on the kitchen counter as I type awaiting their cleaning.

[oldrupert]

valve specs and pics

valve specs and pics are as follows

When sitting on the bike seat:

Left exhaust less than <.038 mm
Left intake .064 - .076 mm

right exhaust .064 - .076 mm
right intake less than <.038 mm


considering valve clearance limits of .03 - .08
the left intake and the right exhaust are within spec (high spec but in)

Could the left exhaust and the right intake be the reason for my lack of compression and backfiring?

regardless I will be redoing the shims on those two and will post back when I have completed.

here is a pic looking down inside the right intake onto the valve. looks a bit cruddy, I hope it isn't fried. The right spark plug looked a little dry like it had been running lean, (white'ish tip).

[pete]

A really good tip I got for checking clearances less than 0.03 is to try to rotate the shim bucket.

If it rotates easily, you have minimal clearance.

If it doesn't rotate, then you have no clearance, and it could actually be holding your valve open a touch. That leads me to believe it could impact on your compression, althought I may be wrong...

[SVSooke]

Pete you are right that will impact commpression.

[BassCliff]

Hi Mr. oldrupert,

Sorry I'm late to the party. I'm just going to dump a TON of information on you. Let me share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[oldrupert]

thanks for the welcome basscliff, your website is great, I have read many of the pdfs and will continue to as I work on the bike. Great clear pics, I love it.

Here is the update on my valves.

I went back and checked the clearances again to be sure. it seems that the two that were in spec are still in spec but a little lower than I first thought.
somewhere between .05mm - .064mm.

I then decided to do my own valve leek down test. I could reach the intake valves because I have the carburetors and boots off right now.
the right intake valve (see picture in previous post)
and the left intake valve

I squirted a bit of diesel fuel in there to see if the level receded while I watched. Nothing noticeable happened. The interesting thing happened when i moved over to the other valve and started cranking (by hand) the engine around to attain a closed valve.

When I started doing this I heard a spraying noise. I looked in as I turned it over and could see a little spray up out of the cylinder into the intake passage.

So either the valves are burnt and are leaking or there is so much carbon build up from the valves not being adjusted properly that it is not making a seal any more.

I will attempt to clean them somehow, any ideas before I remove the head?

[oldrupert]

another update for anyone that cares to watch a problem be troubleshooted and then solved with record breaking speed and lack of funds.

I am an optimist by the way.

I took off the exhaust today to look in at the valves like I did with the intakes.

here is what I saw.



this is the view from the front so the left valve is actually the right cylinder when sitting on the bike.

As was the spark plug in the right cylinder the right exhaust valve is dry and white and so is probably running lean.

the left exhaust valve is black and gummy (sorry for the bad focusing) which I assume is because it was spitting out unburnt fuel and then burning it in the exhaust pipe when the cylinder finally fired up.

I am a learning mechanic with no formal training, just a good brain for how combustion engines work and a computer to look things up on. So any feedback is always a help.

once again I cranked the engine over (by hand) to see what happened in the exhaust valves, and there was no sign of leaking on the compression stroke. Yay for me.

unfortunately when I looked in at the intake valves on the compression stroke (with the spark plugs in this time for proper compression) they leaked back towards the carburetors pretty bad.

I don't know for sure but this seems like a fairly descent way to check if the valves are leaking. But for anyone interested in doing the same this is what else I have planned.
1: Before cranking it over too much make sure there is very little fluid in the cylinder so that you don't hydro-lock the piston and cause more problems.
2: unless you are using oil to check for leaks (which I found hard to use because it's so thick) any other fluid will strip the cylinder walls of the much needed oil film and will mess up your rings really fast if you don't prelube them before firing up the bike. Dump a little oil down the spark plug hole and crank by hand a couple of times, repeat a couple of times to be sure.
3: after relubing the pistons a bit change the oil before you run the engine too much because it will be thinned out a little depending on the amount that went down the pistons.

any other precautions anybody?

sorry for the long posts

[pete]

I'm enjoying seeing your trouble shooting efforts here, good to see you taking the time and doing your best to see what's wrong before ripping into it.

I had the luxury of being able to lap my freshly faced valves to the nicely wet blasted head and I was then able to sit some kero in the valves to check how well they sealed.

[oldrupert]

Work has started for the spring so I have not been able to work on the bike much but I managed little bits over the last month.

-I removed the head and started cleaning it up.
-Removed the valves and springs and stem seals.
-cleaned out as much of the caked on carbon out of the head
-cleaned up the valve seats and valves
-lapped the valves
-installed new stem seals
-reinstalled the valves using the c-clamp and pvc tube method (works great)

-attempted to install the head and dropped a chunk of a tool down the cam chain hole. f#*%%$#ck

all of this was done while the engine was still in the bike frame.

So now I have removed the engine and started a major disassembly.

I have the jugs off and the stator side cover off but I can't seem to get the other side off.
Is there a trick or something I have missed? I have every bolt I can see out including the ones under the auto timing unit.

While I have the entire engine apart, what should I do or replace besides cleaning the place up a bit?

I measured the diameter of the pistons and they are still round and the right size and the honing lines on the inside of the jugs look great still.