compression diminishes to nothing from 1 to 4

[Nessism]

but plugs not wet with gas.

There you go. Get busy figuring out why.

[Paul's Zuki]

Where do I start? Manual doesn't say anything about dry or wet plugs

[bellucci]

I know this is not politically correct, but just to get things moving, dribble a little gas in each cylinder and reinstall plugs. It has worked for me with a cantankerous Yamaha turbo at the beginning of each season...
Curt

[Paul's Zuki]

I know this is not politically correct, but just to get things moving, dribble a little gas in each cylinder and reinstall plugs. It has worked for me with a cantankerous Yamaha turbo at the beginning of each season...
Curt

anyone second this motion? I have thought about this and did a google search and couldnt find anything. I will search here.

[bellucci]

I understand your hesitation. The truth was, I made sure the oil pressure has lubed the cylinder walls and just used ether to speed up the combustion process. I suggested gas as most mechanics don't approve of ether due to it rinsing the oil off the cylinder walls. And since you have a fresh motor, oil is your best friend for those rings...
Curt

[mike_of_bbg]

Sure. Just a few drops. If you can get it to fire even for a single turn, you'll know 100% that compression is not your problem; at least not completely. Full choke? Throttles closed?

I don't think the intake stroke is as prone to reduction in efficacy by a leaky cylinder as compression is. It should still move air...

[Paul's Zuki]

well, turns out and let me excuse myself again as this is my first build. I purchased a carb rebuild kit, which wasn't so complete. all of the jets were clogged up. So i pulled them off and they are sitting in carb cleaner as i type this. they will be there till sometime tomorrow this time as. What next?

[Ghostgs1]

well, turns out and let me excuse myself again as this is my first build. I purchased a carb rebuild kit, which wasn't so complete. all of the jets were clogged up. So i pulled them off and they are sitting in carb cleaner as i type this. they will be there till sometime tomorrow this time as. What next?

Paul, Do you have o-rings in the kit? If not try Robert Barr's cycleorings.com . He has them. Did you put the bodies in the cleaner, or just the jets? "The bodies need cleaning also. Ray

[Paul's Zuki]

Paul, Do you have o-rings in the kit? If not try Robert Barr's cycleorings.com . He has them. Did you put the bodies in the cleaner, or just the jets? "The bodies need cleaning also. Ray

no, I have to get some new o-rings. I am dipping the bodies in the cleaner tomorrow. I have the jets in now and will have to do the bodies 2 at a time. can isn't that big, although I had dipped them previously, but will do again for safe measure.

[1948man]

Read the carb tutorial with pic's at BikeCliff's site. Might want to gently stick a fine wire thru the jets to confirm they're open and spray carb cleaner to confirm it will make it thru the passages. The good thing is, when you do all that, the bike will probably run great considering all you have done for it.

[Nessism]

Carb rebuild tutorial here... http://www.mtsac.edu/%7Ecliff/storag...d_Tutorial.pdf

Written by a highly knowledgeable GSR old timer.

[Paul's Zuki]

one other question. Do any of the vacuum hoses need to be installed to test and start. I have an aftermarket petcock with only one outlet that leads to fuel supply. What of the other nipples that need hoses?

[Nessism]

The carbs have one vacuum port that normally connects to the petcock. If your petcock doesn't have a vacuum port you will have to plug the carb vacuum port in some way otherwise you will have a massive vacuum leak. The carbs also have breather ports that connect to vent tubes. Those need to stay open.

[Homie]

sounds familiar...

Years ago I had a similar low compression problem with an '82 GS750E. Mine was a result of moving where the moving company crated up my bike and then shipped it on end standing on it's front wheel (no kidding!)! Most of the oil ran up past the pistons, into the combustion chambers, and then out whatever exhaust valves were open. When it was delivered it was a real mess. To make matters worse, the upper fork tubes were bent back towards the engine from supporting all the weight and the battery acid leaked and ate whatever it came in contact with.

Anyway, got it all fixed up and went to start it. After a lot of cranking she finally caught and started to run. However, due to all of the residual oil in the upper cylinders, combustion chambers and exhaust, it created a huge oil smoke cloud causing the bike to virtually disappear within it's own smoke screen! Put a couple of fans on her to blow the smoke out of my garage and to keep her from overheating. Let it run for a while until all the smoke finally cleared out and then took it around the block a time or two.

All seemed fine until I went to restart it. It wouldn't start for anything. The only way I could get it to start was to dribble a little bit of gas down each spark plug hole using an eye-dropper. Everything checked out except for the dry/wet compression check which was now low, something like 60 psi across the board. I then did a LEAK DOWN CHECK at 80 psi and confirmed that I was loosing compression pressure past all the piston rings.

Had no choice but to take the engine apart. When I did, I discovered that the upper cylinders where mirror smooth and most of the piston rings were kind of stuck in the ring lands. When she started the engine burned off some of the residual oil and as the engine heated up the rest created a "glaze" upon the cylinders, pistons and rings making it so they couldn't create the necessary seal to achieve normal combustion pressures.

A professional cylinder hone, piston clean-up and new piston rings eventually got her back to normal and going again. The point of my little story is to illustrate two points: 1) 60psi isn't going to create enough vacuum to draw the fuel up out of the float bowl and into the engine; and 2) use a Leak Down Check to pinpoint the exact location of where you are losing your compression pressure. A Leak Down Check is a lot more definitive of a diagnostic tool than just a regular compression check.

[Paul's Zuki]

Well, she's popping out the exhaust and I can hear the carbs hissing. I am as close as finishing this thread to taking it to the stealer I'm so frustrated with this thing.