GS650E Pressure/Fire Problem ???

[Bryan22]

We have a GS650E that is having some issues.

The bike intially ran but not well because of carbs needing cleaning and there was a hint of oil leakage coming from the head gasket. The carbs were removed and cleaned earlier this year.The head was removed and surfaces cleaned. In putting the engine back together. we set the timing according to the manual.. With everything assembled and a try at starting it.... we are not getting gas to the cyl's, we get a delayed but subtle & brief firing with the intoduction of a shot of starting fluid. Spark is good

At a point of brief cranking, a small alum cap on the outside of each of the the outside carbs blows off like a bullet. There is obviously significant pressure being built up somewhere and it appears we are not getting vacuum for fuel delivery.

Any assistance with this is greatly appreciated.

Bryan

[t3rmin]

Yikes. Cams on wrong maybe? I hear alot about it being easy to put the cams back on 180 degrees off. If only one cam were on wrong would it be possible for too much compression to build in the cylinders due to valves not releasing pressure? Just a stab in the dark...

Or maybe the breather tube on the top of the valve cover is plugged? Or maybe the two breather tubes on the carbs are plugged? You should have one breather tube coming from the valve cover going in to the top of the airbox and one coming out of the bottom of the airbox dangling down. Then there are two breather tubes which come out of the carbs between 1&2 and 2&3 which vent into the atmosphere and sit on top of the airbox lid.

[Bryan22]

The cams were re-installed per the manual diagrams. The intake cam on the rear and exhaust to the front. Both with the numbers (2 & 3) and the arrows on the cam sprockets facing the right side so the those along with the timing marks on the crank can be seen on the same side. Everything to be best our knowledge (my neighbor and me) was done "by the book," he has a actual shop manual for the bike.

I will re-check the lines you mentioned.

More advise on this is welcomed!

[Bryan22]

I did check the vacuum lines, everything looks good there. pressure is being built up and directed out the wrong way for some reason. Any ideas?

[t3rmin]

So you've got two vent lines (like vacuum hoses) coming from the carbs hooked up to absolutely nothing? (That's the way it should be...)

I still think it's the cams... If the intake valves were open during compression strokes, wouldn't that blow pressure the wrong way? Having not messed with the cams personally I can't speak from experience, but I seem to remember reading here on the forums multiple times how easy it is to get the cams in wrong, with the marks even seeming to line up right.

[earlfor]

I am pretty sure the cam timing is off. When you set the crank to TDC and then place the cams on the marks, camshaft slots oriented correctly, and cam chain pin count correct, you must set the cam chain tensioner before rotating the engine. Once everything is installed, and the tensioner installed and set, I usually rotate the engine about three revolutions (with the spark plugs out) using a wrench on the crankshaft end. On the final rotation, you must be able to stop with the crankshaft on TDC on #1 and the cams all still aligned correctly. I will bet if you recheck, you will find either you're no longer on the marks, or you're 180 deg out.

Earl

[Bryan22]

I may not be thinking of this correctly as to how it could be off 180 degrees. If everything is done by the book on timing and everything is on the mark.... ? I would have preferred to rotate after setting the marks but did not.

Thanks for your help it sounds like this is what is going on and any other input is great.

Bryan

[Bryan22]

Can someone throw us some info on how the timing can get off by 180 when nothing has been moved and everything was put back together by the book. We don't this to happen again and are waiting for more info before we touch it.

thank you!

[REDDY]

When the caps ?? bolw off the carbs it indicates that piston is coming up with the intake valve open i suspect 180 out.

[Bryan22]

At this point we do agree that that the engine is 180 off. How does this happen when the head was off and was not turned while apart and was reassembled by the book. Someone mentioned that this 180 thing happens easily... how? And how is corrected... correctly? What is the procedure for tackeling the problem. We don't this to happen again and are waiting for more info before we touch it.

Thanks!
Bryan