GS Engine Trouble

[briandr]

Hey all,

I've been having some trouble with my GS. I was on the highway a couple days ago when I lost power and the bike started clattering. I limped home, by the time I got back I was keeping it in 6th, under 3k rpm, anything above that sounded really bad. The head gasket had been leaking, so yesterday I had the time to tear it down and replace that gasket, as well as a carb clean and checking the valves. Tried to start the bike up and got nothing. Thought it might be the spark plugs not getting power, but taking the airbox off and spraying starter fluid in there gets the engine to start for a second or two, with a really bad clatter. Any thoughts or suggestions? At this point I'm pretty sure I'm in over my head, and unless there's a clear answer I'll probably have to take it to the shop.

Thanks

[BockinBboy]

Doesn't sound too good at all... have you check your oil level?

Sounds like a case of low oil, and horrors that follow...

- Bboy

[cHa0s]

Setting of crank and camshaft is correct for sure?
Remove the head cover and one (!!!) camshaft bearing cap. If there are claw marks at the cap or the shaft, you don't need to go to a shop anymore. 

[gsJack]

Did you turn the petcock under the tank back on?  Got vacuum to the frame mounted petcock?  Put on Prime settimg and open drain screw on carb and see if gas comes thru.   

[reload]

yeh if it starts with the starter fluid for few secs then you know the engine is good. sounds like you might be having a fuel flow issue.

[briandr]

Hey all, thanks for the advice. My only worry about it being a fuel flow issue is the noise it makes when it does get started on starter fluid. It's not pretty. But I would probably prefer to rule that out before seeing if I threw a rod or something. I'm sure this is a novice question, but what's the best way to check that stuff? I've got most of the morning today to check that out, I'd love to get this thing starting!

[BockinBboy]

That noise is what prompted me to ask about your oil level... a shot engine can still turn over... if it is making a loud noise, I wouldn't try to turn it on.

See how much oil you've got.  If its too low, then you have a simple answer... drain the rest of the oil, and maybe drop the oil pan to check for metal flakes.  Metal flakes/shiny oil = very bad news.

- Bboy

[ohgood]

Hey all, thanks for the advice. My only worry about it being a fuel flow issue is the noise it makes when it does get started on starter fluid. It's not pretty. But I would probably prefer to rule that out before seeing if I threw a rod or something. I'm sure this is a novice question, but what's the best way to check that stuff? I've got most of the morning today to check that out, I'd love to get this thing starting!

pull the spark plugs (both), put the bike on the centerstand. shift to 6th gear. spin the rear wheel and listen. if it does anything besides SWOOSH SWOOSH that sounds like contact, you have problems.

i'm going to guess (this is really reaching given the current information) that a wrist pin/conrod lost lubrication and is failing.

if lubrication was lost, there can be a host of mating surfaces that are toast.

find the root cause of the noise. it may be cheaper to source a used engine than fix it.

[briandr]

Thanks for all the tips. I thought I might add to the forum a little, instead of constantly taking! I'll even throw some photos in here, since everyone is a sucker for photos. I decided to dig into the engine instead of simply buying a new one. I've got the time, and the thought of really getting my hands dirty was intriguing. I've also got a buddy with a well equipped shop and some knowledge on boat engines, so I went for it. Here's the bike when it was running:



And during the "Take it all off" phase:



Finally got all the way into the engine today to find a blown crank pin bearing:



Also one of the rods definitely needs to be replaced, and both pistons are missing one of the flanges, I was running out of time today and forgot to snap pictures. Maybe tomorrow! So, there will be some cost but probably not as bad is it could have been, plus I now know about a million times more about engines than I did last week. Pretty cool!

I do have a question on the crank bearings. As I'm trying to replace them, I see there are four different sizes. I have the manual, but would love a little clarification on what exactly I need to measure to make sure I get the correct one. I'm also getting a set of lightly used rods, should I wait until I receive those before purchasing the bearings, or is that a non-factor? Anyway, this is probably not exactly the way I was planning on starting my motorcycle experience, but it's all part of the fun. I couldn't have gotten this far without GStwins, so keep rocking on!

[Twisted]

Yeh your engine problems were probably caused by that awful looking front cowl and belly pan! I would ditch them right away. I'll tell you what because I am a nice guy. Post them to me and I'll take em off your hands for free.