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Engine teardown time

  • Thread starter Thread starter MrZig
  • Start date Start date
M

MrZig

Guest
(Reposted from Somethingawful.com forums)

Engine teardown time, and I found the problem.

OK. First thing you're going to notice is the amount of **** inside the cylinders. I'm pretty sure that was this engine's downfall. All that dirt and hair and **** was just laying inside there, eating away at everything. Although, the cylinder walls do look pretty good to me, and all the bearings seem tight EXCEPT..

#2 piston. (Facing forward, the cylinder on the left). The main bearing on the crankshaft is ****ED. How do I know this? Well, when lifting up and down on the piston, the con-rod/crankshaft journal has about 1/8" of play and makes an audible "pop" every time you do this. Now imagine that spinning at 7,000 RPM and... You get the idea. Basically, the crankshaft and conrod wanted to make sweet love to eachother, but everytime they got close, the main bearing kept cockblocking. "I've had enough of this" said the conrod, and with one mighty thrust it punched the bearing in the face, destroying it and thus securing the rod-on-shaft but****ery.

...I feel dirty.

...

...

Moving on, here's what I'm thinking happend to cause this:

Most likely a piece of dirt got inside the engine and clogged the oil passage for the main bearing, starving it of oil and blowing it up. Ever other part of the engine seems well lubricated and smooth (the camshaft caps even fissed out high pressure oil when I took them off). After blowing up, it got so much clearance that it lost oil pressure completely and that's why my oil light came on.

I have not split the cases yet and I'm not sure where to go from here. These are my options:

A) Scrap the entire bike and start anew.
B) Find a used engine somewhere (gonna be $200+)
C) Fix it. How do I fix this? I imagine the connecting rod and crankshaft are both fubar, so I would need to find a used crankshaft & conrod. Would a GS450 crankshaft work? What gives the GS450 the extra 50cc's?

(click to make them bigger)








 
heres what was left of my #3 conrod and bearing. well there isnt a bearing left to see what was left of it was laying in my oil pan. ruined my conrod, crank, and of course bearing. I'd guess that gap to be about 1/4 inch where the bearing used to be. after almost scrapping mine I decided she was worth rebuilding. still havent found a cause to why mine let go.
brokenengineteardown018-1.jpg
 
Dave_17954 said:
heres what was left of my #3 conrod and bearing. well there isnt a bearing left to see what was left of it was laying in my oil pan. ruined my conrod, crank, and of course bearing. I'd guess that gap to be about 1/4 inch where the bearing used to be. after almost scrapping mine I decided she was worth rebuilding. still havent found a cause to why mine let go.
Click to expand...


holy ****. That's pretty much exactly what I'm expecting to see. Maybe not quite as intense, but very similiar.

What all did you do to rebuild it? New crankshaft, rod & bearings? And it's been working fine since?
 
Sorry about your bike. :(

Did you happen to notice all the asterisks in your posts? :-\\\

.
 
Steve said:
Sorry about your bike. :(

Did you happen to notice all the asterisks in your posts? :-\\\

.
Click to expand...

Yea I don't understand why it's all censored here. Besides, when dealing with a broken engine on the end of a string of bad luck, there will be the odd cursing going on ;)
 
Havent got it all back together yet but yes got a used crank and rod from a friend and I replaced all the crank bearings and all the conrod bearings with new plus a gasket set and a couple orings. cleaned and remeasured everything and got out the magnifying glass and checked everything over. this happened after my orignal rebuild just last winter. had about 750 miles on it when it let go. found no cause for it. all oil passages were clear when i checked them. the other 3 conrod bearings were all in excellent shape. all conrod nuts still torqued to spec. this will not happen a 2nd time I gaurentee it. I'm still waiting for 1 more conrod bearing which the suzuki dealer screwed up on from my order last week. hopefully have it tomorrow and back together by this weekend.
 
Any chance that one bearing was the wrong size?

Note to self, stick with roller bearing cranks.
 
^^Roller bearing cranks don't exist on the GSX400 & GS450 unfortunately. Only the 425 and 77-78 GS400's. Twins kinda got shafted on that one.

Dave_17954 said:
Havent got it all back together yet but yes got a used crank and rod from a friend and I replaced all the crank bearings and all the conrod bearings with new plus a gasket set and a couple orings. cleaned and remeasured everything and got out the magnifying glass and checked everything over. this happened after my orignal rebuild just last winter. had about 750 miles on it when it let go. found no cause for it. all oil passages were clear when i checked them. the other 3 conrod bearings were all in excellent shape. all conrod nuts still torqued to spec. this will not happen a 2nd time I gaurentee it. I'm still waiting for 1 more conrod bearing which the suzuki dealer screwed up on from my order last week. hopefully have it tomorrow and back together by this weekend.
Click to expand...


That's extremely weird. Did you do it in a dirty environment? I imagine it was clean. And you prelubed everything? Did you measure the clearances before putting that specific bearing together?

God that would suck to do a rebuild and then another catastrophic failure. That's what I don't want to happen to me.
 
actually i was on my way home from indy time trials and had stopped at bwringers house for a quick visit and carb synch. was running perfect and then about halfway home i thought i heard something but wasnt sure with my helmet on and traffic noise I couldnt really hear anything but she was running fine. then about 35 miles from home she started to hammer and i knew i was serioulsy screwed. :eek: only thing i have figured so far was that bearing was either under/oversized and packaged wrong or maybe even defective material or some such thing. I lubed everything and measured everything on my first rebuild. I'm a machinist by trade and i got access to all the good tools ;). even though it ruined the crank, conrod, and bearing which was bad enough everything else inside the motor came through unscathed and i consider myself very very lucky. I look back on my original rebuild and i wouldnt have done anything different. been rebuilding motors for about 10-12 years and this was the first time something like this has ever happened. a learning experience for sure
 
That's really strange. I might go the rebuild route, and if you're willing I'm sure I could use your advice with it. You wouldn't happen to have another spare crank or conrod would you? Heh. Profile says yer from Idaho - I traveled through their last week on my adventure. Not too far from home.
 
how did you get dirt and hair inside your engine? especially the hair :-k. I'm from ohio not idaho. If your going to rebuild I'd check in the for sale/parts section and even do a search on ebay. I got quite a few parts for mine there. if this motor is really all that crappy inside I'd agree with sqdancerlynn and look for a good used motor complete and part out your old one for good used spare parts for future use.
 
Dave_17954 said:
how did you get dirt and hair inside your engine? especially the hair :-k. I'm from ohio not idaho. If your going to rebuild I'd check in the for sale/parts section and even do a search on ebay. I got quite a few parts for mine there. if this motor is really all that crappy inside I'd agree with sqdancerlynn and look for a good used motor complete and part out your old one for good used spare parts for future use.
Click to expand...

I've only had the bike for about 1000 KM. If that. The dirt and hair, I have no idea. Hair mighta been off me, but there's no way I crammed that much dirt in there. And woops, got Idaho and Ohio mixed up.

I'm currently looking for a used engine. Thing is, shipping one costs a small fortune. Don't really know what I'm going to do with it. :(
 
found this on ebay........
CRANKSHAFT & RODS 76 SUZUKI GS400 CRANK GS 400 @JayJays (#370158211051)
x.gif
. I'm not sure exactly what cycle you got.
hh.jpg
 
Last edited:
Dave_17954 said:
found this on ebay........
CRANKSHAFT & RODS 76 SUZUKI GS400 CRANK GS 400 @JayJays (#370158211051)
x.gif
. I'm not sure exactly what cycle you got.
Click to expand...

Thanks! However my engine is a 1980 GSX400 - basically everything except the head is a GS450. Including the crank apparently.
 
MrZig said:
Yea I don't understand why it's all censored here.
Click to expand...
Most likely because it's not needed? :-k

One of the things that appeals to me about this board is the general civility and lack of trash.
When that stuff is allowed, I'll be outta here. :o

By the way, you start talking like that in my garage, you will be asked to shut up or leave.

.
 
Steve said:
Most likely because it's not needed? :-k

One of the things that appeals to me about this board is the general civility and lack of trash.
When that stuff is allowed, I'll be outta here. :o

By the way, you start talking like that in my garage, you will be asked to shut up or leave.

.
Click to expand...

This isn't really the place for a discussion on swearing, please take that elsewhere if you have a problem. :)
 
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