crankshaft and conrod bearings

[Guest]

Hii there to all of you,

new to the forum, first of all my apologies for the lack of proper english, I'm from a ****hole called Belgium

I have something driving me insane so I thought I'd ask here in this forum (it has learned me quite much before by using the search)


Rebuilding a GSX 750 from 1980, the 16 valve engine

Now I ordered new original Suzuki crankshaft bearings (shells, not the roller types) and conrod bearings as well, now none of them look like the original, which makes me worried

Maybe some of you have experienced this before and could help me get that bike back on the road

Here is a picture of the crankshaft bearings:


as you can see the original has 2 holes for oil traffic I believe, the new one has 3 and are much bigger ?! What to do with that ..
It should be the correct 'superseded' part according to the Suzuki dealer. Also I now have 12 the same bearings, color brown (looked in the manual and followed the codes stamped on the crankshaft and the case gave me the color brown) while original there where 3 different kinds of bearings installed
Offcourse I will measure the clearence with plastigauge before mounting but why 3 different types and now only 1

The next thing which makes me puke is the conrod bearings:


the original has an oil hole to spray the pistons I guess, while the new ones have no hole in it
again color brown according to the holy bible workshop manual
8 the same but that seems right, except for the non existing oil hole that is ..

I hope there is someone out there that can give me an answer !
Used the search and found a topic which ended up with installing the ones without the oil hole, forgive me for beeing sceptic it's the second time I rebuild that engine (first one had a worn down camshaft due to dirt in the oil channel, good thing I had a spare one)

But I can't get it in that head of me the engine will not break down without the oil hole in the rod bearings


Many thanks allready in front guys !!

Ow, I had to use tinypic to oploud the pics because the button above doesn't seem to work

[GregT]

You've got an early 750 judging by the year. The extra holes in the mains will not be a problem. Big end lubrication was a problem with the early motors which appears to be solved with the extra hole area to get more oil into the space. The later motors appear to run at a higher oil pressure too - which can be achieved by shimming the pressure relief valve.
The missing hole in the big end shells is to give upper cylinder lubrication - and cooling. I doubt global warming has got that bad that Belgium will get hot enough to worry anything. Upper cylinder lube is taken care of by oil spilling from the big ends anyway. Keeping enough oil in the bigends was one of the early problems and removing the hole probably helped.

Looks like I may be doing much the same shortly with an ex race engine due to come in from Australia to be gone through.

[GSX750]

You've got an early 750 judging by the year. The extra holes in the mains will not be a problem. Big end lubrication was a problem with the early motors which appears to be solved with the extra hole area to get more oil into the space. The later motors appear to run at a higher oil pressure too - which can be achieved by shimming the pressure relief valve.
The missing hole in the big end shells is to give upper cylinder lubrication - and cooling. I doubt global warming has got that bad that Belgium will get hot enough to worry anything. Upper cylinder lube is taken care of by oil spilling from the big ends anyway. Keeping enough oil in the bigends was one of the early problems and removing the hole probably helped.

Looks like I may be doing much the same shortly with an ex race engine due to come in from Australia to be gone through.

Thank you for the quick reply !
Yes I've read before about that oil pressure, any idea about how thick the shims need to be in order to get the pressure higher but not too high ? Also I have no idea if this engine doesn't allready run at a higher oil pressure from the factory, what year did they change that?

Global warming It's only getting coler over here, a good thing for these aircooled engines

[GregT]

I've said it before so I'll say it again. Suzuki NZ put out a service bulletin advising to shim the oil pressure relief valve by inserting two spring washers on top of the spring. I've always assumed someone found that they fitted - and the increase in pressure was what was needed.
Call it around 2.5mm of shim height.
I've never measured the before and after oil pressure, sorry.

From memory, don't the top side, outer mains have a feed hole for the top end oiling ?

[GSX750]

I've said it before so I'll say it again. Suzuki NZ put out a service bulletin advising to shim the oil pressure relief valve by inserting two spring washers on top of the spring. I've always assumed someone found that they fitted - and the increase in pressure was what was needed.
Call it around 2.5mm of shim height.
I've never measured the before and after oil pressure, sorry.

From memory, don't the top side, outer mains have a feed hole for the top end oiling ?

what exactly is it you mean with top side outer mains ?
the bottom and top crank bearings are exactly the same (with 3 holes)

[GregT]

what exactly is it you mean with top side outer mains ?
the bottom and top crank bearings are exactly the same (with 3 holes)

Have a look in the top crankcase half. Coming off the outer main bearing housing on each end I think there is a drilling which feeds the cam lubrication.
I'm going from memory here, but Suzuki used to supply grooved mains for that location.
Just check that the center hole of the 3 in the shell matches up with the drilling.

[GSX750]

Have a look in the top crankcase half. Coming off the outer main bearing housing on each end I think there is a drilling which feeds the cam lubrication.
I'm going from memory here, but Suzuki used to supply grooved mains for that location.
Just check that the center hole of the 3 in the shell matches up with the drilling.

the lubrication for the camshafts, rockers, etc.. might go through there indeed, from there it goes to the sides of the ciliders 1 & 4 and further up.
How does the piston pin get lubricated? Only by oil squashing around by the crank ? Because the oil hole in the rod will be blocked with the new bearings

[GregT]

The piston pin was never lubed from the hole in the rod. As I've said, that simply sprays oil onto the bores.
There are oiling holes on the top of the small end of the rod.
There's enough oil flung off the big ends and crank to get up there and lube the pin.
Just conventional practise as used in millions of motors.

[GSX750]

The piston pin was never lubed from the hole in the rod. As I've said, that simply sprays oil onto the bores.
There are oiling holes on the top of the small end of the rod.
There's enough oil flung off the big ends and crank to get up there and lube the pin.
Just conventional practise as used in millions of motors.

Took a closer look this evening, there are indeed 2 of the top case crank bearings that feed the cilinder head with oil! But the hole in the bearings doesn't line up with the hole in the case (still gets oil through the groove am I right ? So not that much of a problem)
I measured the oil clearence of all the bearings, it is excellent

Tomorrow I continue the mounting of the crankcase an shaft, no worries anymore about the missing hole then

Looks like everything will turn out fine in the end!

Edit: I have grooves in all of the main bearings, up, down, left, right, doesn't matter much I guess