just askin

[chuck hahn]

My little brother was asking me what the rod bearings on the GS engines are made of.. I said steel, why? He said that he heard some Japanese bikes had aluminum bearings and they failed at low miles on the engines. Now i know the cranks are roller bearing mounted, but was i right in the rod bearings?? Cant imagine any engine having aluminum rod bearings!!!!

[Nessism]

Chuck,

Slap that little bro of yours around a little and set him straight; plain bearing inserts used on cranks and rods are made out of a combination of materials, including sometimes aluminum, but if they are properly executed they don't fail.

That said, the second generation 750, which has a plane bearing crank, is one of the weaker GS's; they sometimes spin their bearings and tear up their valve train. I've heard that you can shim the oil pressure relief to boost the pressure a little which helps. Nothing wrong with the bearings per say, just the oil feeding them doesn't get there the way it should sometimes.

[TheCafeKid]

Chuck,

Slap that little bro of yours around a little and set him straight; plain bearing inserts used on cranks and rods are made out of a combination of materials, including sometimes aluminum, but if they are properly executed they don't fail.

That said, the second generation 750, which has a plane bearing crank, is one of the weaker GS's; they sometimes spin their bearings and tear up their valve train. I've heard that you can shim the oil pressure relief to boost the pressure a little which helps. Nothing wrong with the bearings per say, just the oil feeding them doesn't get there the way it should sometimes.

Man if planes have bearings like those, I wont be flying again anytime soon

I didnt know that about the oil pressure relief shimming Ed, thats some good advice to anyone who owns one.. Where did you pick up that little tidbit of knowlege??

[Nessism]

Man if planes have bearings like those, I wont be flying again anytime soon

I didnt know that about the oil pressure relief shimming Ed, thats some good advice to anyone who owns one.. Where did you pick up that little tidbit of knowlege??

Saw that here Josh. Some guy that claimed to be dealership mechanic from back in the day said that was a trick they would do on the 750's that tore up their cranks and/or cams. Seems like a reasonable thing to do to me based on things people like you have said about your 750 experience.

[chuck hahn]

so just how do you do this trick..i got a 77 and a 78...running fine as of now but i think the 77 has a bit of rougher sound than i recall..

[Nessism]

so just how do you do this trick..i got a 77 and a 78...running fine as of now but i think the 77 has a bit of rougher sound than i recall..

First generation 750's have the roller bearing cranks/rods so no worry. It's the second generation 750 engines that has issues, and has a plain bearing crank.

[chuck hahn]

wonder if this small tick i hear then may be the infamous cam slap i have read about???? mostly i hear it at idle..running doiwn the road at say above 1500 RPM its not noticable..

[chuck hahn]

even so.. hows the shimming done..got me curious now ED

[TheCafeKid]

Saw that here Josh. Some guy that claimed to be dealership mechanic from back in the day said that was a trick they would do on the 750's that tore up their cranks and/or cams. Seems like a reasonable thing to do to me based on things people like you have said about your 750 experience.

Oh Its not an experience *I* myself have had. Thankfully. I honestly wouldnt own one of the 80-82 750s, for not just this reason, but to be frank, I think they're kinda ugly, at least the lunchbox headlamp models.. if I were going to buy a bike that looked like that, I'd get the 1100E of the same livery. BUT, I have bought a parts bike that went to the big breaker in the sky because of that problem, and Larry D came and picked up a replacement motor from me for his 80-82 750 for that same reason.. and I have just seen a fair number of reports.

Honestly I wasnt sure what was causing it for a while..assumed the bearings to be the weak point.. but learned later, and from my own digging into the cooked motor i had sitting here, that oil delivery was to blame....

Did that gent go into detail about how they did the shimming at all? It might be something for someone to try and give feedback on..

[Nessism]

I believe the fix involves shimming the spring on the oil pressure relief pop-off valve, which increases the pressure.

[sk843143]

did the 1100 engines have this same prob .... or was it just the 750s...... as i think i have a slight knock in mine..... (eather that or a exhaust leak)

[chuck hahn]

now look what my little brother has started.. he doesnt even have a jap bike.. hes got an 88 clsssic and a 73 electra glide...GHEEZZZZ!!!

[TheCafeKid]

did the 1100 engines have this same prob .... or was it just the 750s...... as i think i have a slight knock in mine..... (eather that or a exhaust leak)

ALL of the 1100s were roller bearing crank motors. 16 valve or 8 valve.. Frankly the 16V 1100 motor (besides the 1150 perhaps) was the best of the GS breed IMHumbleO. Your "knock" is probably your clutch basket or clutch hub nut.. better look into it

[tkent02]

now look what my little brother has started.. he doesnt even have a jap bike.. hes got an 88 clsssic and a 73 electra glide...GHEEZZZZ!!!

Tell him those have plastic bearings... Made in India someplace.

[GregT]

For those who were asking about the 16v 750's...

Suzuki New Zealand put out a Tech Bulletin back in the day advising to shim the pressure relief valve spring using two 6mm spring washers.
This is roughly 2.5mm.
I have never measured the resulting pressure increase but would assume that it is substantially higher from around 3000rpm up.
This may have been a "kiwi" fix for the problems appearing on the local market or it may have been factory approved - I don't know.
What was apparent is that it was needed - and worked.

Greg T