Srx connecting rods

SR643

SR643

New member
Joined
Nov 13, 2006
Messages
21
Age
45
Location
MI
I have two srx bottom ends they both have rods were the top end measures 23mm I.D. There is no markings on the rods and dont know what year they are. I measured a 838 rod out of a GPX and it is 22mm I.D which uses a 18mm pin and the newer rod measures 25mm I.D and uses a 20mm pin.

My question: Did yamaha ever use different roller bearings for the 18mm pin?

Did any other yamaha cranks fit in a srx case that would used rods like this?

Any help or info

Thanks
 

77 srx was a 440A. The 76 & 77 srx's used the smaller 18mm piston pins. The gpx used the same crank as the 76 srx. 77 was it's own anamial. Still used the smaller pin but more bearings. 78,79 and 80 used the larger 20mm pins. Got it? Now I'm confused. Just kidding.
Dean-o
 
I understand that. The bottom end that I have the top end of the rod is a odd size
I installed a 18mm pin and bearing and it is sloppy loose. I tryed to install in 20mm pin and bearing and the bearing will not fit the rod end is to small.

The rods I have are like a between size So I was wondering if there is a bigger bearing for the 18mm pin.

Or what I even have.

Thanks
 
78-79-80 SRX CONECTING RODS WERE MARKED. (h.o.) WAS STAMPED ON SIDE OF THEM. POSSIBLEY 77 SRX ALSO WAS MARKED. BUT 1976 WAS NOT BECAUSE THIS WAS SAME AS GPX LIKE DEAN SAID. SOMEBODY HAD POSTED I BELIEVE HERE THAT EITHER WIESCO OR COMETIC WAS MAKING DEFFERENT SIZE SLEEVES NOW FOR THIS EXACT PROBLEM. ALSO TO DOWN SIZE cc. I BELIEVE THEY HAD THESE FOR THE OLDER SLEDS ALSO. THERE ALSO ALOT OF YAMAHA MOTORS YOU CAN CHECK ON. 3:16 (yammie tony)
 
77 rod,s

i have the crank out of my 77 apart and the rod,s in my hand and there not marked. my 77 and 76 crank,s are both the same ie both the same amount of bearing,s. it,s the 78 ssr crank that has one more bearing.
 
NO. The 76 has one less bearing on the PTO side. The 77 has 2 bearings on the PTO. Look on the parts section. Dean-o
 
The 78 SSR has larger bearings all the way across and uses the HO rods, like the 78,79 and 80 srx's. I can send pictures of all three if you like. Dean-o
 
deanosmod said:
77,78, 79 and 80 use the samecrank cases...Dean-o
Click to expand...
Not so. The '77 is a different alloy,2 fuel pump nozzles,no oil pump mount threaded holes, and not tapped for the larger cylinder studs. Maybe more I can't think of now. :)
 
They started with the same case (mold) and then drilled and taped. Case mold number is the same. Different Alloy? :oops:
 
Josh is asking, if the piston pin bearings come in 3 sizes the only question is in the size of bearing that the pin takes. I thought the 77 srx ran a bigger pin bearing than the gpx?
 
So was the 80 srx the only one drilled for oil injection
 
yes. 80 had the oil injection. 78 and 79 didn't and the 77 had smaller cylinder studs. The rods in 78,79 and 80 used the larger wrist pin bearings. 76 and 77 srx used the smaller ones. I was told that the 76 srx crank and cases where the same as GPX. I don't have a gpx. Just srx's and ssr's. Dean-o
 
I don't know about the third size. Tony might know. Oh Tony!!!! I know your out there buddy....Later today I'll go out to the shop and look at the parts books. Dean-o
 
deanosmod said:
They started with the same case (mold) and then drilled and taped. Case mold number is the same. Different Alloy? :oops:
Click to expand...
Alright... The illustrations in the '76 and '77 manuals show the cranks the same but the '77 actually calls out all 6 bearings. I'm not sure about which years are actually tapped on the PTO end. Oddly, the ones pictured in the '76 & '77 owner's manual shows them drilled but they are not. Isn't this fun? ;)
 
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wiseco offers 2 topend bearings in 2 different lengths, pt#B1002. i.d is18mm o.d is 23mm and length is 24mm. pt#B1014 i.d 18mm o.d is 23mm and length is 22mm. hope this helps.
 
I wonder if that means one is to be used with a Wiseco piston and one is a stock replacement? I suppose I could measure the distance between the pin bosses.
 
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