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83gs750e and 85gs700e

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

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ive been wondering if any of you guys would know this, since the difference between the 750 and the 700 engine is just the stroke and the valve opening difference, could one order replacement parts for the 750 and put them in the 700 and basicly wind up with the same engine or is it more to it and what exactly changed the stroke, was it a different crankshaft or rod, all i know is one has a stroke of 53mm the other 49mm l
 
The difference in stroke had to be done with a shorter rod and longer crank throw on the 750. Changing the crank and rods will get the 50cc back that Harley stole.
 
what do you think about the cam, think mine will be allright im gonna call around to get some prices on theses parts and might make this my spring project
 
Cams should be alright. Aftermarket cams for 750 and liter class 16 valve motors all use the same part number.
 
The 700cc motor pistons are also domed to make up for the loss of compression when the motor was de-stroked 50cc. I found this out years ago and have used 700cc pistons in my 750 motor (83750ED) to get the compression up to about 10.25 to 1 (from stock 9.6). They work very well with the stage 3 high lift cams I use. You must check valve to piston clearance, with these cams, and if I recall valve reliefs were machined about .020. Good luck.
 
Howdy this is my first entry into the forum and one that I have a bit of info on. The 700/750 conversion engine wise will also require 750 cylinders as the 700's are a bit shorter with stroke reduction. The 750 rods are required too. If you keep your 700 cams it will give the 750 a bit of a boost as they were hotter to compensate for the decreased HP. the 700 crank will have to be replaced with the 750 one also. Although the shorter stroke did give higher revs. This was one reason why Yoshimura raced with the 700 motor on Kevin Schwantz's Superbike. :D
 
Not so on the cylinder block. I have a set from a 750 and they measure the same. The rods are shorter and the crank has a longer throw to end up with the piston rising to the same heighth in the cylinder and pulled further down to increase stroke.
 
You are so right Billy, my mistake. I forgot about the crank differences. :oops: Ken
 
thanks for the replys guys ive got alot of feedback from differnt companies that say they have these parts for me out in california im thinking about ordering them i hope i dont get burnt, there coming from salvage yards the guys there im talking to seem allright i just hate the idea of buying somthing withoyt really seeing for myself what itcame out of
 
Just make sure they are willing to guarantee the parts and not selling them as is. If you find a reputable source let me know.
 
One more thing on the crank and rods. Make sure they are from an '83 E model.
 
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