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The_XL_Board > THE XL BOARD > XR's ONLY! THE ORIGINAL HONDA THUMPER DIRT BIKES Go to subcategory:
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timer
  • Rank:Diamond Member
  • Posts:537
  • From:Canada

Date Posted:11/30/2012 12:50 AMCopy HTML

HI Guys
I got some of the bugs worked out on my 79 Xr 500 a few weeks ago & parts are now on order. The problem is that the bike is a bit of a project & im not sure i have time for another project. I have since seen & looked at a 1991 rfvc XR 600 bike. Ok it has better brakes/suspension/ weighs less & has reported 10 hp more than the 79 XR 500. What my question is, is it a better motor? I look at the Oil in the frame & think thats good as it helps to cool the oil, I also noticed the motor has a paper element oil filter that can be easily changed. these things lead me to think this, although newer & not a twin shock: will be a more reliable  machine for years to come, but with still enough of an attitude  for me. Is it a better, more reliable motor?
Thanks
Timer
woosh #1
  • Rank:Diamond Member
  • Posts:1568
  • From:Unknown

Re:79 XR 500 vrs rfvc XR 600

Date Posted:11/30/2012 3:22 PMCopy HTML

If properly cared for its a good motor. The top end is more fragile than the non rfvc engine its common for people to have topend failure with the rfvc engines. My first one being a 350r was toast. I thought it just needed a valve adjustment but I was wrong. Someone had destroyed the topend. No matter how little clearance I set the valves at they knocked horribly. They were so worn when I removed them they were no longer rounded they had a point on them like a roof on a house, the cam was also horribly worn as well. So it all had to be replaced, worked great for a while afterwards. I then put a different head on it and still cant get it to run. I need to put another carb on and tune it. I really like the rfvc enigines just dont forget to change the oil or let it get low because you wont like the results.
timer #2
  • Rank:Diamond Member
  • Posts:537
  • From:Canada

Re:79 XR 500 vrs rfvc XR 600

Date Posted:11/30/2012 11:59 PMCopy HTML

Sounds ok , if you knew the bikes history otherwise . buyer beware.
Thanks
Timer
Swiss #3
  • Rank:Diamond Member
  • Posts:1254
  • From:USA

Re:79 XR 500 vrs rfvc XR 600

Date Posted:12/01/2012 5:11 PMCopy HTML

The RFVC design was Monkey Motion and worked against big cams and performance mods.  IF the engine is stock and was well cared for they tend to run for a long long time.  If they were hot-rodded or run Hot then they typically get rocker/valve train problems.  Check the valve train out for wear if you can actually get the rocker cover off.  Ticking sounds in the top end are problem indicators, sometimes beyond valve adjustments.

The Honda 630 performance kit basically increased the displacement with a bigger bore but the included cam pulled the powerband down the rpm range.  It actually ran stronger everywhere but top end where it was only a tiny bit stronger than stock.  This was a good reliability program for Honda as it gave their riders the extra power they were after without raising the rpms and putting the valve train at risk.

Swiss

timer #4
  • Rank:Diamond Member
  • Posts:537
  • From:Canada

Re:79 XR 500 vrs rfvc XR 600

Date Posted:12/02/2012 6:59 PMCopy HTML

Thanks Swiss


Timer



Go soothingly on the grease mud ... as there lies the skid demon! ...






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