Honda CX 500 Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
762 Posts
Discussion Starter · #1 ·
"...in the beginning, the company searched its existing lineup for an engine it could tune for dirt track racing. Its engineers settled on the CX500 mill - a four-valve, shaft drive, 80-degree, 500cc V-twin with its cylinders sticking out the sides"



Just thought I'd share this article for those who don't receive American Motorcyclist







Another article about the NS750 can be found here
 
  • Like
Reactions: Godzilla777

·
Registered
Joined
·
2,601 Posts
Had they spent more time and $$ they probably could have nailed it.



Much like the oddball engine I've got in my car was a testbed for the Cadillac Northstar.

Total flip of the coin, perhaps the most complex engine to maintain should anything go wrong.
 
  • Like
Reactions: Godzilla777

·
Registered
Joined
·
228 Posts
I thought it was a really fast motor, they just couldn't keep it cool enough throughout the whole race. When she was cool she would fly. But when she got warm it would bog and over heat.
 

·
Registered
Joined
·
2,601 Posts
As I read the block wasn't capable of being bored out that much and still handle it.



Expensive casting to redesign, could have been done, just didn't happen.
 

·
Registered
1978 CX500 "The Grub", 1983 GL650I "Nimbus"
Joined
·
11,447 Posts
As I read the block wasn't capable of being bored out that much and still handle it.



Expensive casting to redesign, could have been done, just didn't happen.
According to the article, they oversized the cylinder sleeve, which reduced the water jacket. With the inhibited coolant flow, they started getting hot spots in the system. It was also implied that race rules prevented anything but pure water as coolant.



R
 

·
Registered
1983 cx650E
Joined
·
1,014 Posts
I remember this, It wasn't competitive because it didn't make enough power. It was reliable though.
I thought they won one and were leading another when a chain broke on the last few laps. (Just from memory) As the other fellows said; it made good power, but they couldnt' keep it running right or together.
 

·
Registered
Joined
·
816 Posts
Well, that was cool to read! I seem to recall seeing a picture of this bike back then; may have been in Cycle or some other mag I used to get. Would be cool to see it in person if it's still up at the museum in Ohio.



First thing I caught looking at it is the carbs and exhaust switched out on the heads!
 

·
Registered
Joined
·
192 Posts
According to the article, they oversized the cylinder sleeve, which reduced the water jacket. With the inhibited coolant flow, they started getting hot spots in the system. It was also implied that race rules prevented anything but pure water as coolant.



R
Most racetracks only allow water as a coolant since antifreeze is too dificult to clean up and is slippery. Water is the best coolant as it transfers the most heat quickly. One of the reason that Honda quit is because the rules were changed to eliminate anything but air cooling. This was done to maintain Harley as the dominant race winner. The only way that Harley can ever win is to change the rules and eliminate the competition.
 

·
Registered
Joined
·
8 Posts
As I understand the story, Honda had a mad scientist tuner named Jerry Griffith turn out the prototype NS750 engine and then HRC turned out a very small number of parts to convert CX500s into NSs- the heads, the cam, the left-side engine cover, etc. I've been told by Gene Romero who ran the RS team that a total of 7 NS bikes were built and that 6 of the frames were C&J single shock, 1 was a dual-shock by a local tuner. I'm having no luck inserting links into this message, but if you goodle -image NS750, you'll see the Bergstrom bike that was in this article, Chris Carter's NS, and the dual shock NS. These bikes are frightfully rare and never come on the market. RS750s are also rare but around 50 of them were built and they do sell now and again. Anyway, it seems that there were 2 fundamental problems with the NS- 1 was that it overheated and the other was that the crankshaft ended up too high in the chassis (dirttrackers are really sensitive to crank location) and the bike wouldn't hook up well enough. Honda fixed both of those problems in the RS and that bike could still win an AMA GNC if you could get the parts to run one. Honda stopped making RS parts cold at the end of 1988 and while most parts are available (there's a brand new RS crank on EBay right now), you just can't get enough parts on a steady basis to make running one a realistic proposition.



And yes, the AMA was long beholden to H/D. They never outlawed watercooling (currently, the 650 Kawasaki Ninja twin, the SV650 Suzuki and the BMWF800 twin are all doing well in the GNCs and are all water cooled), but they did restrict and add weight to the RS until the XRs could finally keep up and there is supposed to be a letter from Soichiro Honda himself, on Honda letterhead, addressed to the AMA telling the AMA to "Go F... Yourselves" when Honda pulled out of GNC at the end of 1988.



I just joined this forum as I'm starting the process of building a CX dirttracker. It will have to be turned 90 degrees like the NS to allow a chain drive and it looks like I might be able to do the head swap to get the carbs on the right (when we fall in dirttrack, 90% of the time it's onto the left side and you'll just rip the carbs off if you leave the layout stock). I haven't decided how to address the crank height issue but have some ideas. If I ask goofy questions, it's because I'm pursuing a goofy project!
 

·
Registered
Joined
·
816 Posts
al249v,



Nothing goofy about your project. I think it would be very cool to see your work as you proceed. The fact they can be turned 90* and chain driven is pretty cool in itself. Thanks for the further history behind the NS.
 
1 - 15 of 15 Posts
Top