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Discussion Starter · #1 ·
Continuing the story of the broken twin-engine project (now single engine), we've been running the engine up through 5th gear and the chain drive is smooth and true. I'm running 18T countershaft and 42T rear. Can't remember if this was up....here is the link to the video of the engine fire up (after converting to single 680cc unit):

http://home.earthlink.net/~leinfam/sitebuildercontent/sitebuilderfiles/mov07875.mpg



Time getting short, body work repairs tonight.



JimL
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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I must have missed an earlier part of the story. Why'd you abandon the twin-engine design?



R
 

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I must have missed an earlier part of the story. Why'd you abandon the twin-engine design?



R


during the initial start up and run test, the connecting power train between the two motors suffered catastrophic failure. only one engine survived.
 

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Continuing the story of the broken twin-engine project (now single engine), we've been running the engine up through 5th gear and the chain drive is smooth and true. I'm running 18T countershaft and 42T rear. Can't remember if this was up....here is the link to the video of the engine fire up (after converting to single 680cc unit):

http://home.earthlink.net/~leinfam/sitebuildercontent/sitebuilderfiles/mov07875.mpg



Time getting short, body work repairs tonight.



JimL
what type of carbs are u running on it??
 

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Continuing the story of the broken twin-engine project (now single engine), we've been running the engine up through 5th gear and the chain drive is smooth and true. I'm running 18T countershaft and 42T rear. Can't remember if this was up....here is the link to the video of the engine fire up (after converting to single 680cc unit):

http://home.earthlink.net/~leinfam/sitebuildercontent/sitebuilderfiles/mov07875.mpg



Time getting short, body work repairs tonight.



JimL
Go gitum Jim. You rock.
 

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Discussion Starter · #7 ·
Here's a pic out in the street, this evening. My oldest son is working on the "silver wing feathers" paint for the side of the fairing. We still have to put on the numbers, stickers, readust the valves, and drain the fuel tank (you have to report with a dry tank, at the fuel truck). Meanwhile, the shaft drive bike is moving quickly....we finished the rear sets and remote shifter, made the bars, working on the fairing mounts, and other bits. May have that one fired up tomorrow night or monday night.



Very tired today....the paint job finished up about 1:30AM, and we were back at the shop by 9:00AM/\.



JimL
 

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Discussion Starter · #10 ·
Carbs are 38mm Mikuni flat slides....running the same thing on the CX500 bike. I've got a lot of cam and porting in these, plus the big valves....I suspect these would be too much carb for the street.



JimL
 

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Carbs are 38mm Mikuni flat slides....running the same thing on the CX500 bike. I've got a lot of cam and porting in these, plus the big valves....I suspect these would be too much carb for the street.



JimL




Jim, on the old forum you discussed this cam mod, and thought it could be applied to the street. I've talked to Jones Cam Designs in NC about reproducing cx500 cams, and would be interested in hearing about the changes you made to them, so if a batch of new cams were made they could incorporate this "mod".
 

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Discussion Starter · #14 ·
It's a little confusing to look at the results because of the chronology of events. Last things first, I finally put the record at 144.360. Here's how it went:

- 1st run (first time I ever rode the bike, to tell the truth) was 136.699. I discovered I didn't have high enough gearing...the bike went right straight to 10,000 RPM in 5th gear (about 147) and then did a series of snaps to the right, followed by big weaves. After I slowed down below 140 it was ok, and my measured mile was the speed shown.

- 2nd run (after deciding to realign the rear tire) this was my Monday morning return run in a little wind from the right. I ran through at a little under 10,000 RPM, using about 3/4 throttle, and went 145.384 with no handling problems. On this run I ran down the left edge of the course. I now had the record at 140.855, which was not acceptable.

- 3rd run (another qualifying run, but against my own new record) Believing the bike was ok and the left side of the couse was good, I tried to run a 10,000+ RPM pass. This time I was in trouble before I got to the 1 mile mark and nearly hit the sign. I tried to keep my speed through the weaves, but only ran 140.875. That was enough to allow another return run the next morning.

- 4th run (after deciding I must have had wind gusts on the 3rd run) I had a strong enough wind from the right, that the banners were fluttering at the start line. The bike hit the 2-mile line at over 146 and I went full throttle to see what would happen. It pulled cleanly to over 10,500 and was about 1/8th mile from the 3 mile (end of the measured mile) when it pitched right and began weaving again. I kept the throttle open, trying to preserve what I could, and got a 147.846 mile. This made the new record and I was done.



After the fact, I noticed that the front fender has rubber marks inside the left side, and the fender is not symmetrical (angled right on the forward edge). I'm confident the fender blows sideways at around 150 and kicks the front tire out of line. After that, it doesn't recover until below 140. Next time I'll just skips the front fender.



I'll make a shorter post to tell about the 500cc bike, with pics.



Thanks, JimL
 

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Discussion Starter · #15 ·
The CX500 shaft drive bike made a first pass at 119, with jetting too rich. We went down to 220 mains and lowered the bike about 2 inches, which resulted in a second pass of 124.502. This put Dan Wagner in impound (he was .2 mph over the old record). The next morning saw some shifting difficulty (due to belly pan interference with his foot) and a disappointing 123 mph; not enough for the record. We notched the belly pan and bent the shifter and wend straight back in line for another try, resulting in a down run of 125.977 and a trip back to impound. I changed the main jets down to 210s and we covered the bike for the night. The next mornings return run was perfect and Dan went 127.214 for a record average of 126.595. This was a close call, because the bike ran out of gas at the return road, about 30 seconds after clearing the 3 mile!



Below are pics of Dan and I after the event, Dan looking at his 127mph time slip, and the bike in impound as I prepped it for measurement and record certification.



Regards, JimL
 

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Congratulations to the both of you! Well done!



In hindsight, I would imagine that running the bike with one motor and finding the front end problem was much more forgiving than with the two engine setup. You may be lucky as well as good! Since you kept in the throttle it may have gotten much worse at higher speeds.



Are you still going to try the 1350 setup for next year? I Hope!
 

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I'm a bit dense. Are we saying that the land speed record for the gas 500cc and 750cc are held by Honda CX?

Great pictures, astounding job.

Rusty
 

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That's what it means! It's like the funny little geek that everyone laughed at in school until he became a tycoon!

There not laughing at out bikes now are they!
 

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Discussion Starter · #20 ·
Thanks, gentlemen. To answer a few questions and fill in a little:

- The records set are for Pushrod class engines. Pushrod engines do not compete against 2-strokes or OHC stuff. Flatheads run in pushrod class with a 50% displacement allowance (for example: 750cc flathead versus 500cc pushrod).

- Plans for 1350 class are on hold, due to my approaching retirement and a desire to find out how fast this 750 bike will go. I believe it will run about 160-162 with some more work and improved aerodynamics. I was geared so low, this year, that I could easily spin the tire at 140MPH (in 5th) by giving it full throttle.

- The carbs are probably too small. These seem about enough for a 500, but no more. We may need to go 39-40mm on the 500, and 41mm on this 750 class bike.

- The 500 will "borrow" my ultra-heads in order to move that record above 130 (I'm planning to tune for 133). These heads have oversize CRF450R valves with 5.5mm valve stems, additional port work, and a little tighter chamber. I should be able to set Dan up at about 70HP.

- I'm looking for another CX500 chassis to work with, in order to de-stroke a 650 from 674cc down to 648cc (for the 650 pushrod class, modified chassis). I can gear this bike up to about 142-144, which would be far above the current 120 mph range. I already have another Katana front end, built heads, carbs, manifolds, etc. This one will be extended the full 10% allowed, to put my son in the books.



Here's a pic of sunrise as we waited outside the impound gate, to go out for our final record runs. Return runs start about 7:00am.



Regards, JimL
 

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