Photos appear at the bottom of this page.
I had a lot of Ducati singles before I switched to my first little Honda twin. I enjoyed riding the Ducks (and was sponsored by Fred Mork on a very nice 350 for a season), but I grew to loathe some of the design "features" that often kept my bikes from running for any appreciable length of time. My friend Henry Deaton had been roadracing a sloper CB175 (all future references to 175s are about the CB160-style sloper, not the late 1969 (1970 model year) vertical cylinder 175) with AFM, and I found myself intrigued by the styling and construction. Horizontally split crankcases, real electrics, and no bevel gears - you could even get parts from your friendly local dealer! It didn't hurt that I already had a 750 Laverda twin, which looked a lot like a Super Hawk, heavy on the steroids/pasta.
After discussing the potential of the engine with Craig Hanson who worked on a number of my bikes I bought a 175 rolling chassis with engine from Henry (this was about 1986). As the 175 was not terribly effective against full 250s, we decided that we would shoot for building two identical engines that would be competitive in the vintage 250GP class. Henry had Craig modify a 160 chassis for his pumped up motor, and I built a frame to house mine.
When I got my engine assembled and into Henry's modified frame I rushed down to the AMA/AHRMA national at Laguna Seca. I was pleased with the performance of the very roughly tuned engine.
My engine received a long evening of tuning on Craig's dyno after the Laguna Seca race. I can not stress too heavily how important dyno tuning is to a race project. When it was first run on the dyno my engine put out the grand amount of 12 bhp at the rear wheel. An evening of dyno tuning which included changes only to jetting, timing, and velocity stack length bumped the horsepower up to just over 20 bhp @ 12,000 rpm. Power was still increasing, but we didn't run any higher on the dyno, although I later used an occasional redline of 13,000 on the track. I might have been able to get half of that increase on my own, but since many of the changes resulted in increases of one-half to one horsepower I would have never realized the full amount. Dyno time is the cheapest horsepower you will ever buy! My Honda was competitive with most 250 singles. In fact, the next year at Laguna Seca (the first AMA/AHRMA national using the extended track) I spent the whole race dicing with (and beating) a 250 Bultaco, which should be one of the faster 250s around.
At an AFM race at Sears Point they were doing noise checks. The CR216 was measured at 133dB. When I ran it on Craig's dyno that was done one evening, and his neighbors in the industrial park were not bothered by the noise from the 1000cc Kawasaki and Suzukis he often had on the dyno. After a couple of pulls with the little Honda there were people looking in wondering what all the racket was. LOUD.
On the way to the pregrid at a Sears Point race the rear tire picked up a piece of gravel and managed to toss it through the small gap between the top of the splash guard and the underside of the seat and down a carburetor. That broke a chunk out of the intake valve and snapped the cam chain. I never got the bike back together after that.
I wrote a little tuning guide for the 160/175 bikes (about 16 typewritten pages), documenting the things we found out while developing my bike and Henry's. It covers both engines and chassis. The PDF document is available from me for $20. I've sent out about 130+ copies so far, and haven't had anyone yet tell me that they didn't think it was worth the price. It will probably be of more value to someone who is new to building a race bike, and since cylinder head porting and crankshaft work were farmed out it won't be telling you how to do that kind of work yourself. Drop me a line if you are interested in purchasing a copy.
The CR216 and most of the spares went to my friend Stephen Gillen who raced it in the 2009-2014 seasons. It has since gone to a new home.
If you've got a trick 160/175 I'd like to hear about it or get a picture to add to the web site (but it has to be TRICK!).
Here are some photos I've recently scanned of the Honda CR216. I also made fresh copies of some of the photos that have been up on the website for years..
When I first met my friend (and now the owner of my CR216) Stephen Gillen he was riding a vertical-cylinder CB175 (henceforth referred to as a V175) on the streets of the SF Bay Area. After we'd known each other for a bit and talked about the small Honda twins he decided he wanted to "cafe" his bike. He got a replica Cotton Telstar fuel tank from a shop in Australia, but when it got here it soon became clear that it wasn't going to fit on the V175 frame unless either the tank or the frame was hacked about. I agreed to take a look at the issue and we decided that the frame should be modified.
This was not a hard decision to make because the V175 frame is not a particularly elegant design. It does the job as a commuter bike, but it was definitely built down to a "save money wherever possible" standard.
Here are a series of photos that I took during the process. This modification process, as is not uncommon, ended up being one of those "we should have just built a new frame from the start and been done with it" scenarios. Oh well . . . . .
Here's what happens when you put cheap pattern valves in your high RPM race engine. This is one of the modified KZ550 pistons and the head of the valve. Modified OEM Honda valves worked fine.
My friend Stephen Gillen has been making some aluminum bodywork for the 160/175s. Here's his latest for a V175:
After riding Craig's 160 I did some weight distribution measurements. Big people on short/light motorcycles make for a massive weight shift to the back. The 160 could use a longer swing arm to help that situation, but making it longer with the same size tubing makes it less stiff, so ideally it should be a new part made from larger tubing.
I had a lot of fun riding the 160 at Willow Springs on Sunday, though it was definitely the slowest bike on the track (not surprising as it is almost dead stock). Still, I wasn't last. Close, but I did beat a couple of people. The straights at Willow are very long on a slow bike. :-)
I was curious about how a rider my size would affect a small, short wheelbase bike so yesterday when I got the 160 unloaded I found a level spot on the garage floor and some boards to make a spacer the same height as my digital freight scale and did some weighing:
221 lbf -- for a 6' tall rider in full gear (Shoei RF1000, Alpinestar Super Tech R boots, Held gloves, and Helimot leathers, back pad and chest pad) (197 lbf stripped stripped weight this morning). That's 24 lbf for protective equipment, but I don't think I'll go the Rollie Free route with swimming trunks as the riding gear.
246 lbf -- CB160 with approx 2/3 fuel load, stock tank and fenders 50" wheelbase
For a different project I'd done a CoG spreadsheet that let me plot horizontal/vertical Cartesian coords for the mass center of each part on a bike which would then be summed for an overal CoG number. I modifed that to do just horizontal weight distribution and plugged in the above info. I've rounded slightly on some of the following numbers to make them easier to deal with.
Bike only weight distribution: 48.4%F, 51.6%R
Rider in full tuck scooted up against the back of the fuel tank (a position which had my eyes several inches in front of the front number plate so I can't imagine riding like that): 47%F, 53%R
Rider scooted backwards against seat back (which is 33.5" behind the center of the steering stem nut): 42.8%F, 57.2%R
So when you add the rider in a typical tuck the bike becomes significantly tail heavy
With a 54" wheelbase, bike CoG and rider kept at the same distance fromthe front axle (this could be done by moving the engine a little forward to offset moving the mass of the rear wheel back, basically what I did on the 216)
Rider in full tuck scooted up against the back of the fuel tank : 51%F, 49%R
Rider scooted backwards against seat back: 47%F, 53%R
A longer wheelbase would still have the bike be a bit tail-heavy, but with the rider's butt moved back the overall weight distribution would be essentially the same as the standard wheelbase bike with the rider in a maximum forward riding position which is unlikely to ever be seen in real life except momentarily during a trip over the handlebars.
If the above are recalced with a 20 lbf lighter bike but the bike only CoG being kept constant (so the weight is evenly pulled off the bike) the front/rear distribution will shift very slightly to the rear.
On 01 May 2014 Stephen reunited me with the CR216 at a Sears Point AHRMA national. I wasn't last, I passed a few people, I didn't crash and I didn't hurt the bike, me or anything else so I'm counting that as a win!In a Sears Point garage Stephen, thanks for the sponsored ride!
I wrote a tuning guide for the 160/175 twins some years back and sold quite a few copies over the years. At this point (2017) I'm moving away from vintage bikes (been doing that since they were new 45+ years ago) and I've decided that I'll make it available from the website from here on. I've not kept as current on the scene with the Honda racers and it may be that large portions of the information are available now at other sites, so WYSIWYG. I am retaining copywrite to the document
For more information contact us by usinghttp://www.eurospares.com/cr216.htm