r60us
09-19-2008, 01:52 AM
For the one person other than myself who wondered what if...
* Installation of an R100 camshaft in an R60
* Installation of an R60 camshaft in an R100
During the past summer I had the opportunity to test both. Here's the seat of the pants result... I'll spare you the technical drivel, lots of generic and airhead specific data on the 'net.
An R100 camshaft in an R60 moves the torque band up the rpm range, improving performance in the 4000+ RPM range; it feels more like a second generation R65 which has the same 308 degree cam duration as the R100. The cam kicks in around 4000 rpm. The engine revs more freely and without fuss to the redline, even in 5th gear (3.56:1 final drive). Average fuel consumption of the freshly rebuilt engine over 900 miles at 60 mph with a 3.56:1 rear drive was a respectable 49.3 mpg (59.2 imperial). The only downside is that low rpm torque (below 4000 rpm) suffers somewhat. The air intake noise level is slightly higher under acceleration below 4000 rpm due to the earlier opening of the intake valves. No changes were made to the 600cc engine other than installation of the camshaft. The carbs were left at factory settings. Engine idles normally with no spitting, no hesitation when opening the throttle. Carb rejetting would likely result in additional performance improvement. If your R60 spends most of its time above 4000 rpm, IMHO the swap is definitely worth considering.
An R60 camshaft in an R100 makes a really nice touring bike - with the milder 284 degree cam, the engine is very relaxed, spinning easily, quietly and smoothly with no fuss or muss. The torque band is moved lower in the rpm range; at 3000+ rpm, there's no need to downshift to pass, just roll on the throttle and it spurts ahead. With 3.09 gearing the bike cruises effortlessly at 70 - ??? mph.
Incidentally, the cam swaps were left in place since the R60 engine is destined for installation in a Dnepr sidecar outfit (~4000 rpm @ 50 mph) and the R100 engine runs so well for my style of riding it would be a shame to tamper with it :)
* Installation of an R100 camshaft in an R60
* Installation of an R60 camshaft in an R100
During the past summer I had the opportunity to test both. Here's the seat of the pants result... I'll spare you the technical drivel, lots of generic and airhead specific data on the 'net.
An R100 camshaft in an R60 moves the torque band up the rpm range, improving performance in the 4000+ RPM range; it feels more like a second generation R65 which has the same 308 degree cam duration as the R100. The cam kicks in around 4000 rpm. The engine revs more freely and without fuss to the redline, even in 5th gear (3.56:1 final drive). Average fuel consumption of the freshly rebuilt engine over 900 miles at 60 mph with a 3.56:1 rear drive was a respectable 49.3 mpg (59.2 imperial). The only downside is that low rpm torque (below 4000 rpm) suffers somewhat. The air intake noise level is slightly higher under acceleration below 4000 rpm due to the earlier opening of the intake valves. No changes were made to the 600cc engine other than installation of the camshaft. The carbs were left at factory settings. Engine idles normally with no spitting, no hesitation when opening the throttle. Carb rejetting would likely result in additional performance improvement. If your R60 spends most of its time above 4000 rpm, IMHO the swap is definitely worth considering.
An R60 camshaft in an R100 makes a really nice touring bike - with the milder 284 degree cam, the engine is very relaxed, spinning easily, quietly and smoothly with no fuss or muss. The torque band is moved lower in the rpm range; at 3000+ rpm, there's no need to downshift to pass, just roll on the throttle and it spurts ahead. With 3.09 gearing the bike cruises effortlessly at 70 - ??? mph.
Incidentally, the cam swaps were left in place since the R60 engine is destined for installation in a Dnepr sidecar outfit (~4000 rpm @ 50 mph) and the R100 engine runs so well for my style of riding it would be a shame to tamper with it :)