zacapa
Race Dog
- Joined
- Feb 28, 2012
- Messages
- 2,110
- Reaction score
- 3
- Location
- East Coast of Africa in the Hills
- Bike
- Honda XR650L
As much of my free time is spent in the garage getting my hands greasy with my R80 Mono sometimes off road bike and the rest of free time trolling the interwebs it got me thinking if theres a chance that we could start a new topic related to how performance in the airhead may be improved by simple means. This is like sharing of information of such things as jetting setup for the Bings, what kind of exhaust system you are using, how do the balance pipes in the exhaust affect the torque delivery. How does advancing or retarding the ignition timing affect the torque delivery and all such things. I'll start of with some general data I have collected for my bike and what works or does'nt work for me.
Bike in question R 80 Monolever roadbike 1985, mileage 129000km
One set of new piston rings fitted when I broke one on re-assembly about 10 years ago - mileage since then about 25000km
Cylinder head overhaul, new valves - valve guides - valve springs etc. at 104K km (same time as the piston rings above)
Two into one exhaust system by Powerflow - more or less equal length headers going into a Y piece into silencer (loud)
The bike has been a bit stripped of excess weight - currently sitting around 180kg with a dry tank.
Observations:
1. Oil consumption is still minimal, I used 6mm of oil measured from the max mark on dipstick on the GKG trip of 1560km total. Dipstick measures 22mm between max and min mark so I'm happy with that. The trip back was also high speed at times (for an airhead) in the 130 - 160 km/h region so I think this says a lot for engine longevity and oil control.
2. Valvetrain is a bit noisy like most airheads but better than some. My end float on the rockerarms measures between 0.05 - 0.10mm so maybe thats why she's a bit noisy
3. Theres a flat spot between 4500 - 5900rpm. Below and above that she pulls great. Would I benefit from fitting a balance pipe to the 2 into 1?
4. When calculating the gearing according to revs, gear ratios, final drive and wheel circumference the gearing in 5th gear is: 5000-131, 6000-157, 7000-184, 7200-189km/h
5. On a good day on the flat with no wind she will do just more than 180km/h with me trying to be as small as possible. This seems to suggest that the gearing is spot on and theres room for a little more Vmax.
6. Does retarding or advancing the timing say by a degree or two bring any benefits in terms of performance or torque?
7. Any of the guys out there dual plugged your airheads? what gains?
8. Bridgestone BT45 are working well for me, the tyres have very good grip at the expense of outright mileage. Getting about 4500 from the rear. Rear tyre wear 2mm of tread over 1560km, total tread depth 7mm when new. Front will last a bit longer but sides are wearing faster than middle - will have to replace at about 8000.
9. Braided stainless steel line to single brakedisc has worked wonders for better braking.
10. I fitted a Wilbers shock (special order) some time ago and found the spring to be way too hard. Replaced that with the softer original BMW spring and all was good again.
In the meantime will keep this thread updated when and as things happen, please post your insights and comments.
Lets discuss airhead performance tweaks................
Bike in question R 80 Monolever roadbike 1985, mileage 129000km
One set of new piston rings fitted when I broke one on re-assembly about 10 years ago - mileage since then about 25000km
Cylinder head overhaul, new valves - valve guides - valve springs etc. at 104K km (same time as the piston rings above)
Two into one exhaust system by Powerflow - more or less equal length headers going into a Y piece into silencer (loud)
The bike has been a bit stripped of excess weight - currently sitting around 180kg with a dry tank.
Observations:
1. Oil consumption is still minimal, I used 6mm of oil measured from the max mark on dipstick on the GKG trip of 1560km total. Dipstick measures 22mm between max and min mark so I'm happy with that. The trip back was also high speed at times (for an airhead) in the 130 - 160 km/h region so I think this says a lot for engine longevity and oil control.
2. Valvetrain is a bit noisy like most airheads but better than some. My end float on the rockerarms measures between 0.05 - 0.10mm so maybe thats why she's a bit noisy
3. Theres a flat spot between 4500 - 5900rpm. Below and above that she pulls great. Would I benefit from fitting a balance pipe to the 2 into 1?
4. When calculating the gearing according to revs, gear ratios, final drive and wheel circumference the gearing in 5th gear is: 5000-131, 6000-157, 7000-184, 7200-189km/h
5. On a good day on the flat with no wind she will do just more than 180km/h with me trying to be as small as possible. This seems to suggest that the gearing is spot on and theres room for a little more Vmax.
6. Does retarding or advancing the timing say by a degree or two bring any benefits in terms of performance or torque?
7. Any of the guys out there dual plugged your airheads? what gains?
8. Bridgestone BT45 are working well for me, the tyres have very good grip at the expense of outright mileage. Getting about 4500 from the rear. Rear tyre wear 2mm of tread over 1560km, total tread depth 7mm when new. Front will last a bit longer but sides are wearing faster than middle - will have to replace at about 8000.
9. Braided stainless steel line to single brakedisc has worked wonders for better braking.
10. I fitted a Wilbers shock (special order) some time ago and found the spring to be way too hard. Replaced that with the softer original BMW spring and all was good again.
In the meantime will keep this thread updated when and as things happen, please post your insights and comments.
Lets discuss airhead performance tweaks................
