Better throttle response?

[Mucci]

I've got a stock '83 R65. It's a great bike but it'd be a whole lot more fun if it had better throttle response. It's a bit sluggish down low and with all the tight mountain roads around here it's definitely noticeable.

On my single cylinder dual sports (DRs) I've gotten great throttle response from a high flow muffler swap, air-box mod (cutting out the top) and upjetting. I was wondering if a similar trick on these bikes would do the same. The airbox on these is much more visible so I'm not sure I'd want to cut a hole in it but just looking for some ideas before making any changes.

[georgesgiralt]

Hello !
Actually to get this on my '82 R65, I did the contrary.
Put the asymmetric cover to the airbox, sturdier springs on the carb and needle on 3 position, needle jet at 2.64 and 135 on the main jet. I enjoy every minute I spend on this bike.
But YMMV ...
Just my 2 ¢.

[Bob_Roller]

Have you gone through the carbs at all ??
Carb synchronization, throttle cable balancing ??
Valve clearance check, ignition timing check .
I would not start altering things, these bikes run just fine as set up from the factory .

[Matt Chapter]

The earlier motor (pre '85) likes to spin.  You'll find a lot more joy if you keep revs above 3k and stay away from "down low".

Failing that, I'd look at a tune up before any mods.

[DonC]

Mikuni carbs...my $.02

[SoloLobo]

I have Mikuni's but normally ride between 4,000 and 6,500 RPM's

My advice when you want acceleration, drop a gear and hammer the throttle

[svejkovat]

I'm late to the thread but will definitely second the opinion that the r65 loves it above 45K.  Ridden a few other r bikes and it takes a little getting used to.  But this 650 is so damn smooth, responsive, and quiet up there that you hardly notice.

Mine is an '83.  What changed in '85?  I'd be interested in taking one for a ride if the torque curve is that different.

[Matt Chapter]

What changed in '85?  I'd be interested in taking one for a ride if the torque curve is that different.

The R65 went monoshock in '85, so frame changes and such.  The motor is very similar but tuned sliightly different. Apparently the monoshock has slightly higher compression?

I think the difference is small but noticeable, but it's been 5+ years since my mono had a motorectomy so I don't really remember.

[Mucci]

Sorry should have mentioned I've completely gone through it. It runs great, just looking for better throttle response and low end torque.

In the past 6mo.
- New Rings (and all associated gaskets and seals)
- Ultrasonic carb clean and rebuild
- Cables lubed and set to spec
- Carbs sync'd to spec
- Plugs & wires
- Air filter & fuel filter

All set to stock specs with stock airbox and exhaust.

What Mikuni's are you guys switching too? I assume a cable slide pumper of some sort?

I know they do well over 4k but that's not what I'm inquiring about. You can't launch from 4k every time
...well....you could I guess

[Barry]

If it is the O rings, next time a high idle occurs you could test it out by checking for a gap at the throttle stop either visually or with a thin feeler gauge or you could just press on the throttle arm to ensure it's closed on the stop.   If the idle speed doesn't drop you'll know it's something else.

[Matt Chapter]

To make a long story short, you're riding a 35 year old mid size motorcycle that makes ~33 ft-lbs of torque at 6k rpm.  There's not much more "low end" to find.  A drag bike this is not.

If you truly want to get off the line quicker, you might be able to change final drive ratios, although I think the R65 already has the lowest ratio and a more common mod is to switch to a higher ratio for lower rpm at cruising speed.

Another possibility is that there may be some driveline slip - although I suspect my clutch is on its last legs and I still manage to launch well enough.

Another area to investigate is throttle cables - even though you've lubed and adjusted them, they could be stretching.  You can also adjust the throttle free play at the handle bar.

Lastly you could consider a simple mod a few others are doing - the "860".