Low Rev Blues

Greetings and Salutations,

I'll try and be concise. Have a 98 (Dec 97) VFR800 (believe it's from the UK, I live in Southern Spain). No mods that I'm aware of. A month or two ago I felt it was running rough at low revs and I do have to navigate urban landscapes frequently. The workshop aparently changed the plugs. I fear they've installed "cooler" plugs. It ran real smooth for a short period but is no longer smooth. Now the weather's turned wintery and it needs lots of choke for a good period of time before the temp registers on the control panel LCD readout. That's when I shut the choke off as if I do so beforehand it tends not to want to idle. Idle speed is around 1000 RPM. Is that too low? Are the cooler plugs also influencing things? I find it hard to get smooth acceleration and "behaviour" of the motor when riding in town. It's an "all or nothing" feel. I really have to concentrate on how I use the throttle, even when I open it up so it coordinates with the chain tension taking up and the tendency of the motor to drop all the way down to the 1000 RPM idle speed in between gear shifts (and it drops in a nanosecond). To my liking, it's too much mental work in order to achieve a smooth ride, takes the fun out of riding having to concentrate so much on all these factors. Why does this bike drop in revs so quickly whilst changing gears? It does so to the extent that I notice what seems to me to be an exagerated "braking" effect (if, once I've let the cluth go I haven't matched the necessary revs with perfect precision), as if I were intentionally using the gears to slow down instead of the brakes. On occasion and if it's cold, I have it in gear and, so as not to experience the "braking" effect of the drop in revs, I "free-glide" by using the clutch to just roll, the motor just cuts out dry. No blubbering, it's like hitting the engine "off" switch. I'm sure it's not the footpeg safety cut-out feature short-circuiting. Anyway, this is probably too much for one post/topic.

Any gurus make any sense of this? I've been riding for 20 years and can get my head around the mechanical/engineering concepts, just never bothered commiting it all to memory.

Also need a pair of grabhandles for the pilion(s).

Cheers and Happy New Years.

To start with, set your idle to 1400 RPM. The tach reads much higher than the actual RPMs.
Don't let off the gas all the way when changing gears, just slightly. Also, slip the clutch when changing gears if you have to.

my 98 needs the starter valves synced about once a year, it idles rough otherwise. Cooler plugs perhaps, maybe you can look at the parts list and find the part number they installed to find out? 1200 - 1300 rpm is about right for idle.

Thanks guys!!

Well at least two confirmations regarding the idle being too low, as I suspected. Will check parts list regarding plugs (don't have it on me). I must admit I just bought the bike not long ago and I'm used to the Kwaka 4 in-line GT750 and a BMW R850 which both run a shaft-drive transmission!! I assume these V4s are chunkier in the vibration department and that I shouldn't expect too much of a smooth ride at low revs. Is that correct? Or is it the sort of thing mechanically lazy individuals are likely to say (coz they couldn't be bothered spending the time or money)??

Had considered synching the starter valves. Is that an expensive operation? Can it be done at home easily? Don't have much time myself really, nor access to a decent garage (mine lives in the street, gulp).

Jeremy, when you say "slip" the clutch, you are refering to...??? I usually just give it a little flick when changing gears on the run, the holding it in to "glide" is only when pulling up or manouvering between obstacles at low speed.

Thanks again for your contributions.

Dive to rile, rile to dive.

Auspa�ol.

Auspa�ol, Jan 2 2007, 06:18 AMThanks guys!!

Well at least two confirmations regarding the idle being too low, as I suspected. Will check parts list regarding plugs (don't have it on me). I must admit I just bought the bike not long ago and I'm used to the Kwaka 4 in-line GT750 and a BMW R850 which both run a shaft-drive transmission!! I assume these V4s are chunkier in the vibration department and that I shouldn't expect too much of a smooth ride at low revs. Is that correct? Or is it the sort of thing mechanically lazy individuals are likely to say (coz they couldn't be bothered spending the time or money)??

Had considered synching the starter valves. Is that an expensive operation? Can it be done at home easily? Don't have much time myself really, nor access to a decent garage (mine lives in the street, gulp).

Jeremy, when you say "slip" the clutch, you are refering to...??? I usually just give it a little flick when changing gears on the run, the holding it in to "glide" is only when pulling up or manouvering between obstacles at low speed.

Thanks again for your contributions.

Dive to rile, rile to dive.

Auspa�ol.

The VFR does not like to be lugged, and will shake and run like crap at low revs, it needs to be revved to be smooth and happy.
If the engine speed is falling off between gear changes, fan the clutch a little bit, as in go through the friction zone slower than just grabbing and releasing the clutch. This will smooth any difference between the engine speed and wheel speed and will eliminate the harsh engine braking.

Auspa�ol, Jan 2 2007, 06:18 AMWell at least two confirmations regarding the idle being too low

It's too low.
There, that's three. (IMG:style_emoticons/oldemoticons/fing02.gif)
Good luck.