Lumpy VFR 5TH GEN

[Jonnyvt]

hI

 

I have recently purchased a lovely 18k miles 1999 (pre cat) 800fi.  I must admit to be a little disappointed with the bike; so i wanted to see what others thought - this is the only one of these i have ever ridden, but do also have a 1986 VF500.

 

I have found the VFR motor to very lumpy, worst at low revs (under 5) but also at higher revs; this seems to get worse in warmer weather. ive serviced the bike, inc a plug change (these were brown in the middle and a little dusty on the edge. Also synched the starter valves and changed the fuel pressure regulator.

 

I was really expecting it to be turbine smooth, not thump like a v-twin!   Is it normal for these motors to thump like this?  or is there something wrong (no EFI codes showing).  What are your experiences of this motor?

 

Many thanks

 

Jon (UK)

[JimMoore]

Sounds like there is something wrong. Mine pulls cleanly from 1500 rpm to redline. The opposite of "lumpy."

[interceptor69]

My '98 also pulls smoothly from down low to redline.  I wonder if clogged injectors could cause this behavior?  Is this condition constant?  Never varies?  You mention it's worse in warm weather.  Air filter new/clean?  Also wonder if you adjusted the starter valves properly.  I remember one member being surprised that he had adjusted them opposite of what he thought the manual indicated.

[vfrgiving]

I wonder if it's the firing order you're noticing, it isn't even like the VF500 you have experience with.  I have a Magna, which has a 360 crank like the old VFs.  It revs turbine smooth. 

 

 The VFR800 revs with character. The VFR800 fires like two V-twins synched up 180 degrees apart due to the crank.  That's why it sounds so awesome with an aftermarket pipe.

 

I'd suggest finding another UK member with VFR experience and let them take it for a rip and get their opinion if something is off.

[VeeEffArah]

With that low of miles, it seems the motorbike has sat for some time. I would also investigate the fuel filter, but be advised it is inside of the tank.

Simple checks such as the connectors to the ignition coils and also the main ground bolt is tight, right side of bike just under the rear cowl.

 

Concerning the starter valve sync, I did my 2000 recently and noticed a huge difference in starting, idle and running, when adjusted "the new / corrected way".

On my meter, #1 and #2 were steady at like 20, so I set #3 at 22 and #4 at 21. WORLD of difference versus the way the manual has it explained.

 

Here is the link to that thread...

 

 

 

 

[Jonnyvt]

Thanks everyone for all your great responses - i am going to try the 'reverse' starter valve sync (as i had do this the way the manual said) then try another VFR (Andy Bolas of the VJMC) and then i will have the injectors cleaned, once i have the courage to take off the throttle bodies!

 

Thanks so much again, I now know where to come for great advice.

 

Jon

[vfrgiving]

All of this work is good things, but I have a feeling afterwards you'll still notice that V-twin lump as you called it.

 

I remembered a quick conversation I had with an older guy last year outside a gas station.  My VFR was idling as I was putting my helmet on, and as he passed he asked "is that a V-twin?".  He was obviously familiar with bikes, but not the VFR.  This wasn't the standard GSXR or Ninja idling and he could tell by ear something was different.

 

This is probably the best explanation I've seen about what's going on with the firing order

 

 

[Mohawk]

I can't recall what the manual says. But this is my crib sheet kept on the inside  of my gauge box.

Cylinder-1 is reference & not adjustable. Cyl-2 should be equal to Cyl-1. Cyl-4 should be -10 from reference & Cyl-3 should be -20 from reference. All figures are MM of vacuum. 
 

When set like this on a stock or aftermarket 5th gen exhaust the engine is super smooth & revs very crisply. Make sure you have a 5th gen exhaust, as 6th gen will fit & rear headers are closer to same length so uses different vacuum settings. On 5th gen front pipes do NOT cross & #1 cylinder is the top/rear most pipe by right foot peg. 6th gen front pipes cross each other because #1 cylinder is inner/forward pipe by right foot peg, thus front pipes cross to keep the front rear cylinder pairings the same.

Cylinders on all VFR's are 1+3 at rear & 2+4 at front, with #1 at rear left when sat on the bike. 

[Jonnyvt]

Hi Mohawk

 

Are these the starter valve settings use have used?  i set them as per the manual, but based upon what i have learned on this forum, i have got the MM on 3 & 4 the wrong way round!!! so im gonna redo these at the weekend,

 

Many thanks

 

Jon

[Skids]

Does your model have a PAIR system fitted? If so, I'd suggest removing it. 

[phoenix655]

Mine was very lumpy and really didn't like being below 4000 until I did the starter valve sync like in the thread above and it made a huge difference. It's still not great below 3000 rpm but I think thats just too low for these bikes no matter what, maybe the carbureted bikes are better at really low RPM. It also made the throttle response a lot smoother, it was very twitchy before and was really difficult to smoothly apply throttle at low speed. I also removed the pair system and flapper but I'm not sure that did anything.