Vfr800fiy stuttering 3.5k

[Hawky]

Hello all I’m a new member I’ve been riding for 46 years had over 50 motorcycles only have two at the moment a bmwr1250gsa and my Honda vfr800fi 2000,if possible I need some advice please I bought the bike 3 weeks ago it hasn’t been on the road in 7 years .The bike has 9,500 miles and is in immaculate condition it’s honestly spot on except for the issue I have it’s a little lumpy on tick over not terrible but not quite right,when I took it for the mot around 3.5k rpm it’s stuttering almost like a misfire then at 4k it’s running okay it with rev out without a problem . I haven’t pulled the plugs yet I filled the bike up with fresh fuel and it’s still not right im wondering if it’s the coils or a bad earth, or some fuelling issue for a 23year old bike it’s incredible on the road and I love it just hoping I can get it sorted before the weather improves thanks in advance for any replies.

[Bren]

I would in order;

Check tank for rust, 7 years is a long time to be standing.

Check, clean (if K&N) or replace the air filter.

Check the starter relay and other connections in that area for crispiness or overheating. 

Check main ground, right side of bike behind the rear fairing level with the battery box - clean and tight.

Check battery connections are tight and the battery is good, get a load test done even if new.

Balance the starter valves, your symptoms sound like they need doing

A can of injector cleaner, may or may not help. 

 

It could just be that it needs to have a few tanks run through it to wake it up again.

Good luck 👍 

 

[Hawky]

Thank you I’ll go through them tomorrow 

[interceptor69]

As an aside I guess I didn't realize the starter valves had anything to do with normal running.  I thought they only affected start up.  Mine have never been checked/adjusted since 1998.

[Grum]

With only 9,500 miles on a 23 year old bike probably means a lot of quiet times. This could cause injectors to gum up along with some nasty condensation build up within the tank. If after running a couple of tankfuls with high quality fuel injector additive doesn't work, then it would be a good investment to have the injectors professionally cleaned and flow balanced.

 

For info, the Starter Valves on a 5gen are not set equally.

Cylinder 1 = Reference, non adjustable.

Cylinder 2 = Matched to 1.

Cylinder 3 = 20mmHg More than 1.

Cylinder 4 = 10mmHg More than 1.

 

Wouldn't hesitate in fitting some new Iridium Plugs - NGK CR9EHIX-9. Plugs can certainly cause the symptoms like you're having.

Good luck.

[Grum]

5 hours ago, interceptor69 said:

As an aside I guess I didn't realize the starter valves had anything to do with normal running.  I thought they only affected start up.  Mine have never been checked/adjusted since 1998.

Agree, set for optimum idle and small throttle opening smoothness butterfly operation has the greater effect beyond that. And of course the fast idle wax unit acts on the S/V's.

Not sure on how badly adjusted S/V's would need to be to have a bad effect on higher RPM's, but would imagine by then idle rpm would be crap.

[Mohawk]

Starter valves may account for rough idle & initial throttle. 3500rpm is where the ignition advances to full advance & if the fuel air mixture is not right the bike may baulk, I was able to demonstrate that with the RBR ignition advance control. To much advance causes a stutter until the rpm reaches a level where the fuelling matches the advance. So I"d say its fuelling & if the bike has been laid up that long its not a surprise. Drain the fuel, flush the tank & clean the injectors. Run raw carb/injector cleaner through the fuel pump in the tank & the injectors. Leave it to soak for a few days, then do it again. That should solve the fuelling issues then enjoy. 

[Bren]

7 minutes ago, Mohawk said:

 Drain the fuel, flush the tank & clean the injectors. Run raw carb/injector cleaner through the fuel pump in the tank & the injectors. Leave it to soak for a few days, then do it again. That should solve the fuelling issues then enjoy. 

Im a bit confused, may I ask a question?

How would you do this? Sorry if it sounds simplistic but how do I run injector cleaner through if not from the tank? Do you mean pour cleaner in the tank and crank for a while to charge the injectors and then leave to soak? 

Thanks, Bren 

[Captain 80s]

With a hanging auxiliary fuel container.  Or get creative with a cleaned old chem container and feed the pump.  Drill a hole in a cap slightly smaller than the tube you will use and force it thru a little.  Wrap in a rag for insurance and don't hold it directly over the bike.

 

EDIT:  Never mind....   forgot about stupid internal fuel pump. 

 

I suppose if you are properly cleaning the tank, there should be a way to use the pump in this manner outside of the tank.

[Mohawk]

I remove the injectors & fit a hose fill with cleaner & use an air pump to pressurise the hose then tap 12v through the injector contacts. Acts just like it should then leave to soak overnight & run some more through & check the spray pattern. I have revived a few sticky injectors with this technique. 

[Dangeruss]

On 4/10/2023 at 10:29 AM, Hawky said:

 I’ve been riding for 46 years had over 50 motorcycles 

Best part of this post! Hopefully you didn't crash too many of them. We did our honeymoon in Wales, would love to spend time there on a bike.

[Hawky]

Sadly at 19 I had a serious road accident but that’s life I was riding 9months later in plaster 🙈 just a quick update I did a full service oil/filter air filter brakes bleed  and I believe it was the spark plugs I fitted new ngk iridium one and bike is running sweet as a nut ,thank god 👍🏼

[Grum]

14 hours ago, Hawky said:

I believe it was the spark plugs I fitted new ngk iridium one and bike is running sweet as a nut ,thank god 👍🏼

Good news, glad it was as simple as new plugs.

I knew of a 6gen with exactly the same fault, plugs removed looked fine! New ones fitted, problem solved.

Yep, plugs can cause strange things.

[Skids]

Glad you got it sorted.

 

Fortunately I didn't have any running issues like you did when I resurrected my 2001 VFR last year that I bought with only 8900 miles on the clock. Only major issue was with fitting HEL braided hoses that didn't fit.

 

Thread here.