Restricted???

[Silverlegacy]

When i checked my air filter not so long ago i found some of that sludge in the air box? wasnt sure what it was so cleaned it out? but cant remember seeing any last time i checked it?? not sure what causes that?

[Punkstig]

Engine breather hoses lead into air box, any oil pushed into the air box will mix with moisture causing your milky gunk, it's not a problem as that is happening outside the engine, if you see that mixture through oil sight glass or when changing oil that's when you need to worry!

[Silverlegacy]

Thanks punkstig.
Luckily it's not like that in the engine.

[Punkstig]

Speaking of k&n filters I just find out I have one - on the boat engine!

[Silverlegacy]

Hi again,


Was doing some more research into this lean running thing.
A few sites have mentioned about adjusting the carb needles to make the engine run slightly richer? as mines running lean i am not sure if this will help any?
My Dynos on Page 3 i think so not sure if that will help to see if making the bike run slightly richer will help calm down the problem or even if it can be done at all?
I might have the wrong end of the stick (or needle)
thanks all

[Fazerider]

Raising the needles a notch will richen it up slightly, but are you sure you want to get into tinkering with carbs? It'll mean quite an expense in further dyno runs to check the effect and it seems to me you're feeling something that isn't visible on the graph anyway as the power curve looks quite straight.
If the bike is running excessively lean (and that air/fuel ratio curve looks pretty similar to the one Red98 posted) you'd get pinking which should show up on the power graph. I can't think why it should appear on the road, but not on the dyno, but you could check by running a tankful of higher octane fuel through it to see if that makes a difference.

[Silverlegacy]

Hi,
It's more to do with the air to fuel.
On the bottom graph it shows the lean patch at 6-7k rpm.
That's what I feel on the road, so matches perfectly with the feeling I get, although once you push past it, it improves. Not that I get much chance to thrash it about.
Just thought that maybe adjusting the needles might help push that lean patch a little higher up the Rev range .

[Fazafou]

I was in a similar situation but different vehicle (long story) and ended up buying an air fuel ratio sensor and gauge off Amazon. While it was about 120 quid, when compared to repeat dyno sessions it's a cheaper alternative and you have a sensor and gauge to keep.

Either just shove it up the exhaust or cut a hole after collector box and brazed the collar on to fit the sensor (before any cat).

Works brilliantly and you can see the AFR in real-time as you're tuning and even while riding if fitted into the exhaust properly.

This way you can make adjustments to needle heights and see where it leans out in rev range and by how much.

I don't know if you want to go this route, but I learnt more about carbs in that one tune up than I have in over 20 years riding, so you could use it as a learning curve too

[Silverlegacy]

Cheers fazafou, I will have a look at that and see.
It's not a massive problem with the bike, it runs really smooth below 6k rpm , so just up shift before I get there, do a bit more low speed commuting than high speed journeys .

[Paulfzs]

i had aweak spot about 4-6k then after that the front forks would extend and it would fly off... nothing better than slowly going from 4-6k then pinning the throttle   :evil

[unfazed]

Remove the Air filter, hold the throttle open full, using a mirror and small torch/light look in to see if there are restrictors in the inlets.

If there are no washers in the inlets remove the tops of the carbs to see if a yamaha restrictor kit is/was fitted.

See pic

[Punkstig]

Riding around below 6k rpm, what's that all about?

[Silverlegacy]

Bike been dynod so definitely not restricted.
Nice I get the bike up to 6k it started to feel strained and a bit vibey. So tried to keep it below and just shift up as I hit 6k . Not ideal but bike runs really smooth that way, just not overly nippy.
After reading stories of people getting there's jetted and either being worse or doing nothing I don't think I want to spend £300 getting it sorted.
So just trying to see what else I can do, wanted a new exhaust but heard it could lean the bike out even more which might be bad news.
Might try adjusting carb needles one notch and see if it makes any difference?

[unfazed]

Check the charging, a slightly over charging regulator can cause similar symptoms

[Silverlegacy]

Check the charging, a slightly over charging regulator can cause similar symptoms

Not sure how to check this as not overly technical?
Although I have read through a old thread and that was the problem, so might very well be?
I'm pretty sure I read somewhere about engine charging the battery at certain revs? Although I don't know the technical details sorry.
Bit of a tech noob on here, so appreciate everyone's knowledge and patience.

[Punkstig]

Nice I get the bike up to 6k it started to feel strained and a bit vibey. So tried to keep it below and just shift up as I hit 6k . Not ideal but bike runs really smooth that way, just not overly nippy.

The power comes in after 6k, riding it below that and it'll never be overly nippy no matter how much you spend on Carb setups, air filters and exhausts!

[rhinoeli]

I would certainly suspect something in the carbs:
- leaky diaphragms
- one or more jets blocked
- float level too low

Sooner or later you'll have to take the carbs out, check them, clean them...

Other thoughts:
- fuel filter blocked?
- fuel pump?
- TPS?

[Silverlegacy]

If I can work out that issue between 6-7 k then hopefully it will give me an incentive to ride it more for fun rather than just commute, it's one of the only bikes I've owned I've not used of a weekend for rides out.
Might look further into this regulator thing?
I did notice something with the lights and lights on the clocks getting slightly dimmer when it was still dark around 7am, probably more so the lights on the clocks, although it has got an extra temp gauge and a analogue clock fitted to it drawing power? although doubt these are high usage items?

[Silverlegacy]

I would certainly suspect something in the carbs:
- leaky diaphragms
- one or more jets blocked
- float level too low

Sooner or later you'll have to take the carbs out, check them, clean them...

Other thoughts:
- fuel filter blocked?
- fuel pump?
- TPS?

Ive tried to check as much as i can,


carb rubbers not leaking, although not cleaning carbs yet as might be a bit beyond me to be honest.
I fad fuel filter off, blew it out and cleaned it and its ok, not sure about fuel pump but seems ok? Ive adjusted TPS when i did my carb sync and its fine.


Starting to wonder now after reading through Red98's Stutter thread as to whether it might have anything to do with the regulator? although symptoms seems similar, ive probably not done a very good job of putting them into words.

[rhinoeli]

carb rubbers not leaking, although not cleaning carbs yet as might be a bit beyond me to be honest.

I am talking about the diaphragms inside the carbs, not the inlet rubbers.