Benelli Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
380 Posts
Discussion Starter · #1 ·
Has any one found they are using a lot of oil or that when the air box is off the crankcase breather is puffing out fumes?

My does, the bike has done a little over a 1000 miles on the clock.

Is this the cause why many of our bikes are cutting out when hot ?

It could be rings or head gasket letting cylinder pressure vent into the crank case.

Has any one else had similar diagnosis?
 

·
Senior Member
Joined
·
5,934 Posts
Has any one found they are using a lot of oil or that when the air box is off the crankcase breather is puffing out fumes?
Mine's fine. Uses very little oil & blow-by is not noticeable. She's done nearly 46,000 km.
My does, the bike has done a little over a 1000 miles on the clock.
Is this the cause why many of our bikes are cutting out when hot ?
Don't think so. Mine cuts out on occasion, but doesn't have your symptoms
It could be rings or head gasket letting cylinder pressure vent into the crank case.
If it's done it from new (& probably has), chances are, the ring gaps are lined up.
Either that, or the rings never bedded in from the beginning. Which is quite possible, given the "softly softly" running in procedure.

Do a compression test. That will provide the answers you need.
 

·
Mid Life Crisis
Joined
·
107 Posts
Cutting out when hot....is your air temp sensor still mounted in the air box...if so it'll be covered in the oil you refer to and giving spurious readings due to the heat of the engine ( as well as being cacked up). Relocate it to the front RHS of the bike. It can be cable tied to the fairing frame and tucked under the plastic trim panel. Should tick over fine then.....seal the hole in the airbox with RTV sealant and re route the drain pipe while your at it.

Dave H
 

·
Senior Member
Joined
·
1,841 Posts
Dave, I would not recommend fitting the inlet air temp sensor at the front of the bike. I will try to explain why I believe so....The sensor is there to supply temp data of the air entering the engine,the ecm trims the fuel input to match the inlet air,the inlet air when you start the engine from cold may well be the same as the air temp at the front of the fairing,but when you ride and also as the engine is revved will cause the air temp in the air box to reduce. The ecm will adjust fuel to maintain correct fuelling.If the sensor is in the fairing it is giving incorrect data except from cold start.
The problem of the dirty sensor can be rectified by fitting it higher as I believe Errol has done or I have fitted mine in the air intake duct.
Hope you see what i mean
Colin
 

·
Mid Life Crisis
Joined
·
107 Posts
Colin..theory sounds good.....but the proof of the pudding & all that. Mine was modified by Rusty Russ and truth is it has never run better.
 

·
Registered
Joined
·
113 Posts
sensor

DaveH/Russ spot on , Benelli have moved this sensor outside the airbox, Now located in still (atmospheric) air inside the top cowling. This avoids weakening of the mixture due to excessive heat because where the sensor was mounted in the airbox it almost touches the rocker cover creating a false reading :)
 

·
Senior Member
Joined
·
1,841 Posts
Dodgy,are you saying Benelli have said to move the sensor as a call back ? or are you saying the current models are factory supplied with the enterance air sensor in the fairing?:confused:
The fault described i accept,the overheat/dirt problem is rectified,but the ecm will not be richening as the intake air temp decreases therefore you will be running weaker at high speeds!. The ecm was designed to operate in this way.
I know where I want mine !!:)
 

·
Cafe Racer member
Joined
·
676 Posts
Colin think a little harder.
The incoming air is going to be about the same at the entrance to the intake as inside the intake. (when riding) The air does not have alot of time to increase or decrease as it flows across the intternal hot surfaces, due to the large volumes that are moving through.There might be a small change to the actual air temp, but not enough to to warrant a change to fuel/air ratios. Outside air temps on a cold day versus hot day will make these difference great. The air intake will also be in clean air.
just my 2c worthg

Paul
 

·
Senior Member
Joined
·
1,841 Posts
Paul,I am not thinking it up, I am simply refering to the explaination of what the suction air temp sensor is, from the Benelli workshop manual !
Suction air temperature sensor - placed in the air filter box. Considering that the
density of the air (and therefore the quantity of oxygen available for burning the fuel)
varies with the temperature, a suction air temperature sensor has been provided.
Variations in the air temperature (and therefore the density of the air) are compensated
by adjusting the quantity of fuel injected at a level conforming to clean combustion
and low emissions.
The air at the sensor in the airbox will reduce in temp when riding fast and will increase if stationary,that is why the sensors are put there. A simple way to understand windchill is to check ambient temp outside,then drive along at a reasonable speed then place a temp gauge out the window, you will see a drop relative to the speed.
A very good example of how this works is truckers use of the wind chill, they fit a can holder outside on the mirror bracket and leave there drinks outside in the wind to cool down. It also works well with Mars bars !!!
Here is a good graph of windchill factors its quite suprising.
http://en.wikipedia.org/wiki/Image:Wind_chill.png
 

·
Registered
Joined
·
254 Posts
Wind chill only has an effect on heat generating objects or objects of different than surrounding temps. Cooling down a beer faster outside the truck will work, however, it will not get any colder than ambient temp. Your thermometer will read the same temp in stationary air as it does with wind(until compressibility comes into effect at very high speed). However, where the airbox temp sensor is placed can make a difference. I see both sides as having good points.
 

·
Senior Member
Joined
·
5,934 Posts
Air box air temp sensor - 101

It is a commonly available beer chiller, it contains a fan and a metal plate that cools due to the wind factor.
heres another one,with spec.It states 18celsius below ambient I think I need a cold beer !
http://www.globalsources.com/gsol/I/Car-refrigerator/p/sm/1000475462.htm
Although it's not stated, I believe that link refers to a fridge / heater, which cools / heats using the Peltier-Seebeck effect. Pass a current through the junction of 2 different metals in one direction, and the junction temperature increases. Current in the other direction, the temp decreases. It's grossly inefficient, but cheap, and has no moving parts, except for a fan to distribute the heated / cooled air.

If you want to cool to less than ambient, using wind, you need to evaporate something - usually water. This is the principle of the "Coolgardie Safe". Soak the asbestos surrounding a sealed metal box (containing beer) in water, and place it in a breeze, in the shade. Cooler beer results. (It's also the principle behind the hessian water-bag)

The problem with the temp sensor in the Benelli airbox, is not intrinsically due to moving air in the box, or wind chill, or evaporation, but the fact that, if the air is NOT moving, the sensor will, in it's original positon, detect the engine heat, rather than the ambient temperature. If the air IS moving, the rising, engine heated air, will be swept away, being replaced with ambient temp air.

If the sensor is repositioned higher, inside the box, the engine heat will be less able to reach it, when the bike is NOT moving (and still completely unable when it IS moving). Even better, if the sensor is mounted inside the air duct, or further from the engine (as it appears Benelli have now done).

Of course, there is another way to heat air. Pressurise it. There's the challenge, though. Can you ride fast enough, for the air, inside the airbox, to compress enough, to increase it's temperature? Good luck with that one :rolling:
 

·
Senior Member
Joined
·
1,841 Posts
Hi errol and jlsb8, Thanks for explaintions,:clap: I drank my cold beer:blur: ,still not sure!, so i did a little experiment. I measured the ambient air and then checked it at speeds, i now agree that wind chill does not occur,in fact what actually happens is the sensor warms slightly (about 0.7C degree at 70 mph).I suppose from friction of the air on the sensor.
Just going back to the begining though,why did benelli fit it in the airbox if outside is better. My suzuki also has one in the airbox and the Triumphs that use the same ecm have it fitted in the airbox at higher level though.I wonder if at slow speeds the engine heat warms the air in the box and this is why they are normally fitted there ? I suppose experiment 2 will be test the airbox temp in use,unfortunatly it is snowing here!
Colin....
 

·
Senior Member
Joined
·
5,934 Posts
I reckon that inside is better, 'cos at idle, the air will (most likely) be warmed slightly from the engine. The problem is to find a place for the sensor that will read the true average temp of that air. In the centre would be best, but a little hard to do. In the duct would be ok as well, since it's some distance from the engine & exhaust. Just a little difficult to mount.
Triumph has possibly found the best compromise, up high & at the entry. (They use the same sensor as on the 900 Tre)

You know, it probably doesn't make any difference, if you don't hang about, standing still!

On the subject of Triumphs. :mad: I've got a mates 955 in pieces at the moment. 70,000 kms and it looks like it's big ends are worn out. It's an absolute pain in the arse to pull apart too. Not once did they bother to oil a screw thread before they installed it. :doh: Almost every screw has "picked up" - at least slightly. I've destroyed a couple of torx bits & have had to source a set of impact bits to finish the job.:doh:
Hows about you knock on their factory door and offer them a can of oil?
 
1 - 15 of 15 Posts
Top