Why?????,this is doing my head in.....

[kevspeed]

Ok, 3 different scooters,exactly the same problem, but why?
Scooter number 1.....,Bog standard Li150 series 3,as Mr Innocenti intended,good fuel and flow,correct ignition timing,good plug of the correct grade,etc......,will not run properly with an air filter,feels restricted,max speed 40mph if im lucky.
Scooter number 2.....,Bog standard Italian GP 150, again,as Mr Innocenti intended except for a 42 clubman,good fuel and flow,correct timing,good plug.......Will not run properly with an air filter fitted,40 mph max.
Scooter number 3........Standard Indian GP200,22mm carb,Indian big bore pipe as supplied when new,again good fuel and flow, good plug,correct timing,will not run properly with an air filter fitted.
Took it out just now,45 max,stopped,pulled air filter partially out of the airbox,and wedged it there with the airbox spring clip,runs as it should,speedo indicating 55 plus,but not flat out,so what is it with these air filters??
The Li has a standard scootopia filter,as does the GP 200,the GP150 has an Italian made filter (MCA)?
Any ideas??

[tippo88]

You might want to look at the thread I started on "normal spitback" mine is very sensitive to the intake even to the extent that just adding a a hose, never mind a filter, affects its performance.

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[Warkton Tornado No.1]

We all know how we get tricked into looking in the wrong direction with these problems, so here goes.....

How old is the fuel?

Apparently, we might get six months maximum use of current petrol if we're lucky! That is also dependent on what the fuel is stored in.....

Water absorption from the surroundings. Air etc.

There may not be any such thing as 'fresh fuel' bearing in mind the station's underground tanks. They go from warm to cold over the course of 24 hours, get emptied, therefore drawing in more air & the moisture within.

I had an airtight five litre plastic can of Super that I thought should be alright. It wasn't twelve months old. I poured it into a Honda VFR400 just to start the thing as it had stood for some time. Not a hope! Occasionally fired. 'Fresh' fuel allowed it to start.

[kevspeed]

Fuel bought on my way home from work the evening before from the Tesco station which has a very high turnover.
All three scooters running Castrol mineral oil at 3%

[kevspeed]

The thing is,these scooters are virtually 'factory' spec,so why the difficulty?

[scooterslag]

Must be a bad batch of air filters , I know they are two different makes but could they both use the same supplier for the air filter media? (paper) Used to work for a medical supplier making pharmaceutical filters for blood, drugs etc and we'd supply media to other manufacturers or just slap their label on our products. Paul

[B-Race Tuning]

Were they ok before, with the filters? Was this Wednesday that the temps were floating around 30 c?

[rainbowrunner]

are you using the type of filter that has a separate metal blanking plate ? I once put one in at the bellows end instead of the back end if that makes sense lol if you have it won,t get any air until you take the bellows off

[kevspeed]

Were they ok before, with the filters? Was this Wednesday that the temps were floating around 30 c?

Had the problem for a while,its only just started to get to me,im quite a patient sort of person,so i have re checked everything several times just in case i was overlooking something glaringly obvious.
The thing is that as i said,the three scooters are virtually factory spec,so i should have no problem,the filters are new,or virtually new and clean,jetting in the carbs are as factory,and genuine Dellorto,so the only common denominator is the filters themselves.
It seems so odd that the engines cant get enough air all of a sudden.
Somewhere i have an old filter i kept from a mates SX200 when i serviced it last year,ill try that in place of the new ones.

[kevspeed]

are you using the type of filter that has a separate metal blanking plate ? I once put one in at the bellows end instead of the back end if that makes sense lol if you have it won,t get any air until you take the bellows off

Im all ok on that score. A couple of years ago i sorted a fellers GP that had that problem, the air filter had been replaced with the type that has the backplate built in,and was fitted with that end facing the hose,and the original backplate fitted in the open end