Rough running

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72degrees
Posts: 1549
Joined: 31 Aug 2007 21:24
Location: West Midlands

Re: Rough running

Post by 72degrees »

My road bike is currently 375 with an L5 cam and NLM 2:1. I wanted to try the Pollinis to get the intakes tucked up under the tank (trickier with a 350 in a 250) away from the weather and in theoretically stiller air. The S&Bs have a much greater surface area of filter material. I've gone down on main jets from 132 to 118 and now need to lean off the mid range (260T atomisers and X1 needles). I'm swapping the bottom ends over for this hill climb season so the ? (reground) cam will be in use on the road bike. I'll be waiting to fiddle with the Pollinis, covers and jetting more then as the hillclimb engine has been on PHBH28s with S&Bs running 125 mains.

The hill climber will stay on S&Bs. The Pollinis may not be more restrictive than a standard air box and filters.
'It must be a .....'
Posts: 365
Joined: 12 Sep 2010 12:25

Re: Rough running

Post by 'It must be a .....' »

Hi, earlier in this thread I suggested using the Polini air filters as an alternative to the original filter box; I've used them on a 501 engine with 28mm carbs.
They are performance filters intended mainly for for 2 stroke scooters with the advantage of weather protection.

Steve is right and they flow more air without the cover as confirmed by a local scooter tuning shop (he uses very similar Malossi E5 foam filters but Malossi don't do a 90 degree filter).
Also with performance in mind you need to consider the filter oil you use, some filter specific oils are perhaps too thick and sticky for this type/size of filter; scooter tuning guy uses light engine oil.

PS Malossi also produce transparent float bowls for the 28mm PHBH Dellorto which are great for checking out what's going on in there.
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: Rough running

Post by norbert »

Now that we have already invaded this thread about rough running talking that much about these Polini filters … here we go … for something completely diferent: The Larch (do you remember ?)
So I´m going to give the O-rings a try.
Dulcinea is quite slim and there is not much place for an airbox under my tank (an english one).
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This ist the way I had it till now: the original 42mm tube to the airbox of a 500, cut between the folds, where I mounted some cheap K+N copies. After the very first real hard shower I fixed an alu plate in front of the first filter and from then on had no more extra problems with rain. But I´m sure that these filters are a mess, although I fear that there are more reasons than only that for the way the motor behaves. The carbs are supported from their caps to the original airbox boreholes. It seems to me that the rubber inlet manifolds of the 501 have the shortest lives of all. Don´t know why but they are a fountain of ongoing pain and sorrow. If you don´t use the original filter boxes, you have to catch the carbs anywhere! And this way you can take the filters of. They dont weight much the two versions, the Polinis even lighter and a bit wider..
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After spending some K+N filteroil I wondered wether this was a good idea, treating a foam filter. We`ll see. I have to wait for dry streets, they are already salty.

…it must be a… (Ian?), What main jet do you use with that Polinis for a 501?

Having made 12000 km still it´s not going like it should.
With Rocinante a 501 R motor from a Camel in a 3 1/2 chasis with original 350 airbox with or without filterelemts inside and original 350 doblefold Lafranconis f0r 350 it works very well, using a bit rare setting of the PHBH28: slide 50 (instead of 40), atomizer 268T (instead of 264 BC), but with the same needel X18, main jet 130-140.
I´ve put the same configuration in Dulcinea, who weares a somehow enlightened 501 with L5 that should turn easily in upper ranges, but does not. I´ve also tried the original setting for the 501 with slide 40 and atomizer 264BC. The problem was the same: till 5000 well and then, when Rocinante begins to run, no punch :? :roll:
'It must be a .....'
Posts: 365
Joined: 12 Sep 2010 12:25

Re: Rough running

Post by 'It must be a .....' »

Hi Norbert, when running with the Polini filters I was using these settings:
Pilot 42 (original Coguaru jet 55)
Starter 50
Main 128 (original Coguaru jet 76)
Needle X18 (2nd groove)
Atomiser BC264
Slide 40
Float Valve 250

Now experimenting with smaller main jets (122) using a 500 airbox/filters mainly because it was easier than sorting out a more permanent way of supporting the carbs with the Polinis fitted; at some point I'll be putting the original 500 engine back in the bike.
The PHBH carbs don't like vibration and need to be rubber mounted as the vibration upsets the floats; might be worth looking at given that the 500/501 engines tend to vibrate more around 4500/5500 rpm.

You might find this thread interesting: viewtopic.php?f=7&t=5061&p=26624#p26624

Hope this helps, have fun, Ian
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: Rough running

Post by norbert »

Thaks Ian an intersting thread :P

Did the first testriding today beginning with 140 (to be on the safe side), then 150 (worse), ending up with 130 (the best till now) and then it became dark and lousy cold. My instument to measure the jets only goes in steps of 10. Anyhow also brandnew Dellorto jets often are marked a bit smaller than measured :roll:
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: Rough running

Post by norbert »

Just to keep you informed (remembering the thread talking about oririginal filterhousings).

I´ve done now 21.000 km with the pod filters K+N replica and Polinis together. The rubber manifolds are still in good condition (not sure that I ever reached 20k km with Rocinante with the original filter housings) and no false air intake ever :shock: So the hanging of the carbs are ok. I have taken off the carbs with the Polinis maybe two times and had to change some of the O-rings when mounting again because they are getting wider (now changed to 41/2)

Ian, meanwhile I´ve gone much leaner:
slide 50
needle X18 (first or second notch, it´s written on the float bowl but don´t remember now, I guess right now second)
idle 45
choke 50
main jet 115 (measured not what´s written on the jets)
running well.

Meanwhile I discovered that when I ordered to convert some 350 camshafts to L5 II many years ago they returned L5 but not L5 II. That will be the real reason why Rocinante with a standard Camel 501 R is still a lot faster and rising revs better than the motor of Dulcinea although it was made lighter at many points. And the half faring will do some km/h speed as well.

I think the Polini filters need significant smaler main jets than the K+N. And they dont give Problems with rain :wink:

norbert
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