pm pipe + malossi 166 + pollini venturi intake.

[pecker]

Hello everyone just thought you may want to know whats been happening with my situation,
First up i wanted to check speeds i was doing so purchased a small GPS speedo and attached just above speedo in little crevice via velcro.
Well i was surprised that my speedo was miles out, 50mph on speedo was 60mph on GPS - 40mph was 50mph on GPS and 30mph was 35mph on GPS, so thats that.

After quite some time fiddling and loads of plug chops struggling with a very high MJ and a very light plug i thought i would give PM a ring for any info they could give, they had never heard of such a big MJ and said there must be a leak.

So i had carb/ tray/ gaskets off, done the old mirror trick, there was a slight split in gasket under carb( so possibly a cause). every thing all cleaned up new gaskets and all put back together, and checked head,(re torqued).

After reading so much differing opinions decided to go back to autolube, initial testing showed an amazing difference with my MJ coming down to the mid 120's and getting a nice coloured plug.
At runs around 55mph to 60mph GPS.

THEN the problem came back cutting out/ possibly seizing/ fuel starvation. Adding 1% oil to tank also had no benefit.
Spoke to people who i bought kit from, they thought could be fuel, so i checked flow rate, and it was what it should be that they recommended, so that was that.

At this point i realised that to possibly get a positive outcome i would need the cutting/porting work as detailed in instruction booklet ( matching the cases/ opening up the inlet and cutting the crank).
So started to ring around and on the off chance posted a question on south west scooters facebook page.
I had a response from a chap from a local club who said that he was able to carry out the work.

So i picked up scoot from the nice man at the weekend, with previous mentioned work completed and also fitted with 24/24 carb and sip speedo and sip tap, starting with a 52/140 idle / 160AC and 125MJ to start with and pre mixing 3%.
obviously going to take things slowly but initial test runs look/feel positive, feels as if its breathing lot lighter.

Have been upto about 60mph (half throttle ish) GPS and SIP speedo short runs and getting to around 240f's i think i read around the site that PXG recommended 250f to 300f is a reasonble safe working platform, so hopefully im in the right ball park to start from.

I would appreciate, if any of you could put up a few temperature figures for reference from your experiences, and possibly expected RPM'S at certain speeds maybe 55mph - 60mph - 65mph .
I hopefully will post further positive updates in near future.
As always
All the best
pek

[pecker]

And forgot to mention also upgraded clutch centre gear to a 21 toother,
pek.

[pecker]

An update for those interested, all is going well having been able to get out and do some good runs at all sort of speeds, just last weekend changed IJ to a 55/160 as i was getting dark(blackish) plug with the 52/140 @runs of four to five miles going 60ish mph (half throttleish) 7000rpmsish on dual carriageway.

After a couple of nice short/medium runs earlier this week today i was able to have a good one including a nineish mile blast at about 65mph 7500rpm ish temps upto 255f ish,holding throttle at about three quarterish, plug chopped and still have a dark(blackish) plug.

So if im reading it right,this gives me scope to possibly reduce jetting down slowly bit by bit to get better economy/performance.

What would you guys expect regards to IJ size, a leaner jet with the bigger number being a 140 or 160?
Well thats it for now,
Cheers
pek
p.s. anybody else on the castrol power 1 (tesco £2.50 a pop) jobbies.

[pxguru]

In my opinion (and there are a lot of opinions here) a 55/160 IJ is richer than a 52/140. I would have gone down to a 50/160.

What size main jet, atomiser and air corrector is in there now?

With your main jet within a few sizes of correct (sounds like yours is), to check the pilot jet size, ride along for several miles at no more than 1/4 throttle and check the plug colour. Try to get a digestive colour here before changing the main jet.

[pecker]

I refer to three idle jet charts and it is hard to be 100% confident in which jet is leaner/richer.

Just managed to add 50/160 ij to a order i placed yesterday for a few bits(including a 48/140).

Is there not a ij between 55/160 and 50/160 (been looking but cant see anything so far)

Currently have a B3 mixer 160 AC and 125 MJ, I will definitely do the low speed test NEXT, i have a nice back road to next village of about 3-4 miles that is reasonable quite that is perfect.
Very interesting regarding temp gauge how it reacts to big headwinds and upward gradients, also how it jumps up when engine is cut doing chops.
cheers
pek

[mijapxman]

If your still looking for rev = speed, have a look on scooterhelp.com, in the tuning then gearbox part, it's very accurate, I know as I helped him fix a mistake in one of his calcs a good few years ago, lol.
I'm finding your thread interesting as I've never used a venturi intake.
All the best.

[pecker]

Thankyou mijapxman, for that info i will take a look, happy to hear you are interested.
cheers
pek

50/160 IJ just turned up, so time to test.

[pecker]

Not sure what i learnt today,
(1) Changed 55/160ij to a 50/160ij, started up didnt pay any attention to tick over and went on a 2 1/2 miles trot at 28mph 120f, plug chopped and had the same dark (blackish) plug and dampish.
(2) Then decided to tweek mixture screw in/clockwise/leaner a 1/4 turn to try to get better plug colour.
(3) Struggled to start, when sort of going it was VERY smoky and would not rev out.
(4) Flipped it the other way, anti-clockwise and got the same results and didnt fancy going further with the 50/160 at the time.
(5 Then tried a 48/140, again still a bugger to start and was much more smokier than usual and for quite a long time would not rev out, eventually did but was no where near able to tick over by tweekinig tick over screw.(with mixure screw in original position)
(6) Popped 55/160 back in, started no problem and ticked over, then rode home.

Before today the carb has not been touched regarding mixture screw, also i am currently using electric start.
Cheers
pek

[jimscoot]

Mar 4, 2017 20:55:21 GMT pecker said:

Not sure what i learnt today,
(1) Changed 55/160ij to a 50/160ij, started up didnt pay any attention to tick over and went on a 2 1/2 miles trot at 28mph 120f, plug chopped and had the same dark (blackish) plug and dampish.
(2) Then decided to tweek mixture screw in/clockwise/leaner a 1/4 turn to try to get better plug colour.
(3) Struggled to start, when sort of going it was VERY smoky and would not rev out.
(4) Flipped it the other way, anti-clockwise and got the same results and didnt fancy going further with the 50/160 at the time.
(5 Then tried a 48/140, again still a bugger to start and was much more smokier than usual and for quite a long time would not rev out, eventually did but was no where near able to tick over by tweekinig tick over screw.(with mixure screw in original position)
(6) Popped 55/160 back in, started no problem and ticked over, then rode home.

Before today the carb has not been touched regarding mixture screw, also i am currently using electric start.
Cheers
pek

[jimscoot]

Hi Pek. ive been running a Polini setup for a couple of years and just recently changed to the mark III version of the Malossi166.

I must say its a fantastic upgrade and im easily matching tuned Malossi 210/221`s.

if you can see in my signature its certainly taken some work to get it to run that way.
The readspeed CDI retards your standard static timing of around 18/19 degrees to around 15/16 respectively.
This is a late model 2011 onwards with the new variable ignition Cdi so may not work with the old blue CDI/stator setups.
you probably want to retard your static timing to around the 16 degree mark, this will certainly help with reducing heat.

After getting your timing right you can start to focus on your jetting. Ideally you will want to settle on the 160/be3 and around a 125/128 main jet with a 50/160 idle (you were spot on there)  The Polini venturi is fantastic keep using it. Try to get your idle mix screw around the 1.5 turns out (this is its ideal setting any more than 1/2 a turn past this point and then you will either need to richen or lean out the pilot jet) you may want to drill your carb float hole out to 1.8mm to help with flow but don't drill any larger or you will have flooding issues.
Make sure your using a high volume airbox lid otherwise the Polini Venturi cant breath, Pinasco make a good one
This should get you in the ballpark, good luck
Jim
A little video of how she goes[

[pxguru]

Didn't go quite as I expected with the pilot jets. As jimscoot confirms 50/160 should be about right for yours and 55/160 should make it run blacker. Main jet, atomiser and AC are all ok for now. You should have your carb drilled from the standard 1.6 out to 1.8mm (but that won't help this issue).

What also makes them difficult to start when lean/without choke, run black and smoke is a blown main seal. How is the gearbox oil looking? As Sime just confirmed with his; if after a decent run out, the gearbox oil is really still ok (quantity/viscosity/smell) then the main seal is likely to be fine.

Timing is another tweek and without a fancy box on the CDI the IT mark at 18 degrees is a good place to start. As a general rule the earlier it sparks the more power it will have, that is until it all melts and needs a full rebuild. With all tip top mechanicals, a centred head that fits your piston properly and a well set up carb, it is possible to run up to 21 degrees with little problem. It does take a while to get really set up well and timing the same (but opposite) as jetting begin safe at a low setting and work your way up one degree at a time.

[pecker]

Cheers for the responses pxg and j'scoot plenty to think about,
I saw your video j'scoot on MV when you put it up and very much liked what i saw, are you now settled on your IJ at 50/120 as in your signature, because looking at one of my charts your 50/120 compared to the 50/160 IJ what you and pxg expect is nine positions difference ??
I have seen the air box you talk of and is defiantly in my thought process.
Also i will try and get the mixture screw to a 1 1/2 setting with the 50/16 IJ.
Just checked gearbox oil px guru, and all looks/smells good.
Thankyou regarding the carb drilling advice, which i will get done.

When adjusting mixture screw i use a bent spanner(round end) held with a little pair of mole grips, little dab of tippex on screw to be able to count turns, this is a little tricky and takes time, do you guys do it any differently
cheers
pek

[phattanglo]

Starter motor removal gives you lots of access😀

[pecker]

Phattanglo it is a pain with the leccy start,
I have had brief words regarding lightened flywheel (pinasco) I think, which if used as a upgrade has to do away with electric start, so I may end going down that road.
But am i right in thinking what you gain you lose it elsewhere ?

Managed to check mixture screw for original setting and was slightly over 1 1/4 turns out.
Think I better re- thougherly check GB oil.
Cheers
pek

[pxguru]

Why do you think a lightened flywheel will make yours go better?

It does sound to me yours has something wrong. It should never be difficult to start with what you have done. No jets you have are big enough to make a black oily plug on the 1/4 throttle plug chop run. This is due to something else a little more ominous....unless you just need a new spark plug. Really hard to tell from here.
As soon as the throttle is opened past a few mm the mixture screw has no effect. Anything happening after that is jetting.

[pecker]

Hi px guru, thanks for the responses, the flywheel issue I thought may help in a acceleration and pick up after low revs situation,
The plug was new after the build so has only done work that I have described recently.
Like you said something not quite right,
Just of the top of my head im using a 9 plug like jimscoot, and is a cold running plug they say, possibly it didn't like the slow run then became flooded/bunged up or something???
As always, all the best
Pek

[phattanglo]

9 is pretty cool but if your setup runs naturally hot then it might cancel the cool plug out. It's difficult to quantify but if malossi specify a plug and ignition timing, then I guess you have to work around that re your jetting.

[pecker]

Yes phattanglo, in the booklet they recommend the 9 and timing @18 degrees along with the engine work I've mentioned.
I'm scratching my head a little regarding jimscoot IJ seems really rich to me, is the big number at 120 a clue somehow.
I did try a 52/120 way back before I had engine work taken out,but at that time gave me knock.

Another thing I have been thinking about is I believe that j'scoot is in Australia if not mistaken,and so potentially 20 degrees in temperature difference.
Maybe not revelent, but thought I might throw it into the mix.
Cheers
Pek

[jimscoot]

Pek try a resistor plug like a br9es instead of a b9es. Also make sure the two screws that hold the carb float bowl top are tight,
And you need to remove the standard carb box lid and use a higher volume type.

Report back

[pxguru]

Nice try Pek but the air temperature difference won't change a black oily plug into normal running colour. There is something wrong that is making it run black. A 50/160 should run well in yours, maybe 52/160 or 48/160 but either way pretty close. The smaller sized pilot jet air holes have their uses but will just make this really complicated.

As jimscoot says, could be a slight fuel leak. This would make it hard to start for sure. I doubt it is the main seal or you would be complaining much more about how it runs. There is something clouding the issue.

Timing at 18 degrees is where it should be for now. Once it is all set up and running great, upping the timing timing a degree or three and being sure there is no issue will make it a bit faster, especially in mid range.

If you have the same venturi intake as Sime66 you might want to see what he did to his in this thread
vespa.proboards.com/thread/5222/brief-build-update?page=18
Modified so there is no need to keep taking it off and less restriction to air flow into the jets.

[sime66]

I've been watching with interest, but not much to add as we already have pxguru and jimscoot on the case, but as I got a mention.......

I don't know if either of you two with the Polini venturi have considered whether the Polini filter is open enough; I've gone to a RamAir filter, which is same diameter as carb box inlet. I also noted you mention about a larger carb box top; that had occurred to me too.

Anyway; I'll leave it in the expert hands you already have - hope you get it sorted.

[pecker]

Again thanks boys for the responses,
I have been using the BR9ES plug since the work was carried out,I had the sip Speedo fitted in tandem and the BR9ES is what sip recommended in the fitting booklet.

I did carry out simes little trick with the Ventura but only giving access to MJ'S, so I will trim a little more to give access to IJ'S

I will check the status of the screws that Jim mentioned for leak.

Whilst looking around I have been aware of the bigger carb lid, seeing it @ sip and beedspeed for around £50 and other places upto £60ish (pinasco) does anybody know of any alternatives or similar mods to compare ??

Sime I think made a great point regarding the foam filter, which I think we could look further into.

If I'm reading between the lines correctly we are now trying to get it breathing weaker, by trying to get more air into the equation.
I presume filters are a restriction, would it be worth a try with out the foam just to see (sensibly).
Cheers
Pek

[pxguru]

With the idle jet covered by the Polini venturi, the slow running could be affected. This might be all it is. The size of the carb box lid and the smaller size of the Polini air filer would only cause restrictions at higher rpm and more open throttle. For the 1/4 throttle problem you have here it's not such a big deal but something you should think about anyway because once the pilot jet is sorted it's onto the WOT runs to set up the main jet.

Once we find out what this problem is the 1/4 throttle plug chop will be lighter coloured with a 50/160 pilot jet.

[pecker]

Pxguru, before I go of to investigate are you happy with the 1/4 throttle-slow run chop @30ish mph for around 2 1/2 Miles in third, is there also a rpm figure to look for ??
Not a great deal expected to be completed this weekend as its a big beers day at football on Saturday, but will do my best on Sunday.
Cheers
Pek
UTC

[pxguru]

Its not really about rpm, more about where the throttle is. Just be sure it stays under 1/4 throttle and it will be running mostly on the pilot jet. If you do it twice in both in 3rd and 4th you will have a clearer idea of how it runs and if its safe.

[pecker]

PHEW !!!!! After struggling for a few weeks with revs dropping off at low speed and massive deep bogging at a stop,and getting black oily plug and smoking like a pig (and breaking down in the middle of Exeter).. managed to cure it on Saturday after a lot of headscratching,

The cause of the problem i think was something jammed or caught in the thread in which you screw the idle jet into carb, and therefore not allowing it to sit down correctly.

It's so frustrating something so small can throw a spanner in the works..

I'm just so happy to be up and running more normal again and be in the game,
Just fitted the pinasco lid that Jim runs and recommended,
Gee whiz really helps with acceleration (front end lovely and light hee hee hee!!!!)
Have the 50/160 IJ in at the moment and initial temperatures​ look good, but haven't done chops yet since cured but will do to get everything correct, along with the 1.8mm drilling of carb, also i have invested in a Ramair filter to connect.
Also i noticed that it revved out better at speeds getting easily to 8000rpms.

I will report back now after hopefully able to carry out tests @ under 1/4 throttle and @ WOTish speeds.
And also buzzing to get to teignmouth next weekend.
As always all the best everyone
Cheers
PEK.

[mijapxman]

Pecker, I'm glad your up and running more normal again.😀. I'm still following your thread with interest.

All the best.

Jim

[pxguru]

Well that sorts out that mystery. I have done the same before but by forgetting to tighten up. While turning round to park up I was thinking it should be leaner now......maybe the choke is stuck on......maybe the jet is no good, then maybe I'm a numpty

At least it works now. Get the front wheel back on the ground and do the plug chops as soon as you can. Slightly too lean and at 1/4 or WOT and it will bite you hard

[pecker]

www.flickr.com/photos/149356875@N06/shares/5ttcQV

[pecker]