Modern Vespa

Rotory

Oh lol… you had the info on the first post… and re-reading the thread lol…

Been too long in between posts

Set the timing accurately and jetting will be easier.
If it actually needs a B9 the motor won't last long. B8 is usually plenty.
X2 on clip 2 is a good place to start. First check is the atomiser. With no main jet it's easier to decide which atomiser goes with that needle.

OK, i got some updates this evening!

First off, I installed a TT tach yesterday afternoon.
I first installed ear muffs, then set the initial timing at 24 degrees @ 3k rpm. While the scooter was on the centerstand, i revved up the throttle to check the timing degrees at a given rpm. Here are my results...
24 degrees @ 3k rpm
22 degrees @ 4k rpm
21 degrees @ 5k rpm
20 degrees @ 6k rpm
17 degrees @ 7k rpm
15 degrees @ 8k rpm
14 degrees @ 9k rpm
engine doesn't rev past about 9.4k rpm and if it does, then it bogs back down to around 6-7k rpm.

- switched to MAP 4 on the v6 CDI.
-30 mil Dellorto.
-300 needle seat.
-x2 needle, clip 2nd down from the top.
-AS 266 atomiser
-55 idle
-main jet currently removed
-B8 plug installed
-SIP ROAD XL Viper Box by Nordspeed

Does this all sound like i'm on the right track so far?


Nope, Trailtech doesn't make a red colored tach anymore. Maybe since KTM recently bought Beta that TT will produce a red tach again?

I haven't done any test rides yet. I'm not sure if my timing is correct or not. How do those number sound to you?

Timing is good to go. While on the stand, what is the throttle position when it starts to splutter?

From 3000 to 7000 rpm the engine felt decent, but then the throttle sharply cleaned up starting at right around 7000 rpm and then stayed revving clean until about 9000. Then it kinda blubbered its way to about 9400 rpm.

The important bit is what position the throttle is. If open to WOT it should be so rich it cuts out but somewhere along the way the rpm revs to like 9000rpm but with some splutter. This throttle position.

I'll have to double check later today, but i thought it was around 3/4 throttle (while at 9k rpm) before it started to splutter?

Make sure the throttle grip is marked. Guessing accurate position is impossible. And jetting in takes long enough as it is.

I marked the grip this evening and here are the results with the throttle grip at any given position...
1/4 turn open - 9700 rpm
1/2 turn open - 8800 rpm
3/4 turn open - 6500 rpm
100% open - 2600 rpm

When you ride it how does the first 1/4 feel? What is the float level and weight?

I haven't rode it yet. Just revved it up while on the centerstand. I'll test ride it tomorrow, but as sputtery as it is on centerstand, it might be difficult to actually ride it back up the hill to my house.


I didn't check the float level yet. I do own a float level gauge tool, so I have zero excuse not to measure it tomorrow. But a question before I measure the floats...since the carb is mounted tilted back, wouldn't that affect the measurements? And carb float weight...what's that? Do I actually need to put my float on a scale and weigh it? They're currently the stock floats that came inside the Dellorto carb.

There are quite a lot of floats for the phbh. None are stock. Just depends on what the carb was configured for.
The weight in g is printed on the he float. A black 11g would be ideal. The white ones are less adjustable.
Any float can be jetted in but might take $$$ in jets to get there. Cheaper to get a new float.
The first half throttle should be the same with or without a main jet. Should be able to get this ok on the stand. Will need a few videos listen to though.

I just measured the float height and it's exactly at 24mm.

The float weight is 6.5g. I google searched on Dellorto's website and there doesn't seem to be any other weight of float available.

This particular 30 mil carb came with a Malossi rotary intake kit that I bought some years ago.

I have no idea how to make the first half throttle to be the same with or without a main jet. I also have no idea how to send a video, other than by a text...which probably ain't going to happen internationally.

So it it time for me to start installing some random main jets in the carb and doing some test rides?

That float is the lightest one that fits that carb. Although you've set at the correct height, a lighter float has a lower level. This one is better to start with
https://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/carburettor-parts/phbh-parts/9010-float-assembly-phbl-phbh-black/
It might end up a bit lean mid but we'll soon have some idea.

How many turns out on the mix screw when adjusted correctly?

Videos on YouTube and link here.

You will be surprised at how rideable the scooter will be without the main jet. The point of tuning the carb without the main jet is make you focus on the atomizer and needle. Once you go beyond 1/4 throttle you'll find it flood out thus isolating the calibration point. You will be surprised you can go 55 mph in 4th gear no main jet and just a little more throttle you know what happens then just go back to 1/4 and all is good. My carb tune went as far as a special clip washer to adjust the needle a 1/2 clip distance.

Follow Jacks steps the PHBH is so much easier to tune than a si and a better carb overall. After having purchased many un-needed jets I no longer regret, they have become my tools, my gauges.

I did a couple test rides today. I started out with a 145 main jet and it was way to rich. I then dropped it down to a 138, and then finally down to a 135. The scooter does climb hills much better than it used to. The CHT has dropped down to right around 300 degrees (when cruising at 6000 rpm). At around 7~7500 rpm the temp is around 315 ish. It still feels a little rich though out the whole rpm range. Here are pics of the spark plug. It's possible I might need to drop my main to a 130?







Last edited by whodatschrome on Thu, 29 Sep 2022 00:59:38 +0000; edited 1 time

Just a reminder from earlier

I have done literally a months riding with the phbh. 12km everyday, for nearly 30days to test out the jetting.

I rode to and from work, 80% of which was on a 80km/h speed limit

Whodat - for my money:
- Pluig color will change quickly if its already colored up - like yours - so that's good.
- I like to use a hill and run it up in 3rd. Something that keeps it under load and WOT for a good 30 seconds if you can.
- kill motor - coast - pull plug (after a few min to let it cool) and shoot that pic.

That way - you can REALLY tell what's happening at WOT.
Otherwise - your plug color is a giant mix of things.

Been following along.
One question I have tho.
That plug looks like it has the original washer on it.
Shouldn't have the washer if you are using an under plug sensor - which you probably already knew.
Any chance you are using an in head temp gauge?

No i haven't done an official plug chop yet. I just did a varying higher paced ride-a-long. It was about 3 miles of cruising at 55-60mph (so that i could see and compare the current CHT reading to my original temps and jetting), then a full 1 mile at a quicker pace...probably 70-75mph on the highway. Then it was another 3 mile medium romp while climbing the hills to get back home. But yeah, i still need to do a plug chop.

Good eye on the plug washer. I actually have my temp sensor located under the inner lower cylinder head bolt. Definitely not as accurate at a sensor that screws directly into the head, but at least i got something.

...and 80% of my riding is closer to 100km/h. Sometimes my commute is 24km and other days it's 40km. I do remember your (130mj) jetting post from earlier. I figure if i'm riding at a faster speed for longer distances, that i would want my jetting a tad bit richer?

ok - so that was what I was fishing for.
so the whole 300° thing is based on under plug.
what's the difference one might ask?
well... a lot actually.

The numbers are all relative to where you take the temp from.
I have mine in the head.
For fun - I put a sensor ring under the plug too.
Then I just plugged the sensor from the spark plug to the head sender.
My 300° at the plug is 350° at the head.

You may be running cool right now - and just not know it.
Keep on the track to getting it properly jetted in.
And if you have an under plug sender you can use - put that on so that you can swap back and forth at some point to learn the difference on your particular set up - between head bolt and plug.

My guess: It's gonna be significant

Thank you for that insight. I didn't realize that 300 degrees was based off of the temp under the plug. I think i might have a ring style sensor in my T5? I haven't rode that scooter for 10-12 years so i wouldn't feel bad about robbing it.

NP.
Kinda fun to have them both on there, just to swap back and forth in real time between the two.
Once you have this thing jetted in nicely - its gonna sing.
Going back to the peanut gallery now.

You kinda answered your own question when you said you might need to go to 130

The thing is, the x2 needle is doing most of your work when you're riding, even at 100km/h youre at 3/4 most of the time.

And that is plenty rich for the Malossi.

You should try a 128 for fun, you should find it rides better.

To summarize, 300F under the plug is the target for sustained WOT. Measured elsewhere the plug temperature can be estimated(often+50F). For the purposes of jetting its better to suffer with the ring under the plug.

Use the main jet to adjust the sustained WOT temperature. The needle etc. is for adjusting everything else.

I didn't have time this morning to swap a temp sensor ring under my spark plug this morning, so I don't have any updates there. I did decide to ride the scooter to the gym though. It's about a 12 mile ride, with about half of it on the highway. I keep my rpm at about 5500-6000 and the temp was around 320 degrees. I stopped off at my friend's exhaust shop afterwards, and then a 17 mile ride home on the highway. I kept my rpm at 6000 and the temp climbed to 330 ish degrees. I then brought my rpm up to 7000 for about a half mile, and the temp stayed the same at 330 degrees. The stock speedo is so darn inaccurate that I have absolutely no idea what my speeds are. All I can go by is my rpm (and I have stock P200 gearing, T5 fourth, 24 tooth clutch).

I just did a plug chop. I found a hilly area, but not too steep so that I could still reach max rpm. I pinned it in 3rd gear for about 40 seconds. The rpm maxed out at about 7800 (even during a slight downhill). At the end of the run I immediately killed the ignition.

One side of the plug is a little bit lighter than the other side. Here are the results on my B8ES plug with a 135 MJ...











Last edited by whodatschrome on Thu, 29 Sep 2022 01:01:10 +0000; edited 1 time

Hot. Up the main jet 5

I went back and editied a couple of my postings, but it turned out i had a 135 main jet when i did the ride yesterday and the plug chop today. I just installed a 140 MJ, but since it's raining out right now i might wait until tomorrow or the next day to do another plug chop.

I did another WOT two mile ride on the highway and a 3rd gear plug chop today with a richer jetting (it's now at a 140 mj). I haven't made the time to swap a temp sensor under my plug yet though.

For the WOT ride, the traffic on the highway was fairly lite. I had a two mile stretch where I pinned the throttle in 4th gear. The scooter wouldn't rev higher than 7150rpm with a 140mj, so it definitely doesn't rev as high as it did with a 135mj. The CHT maxed out at 320 degrees today, whereas yesterday with a leaner jet it maxed out at 330 degrees...but then again the ambient temperature outside what about 15 degrees warmer out yesterday.

I took the exact same route for my 3rd gear WOT plug chop. The plug might look a little darker?...but at the same time, it was cloudy this late afternoon so the picture of the spark plug might look darker than it did yesterday (when I took a picture of the plug when the sun was out).

So final results of today's test ride with the richer jet are...
-less power to climb hills,
-doesn't rev as high under load,
-CHT is maybe(?) 10 degrees cooler at WOT

Plug still looks hot. Go up to 150 MJ. When the main jet is too rich it splutters. And you're not saying it's spluttering. Plug looks hot. CHT on the stud is 320F at the plug that would be 370F. The wear rate is high at this temperature.
Focus on WOT, the not pulling is to do with the needle.

So on that plug chop yesterday late afternoon i used a 140 MJ. Earlier this week i took a short test ride with a 145 MJ and it was pretty spluttery and the scooter had troubles accelerating and reving out. Wouldn't installing a 150 MJ make it even worse?

Ok if 145 is spluterring when at WOT, 150 will probably be worse but best to try it and make sure it's even worse.

Why is the plug getting so hot? Something is wrong. Compression, timing or the exhaust blocked/ restricted are the usual suspects.

There are 2 floats for PHBH... WHITE is lighter, for gravity feed... BLACK is heavier, for pumps.

It's in here somewhere:
http://www.iwt.com.au/private/Dellorto%20manual.pdf

I could reinstall my Sito+, i'm betting by doing that the temps would go down. I did some google reading and it was brought up that the Viper box makes the CHT higher than most all other boxes... https://scooterlab.uk/vespa-big-box-exhaust-shootout-feature-2/ Scroll down to the bottom of the article. There's a green colored background screen with "Outlet pipe diameter". It's only a short paragraph long. Most people here on MV don't like the Sito+, but i have never had any complaints about them for the past 20+ years.

I just did another test ride. This time with a 150 main jet. The scooter definitely was slower and had less power...especially up hills. The engine would max out in the highway at about 6800 RPM. It would reach 6800 rpm at about 2/3 throttle, and then just sputter after that. I also installed a temp sensor under the spark plug (and no, I didn't remove the plug's crush washer). My CHT was a little bit lower at 6800 RPM WOT, which was 320 degrees. The temps were about the same (or maybe just a pinch higher) at around a cruising RPM of 5500~6000.

And here are pics of the spark plug. Honestly it looks a little lighter with a 150 MJ than a 145. It could also be camera angles and makeup that is causing my plug to look light?

Whodat.
Can sense a bit of the frustration.
Like your turning the nobs - but the damn volume is going up and down randomly.

The plug in your prior posts (140MJ I think) has a touch of gray.
That's awesome if you are the Grateful Dead - but not so good if you are a 2 stroke.

Something's amiss.
You go richer and it complains.
You go leaner and it looks like its starving.

Don't know much about the exhaust - but I'm guessing this is air sneaking in or whacky timing.
Think - not sure you leak tested?
If yes - maybe that extra washer on the spark plug is not doing you any favors.
But since you have been wrestling since before you put that temp ring on - Im wondering if air is sneaking in somewhere else?

Just behaving to knife edged (one jet too lean, one too rich).
Whats the status of this blimp?
Are we air tight?

Yes, i have to admit there's a bit of frustration, but not too much since i have other scooters that i can ride. Ideally i'd like to get this engine sorted out before the rainy season begins (i'm located in NW oregon). As to having a cylinder kit, i could really care less. If i knew that the jetting would take more than 3 days to dial in, then i would have just installed a stock cast iron top end instead...which i might still do. By doing that i can install the stock mixer box, find a 24/24 carb, and hook back up the autolube. I'd have the jetting dialed in a matter of seconds.

-No, I haven't done a leak test on the engine.
-Yes, the plug is grey. In fact there really isn't any brown color to it at all. It's either been black or grey.

I have heard that the HHP ignition boxes have had some issues in the past. Maybe mine is also?

I also don't think it's the extra height from the sensor ring that's tripping me up.

There would be absolutely zero love lost if i went to a stock 200. I really love having the simplicity and convenience of auto-lube.

People don't like the Sito because it sounds terrible not because it doesn't perform. People being people some will like the terrible sound.
If the outlet stinger size can't handle the capacity then the piston gets really hot really fast at WOT.