P200 speed query

[chords]

I have a standard p200 engine with a sito plus exhaust and a sip fast fuel tap and after taking it a run my speedo clocked a top speed of 65mph which I was well impressed with but when I came into a town and passed the slow down signal while doing 40 it clocked me at 31mph. Now I know vespa speedos can be way off the mark so I used a GPS speedo app on my phone which was roughly 9 mph slower than the speedo and it gave me a top speed of 56mph on a straight going both ways to take wind and slope into consideration. The last vespa I had was 20 years ago and was a px125 standard and from memory the p200 doesn't seem to be any faster although the pick away is really fast probably due to the sito.
So my question is..... Is 56mph about right for a p200 with sito plus?
If not are there any wee tweets that need done along with the sito..... I'm sure the guy said he upped the jet.
many thanks in advance guys...... Scott

[jid1973]

I have a px125 with a 177 kit, up jetted, reinforced Cosa clutch and my cruising speed is about 55mph.

I would have thought a p200 would have been a lot quicker.

[sbwnik]

A p2 should peak just shy of 65, so something isn't right. Is it a fairly late one? A lot of those were built with the ignition set to the wrong mark.

[chords]

Not sure how old the engine is, I'll phone the guy I got it from and find out, I thought 56mph was a bit off the mark.

[sbwnik]

Also, make sure the heart shaped indentation has been drilled out, and the carb upjetted on to suit. This makes a lot of difference.

[chords]

Heart shaped indentation? Is this on the filter? If it is will it just be a case of drilling and cleaning?
Thanks sbwnik....

[sime66]

The chappy at the bottom, left of centre on this image (you might find the shape, but no holes):

If you play with your filter, check your jetting afterwards; I got myself a soft-seize last year after just cleaning mine.

My PX150 (177) with p2 carb also does mid-fifties (gps speedo) quite comfortably, and my dash speedo also over-records it by about 10mph from 65 to 55 (ish)

[sbwnik]

That's the one. I think it's a 5mm hole and a 2mm one. You may find that your filter is already drilled though, some are.

[bryno]

My P2 with 8mm 'hole in the heart' 2 point upjet & standard pipe performs as Nik says, just about makes 65 on the flat on the clock, but I'd say it's not far off accurate.

Worth checking the timing after you've looked at the main jet and filter, then maybe the rings, could be just a bit tired..

[chords]

Great guys ty.... Away to check the filter and drill if needed. Have you got an idiot guide to the carb and how to check the jets please.
Once again thanks in advance..... Scott

[chords]

The filter has NOT been drilled and the big jet says BE3 on it if that helps and also says 160 near the top. The small jet says 55 160 on it

[bryno]

it's the small jet on the end of the main tube you need to look at. will probably be stamped 116 if its standard.

[chords]

Where is that small jet? Not the 2 jets under the filter?

[sime66]

The larger of the two jets there, splits into three parts:

If you look carefully at the above, you will see the RH piece (between the 2 and 5) has a number on it (I think this one is a 116)
It pulls out if you need to (by hand, not tools that might damage it). for now you just need to read it.

[sbwnik]

The bit that you want is between the 2 and 5 on the keyboard there, the last bit that's stepped down. It should pull/twist off.

[chords]

Ok an update here..... I will take the jets back out and look. I drilled the heart shaped hole and put it back on and headed back to the road I tested my speed on..... The vespa seemed to bug out and get stutters when reaching 40ish in 3rd and the same at50ish in 4th but by the time I got to the road it had cleared......
Results..... Pre hole it was 55mph one way and 57mph back the way due to a slight slope so average was 56mph ..... After drilling the hole it was 58mph oneway and 62mph so average was 60mph. Came home and had a bite to eat and out on it again and same stuttering to start with but cleared again and got same speed.
So all in all I have gained around 5mph from drilling so thanks very much guys..... I hope the stuttering won't be permanent.
Thanks again..... Scott

[chords]

Ok I took out the big jet and it says 118 on it..... The small jet looks different and all it says is 55 160 on it. My gps pre air filter hole after running around for an hour says top speed I got was 56 and I drove on mostly straight roads with no hills...... Same road today and gps says top speed was 63mph so I think I'm getting closer to where I should be.... Is the 118 jet big enough? Do I need to change the small one?
Many thanks again guys....... Scott

[bryno]

Cool, you do need to check the jet is bigger than standard though even if it feels ok, if not, you are certainly running leaner now and potentially risking a seizure..

[chords]

Standard jet size for the stock p200 from research seems to be 116 so it has been upgraded to a 118 which is the size the guy who sold me the bike says compliments the sito, but I'm not sure if drilling the holes mean I should maybe try a 120 jet. I take it it's just the big jet you upgrade? Any advise on size of jet I need?
Thanks...... Scott

[sbwnik]

I'd try a 120, but I never upjetted for a Sito + so you could well be in the right area.

The spluttering sounds like it's running rich though?

[chords]

Ordered a 120 jet and also a 122 just in case.... When will I know I have the correct size jet on? Will it just "feel right"?
Thanks again."...... Scott

[bryno]

You can do a plug chop test if you want to be sure it's right - run under load on near full throttle for a say half a mile (up a bit of a hill is good), then cut the engine coast to a stop & check the plug colour.

[sime66]

I've put a 120 in my carb this morning, to suit the Sip Road 2 that's going on tomorrow. (Best to start big on main and work down).
When I've got the engine in and running, I'll be plug-chopping again, and will post some images of plug for you to compare.
The clever blokes on here will advise, if you do decent plug chops and post images.

Here's a good little web page for a ball-park set up (It ain't gospel - you have to do it for your own scooter to get it right):

secure.vicon.com/jetting/php/index.php

[chords]

Thanks guys..... I will do this after lunch and post results... I take it a brown chocolate colour is good....White needs more fuel and black needs more air.
thanks...... Scott

[bryno]

^ yep, you got it.

[sime66]

As you said, but this is just for main jet adjustment.
On ¾ to full throttle a plug chop will be showing you what your main jet is doing, so colours as you said, but,
Light-side of light brown = Main too small = Up-jet (Before hammering to check your top speed )
Dark-side of light brown = Main too big = Down-Jet (not really 'more air')
All you’re checking is the main jet.

[chords]

Cheers guys.... I will do it tomorrow and update as I've just been out to the vespa trying the new flasher relay . Gonna update my other thread and go to bed for night shift.
Thanks guys....... Scott

[chords]

Done a plug chop test and took the spark plug out..... It was a very light brown colour and the longer I had it out it turned lighter as it dried.... It was like between a beige colour and a light brown colour so I guess I need to up my jets more. I'm on a 118 and will have a 120 and a 122 on Monday, I'm guessing that the 120 will do the trick so shall I try that first or the 122?
Thanks in advance..... Scott

[bryno]

sounds like you are pretty well there, 120 probably fine

[chords]

Hi guys.... Sorry it took me a while to get back to you..... Here are photos of my plug after the chop stop tests. My jets just came today after a week and I have uped my 118 main jet to a 120. I also have a 122 to try but not sure if I need to, the plug still looks a little lean but you guys will know best. I had a 2 mile run then sat for 1/2 mile at 3/4 revs or above and cut the engine..... Left the flug in for a minute then took it out and took these photos after about another minute or so. Hope you can make them out.
Thanks guys..... Scott