Modern Vespa

Been a busy few days. A long way from rotary inlet now. Liking the way it is going and just been getting on with it. Inlet looks so big now, still ever so slightly smaller than the area of the 38mm carb but will be plenty enough. Probably too much.

I gave the cylinder a few more degrees here and there too, while I was at it. Cylinder is now maxed out. Near enough 72% as well.

Ready to put the cases together tomorrow. Seal and new 9 ball bearing in. Not changing anything else. Was all done last year. Might have to go Christmas shopping some time tomorrow but still on for running soon.

Going to run for now on still ok rotary Pinasco race crank. Inlet is so big it shouldn't make much difference.

Jack, as I've been doing my research on reed valve for the smallie, I've seen it said to try to port the intake to "point" the flow toward the middle of the crank. I can't really tell if you've done that here, but was wondering if that really is a thing and how you can do it.

I've been following this guy on FB, and that's exactly what he tried. S&S reed intake are similar... the reed is angled so the point of the V is aimed between the webs rather than directly at one web.
He actually said he was a bit disappointed with the results but you can see here that it made a definite difference in the mid range, picking up 1hp/5% through the important rev range.
This is a VMC 177, using a modified MRP block.

so that looks more like it's on the reed block to do the aiming, not on your porting job, right?

Pointing the inlet to the centre is where there is more space, so gets more in. There is something in this theory. On the 200 there just isn't the metal to do any pointing with. Its all so thin theres nothing left. The Vforce 4 reed block only just about goes in the manifold. Might angle a few degrees but not really worth the work. As this gets nearer to running, I'm starting to feel this may be too fast but there are worse problems to have.

Ginch, cutting that much off the reed block will increase crankcase compression. If the port timing is not near the limit this could be a factor. Interesting though.

Hopefully all the stuff back inside and casings together by tonight.

MRP 38mm manifold. Its a pretty cool piece of machining.

Once the enigne is in and I can sit my bulk on it, I'll see how close it is to the panel. Looks like this snakehead will fit the carb but is much taller than the metal cap. It will save some mm overall and might be worth it.

We're in. Spent all day at it yesterday. Custom fitting everything. Leakdown tester leaks but was holding for long enough. Small leak on the reed block to casing that I re-sealed and now ok. Some threadlock had ran into the sealer. Only other leaks found were in the test gear and the bodge I did to try to block that massive inlet hole.
Anyway, engine is in. Started about 4th kick and ran surprisingly well. Moved all jets from the 30mm VHSH to the 38mm VHSB and it seems to be not far off. Videoed the evidence but my YT channel has been deleted. I'll make a new one and upload later.

It revs like a maniac. Was agressive before but now it feels and sounds just like a motocross bike. Not that much reed noise with the bellows on. Think I might like it.

Test ride is going to be quite exciting. Only a new main bearing and seals, so full thrash, as soon as I have filled the tank.

Video evidence - or it didn't happen - as they say.

that's a mighty big intake

wow that manifold looks a little more compact compared to my old Malossi and it's holding a 38 you're right they may never know what passed them. Is that a standard bellows?

The good news is that it runs. Powerband is going to be great. It's actually dangerous in 1st. Because its a bit rich at the bottom, the power hits hard as the richness clears, then it just goes mental. Impossible to hold the front down in 1st. Have to get as quickly as possible into second gear to have a chance of staying on, then into 3rd, where it will make 9500 rpm a few seconds later without really holding it out. It is quicker than before. No doubt about that.

Her's proof it actually runs.
I'll do a riding video once it stops raining (maybe Sunday) and the jetting is less rough.

The not so good news is it has a leak. Everytime I stop there is a puddle of 2 stroke. Has to be the reed block to manifold. take the carb off and petrol stinking oil mess everywhere.
I pressure tested without the reeds in, so it has to be that. It's all got to come to bits again. 3rd time.

Pulling back out such a pain.
Perhaps would have been easier setting it up on a ramp stand.


Sounds great!
That's a whole lotta carb.

yes it sounds great! lets see it drive. curious what your speeds are.

Still going. Fixed the reed block leak and re-did the pressure test after getting a new bung for the inlet. Now all good. Runs lovely. Really strong and smooth.

It is fighting me though. Few days ago all the lights went out. Didn't take so long to realise the stator was open circuit. Fixed it went out. Revved to 9500 and rev counter goes wild and the lights go out again. Luckily not so many miles from home and only dull not dark. Fixed it again but this time with a piece of solid copper wire.

Still jetting in. Pilot and 1/4 now good and just working on fine tuning the mid. this carb seems to have a bigger target window. Mid is running weak but not so far. 3/4 is really weak and the main jet is now 180 and not spluttering enough. This means the needle is too shallow. I have one more richer taper (K3), so let's hope it works. Should get the main jet down to around 170.

Goes over 8000 rpm in top gear easier than before. Really liking it and the reeds are quieter than expected.

Certainly one of those weekends. Finally made a riding video, so you can have some idea of what I'm wrestling with.

Then about 1/2 hour after this, before getting a better run, I fell off. Just lost the front pulling away on a bad road surface. Scoot all scuffed but I walked away fine. Rode home no issue. 10 years since this scooter has been down the road. I have fallen off others but not this one. Dumb.

This video gets to about 8100 rpm in 4th. And is slightly uphill. Seen it at 8700rpm in top a few times on the flat but so twitchy its hard to look.

Sime66 if you can get any data from this sound recording it might be interesting.

What do we know about steering dampers?

Wow that sounds so crisp what is your speed? Sorry about the bad road surface.

Bummer on the wipeout Jack - I'm glad you walked away undamaged. And that engine sounds awesome.

Steering Dampers? What about balancing the hub and rims/tires first? Just a thought.

Ouch!! Everyone seems to be having set-backs at the moment; I'm going back under the duvet until Easter.....

Seriously, hope it's all repairable without too much aggro; glad it was pulling away and not at speed.

That is a nice clear video from which to grab a .wav to play with; it sounds great too, and I have got some results to chew over.
Do query anything that seems dodgy; I'm rusty with GSF Dyno and always better at numbers first thing in the morning. I do have some numbers for you though.

Using gear ratios:
3rd: 6.32
4th: 4.71

And all previous GSF front end as before (unless you provide any different data), I get a good curve for the long 3rd gear acceleration:

28.68 PS @ 7932rpm
26.11Nm @ 7486rpm
9376 rpm max (120kph/75mph)

For 4th gear, initially I clipped a bit of 3rd curve, which gave you 50PS, but you can see the correct part of the curve, so I had a second bash, and, although a bit more uneven, the result is:

29.15 PS @ 8592rpm
24.47 Nm @ 7434rpm
8592 rpm max (147kph/92mph)**

I thought you'd be higher than 30 PS, but you know the correct way to do a recording is a full rev range from as low as possible to revving out in 3rd; your 3rd gear curve starts at about 5700rpm, and your 4th starts at about 7000rpm, so that might make them inaccurate. There is another 4th gear curve towards the end of the recording, which I might have a look at, but to my old deaf ears it sounds lower than the first.

** I know there's a % adjustment for tyre bulge, but that one seems a bit dodgy doesn't it? What speed do you think you were doing? Seems reasonable 800rpm between 3rd and 4th (9300-8500), but 92mph! You said 8100rpm in 4th above, which is 87mph (before tyre bulge adjustment).

Anyway, you can kick that about, hope the stuff below makes some sense and doesn't raise too many questions that my rusty grasp of GSF can't answer:

Cheers for that. Been a while but you managed GSFDyno just fine.

22/65 primary, so 4.92 putting the speed back into the real world. Newish 350x10 tyres on tubeless rims.

Your rpms from the recording concur with what I was seeing in 3rd. I usually take it to 9300rpm when changing into 4th.

Scooter help put 8700rpm at just over 90mph with the 22/65. I reckon its nearer 86mph with tyre bulge.

Definately 30bhp all day long but according to my prediction software its more like 44bhp. Bear in mind with the camera I am riding bolt upright and over 80mph it does get a bit windy. What also agrees with this is it is running nice and clean with a 185 main jet. Thats big jet.....even for a motorbike!

I think it's petty likely that the actual final power figure is not that accurate using GSF Dyno from a sound recording on the road, but it's still interesting for confirmation and comparison with expectations; I'm sure yours is higher, and I'm happy to have another bash with any new data (I noted the gear ratio change). The revs always seems pretty accurate, I suppose because it's just the frequency of the recording. Also, I searched back, and before we used 50mm off tyre circumference for bulge; my memory was a %ge, but it was 50mm.

With 4.92 I now get 90.4mph, and less the 50mm I get 87.1mph, so we're all pretty close (have to measure the tyre to improve the accuracy).

Coincidentally, I also made some sound recordings yesterday because I want to have a comparison between engines when I swap. Again, it's the comparison between the two (with the same errors for each set of data) that's more important than the final number. I haven't done anything with my recordings yet because they're not clear due to it being very windy, and not fast because it was very wet too, but I may post something in a day or two on my thread, or get better recordings this weekend when the cold forecast might give me better numbers anyway. Doing yours has been a bit of a refresher for me.

You can build a board to record the ignition signal straight off the bike instead of a mic recording. I'm planning on doing this as soon as I get my build running as I've found the mic recording to be useful and close but not consistent.

Sorry to hear about the off Jack! Any further info on how to go about this Swiss? I bought a little recorder but haven't got around to do much with it yet.

They have schematics for either line in or mic in. I have not tried yet but assume a line in board would work connecting to cell phone through a mini Jack to whatever cell headphone connection yours uses. Or or could connect to your mini recorder if it has an input. I have field audio recorders for video I can use if my cell phone doesn't work with that schematic.

http://atom007.heimat.eu/tmt/gsf_dyno.html#Dynamo

Dang, sorry to hear about your scooter getting scuffed up Jack. That sort of thing leaves a pit in my stomach even when it isn't my scooter.

Cheers Swiss, appreciate that.

Thanks for the concern guys. Still rideable and all the scuffed bits needed painting anyway will be back to its usual used and abused looking self before Summer.

They are balanced ok. No vibration. Its happened many times now. The front goes light and starts to tank slap during acceleration.

Any steering damper kits worth considering?

Haven't been on the 221 for a while but will be able to soon. Need to make an order and think it's time for some new shocks.

Any opinions on these?
https://www.sip-scootershop.com/en/products/shock+absorber+kit+sip_76000pbb

As far as I know, there's no steering damper kits that have ever been offered for any vintage Vespa. There was a steering "damper" that was an option that was from India. I think it was from LML?...I can't remember, but it was designed for sidecar use. And it wasn't so much a "damper" (it had no hydraulic fluid) since it relied on friction to slow down the steering. The body of it would bolt to the steering neck (right below the headset), and the other portion would bolt to the lower headset. It was definitely a craptastic design. If you wanted more "damping", you would tighten the two pieces up tighter together with a wrench. The contraption was prone to premature wear since it was friction based, and the two pieces that would rub together would wear out. One could have the same outcome if they simply over tightened the steering bearings! So definitely stay away from that kit!!

Hey Jack, I must have the 1.0 version of that rear shock. The damping on it was great, but the spring rating made it hard as a rock. So much so that it was halfway dangerous! It looks like from SIP's description on the link you provided is the 2.0 version. It sounds like SIP has finally sorted out their stiff spring issues. I haven't tried the 2.0 version personally, but my friend (dealer) who buys LOTS of shocks from SIP said he's likes them a lot (I had this discussion with him last week).

Thanks WDC. Yes, they are the 2.0. That must mean they fixed it. Probably worth a go then. Don't want race shocks, as it's used like a tourer. Shocks on it have done maybe 15000 miles and feel like they're done.

Not sure what to do about the steering damper issue. I didn't find anything suitable. Front tyre is a bit worn. I have a few new ones in stock. Might just be that making it worse.

WDC, the v1.0 SIP Performance rear shock was recalled 2/3 years ago for safety reasons. I had to send them a video of me destroying mine before they would credit my account. Jack, I ended up buying a YSS Mono E shock with the credit, which has been fantastic.

hmmm....i must have missed the recall a few years back. I've had this silly shock for about 4-5 years. I probably only put a few hundred miles on it because it was just too stiff. It sure would have been fun to make a video of destroying my shock!...a bit therapeutic i'd say. I also currently have a YSS front shock for a PK. For my application that shock was a bigger POS i have ever come across! I'm glad it's working for you. Apparently Ginch wasn't impressed with the YSS either.

When I went to leaner - I lost my steering damper.
Didn't think I'd need it - until I started taking it out on the hwy...
Would be nice to have one. Am pondering a solution of my own.
But along the way - found this out of Malaysia - thought it was the slickest of the lot (others call for all sorts of holes and welded what not).
This looks to be bolt on. Kinda like.
(place is called Scooter Clinic - and my guess is - you could buy one for not a lot if you wanted to take a flyer on it to see...)

we need a link to this.....when i say "we" i mean "I"

could be a nice bolton to my lambretta suspension..... can i mention Lambretta here? oh well i already just did

chuckled.
Damper system seller here: https://www.facebook.com/117260908926135/posts/steering-damper-siapada-yg-berminatynwa/139559486696277/

Aliexpress damper here:
https://www.aliexpress.com/item/32948616122.html?spm=a2g0s.9042311.0.0.6a594c4dRomZwP

I found this one the other day which is not too invasive either. No link, it was a youtube video of a young Italian guy showing off with no gloves (sorry just described every Italian Vespa youtube video).

CM the link to Aliexpress gets us there but not the specific one.

Ginch's set up is much neater.
Nothing coming down from bars.
Like!

Here is a better link.
These guys have a ton of these.
There are many others on there too.
Keep an eye out for two lengths - 330MM its the longer one I think - from memory.

https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20200511161246&origin=y&SearchText=yowling+steering+damper

I think I chose mine - cause it was orange...
-CM

Little sleuthing.
Looks like it is made by a company called D.B. something. Cant make it out.
Anyone know who that might be?

I think it would be a tight fit for the rider's knees if there was a passenger on back.