Modern Vespa

I was all going so well a few posts back. I know you've tried many combinations but where you were at the AC140 BE5 118 was going in the right direction. This is nice safe jetting, which might only need a tweak later on.
All the rest is the pilot jet. This is not easy, probably the hardest part but all that was left.
21 degrees on a big squish is ok but can be (usually is) problematic at sustained high rpm.

Hey Jack, I can go back to the 140/BE5/118. It felt good also.

What should the timing be with that much squish?

Thanks!

Its not the timing that's the issue, it's the big squish. At the 3mm squish size the conditions for high rpm detonation are perfect. Stay away from sustained high rpm and its all ok or turn down the timing and lose low end power.
Putting the head on a lathe to make it fit inside the cylinder is the best long term solution. Might get discount for doing 2 at once.

Pinasco makes a 190cc, 60mm stroke cylinder kit. The difference though it is 3-port and the cylinder head is centered. I can't seem to find anything with a 2-port and offset.

Scott as it stands right now, and I'm staying on hold until my air filter comes in as well I'm still looking for a source for a VMC, but when I put in the 160/BE3/116 everything seemed to clean right up and there's still lots of room for more twist on the throttle after 60mph , only downside is I'm getting 293F on the trail tech when I sustain a speed of 55mph. I think for now I'm going to try moving the mj upward to see if I can lower the temp and keep that top end and bottom end performance. I honestly think the 3 port compared to 2 port makes a very big difference. Now this is what is working for the DR180 which is the old style long run in cylinder and perhaps that's why it's working different for me, that and the 3 port, also I must have the same carb as you because my mixture is also at 1-3/4 turns.

Are you wanting to race? We can do this long distance, but GPS proof only!

I agree with you. That's why I've been "experimenting" with the various combinations of jets, and listening to the ones that have gone before me like SoCalGuy, Birdnest, MJRally, etc.

Chris has been running with a 160/BE3/118, but short runs, heat cycling mainly, and with a CHT gauge. We're going to compare notes tomorrow and make some decisions as to what to do.

It'd be great to have a machine shop that can mill 1.75mm off the head, like Jack suggested. Easier to remove the head than the piston cause I'm sure SoCalGuy is correct also about having the base of the piston shaved.

Then there is putting a 60mm crank, which isn't going to happen because this baby has plenty of power, and is only 2 port after all. That would require me taking a trip to Southern California and bribing CM2 do do some case welding to cut a third port.

Bottom line is I have limited time, and limited funds. What should've taken a 1/2 day has taken weeks - a little here, a little there, and only a few (3 or 4?) focused efforts of running and changing jets. I'm getting beat into submission to just deal with the low down stutter, BUT, I'm not quite beat yet.

Scott I'm already getting into race mode, I'm going to have to put an app on my iPhone to see just how fast this little build will go because I swear I'm hovering at 60 and twist the throttle and the seat of my pants tells me there's so much more there, but of course it only has the 8" wheels. Thumbs up to GickSpeed he did a great job on both front and rear brake setup.
Did Chris go down as far as 116 and then go bigger to the 118mj?
When you say low speed stutter how exactly would you describe it ? Like leaving first and then into second ? I know you're running a 3 speed so I would imagine it's not 2nd to 3rd?

If your cylinder head has a central spark plug, it's not bad to have it chucked into a lathe and remove some metal. I had a DR with an offset spark plug and used a 4' x 36" belt sander and 1000 grit sandpaper. Then finished it off with a piece of glass and finer wet and dry sandpaper.

The kicker with this head Christopher is it already fits inside the cylinder, which means I'd need to take material off on the outside o the ring that fits inside the cylinder. CM2's new *KITT should be able to do it, when he gets it dialed in, and installs the AI, that is.


*Knight Rider's steed

No - we went from bigger down to 118 - and it's probably too lean for running a 160/BE3 combo If you are cruising along at say, 20 mph and you are trying to keep an even speed on level ground - if your throttle is at 1/4 throttle (or close) it'll gurgle or run rough until you either put load on it (more gas), or slow down (less gas).

We marked the throttle for 0, 1/4, 1/2, 3/4, and WOT with a sharpie to tell when it is actually spluttering, or stuttering.... At least we know definitively where it is happening...

Did you try larger idles? I fought this suggestion from Jack for so long, and I'm finally on board with this as I've tried 50/120, 52/140 and 55/160 and surprisingly it ran much better on the richer idles than what i originally thought was correct. Plus so many of the other guys on here mentioning much richer idles got me wondering why my setup would be any different.

I'm currently at 48/140 with 110/be3/130 main. Need to still test the main stack in 4th gear over miles to see if i still need to come down closer to 120 main or not, but the plug is looking real good so far.

Defiantly sounds like the idle jet either too small or too big. I don't get that symptom at all then again I don't spend much more than a second at that speed.
So would you think if you pulled the air filter and ran without it would go leaner and visa versa to help troubleshoot the low end of the spectrum ?

Quick question:
Is it the sound or performance that bugs you at that 1/4 throttle?

For the heck of it, I put on earbuds and blasted techno music.
Couldn't hear the engine at all. The sound that was bothering me didn't affect performance/acceleration at all.
Riding with a tuned engine that needs to run on the rich side. Plugs look nice and just rich.. enough.
IMO trying to dial that in to sounding like a stock engine is like wrestling pigs. And too dangerous.

The largest we had was 55/160, but we just got some others. That's something that we'll try tomorrow. Thanks for bringing it up! I'm still debating in my mind to dial it in with a 140AC & 116 or 118 MJ, or go with a 160AC and 122 or 124MJ.

Tomorrow will tell Currently running without the filter to just make it easier to dial in. When I think it's there I'll put the filter back on and see what's what. It'll be nice to try different Idle jets than the three we had before. Performance - it stutters and isn't clean right there. I did the same the other day while tuning and turned the tunes way up - It was one of those Lt Dan days when he was tied to the mast for me, so I was doing some, shall we say, questionable tuning practices...

And yes, thanks for the comparison R8 to wrestling pigs. I wouldn't want to get into a ring with WhoDat's dog!

If it's not dialed in by tomorrow's run, I'm picking the best and going with it!

Didn't Jack have a procedure for drilling out idle jets?
Wouldn't this 140AC & 116 or 118 MJ, or go with a 160AC and 122 or 124MJ be very similar to each other. Sorry still learning.

Don't know - not interested in drilling jets when I can buy them... Yes, but more air (and fuel) leaves more potential for things to go boom at WOT. My limited knowledge anyway. Somebody else (anybody else) could explain it better than that. Swiss did a good job number of posts, and CM2s thread did a fine job, but it's lost in the north forty of that thread. That is what JetIJack has been trying to get through to us luggheads, or at least I think it is...

Questionable tuning practices work sometimes. Take notes, regardless.

Does your 1/4 throttle stuttering get better with smaller main jets?

Here's an interesting to me theory, on my SI carburetor. I switched to a P200 and different carburetor before I was able to prove it out. I found that a bigger main jet was needed for a larger cylinder with the same air corrector, no surprise there. I also found, that larger jets caused low end issues on my DR177 setup to include stuttering. The main was having overlap even from 0 - 1/4 throttle, maybe the larger jet and air corrector were letting fuel come through the main circuit due to less resistance? I had also wondered about velocity through the main circuit with larger jets.

I wanted to try and go all the way down to a 120 air corrector on the main circuit and dial it in from there. That would put the main jet back down to a close to factory jet size.

I figured not much cost in jetting if I was way off base and it didn't help. Anyway just something to think about if your having the same issue I was.

Interesting theory indeed! Well, I'm liking the theory, and won't take much to try it first thing this morning! I'll go with 120/BE5/115 and work down from there.

Thanks for sharing the "theory" Christopher. We'll see how it turns out....

Ok got myself mixed up on the 140ac compared to 160ac , definitely the 160ac is bringing in more air but also with the bigger jet I would think would be like a blanket of fuel. So in actuality if you used a 140ac which is less air would you not be able to go with smaller than a 116mj especially with the BE5? I can kind of see how some would like the 160 but I would think the 160 would work better with the BE3.
Sorry if I hurt your head Scott.

My guess at this try ( if I'm allowed one ) is it's going to be extremely rich from first to wot.

Bitchen day yesterday!

Donuts & Coffee - Check!
Perfect weather - Check!
Working on tuning scooters with your buddy - Check!
New member of 60/8 club - Check!
Running out of gas - Check! - Wait, whaaat?
Still rough at 1/4 throttle....bummer.....

Yeah, A great day for riding (50 miles or so), but we still have roughness at 1/4 throttle. We tried lots of variation, but to be fair, it was a bitchen day, and I was all over the map trying different jetting combinations, just to see what results I'd get.

The whole running out of gas and getting towed with a bungee cord thing - I went to reserve about 1/2 way up to the North Fork Bridge. I figured worse come to worse I run out of gas and push it for a mile or two. Yep, that's what happened. Very little pushing though.

I've got some ideas for jetting, but it was just so much fun riding around. We drag raced on an empty stretch of road. We rode side by side through some cool roads and listened to the harmony of the engines. Reminds me of a twin engine plane, how the engines harmonize.

I'm going to quit complaining about jetting and put it back to one of the good settings and live with the 1/4 throttle issue. And move on to upgrading the clutch gear and installing a CHT gauge...

Oh, and as soon as Chris split, the rain started up and hasn't stopped! Perfect timing for a rain free ride....

Always great to get out with a friend.

Probably far fetched but have yous tried swapping carbs with each bike, or did I misunderstand that Chris's bike also has same 1/4 throttle problem?

Haven't tried that.

When he was towing me (Picture this: Me holding onto a 1 meter bungie cord hooked to his rack, trying not to get yanked over into traffic, Chris trying to keep a steady and constant, but slow speed), it was very apparent the 1/4 throttle stutter and not being able to rev through it to clean it up.

Quite the adventure though, to be sure!

Yep I can picture it, the racing probably did in the fuel. Surprised Chris didn't run low as well, good thing he had extra, which just reminded me, couldn't siphon a bit from Chris's bike?

We did just that, but my scoot loaded up and I wasn't sure if it was low on fuel or what, so to be on the safe side, we towed with a Bungie. Ha!

Those roads look fun to ride on and glad you guys are enjoying the fruit of your labor. He's gone plaid! Congrats all around.

OMG those jetting notes..
Putting mine to shame!
In the end I ended up cheating. Looked up a few German setups that were similar enough to mine. Figured most people post successful jetting, or otherwise just leave it blank.
http://lfs.alexander-hepp.de/

Click the top right English flag. Then click on your engine's CC's on the top left drop-down list.

Jerry Can!

Naturally, because nothing says safety like getting towed behind a scooter one handed with a Bungie

Thanks Swiss - 8" wheels are a blast! Thanks for the link R8 - and the kind words about the "meticulous" notes. They're all over the map, but hey, every jet change is listed...Or most of them anyway.

And what in the Wide World of Sports is going on in this world? We passed through Portland recently and I couldn't believe the crazy tent city it's become...

Ada on 8's!

Ada is a little trailer resort which is located at the south-east end of Siltcoos lake and is only accessible by boat, or a winding, one lane road that dead ends at the "resort".

Chris and I have been talking all winter about going to "Ada on 8's". Today it happened.

I did lots of fiddling with jetting along the way, we ate ice cream on the edge of the lake, then burgers at Darlings Marina, on the North-west side of Siltcoos lake.

This area is having a heat wave, so it was in the mid 80s. I know, but usually it's only in the low 70s at best. Totally awesome day and the scooters ran great. The CHT gauges sure helped in watching the temp on the long pulls...

Also, I ran the new LML clutch with a 23 tooth in it. It used to be 22 tooth. I needed a 2mm spacer for the clutch cover (Thanks WhoDat!) and that all ran perfectly, and much nicer having a little more bit of room when I twist the throttle.

A big Thank you to Mattgyver for explaining the gearing scene to me and steering me in the right direction, And ScooterMercato for carrying the clutch gear!

Looks like a fun adventure guys! Thanks for documenting your excursions, experiences, and exciting scooter destinations.

After riding B/62 with the slightly taller gearing I decided to do the same to Rocket 🚀. Im fairly new to this scooter thing, I’ve watched and assisted Scott on our project but haven’t flown solo much. Killed a pot of coffee while watching videos on the task and decided to go for it. All was going well gently sliding the clutch off taking care not drop the woodruff key in the motor when I hear TINK, AAAhhhhhhhhhh! I thought I had the key on top but oh noooo it was lined up perfectly to fall right down the hole, couldn’t have lined it up more perfectly if I tried. After wasting several hours with a scope and magnet I gave up and decided to use the same force that pulled it down the hole to get it out, gravity. So with a step by step email from Scott and a few encouraging texts, out she came. Held the beautiful little lump in my arms like a baby, shake shake shake and TINK. OH what a beautiful sound It was all I could do to get the motor safely on the bench so I could do a happy dance wooohooo🤪

that was a break to be able to shake it out!! good work. You can see the woodruff opening after you pull the washer and nut. sometimes that washer doesn't want to come out and your are tempted to pull out the clutch. do not give in to this temptation. get a magnet and a pick and get that washer out so you can see where the woodruff slot is at before you pull the clutch.

Good save!... Betcha you won't do THAT one again!

Lucky Bear

(Yes, I speak from experience)

I finally got rid of the 1/4 throttle roughness on my P125 (with a Polini 177). I tried all kinds of jet combinations, but what finally did the trick was changing the timing from 19 degrees BTDC to 18. It sounds like the Vespas in the Freakmoped videos now - just not as fast!

Wow, excellent Langolson. And this from just one degree in timing! I'd like to be able to get it within one degree, but timing light and revs change things so I'm shooting for timing at idle.

Thanks for letting us know...

Timing should be set at 4,500 RPM's. Setting it at idle is a recipe for walking home.

Shitshitshitshitshit. How in the Wide World of Sports did I miss that? And my timing light doesn't show RPMs. Hmmm, gotta think about this...I've got an rpm gauge I can hook up temporarily while timing. That'll work...

Thanks for the correction and clarification CM1!