Modern Vespa

Awesome! Glad to see you this picking up again. Still one of my favorite threads. Good luck with the next phase.

Started to dig into it today. The biggest drawback was time. I forgot alot of the little details to make things go faster. I got my son involved to help me out. I remembered that the wheel had to come off to get the exhaust bolt out at least.



After that it was the usual strip down of the covers and carb etc. This is where time came into play. I got the old carb off and replaced it with the vortex before I pulled the cylinder. I was smart enough to remember I needed to jack the bike up and lower the motor to get the cylinder off. Of course this time the motorcycle jack had long been sold on Craigslist and I need a couple 5 gallon buckets.



I then proceeded to pull the shock bolt (my Gucci 9mm bolt from 226). That's when I realized that the airbox hit the frame preventing the engine from swinging down enough to get the cylinder off.



That was about the time when things got sadder. I pulled the carb off and proceeded to yank on the lower airbox. It would wobble back and forth but wouldn't come off. It took the easy route and just called Hotrod Al and asked him "what the heck is holding my airbox on?". Hmm... appears I forgot there is a screw under the carb base gasket... Mine had backed part way out so it made it seem like something was snagging the airbox. I never thought to lift the gasket to look. After that, the airbox came right off and the motor could be dropped enough to pull the cylinder off.



After that, I decided to do a bit of prep work. I took the new piston. New because it's unused. Not really new because I bought it 4 years ago. I bought it from Germany. Shipped it to Al for mods and then back to Florida and eventually to Colorado. Lot of miles on this baby for never being in a motor. I always like to take the pistons and use a file to break all the sharp edges. While I'm at it I always chamfer around the wristpin hole if it intersects the outer surface of the piston. This makes it easier to slide the writpin out after the piston has been used int he motor.



Next is a good time to double check the ring gap. Out of the box, the top ring had a 0.002" gap. I opened up the top and bottom ring gaps to about 0.013"+ with a small flat file.



I realized I didn't have any two-stroke oil to lube the new parts with. So off to the store and the end of today's work.

Assembly continued at a pretty fast pace today. I decided to go with a slightly thicker base gasket this time around. The original one was about 0.08mm and I went with a 0.18mm one I had in my box. All I needed to do was trim it to match the boost port. The port on the HRA cylinder was much bigger than stock.



I went and pickup some oil for assembly etc. I use Honda GN2 in this bike. Its easy to find and works in both pre-mix and injection applications. Of course in the process of opening it, I spilled it on my bike toolbox and the top of my bench...ugh. Not sure how much it matters on a Vespa but we always installed the circlips on the RS125's with the opening facing top or bottom. The thought was that the G forces were less likely to make them pop out. have no idea if there is any truth to that one but this is how I install them. Be sure to remember to install them with the sharp side out.



As before I installed the piston in the cylinder and then slide the pair onto the case studs. This way you only have to stick the wristpin in and not try to hold the cylinder while compressing the rings.



Make sure the circlip is in the groove all the way or things get ugly real fast. I saw a motor once where the circlip came out and the wristpin went into the transfer port...while the motor was running. Destroyed everything. Cases, crank, cylinder.



Also a good time to check that the piston isn't in backwards. Arrow points to the exhaust.

I went ahead and checked the squish. I used 4 pieces of plumbing solder held to the head of the piston with grease. The solder is about 2mm in diameter. I like to use 4 pieces so the piston doesn't rock. In this photo I already rotated the motor over and removed the head to check the solder. You can see how the ends near the cylinder edges is smashed down. In this setup, the squish measured about 1.4mm on all 4 pieces.



After this, I torqued the head down to 15 ft-lbs and assembled the airbox and carb.



Next came time to rest the timing. The motor was running stock timing and I wanted to reset it to 18deg BTDC. I pulled the flywheel off and was thrilled to find I had left marks on the case and stator plate from when I last built the motor.



All I need to do was loosen the three Philips screws and move the plate. Turns out 18deg is basically at the limit of the stock slots. In order to loosen the screws, I highly recommend you get an impact screwdriver. If you ever work on old Japanese bikes you will be faced with tons of Phillips case screws. An impact screw driver lets you remove them quickly with minimal chances of stripping.



Of course I don't always have the right tools. I'm not going to show the picture of my "torquing" the flywheel nut by hitting a wrench with a rubber mallet. I don't have a flywheel holder tool and I didn't feel like breaking out the air impact wrench.

I flipped the bike back on its side and reinstalled the 226 pipe.



After that I loaded up the gas with some extra oil and gave it a few kicks.

This go around I installed an air filter on the airbox. Prior to this I had the bellows between the airbox and the frame. I've heard people say it restricts a bit but honestly, I'd rather have clean air going in the carb.



Here's the filter info if you want to find one. It fits perfectly. It's a UNI filter.



I took the bike for a quick spin around the block. First thing I noticed is how strong it felt. Second thing was how noisy it was. My kids said he heard me 1/2 mile from the house. I think its time to repack the silencer. Hopefully that will help because it sounds like an old dirt bike.

I screwed the adjustable main in a bit on the carb to richen things a bit. It still seemed to pull strong but I gotta remember it still has 2 miles on the motor. I'm really afraid of blowing this thing up after last time.... 4+ years ago.

Then pulled it out again and loctited it I hope? Ask me how I learned this lesson. On second thoughts, don't....

Great.... just what I need. To be honest, I have been debating going to a traditional main jet stack. Something makes me sleep better knowing what the jet size is.

I have been screwing in the main jet screw about an 1/8 turn at a time. I slapped the carb on with no adjustments from when it blew up in Florida. With the altitude here in Colorado it should have been rich. Instead I could here it detonating as I opened the throttle. So far I have closed it about 1/2 a turn. If I remember correctly there is only a turn and a half or so of adjustment at best.

I must have been super lean when I seized it last time.

Last edited by chuckactor on Fri, 03 Jun 2016 02:53:48 +0000; edited 1 time

After my little game of "Grub Screw, Grub Screw, Who's Got the Grub Screw?" and the expensive aftermath (luckily was able to re-use the crank), I JB'd the hole in the bellmouth and run it with a normal jet stack, similar to a Polini venturi I guess.

Are you running a typical 160/BE3/1xx setup?

I can't remember what is in my Vortex as I set it up so long ago. I think it has a BE6 with a 140 main and maybe a stock pilot (55/160). I never got the super rich one to work right.

When it was last on there, I was using the 2nd richest pilot. If I remember correctly I think I had 140 AC, BE3 and about a 150 main. Maybe 155. This is on a 221 Malossi Sport but had pretty much the same on the dearly departed Polini.

Nothing exciting to report. Bike is running pretty good. The carburation needs help. The low end is fair. Mid and top feel real strong. I'm running opposite of my normal. I keep richening the top end every time I go out. I keep expecting it to break up but its still pulling. Nothing to radical yet as I only have 10 or 20 miles on it. I did have it to 65mph and it felt real strong.

I think I'm going to pull all the jets out of the carb and see what's there. I'll probably start by going back to the original 50/100 or 50/120 idle and the monster 160+ main.

Chuck

As you can tell by the black "please don't blow up" plug color, we are keeping it safe.




The bike currently has a 50/120 idle jet in it and a Vortex/BE6/150 main jet stack. The Vortex is currently tuned with about 3/4 of a turn out. I might drop in a 160 main I have. Al's suggestion is to run a jet that allows you to run the screw out between 2-1/2 and 1/2 turn out to gave you some adjustment range.

So far so good, just gotta get some break in miles on it. It's "happy speed" is around 50-55mph. Need to do a few adjustments to get the 40mph cruise speed solid. Think I need to lean the idle adjustment a bit.

Anybody interested in buying a ratrod P200? Lotsa spare parts.

Chuck

Anybody? Comes with a lot of extra parts. All the original stuff and more. Less than 20 miles on a new top end. Maybe 200 miles on the bottom end.

Chuck

Last edited by chuckactor on Fri, 07 Oct 2016 20:40:07 +0000; edited 1 time

For Sale


http://modernvespa.com/forum/post2114117#2114117


Chuck[/url]

That was a fun read