Modern Vespa

Honda in one piece and test ridden. Noisy and dangerous again. Awesome.

221 engine out and split.
Here is the crank wobble. Splitting the engine and taking out the crank I can do one handed in the dark. Turning the engine and holding phone steading is way more difficult. Can just make out the wobble. Its bad but casings still live on. Just need a straight crank. hmmmm.

https://www.youtube.com/watch?v=Xul7WtCfi8g for those of us on Chrome.

I picked up a cheap phone tripod a while back for exactly this reason. It set me back maybe $10 on Amazon and makes things soooo much easier when you're trying to capture a video.

I'm impressed with any motor that trashes a well-made crank. I'll look forward to seeing you get it back in action.

How do you bend the end of a crank like that? Out of balance flywheel? Or is that just what we're seeing on the outside, and more hijinks are going on inside?

It's quite powerful now. Well North of 40 bhp for sure. Same set up as Marco's 49 bhp one but with a bigger carb. Does 90mph sitting up, so about right. Going to down tune slightly, something I don't do often.

Big end is ok, not virgin tight anymore but a few rides left in it yet. Jap nine ball ok too. Clutch Oil seal worn flat. 11000rpm is maybe too much for a blue one, is all I had on the shelf when I last split it. Flywheel bearing is damaged.
Webs are twisted, I think it will straighten but might need a new pin.

Waiting for parts. A few jobs to do while I'm waiting. Done a few today.
Changed the piston ring. Gap was 0.75mm, new one off the shelf was 0.23mm. Not terribly worn but when there's only one it matters.

Grabby clutch. The notched plate was really bent. It's supposed to be bent but not that much. I think that was not helping. I had a spare notched plate and it was much straighter. Old one in the trash. Even spinning it by hand it was smoother, think it will be fine now. Clutch all good, sip CR80 plates and heavy springs. Ready for reassembly at some point.

Going to weld the pin? What crank is in it again?

Just catching up.
Crank vid a bit painful...
You gotta be getting quick at stripping it down and building back up.
What do you think caused it?

Crank is a very pretty Pinasco one. Is a rotary crank, fully polished, flowed, bladed con rod and still in reasonable condition, apart from being bent. I have it in a local workshop now. I almost hope they can't fix it. Then I'll get a bell crank. Called the workshop and the comment was it's bad but they still thought it could be straightened.

I think just heat and power bent it. Revs violently like a dirt bike.Will be fully welded next time. With some down tune the rotary crank won't matter. Thinking I'll leave it at 40bhp and running on the hornet245 for now.

Jack, have you strengthened your cases in any way, particularly around the input shaft?

Main bearing has some work but input shaft is au naturel. Been ok for a long time but really needs the internal plate welded in. If the casings break I can get some VRone casings, there's no downside.

Not updated this for a while. Been back on the Bullet220 for about a month. Going great but noticed the 221 was not pulling mid range as well as it used to. Took the head off and found the piston had melted a quite a bit on the edge by the exhaust. Just about down to the ring. Probably putting it at something like 207 degrees. Way over anything that would have much mid range. Most likely due to running a bit lean at the top, in the CM style. Piston was old and wobbly anyway. New one appears to be 0.2mm bigger. And both marked as exactly the same size. Running much quieter, so probably was loose.

Like how its running now. Looking forward to it not raining over the weekend. Twice round the block and it will be run in. Jetting upped slightly.

Wow. You have a picture?

1. Ginch - you are trouble.
2. CM is to high end lean like Vader is to clean. 🙂

The idle before the storm.
Pretty bad ass.

I had the exact same happen on my malossi 166 piston. Raises an eyebrow when your suddenly revving to the moon and back
For me it was too much timing advance when my LML ignition was doing weird things and auto advancing. Happened so quickly for me the temps hadn't even caught up on the gauge and were well below seize territory.

Question: what's best practice/ can you do you with your cylinder before new rings and piston when you are using nikasil - or do you just let the new rings do that job?

Asking for a friend

This engine already revs to the moon. Will do 10,000 rpm in 3rd, so harder to tell when there's an issue. Mine didn't seize just lost torque. Guessing yours did seize. I did mine when I was trying that Hornet245 exhaust. Really sucked the life out of the engine (Even with a 1.4mm needle and 195 main jet). Exactly as Marco said it would btw. Something to confess? Best thing with Nicasil is to do nothing. Most cleaning or honing makes it weaker and generally shortens its life. I just put this new piston in and rode it like the old one after 20 miles or so. My phone takes bad close ups but you get the idea.

Cool - thanks. Always curious. Remarkably not really. Still running strong. But give me time.

10000 wow I see your point.
I was running much lower timings at the time so it really made me spin out a lot further with a loss of torque like you say. I never seized mine, happened too fast I think for that.
Whilst it's usually quick to wip of the head and check. I use one of those endoscopes cheap from ebay when I want a quick inspection. Works well. I spotted my melted piston with it last time.

wow sounds wicked darn old piston better luck with the new one sounds delicious.

New piston has settled in so well, it's just burnt out its first clutch. 1000 miles since new? Been pulling really hard and going scarily fast again.
Not sitting around eating mince pies. Changed clutch, balanced tyre and repainted exhaust? Had spare plates and springs. Put in 5 XXL and 5 XXXL springs. CR80 plates and new steels. Let's hope this one lasts a while longer.
Not raining tomorrow 😌

Well - given the entire place is locked down - and traffic must be at an all time low - this seams like a pretty Merry Xmas gift.
Sounds like it must be roaring.
Weird how that can make the world just alright.
Cheers.

Plenty of traffic here. Lockdown, Teir4 or not. Dodging it is half the fun.

For those in doubt whether a Cosa superstrong basket is worth the investment. Here is mine after 6 years, maybe 10,000 miles and with various tunes between 30 to 50bhp. Ridden like I stole it most of the time too.

As everyone else was doing it, I decided to blow up the 221 today. Did a bit more tuning 199 degrees exhaust 72% wide now. Felt really good. Liked it. Ran it with no main jet, check. Un-ridable WOT splutter, check. Put in a 200 main jet, check. That'll be big enough to start with, nope, was at WOT for 10 seconds and massive heat seize. Pushed it home, wasn't so far. Details and pictures tomorrow. If I'm in the mood to look.

Ouch! Sorry to hear it, Jack. I've been there and done that.

[/code]

Welcome to the club.

No humor in that moment at all.
The consideration of re-work now required is the worst but to overcome.

I think half my experimentation is a subconscious effort to find motivation for the tear down.

Hoping for some mostly piston damage for you.

Damn even the mighty Jack runs into trouble sometimes. We all feel for you.

The push home wasn't that bad.. i call that penance for the sins you committed on that cylinder! Now say your 5 our fathers and 5 hail Marys and you are good to clean it up and run it again tomorrow!

On the bright side, you were only a mile from home. At least one of mine was a good 6 mile push of shame!

I know the feeling, we need an official I melted a piston club. Hmm

"Piston Melters Club, Go Lean and Walk Home" in a circle around the outside with a half melted piston in the middle?

Awe shucks

I'd rock that logo. I'd even put little gold stars around the outside, one for each piston I've killed.

Jack, that's a bugger!! Such a problem is usually turned into an opportunity to tune some more, but I guess you've already maxed out on what you can do

April fools?

Yeah WOT, hate it. Here's the carnage from my 260 quattrini... cry, cry, cry.

Its bad. Cleaned it up and it runs again but too much damage to ride any distance. Or ride it hard. Need a new kit. Not so much the cost but need to tune it all again.

Might just run the new one stock port timing for a while to see how it feels. Engine is going to need new crank and gearbox after Summer anyway. Is all getting a bit worn looking.

OUCH for both!!! That Quattrini looks like it boiled...

Jack, is that the max you can go on the MHR, porting wise??

Ah crap... really exploded...

Looks like that's pushed to the upper limits, 72% sounds on the edge... amazing you got to do it...

Tough luck. Yeah sure. You'll be grinding up the new kit faster than you can say "größere Auslasszeit".

OUCH x2.

Forget sometimes that just because you have a super high end/ big ass cylinder - it isn't free from all the same foibles as my punny 177 kits.

Just exactly how fast is WOT for 10 seconds on an MHR??!!
That had to make a horrible sound from the rear tire.

To answer all questions at once, I was going for the how far can I tune it and still work within 4 gears. Was really hitting the limits. 72%is a scary grinding job, thought I had gone through to the studs a couple of times but was ok. 199 degrees is normal for a bike. It revved very high. Could do 10,000 rpm in 3rd and 9,000 in 4th. My usual on ramp is slightly up hill and normally would do 76mph when crossing the line. After this tune is was doing 80mph at the same point. Still going uphill. As the hill rounded to flat. I could actually feel the acceleration.

That was another new piston in there. 3rd one in this cylinder. It lasted 3 years. I think I really will just do a mild tune on the new one. The MHR is pretty good out of the box and all the high rpm just over stresses everything. I'll just get it to do 85mph and stop there. Go for some longevity.

Still not sure exactly what happened. The seize was in slow motion, was just like putting the brakes on gently. Empty road, coasted straight into a parking spot. No drama. Was on a 200 main jet, which is really big in any bike. 300 float valve. Dellorto pump. I can only think fuel restriction. Will do some flow tests on the tank (which was near full at the time) and pump. This was the idea of getting it running again quickly. I can now find out what happened before the new cylinder goes on. Any other ideas?

Thoughts from 50K feet.
- 4 post seize says heat expansion of piston vs cylinder studs.
- Failed WOT so fuel starvation or:
- Could be question of piston limits - those MHR are full of variating thickness. Any further work would only create more chance of piston deformation.
- Failure of oil delivery - but assume you are running premix
- Float bowl sucked dry? Longish WOT, hill that made carb at steeper angle. Have you played with float height recently for other purposes?

Putting breaks on gently - but due to piston swelling.
My only experience with piston swelling seizes are that they are immediate and unfriendly.
That kinda raises an eyebrow - its different at least.

Those would be on my list - and are probably already on yours...

Hi Jack. I've noticed your using a helical cut gear primary.
I've always been confused as to what is the better option (pros, cons etc) between straight cut and helical cut gears, what are your thoughts on this?