PX221 - MHR very tuned - 38mm Dellorto
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Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Wed Sep 09, 2020 2:00 pm quote
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.

Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3129
Location: Nashville
Wed Sep 09, 2020 2:07 pm quote
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.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 8066
Location: Victoria, Australia
Wed Sep 09, 2020 2:40 pm quote
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?
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Wed Sep 09, 2020 3:01 pm quote
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.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Sun Sep 13, 2020 12:03 pm quote
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.
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 8066
Location: Victoria, Australia
Sun Sep 13, 2020 6:50 pm quote
Jack221 wrote:
Webs are twisted, I think it will straighten but might need a new pin.
Going to weld the pin? What crank is in it again?
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2192
Location: california
Sun Sep 13, 2020 9:47 pm quote
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?
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Mon Sep 14, 2020 12:50 am quote
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.
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1657
Location: UK (South East)
Mon Sep 14, 2020 12:56 am quote
Jack, have you strengthened your cases in any way, particularly around the input shaft?
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Mon Sep 14, 2020 12:53 pm quote
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.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Thu Dec 03, 2020 2:19 pm quote
Like a virgin
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.

Piston.jpg
Last time it will look like this.

Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 8066
Location: Victoria, Australia
Thu Dec 03, 2020 5:38 pm quote
Re: Like a virgin
Jack221 wrote:
...found the piston had melted a quite a bit on the edge by the exhaust. Just about down to the ring. ..
Wow. You have a picture?
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2192
Location: california
Thu Dec 03, 2020 7:39 pm quote
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.
Enthusiast
LML 187
Joined: 12 May 2020
Posts: 50
Location: England, stoke
Fri Dec 04, 2020 3:53 pm quote
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.
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2192
Location: california
Fri Dec 04, 2020 9:55 pm quote
Quote:
Last time it will look like this.
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
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Sat Dec 05, 2020 12:43 pm quote
Crazyfrog187 wrote:
Raises an eyebrow when your suddenly revving to the moon and back .
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.
charlieman22 wrote:
Quote:
Last time it will look like this.
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
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.
Ginch wrote:
Wow. You have a picture?
My phone takes bad close ups but you get the idea.

melty bit.jpg
Adding about 1.5mm to the exhaust timing. Not good.

Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2192
Location: california
Sat Dec 05, 2020 6:30 pm quote
Quote:
Best thing with Nicasil is to do nothing.
Cool - thanks. Always curious.
Quote:
Best thing with Nicasil is to do nothing.
Remarkably not really. Still running strong. But give me time.
Enthusiast
LML 187
Joined: 12 May 2020
Posts: 50
Location: England, stoke
Sun Dec 06, 2020 5:27 am quote
Jack221 wrote:
Crazyfrog187 wrote:
Raises an eyebrow when your suddenly revving to the moon and back .
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.
charlieman22 wrote:
Quote:
Last time it will look like this.
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
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.
Ginch wrote:
Wow. You have a picture?
My phone takes bad close ups but you get the idea.
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.
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1282
Location: California
Tue Dec 08, 2020 6:26 am quote
wow sounds wicked darn old piston better luck with the new one sounds delicious.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Wed Dec 23, 2020 4:19 pm quote
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 😌
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2192
Location: california
Wed Dec 23, 2020 6:02 pm quote
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.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Thu Dec 24, 2020 3:34 am quote
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.

6 year old Superstrong basket.JPG
6 years just flew by

New steels again.JPG
1000 miles or 3 months on a set of plates.

Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Thu Apr 01, 2021 10:30 am quote
oops
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.
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3129
Location: Nashville
Thu Apr 01, 2021 11:06 am quote
Ouch! Sorry to hear it, Jack. I've been there and done that.

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Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2192
Location: california
Thu Apr 01, 2021 11:26 am quote
Jack221 wrote:
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.
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.
Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 2901
Location: Staten Island, NY
Thu Apr 01, 2021 11:51 am quote
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!
Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1557
Location: Rochester, Minnesota
Thu Apr 01, 2021 12:39 pm quote
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?

Last edited by Christopher_55934 on Thu Apr 01, 2021 12:41 pm; edited 1 time in total
Molto Verboso
Vespa
Joined: 19 Jun 2007
Posts: 1282
Location: California
Thu Apr 01, 2021 12:40 pm quote
Awe shucks
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3129
Location: Nashville
Thu Apr 01, 2021 12:49 pm quote
Christopher_55934 wrote:
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?
I'd rock that logo. I'd even put little gold stars around the outside, one for each piston I've killed.
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1657
Location: UK (South East)
Thu Apr 01, 2021 1:11 pm quote
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
Hooked
PX 200
Joined: 25 May 2016
Posts: 260

Fri Apr 02, 2021 12:16 am quote
Jack221 wrote:
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.
April fools?
Enthusiast
1x PX260, 1x GS232
Joined: 16 Jun 2015
Posts: 98
Location: Brisbane, QLD
Fri Apr 02, 2021 3:15 am quote
Yeah WOT, hate it. Here's the carnage from my 260 quattrini... cry, cry, cry.

20210116_073728.jpg

20210116_073738.jpg

20210116_073805.jpg

20210116_073824.jpg

20210116_073837.jpg

Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Fri Apr 02, 2021 9:59 am quote
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.

DSC_1249.JPG
Worse than it looks. Nicasil damaged.

DSC_1250.JPG
Had to file the lump off to put it back in

Ossessionato
1979 P150X, 1983 P200E, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 2214
Location: Veria, Greece
Fri Apr 02, 2021 10:27 am quote
OUCH for both!!! That Quattrini looks like it boiled...

Jack, is that the max you can go on the MHR, porting wise??
Hooked
PX 200
Joined: 25 May 2016
Posts: 260

Fri Apr 02, 2021 7:09 pm quote
Jack221 wrote:
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.
Ah crap... really exploded...

Looks like that’s pushed to the upper limits, 72% sounds on the edge... amazing you got to do it...
bodgemaster
63 GL, 76 Super (x 2), 74 Primavera (x 2), 06 Fly 150
Joined: 26 Sep 2013
Posts: 5757
Location: So Cal
Fri Apr 02, 2021 7:48 pm quote
Tough luck.
Quote:
Might just run the new one stock port timing for a while to see how it feels.
Yeah sure. You’ll be grinding up the new kit faster than you can say “größere Auslasszeit”.
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2192
Location: california
Fri Apr 02, 2021 9:08 pm quote
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.
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2705
Location: London UK
Fri Apr 02, 2021 11:59 pm quote
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?
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2192
Location: california
Sat Apr 03, 2021 12:16 pm quote
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...
Addicted
PX 150
Joined: 15 Sep 2006
Posts: 533
Location: Gold Coast, Australia
Sat Apr 03, 2021 4:00 pm quote
Jack221 wrote:
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.
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?
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