Sun Jul 17, 2022 3:07 pm

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Sun Jul 17, 2022 3:07 pm linkquote
Although the engine turned over freely and evenly as I was assembling it, it is really hard to turn and uneven once I put the flywheel side case on. It seems to be free in the phase when the piston is all the way out, but really tightens up as the crank comes around and sweeps across the rotary pad. With the cylinder and head on I can hardly turn it at all.

Is the crank possibly not all the way centred, or is there something else I should be looking at?
I tried to attach a video so you can see the effect but I think the file is too large so we will have to make do with this series of three screenshots. All and any suggestions much appreciated.







Sun Jul 17, 2022 3:15 pm

Ossessionato
2007 Stella 225
Joined: 02 Nov 2019
Posts: 3119
Location: Rochester, Minnesota
 
Ossessionato
2007 Stella 225
Joined: 02 Nov 2019
Posts: 3119
Location: Rochester, Minnesota
Sun Jul 17, 2022 3:15 pm linkquote
You have to upload video to a service such as YouTube and link it here.

Sun Jul 17, 2022 6:41 pm

Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
 
Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
Sun Jul 17, 2022 6:41 pm linkquote
I would pull the clutch and check again, If no luck, pull the fly side case. Work backwards until you find the source. Is the engine in neutral?
Sun Jul 17, 2022 9:50 pm

Molto Verboso
GL, PK, PE200 with hack, Sears Rust Badge
Joined: 24 Apr 2012
Posts: 1342
Location: Deep in the heart of Texas
 
Molto Verboso
GL, PK, PE200 with hack, Sears Rust Badge
Joined: 24 Apr 2012
Posts: 1342
Location: Deep in the heart of Texas
Sun Jul 17, 2022 9:50 pm linkquote
You're on the right track thinking it's crank alignment issues.

I usually leave the crank puller on until I get the center case bolts on.... turning the crank and checking during the entire process.

Good luck
Mon Jul 18, 2022 6:15 am

Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
 
Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
Mon Jul 18, 2022 6:15 am linkquote
rowdyc wrote:
You're on the right track thinking it's crank alignment issues.

I usually leave the crank puller on until I get the center case bolts on.... turning the crank and checking during the entire process.

Good luck
That's a good strategy. When working on other engines, my method when mating case halves has been to start with the fasteners closest to the crank, tighten gradually while checking rotation, wrench tight, bring up torque values 5 lbs at a time, check rotation as I go. If any time during that process, something binds or does not feel right, stop and find out what it is.

In one of the SIP engine building videos, they do a dry build kind of assembly where they mate the cases and check things individually; mostly to ensure the x-mas tree and gear set line up and the cruciform is correctly lined up in each gear. This is kind of what I have done with automotive engines; cam in case by itself, crank in case by itself, crank and cam together. Kind of overkill on a Vespa because fewer moving parts but the general idea applies.

Sorry to blather. Good luck.
Sat Jul 23, 2022 11:33 am

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Sat Jul 23, 2022 11:33 am linkquote
Thanks for these helpful thoughts. I have removed the cylinder and head, taken off the clutch and the flywheel side of the case. The crank spins freely. I am looking at whether it might be slightly out of alignment - enough that when I put on the other half of the cases and torque the bolts it binds on the flywheel side.

Looking at the gaps though there doesn't seem room for the crank to come further towards the clutch side. See pics. There is a tiny reveal at the bevel on the bearing where it meets the shaft on the crank. Should it align with the base of the bevel or flush with the top edge?







Sat Jul 23, 2022 3:21 pm

Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
 
Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
Sat Jul 23, 2022 3:21 pm linkquote
The bearing should be flush with those two brackets. It looks correct in your photo but it's hard so tell. The bearing in my Stella case looks similar. One side is machined to a different depth. Is there a snap ring on the other side of the bearing.



Sat Jul 23, 2022 3:33 pm

Molto Verboso
Joined: 29 Nov 2020
Posts: 1127
Location: Los Angeles
 
Molto Verboso
Joined: 29 Nov 2020
Posts: 1127
Location: Los Angeles
Sat Jul 23, 2022 3:33 pm linkquote
What method did you use to install the crank?
Sat Jul 23, 2022 3:42 pm

Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
 
Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
Sat Jul 23, 2022 3:42 pm linkquote
Ray8 wrote:
What method did you use to install the crank?
That was my next thought…
Sat Jul 23, 2022 3:55 pm

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Sat Jul 23, 2022 3:55 pm linkquote
The crank was installed using a puller.
Sat Jul 23, 2022 5:10 pm

Molto Verboso
Joined: 29 Nov 2020
Posts: 1127
Location: Los Angeles
 
Molto Verboso
Joined: 29 Nov 2020
Posts: 1127
Location: Los Angeles
Sat Jul 23, 2022 5:10 pm linkquote
basile bailey wrote:
The crank was installed using a puller.
Get another crank.

That one's shot.
Sat Jul 23, 2022 5:32 pm

Molto Verboso
Joined: 29 Nov 2020
Posts: 1127
Location: Los Angeles
 
Molto Verboso
Joined: 29 Nov 2020
Posts: 1127
Location: Los Angeles
Sat Jul 23, 2022 5:32 pm linkquote
Your issue:



Sat Jul 23, 2022 6:29 pm

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Sat Jul 23, 2022 6:29 pm linkquote
Thanks so much for your help. Thank Ray8 for identifying the problem. I'm pretty ignorant- can you break it down for me: what is wrong and how do I fix it?
Sat Jul 23, 2022 6:34 pm

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Sat Jul 23, 2022 6:34 pm linkquote
..and when I say that I mean how do I ensure the new one doesn't replicate the problem
Sun Jul 24, 2022 6:47 am

Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
 
Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
Sun Jul 24, 2022 6:47 am linkquote
Wow, good eye! I'm not quite sure what I'm looking at on the crank. Looks either mangled or covered with JB weld on the fly side. Can you post a better pic, just to satisfy my curiosity.

Always nice to find a smoking gun even when it costs money. Better than weeks of chasing a mystery.
Sun Jul 24, 2022 7:50 am

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Sun Jul 24, 2022 7:50 am linkquote
Yes, it is really good to finally identify the cause of the problem. I have had this apart and together multiple times. Thanks everyone for your help. What is on the shaft is grease, smeared there by me to facilitate mating the flywheel side case. Here are some more pictures of it that part of the crank.







Sun Jul 24, 2022 8:02 am

Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
 
Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
Sun Jul 24, 2022 8:02 am linkquote
Hmmm…I'm not seeing anything, but I'm quite inexperienced with Vespa engines; bent crank? Scored bearing taper? I'm not sure what was seen. I'm sure someone will be along to point it out.
Sun Jul 24, 2022 9:25 pm

Evil
Old douglas ..smallie with polini 115..super with nasco 177
Joined: 07 Nov 2013
Posts: 666
Location: New Zealand
 
Evil
Old douglas ..smallie with polini 115..super with nasco 177
Joined: 07 Nov 2013
Posts: 666
Location: New Zealand
Sun Jul 24, 2022 9:25 pm linkquote
Looks like crank is still not all the way in.Get the pullar out.Either bearing may also be sitting on a very slight angle (not seated so give them some encouragement down flat with proper tool or big socket) Good luck
After that go shopping for a crank
Sun Jul 24, 2022 11:52 pm

Jet Eye Master
PX221 MHR, O tuned PX200, PX181 Quattrini and some motorbikes
Joined: 14 Jun 2017
Posts: 3528
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX181 Quattrini and some motorbikes
Joined: 14 Jun 2017
Posts: 3528
Location: London UK
Sun Jul 24, 2022 11:52 pm linkquote
If the crank is twisted (happens often) replace it with a 60 crank and 1mm base gasket. Similar money but with free speed.
Tue Jul 26, 2022 5:06 pm

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Tue Jul 26, 2022 5:06 pm linkquote
Thanks for all this helpful advice. I am proceeding by pulling the crank to see if i can find somewhere that the bearing is not properly or totally seated. If I can maybe it means I have don't have to replace the crank…

These pictures of the bearing from the clutch side seem to indicate it is flush with the two tabs and square on. The pic from the interior shows two interesting things to note though: the oil seal is a tiny bit proud with a slight lip (i can just catch my nail on it) from about 1 to 9 o'clock. The other 1/3 of it is all the way flush with the case surface. I have tried hard but can't get it to you bed in any further. Even more tellingly, there is a clear pattern of wear in the case surface where the same section is rubbed smooth. Clearly something is offset. The question I have is does this look like the issue and if so how to fix it? Does this tell us the crank is bent (this wear pattern predates my rebuild)? Or can I cheat the bearing inwards a thou and tighten the clutch side tab that lines up with this wear pattern down the same amount and "correctly" align it?







Tue Jul 26, 2022 5:16 pm

Hooked
Yellow GTS 300 Super, Black GTS 300 Super Sport, Polaris Grey Rally 200, Blue Marine Primavera ET3, Coral Red 50 Special
Joined: 14 Aug 2020
Posts: 237
Location: London
 
Hooked
Yellow GTS 300 Super, Black GTS 300 Super Sport, Polaris Grey Rally 200, Blue Marine Primavera ET3, Coral Red 50 Special
Joined: 14 Aug 2020
Posts: 237
Location: London
Tue Jul 26, 2022 5:16 pm linkquote
Have you had the engine completely back together and fully torqued?

I had some alignment issues initially on a 50 special engine. Initially the crank was binding and then after I fixed that the driveshaft, both fixed themselves as I got all the case parts back on fully torqued them now it's all spinning freely.

I. used one of the crank puller tools to fully seat the clutch side it also helped to keep the aligned too.
Tue Jul 26, 2022 6:03 pm

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Tue Jul 26, 2022 6:03 pm linkquote
Thanks for the suggestion. Unfortunately yes I had it back together and fully torqued twice. That's when the symptoms are most pronounced.
Tue Jul 26, 2022 6:54 pm

Molto Verboso
PX 200
Joined: 25 May 2016
Posts: 1111

 
Molto Verboso
PX 200
Joined: 25 May 2016
Posts: 1111

Tue Jul 26, 2022 6:54 pm linkquote
The wear pattern on the cases are nothing to worry about… sometimes new cases have that.

Seems to be part of the machining process

The tolerances on the cases are usually pretty forgiving, even if they're not straight, they don't bind to the point things don't spin.

I'd imagine the culprit will be your crank, driveshaft or primary…

High chance it's the crank, especially if it's old
Tue Jul 26, 2022 7:12 pm

Addicted
1968 VBB150
Joined: 04 Nov 2015
Posts: 641
Location: OC
 
Addicted
1968 VBB150
Joined: 04 Nov 2015
Posts: 641
Location: OC
Tue Jul 26, 2022 7:12 pm linkquote
Hold up. Does it bind at the same rate 360 degrees? Swap the crank for an easy fix.
Wed Jul 27, 2022 4:15 am

Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
 
Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
Wed Jul 27, 2022 4:15 am linkquote
The seal being slightly proud shouldn't be a problem, I don't think. The crank can only go into the bearing so far before it hits the shoulder on the crank.

You could take the crank to a general machine shop and have them measure it with a dial indicator mounted on centers. A motorcycle shop could probably measure it and straighten it.

I would have it checked for runout and replace it if it isn't straight. If it turns out to be ok, keep looking.
Sat Jul 30, 2022 12:45 pm

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Sat Jul 30, 2022 12:45 pm linkquote
Based on all the helpful input here I inspected the crank to try and determine whether to replace it, take it to a shop to be trued, or persevere. On the basis that it looked measured pretty straight (at least with the limited tools at my disposal), and had been turning over okay when I took it out, I thought I would try reseating it one more time.

This time I started pulling it on using the clutch technique before switching to the crank puller. It seemed to seat more easily, and after torquing up the case bolts it finally now spins pretty freely. Hurrah!

It isn't entirely smooth all the way through the cycle - it gets slightly harder to turn in one spot which I think is as it starts to cross the rotary pad - but it is way improved. Does that seem normal - forgive me but I don't know what normal is in this situation.
Sat Jul 30, 2022 5:11 pm

Molto Verboso
'64 Motovespa 150S (177) , '66 Allstate SF, '65 VBB, '66 180SS
Joined: 27 Mar 2013
Posts: 1457
Location: S.Salem, NY
 
Molto Verboso
'64 Motovespa 150S (177) , '66 Allstate SF, '65 VBB, '66 180SS
Joined: 27 Mar 2013
Posts: 1457
Location: S.Salem, NY
Sat Jul 30, 2022 5:11 pm linkquote
basile bailey wrote:
It isn't entirely smooth all the way through the cycle - it gets slightly harder to turn in one spot which I think is as it starts to cross the rotary pad - but it is way improved. Does that seem normal - forgive me but I don't know what normal is in this situation.
You shouldn't feel any resistance at any point in the rotation and the web certainly should not make contact with the pad.
It's kind of hard to tell if it's smooth all the way around with the con rod doing what it does, but there should be no binding.
Sat Jul 30, 2022 7:24 pm

Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
 
Molto Verboso
Joined: 14 Oct 2016
Posts: 1308
Location: northern New York
Sat Jul 30, 2022 7:24 pm linkquote
If the crank is encountering resistance as it crosses the rotary pad, something is off. It shouldn't scuff the rotary pad and don't keep doing that. Because that is $$$ to repair.

Have the crank measured for realz. Any machinist can do it. How much is your time worth? Can you place a dollar value on the time you have already spent opening and closing the case? Now factor in the frustration and ass ache of doing that. Has it cost as much as having a machinist measure it…or even a new crank yet?

How did the rotary pad look? Anybody had their peanut buttery fingers in there with the JB weld?

Props for keeping at it and chasing down the problem, but sometimes you have to get help to move forward.
Sun Jul 31, 2022 4:56 pm

Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
 
Enthusiast
VBB
Joined: 12 Aug 2016
Posts: 52
Location: Wisconsin
Sun Jul 31, 2022 4:56 pm linkquote
Thanks again everyone. Today I took the cases apart again and checked the clearance on the rotary pad. All good - no issues with peanut butter! This time zipping it up it was smooth with no bumps until I got the cylinder on and then it really tightened up. I took it off again and it turned over as free as could be. So flipped the whole thing on its end so I could put the cylinder and head on without gravity getting in the way. I cinched up the head bolts and bam! it's turning really good now. Not sure I can entirely explain it, I'm just grateful it is working now.
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