Antique Engines and Old Iron
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® General Discussion > Smokstak Down Under
Forgot Password? Join Us!

Notices

Smokstak Down Under For Australia and New Zealand Smokstakers to meet, greet, yabber and yack.

Smokstak Down Under

Villiers two cycle engine clearances?


this thread has 10 replies and has been viewed 968 times

Reply
 
Thread Tools Display Modes
  #1  
Old 01-03-2019, 08:19:46 PM
K-Tron K-Tron is offline
Registered-III
 
Join Date: Sep 2010
Location: Huntington, NY
Posts: 1,955
Thanks: 902
Thanked 992 Times in 686 Posts
Default Villiers two cycle engine clearances?

I am working on a 1948 Villiers MK25C 147cc two cycle engine with a 55mm bore and 62mm stroke. My particular engine must have had a lot of hours on it because so much carbon built up behind the rings that the rings wore thin enough to jump past the pins which keep the rings in place. It did not cause any major failure, but it scored the cylinder a bit. I am mainly concerned about the big end of the connecting rod bearing. This particular engine uses a three piece crankshaft and a one piece connecting rod with brass and steel needle bearings. You have to press the crankpin out to replace the needle bearings. I chucked the crankshaft in my lathe, locked the spindle and measured 0.003" of slop in the big end of the connecting rod bearing off the top of the connecting rod. I cannot find any literature which says what the running clearance should be. Based on the fact that this engine runs on ~10:1 oil mix, I would imagine the play in the big end of the rod should be 0 to 0.001". The side to side clearance is excessive so i wonder how the thrust faces of the rod look like, if there are any. I would like to know how to proceed with replacing the connecting rod bearings, as the crankpin does not appear to be pinned on either end. It may require a special alignment jig which I do not have for re-assembly. I have already purchased new big end ball bearings for the crankshaft, and some brass stock to make new sealing bushings out of. Secondly I cannot seem to find any piston/cylinder clearance specs for this engine. The ring landings on my piston are wore out, so I am either going to have to find a replacement standard piston or go oversize. I would much rather go oversize to eliminate all of the scratches in the cylinder. Lastly does anyone have any recommendations on finding parts for these engines? I have contacted Villiersparts.co.uk and Meetens. I just heard back from George @ Villiersparts, he is pretty confident that he has the parts I am looking for, but says that the specs I am looking for are not available. Surely someone has actually rebuilt one of these engines before. This particular engine appear to be very common in England and Australia on Allen Oxford motor scythes and Howard Bantam Rotavators.



Chris
Reply With Quote
Sponsored Links
  #2  
Old 01-03-2019, 08:50:59 PM
jayvee jayvee is offline
Registered-II
 
Join Date: Jun 2010
Location: Adelaide, South Australia
Posts: 544
Thanks: 706
Thanked 1,692 Times in 379 Posts
Default Re: Villiers two cycle engine clearances?

Hi Chris,
Give John Humphries @ Rustic Spares a try.
He wrecks small engines such as Villiers, Cooper, JAP, Briggs & Stratton as well as some new parts.

He maybe able to help.

Contact: rusticspares@bigpond.com
Web:www.rusticspres.com.au

Hope this helps.

Best wishes, jayvee

---------- Post added at 11:20:59 AM ---------- Previous post was at 11:17:15 AM ----------

OOPS
Made a boo-boo
Website should be www.rusticspares.com.au

jayvee
Reply With Quote
  #3  
Old 01-04-2019, 08:52:41 PM
K-Tron K-Tron is offline
Registered-III
 
Join Date: Sep 2010
Location: Huntington, NY
Posts: 1,955
Thanks: 902
Thanked 992 Times in 686 Posts
Default Re: Villiers two cycle engine clearances?

I spent some time inspecting this engine and I found that the cylinder is worn in a very bad way. My cylinder tapers from 2.170" to 2.177". The bore of this engine is supposed to be 55mm as in 2.165". The piston skirt to cylinder clearance varies from 0.007"-0.013". Piston ring gap varies from 0.118" to 0.130", over four times the maximum spec of 1/32" (0.03125). I believe the first oversize piston available for this engine is 0.020" oversize. I can easily bore the cylinder oversize, its just finding a new 0.020" oversize piston and ring set. I cannot believe how worn out this engine is. The Howard Bantam is not a particularly heavy duty machine. The previous owner of this engine must have worn out several gear sets in the transmission! I still have not been able to find a repair manual or service manual for this engine. Piston to cylinder clearance, connecting rod bearing clearances and bore size information is all a big mystery at this point. I hope George @ Villiersparts can forward me the size of the big end of the connecting rod, and the o.d. of the crankpin so I can see how mine compares. I have a feeling that I will need a new piston, ringset, wrist pin, crankpin, needle bearings and possibly a connecting rod, among the typical carburetor rebuild parts. I better check the ignition coil and see what is going on there.

Chris
Reply With Quote
  #4  
Old 01-04-2019, 10:02:08 PM
Ozlander Ozlander is offline
Registered
 
Join Date: Jun 2016
Location: Rose Hill, Kansas
Posts: 39
Thanks: 0
Thanked 14 Times in 13 Posts
Default Re: Villiers two cycle engine clearances?

I don't think .003 clearance is that bad.
If you have never aligned a crankshaft, I would leave well enough alone.
Not a job for a new-bee.
Reply With Quote
The Following User Says Thank You to Ozlander For This Post:
  #5  
Old 01-05-2019, 12:24:43 AM
K-Tron K-Tron is offline
Registered-III
 
Join Date: Sep 2010
Location: Huntington, NY
Posts: 1,955
Thanks: 902
Thanked 992 Times in 686 Posts
Default Re: Villiers two cycle engine clearances?

You sound quite confident. Would you care to explain how to re-align the crank throws to the crankpin on a Villiers engine?

Chris
Reply With Quote
  #6  
Old 01-05-2019, 02:20:01 AM
cobbadog cobbadog is offline
Registered-III
 
Join Date: Aug 2009
Location: Coopernook. N.S.W. Australia
Posts: 1,725
Thanks: 3,137
Thanked 753 Times in 516 Posts
Default Re: Villiers two cycle engine clearances?

The early 125cc Victa lawnmower engine also has a split crank shaft. You definitely need a jig to put it back together as it is next to impossible to re-align the crank without a jig.
Can the UK supply the oversized piston and rings? If so bore it out to make a better job of it and maybe just be happy with a new top end bush.
Ignitions on Villiers are repairable with new and rebuilt coils readily available. Points rarely need replacing and condensors can be bought or use a film capacitor.
You should get away with the end float on the main as the engine is not going back to work or is it?
Reply With Quote
  #7  
Old 01-05-2019, 02:46:47 AM
K-Tron K-Tron is offline
Registered-III
 
Join Date: Sep 2010
Location: Huntington, NY
Posts: 1,955
Thanks: 902
Thanked 992 Times in 686 Posts
Default Re: Villiers two cycle engine clearances?

Thanks for the response cobbadog. I was afraid that that would be the case. I have been tempted to put the crankshaft in my mill, and machine an alignment pin on both sides of the crankshaft. If I put an alignment pin half into the crank pin, and half into the crank throw, on both ends of the crankpin, I could press the crank throws back together without a jig of any kind. At that point I would be stuck with the crankpin I have and would only be able to replace the needle bearings. That might work out just fine. Surely oversize needle bearings can be had or machined out of dowel pins, and the crankpin re-ground if worn or scorn. I was hoping to use this machine, not commercially, but around the garden. It will fit in many spaces my larger Howards will not. A Howard Bantam rotavator with a Villiers engine is very uncommon in the United States and I had been searching for one to call my own for years. It sure would be nice to be able to use it and have fun with it without having to worry about the engine or transmission cutting out. I made one new worm shaft for the transmission already, I have to make the secondary worm shaft and both worm wheels yet. That way this machine will be able to run and work for another century. I could have started out with another machine, but all of the bantams suffer the same problems, so I might as well fix the one I have. Lots of guys I talked to said to just gas it up and run it. For how rare these engines are in the USA, I decided to rather be safe than sorry. Had I run this engine it surely would have made a lot of bad noises and could have catastrophically failed. On top of the said issues, the PTO side main bearing was totally wiped out.

Villiersparts has the oversize piston and ring set in stock, it is just expensive that is all. I was hoping to find specifics on the piston/cylinder clearance so that when I bore it oversize everything is right. My gut feeling says to use 0.0015" of piston to cylinder clearance per inch diameter of the piston, so 0.0035", but I have not found anything from Villiers yet that says otherwise. I literally just received the carburetor amongst a bunch of other MK25C parts in the mail last week that I sent away for on ebay. I bought my Howard Bantam without an engine. I supplied the MK25C Howard engine long block. It made it over to the United States in the back of a Triumph car. It was listed as an unknown engine on ebay, and I was thrilled to get it. So no, I have not heard this engine run, and have not powered my bantam yet. I really look forward to putting it all together and having a fully functioning 100% mechanically and cosmetically restored machine. This weekend I should be able to test the coil, points and condenser with my merc-o-tronic ignition testing machine. That way I can just make one order of parts from England and be on my way.

Chris
Reply With Quote
The Following User Says Thank You to K-Tron For This Post:
  #8  
Old 01-05-2019, 09:05:11 AM
I like oldstuff I like oldstuff is offline
Subscriber
 
Join Date: Jan 2012
Location: Milwaukee, Wisconsin, USA
Posts: 6,145
Thanks: 1,562
Thanked 7,239 Times in 2,657 Posts
Default Re: Villiers two cycle engine clearances?

Having done hundreds of built up cranks, that .003 clearance in the bottom end is fine. What's the clearance between the rod side and the crank disks. Feeler gauges will tell you. On such a low revving low power engine, anything under ~.015 should be good.

As to piston to bore clearance Let's say 2" is the standard bore. The pistons 'should' be provided undersize to give you the right clearance.
So if you are to bore it .020 technically you bore it to 2.020 and the +20 piston should be clearanced correctly. *But measure everything first to be sure.

*Some engines were the opposite. Pistons came to the dimension, such as 2.020 and you had to bore it with the needed clearance, say to 2.025.
The later two stroke engines on bikes held some decent tolerances. For example on a 125cc mx race engine I'd bore it to give me .01mm clearance. 0.394 thousandths!
But on your oldie It'll need a lot more than that to keep it from seizing.
Reply With Quote
  #9  
Old 01-06-2019, 02:21:06 AM
K-Tron K-Tron is offline
Registered-III
 
Join Date: Sep 2010
Location: Huntington, NY
Posts: 1,955
Thanks: 902
Thanked 992 Times in 686 Posts
Default Re: Villiers two cycle engine clearances?

Tonight I re-checked the clearance in the big end of the connecting rod. This time I put the crankshaft between centers and used a tenths indicator. I measured 0.004-0.0048" up and down movement in the big end of the connecting rod bearing. This value changes based on the position of the needles in relationship to the crankpin. The side to side clearance between the connecting rod and crank throws is 0.015". I just finished designing a jig to hold the crankshaft during the pressing operation. I am going to machine the top flats of the crank throws flat so that I can use this as a critical surface for straightening the crank once pressed together. I am just not happy with how this crankpin and associated needle bearings feel. My brother and I looked at this crankshaft for two hours and still cannot figure out how Villiers accurately assembled and align these crankshafts other than using two super heavy duty cast iron crankcases to draw the cranks together with bolts. There are no hammering marks, and since the crank throws are sold individually they did not just press it all together and finish grind it as an assembly. I think our method is going to work. Once it is done, we can put it between centers and check run-out and adjust as necessary until its perfect.

Chris
Reply With Quote
  #10  
Old 01-06-2019, 08:25:55 AM
I like oldstuff I like oldstuff is offline
Subscriber
 
Join Date: Jan 2012
Location: Milwaukee, Wisconsin, USA
Posts: 6,145
Thanks: 1,562
Thanked 7,239 Times in 2,657 Posts
Default Re: Villiers two cycle engine clearances?

Truing a built up crank is a bit of an art form. Go on utube and search crank truing and watch a bunch of the vids. No need to machine anything on the crank. Centers, dial indicators and a hefty lead hammer are all you need. Of course take the crank out of the jig when hammering on it. Hand hold and whack it where needed.
Now imagine truing a crank from a 3 cylinder 2 stroke such as the Kawasaki triples from the 70's!

Varying big end clearance around the pin says there is some wear. Usually what happens is the surface of the pin will spall off some of the surface as they are carburized parts.

If you're going to do a 100% resto, see if you can get a rod kit. These typically come with the rod, needle bearing, crank pin and side thrust washers. Pics are of a Yamaha 200cc atv crank that I built up to put in a 50cc bike. Which by the way easily goes over 90 now.

This guy does an excellent tutorial.
https://www.youtube.com/watch?v=6lKL...XVxw-AVMCmOY6L
Attached Thumbnails
Click image for larger version

Name:	IMG_7046.JPG
Views:	51
Size:	110.1 KB
ID:	325810   Click image for larger version

Name:	IMG_7047.JPG
Views:	51
Size:	113.6 KB
ID:	325811   Click image for larger version

Name:	IMG_7049.JPG
Views:	47
Size:	104.9 KB
ID:	325812  

Last edited by I like oldstuff; 01-06-2019 at 09:31:34 AM.
Reply With Quote
The Following 2 Users Say Thank You to I like oldstuff For This Post:
  #11  
Old 01-06-2019, 01:43:21 PM
beezerbill beezerbill is offline
Subscriber
 
Join Date: Sep 2012
Location: Boulder, Colorado
Posts: 1,171
Thanks: 182
Thanked 631 Times in 423 Posts
Default Re: Villiers two cycle engine clearances?

Using the rim of the wheels should be enough for initial alignment. I would not machine anything away from the wheels - you might find they are hardened, and machining material away will upset the balance. Also drilling the crankpin for keys is not a good idea - it could lead to stress cracking in the wheels and besides, the crankpin is really hard and won't drill. Final alignment is done using a lead or copper hammer - sounds brutal but this is how it is done.

Best would be to find a shop that is familiar with pressed-up cranks. They have the experience and tooling, and a single-cylinder crank like yours should be pretty simple for them to do. If you try it yourself you will need a really good press, about 20 tons minimum for a crank that size and one that doesn't squirm or distort as it is loaded. Distortion in the press can lead to the pin going in crooked which can lead to a wobbly crank and in worst case can irreversibly distort the hole in a wheel. And you will need to develop a feel of how to knock the wheels about for the final alignment after they are pressed together - this takes a while. Best to start with about a 5 pound copper faced hammer, and start with light taps.

If you have trouble sourcing a rod kit, try Alpha Bearings.
http://www.alpha-bearings.com/
Heck, they can probably recondition your old rod if you can't find another, and fit you up with mating pin and needles.

a couple of additions:

Another reason for a rigid press is it helps, when adjusting the side clearance on assembly, that the press doesn't "wind up" and jump all at once, and overshoot your side clearance. Then you have the problem of having to slightly separate the wheels on the pin.

Also, it would be good to know if you have a stepped crank pin - one that is larger where it fits through the rod than it is through the wheels. This is uncommon, and very unlikely in your case. If you do have a stepped pin, you will need to make up a bolster that supports one wheel and lets you press the pin, with other wheel still on it, out of the supported wheel.

If you do overshoot when setting the side clearance, you will have to resort to such a bolster anyway, so it might be a good idea going in to have at least an idea of how you could make a bolster.

Last edited by beezerbill; 01-06-2019 at 02:52:33 PM. Reason: coffee kicked in
Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Villiers two cycle engine connecting rod bearing woes K-Tron Small Air Cooled Gasoline Engines 1 01-02-2019 02:37:53 AM
I.D this Villiers Engine please! boyblunder Unidentified Engines 12 05-30-2009 09:05:57 AM
Villiers Engine MaytagRepairMan Small Air Cooled Gasoline Engines 5 05-23-2009 05:04:45 PM
History of a Case traction engine & clearances B.L. Rodenkirch Steam Stationary Engines, Traction Engines 5 12-07-2007 08:35:40 PM
Valve clearances for LeRoi engine Ironman Hit & Miss Gas Engine Discussion 2 04-30-2007 11:49:31 AM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 12:22:45 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2019 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277