I recently acquired a ys .61 ar that appears to be in good shape. however, i want to do a complete tear down and rebuild. it has already been briefly examined by navav2002 who concurred, 'it is a keeper'. what steps do i need to take to rebuild this engine?

thanks in advance, david

Be Happy to help you with that if you wanted...But if not..Here is My .02 worth...

Once Again...I'm not an Expert...There may be more knowledgeable folks on this subject..If so chime in!! Feel free to correct me if I'm wrong!! I've just bought several used engines lately which I've spent allot of time going through and re-building...

YS 61R AR Manual:
http://maxupload.com/8AAADAF5
(note: Adobe Reader may need to install Japanese Language Pack to read correctly)


Get your parts together:

Bearings:
You could consider upgrading to Ceramic bearings with Stainless Steel races at this time...If not Ceramic..I'd recommend a good set of Stainless Steel from Boca Bearing bearings over the factory YS bearings..

I've not ordered from this guy yet..But he posts around here in some of the speed engine type forums...He seems like he's got a good philosophy and stands behind his products...People seem to be happy with his bearings...This is allot less expensive alternative for Ceramic Bearings than what Boca offers...I normally buy with regards to Quality over cheapest price...But folks seem to like his quality...He offers a C-3 (Or Better) Radial Play bearings and Stainless Steel Races are Optional for an extra $5 or something...His prices are about $30 + Stainless Upgrade...So a little more realistic than Boca Bearings in the price category...I thought I may try a couple of sets of his bearings in the near future:
http://www.rc-bearings.com/

Boca Bearings...Pretty well known for replacement bearings...They offer a C-2 Radial Play Ceramic/Stainless bearings sets but are expensive ($60-$90 per set)...They normally have a wide range of bearing choices from $11 on up to the nicest Ceramic set at $80-90 per set:
http://www.bocabearings.com/


List of parts from YS you want to consider:
Gasket Set - YS1190
Diaphragm - YS1130
Plunger - YS1145
Plunger Spring - YS1150
O-Ring Set - YS1175
Cylinder Head Gasket - YS1010
Throttle Arm and Screw - YS0375
Check Valve - YS0405
YS Fuel Filter - YS1195

(Optional But Recommended as you see fit)
Needle Valve Assembly - (NLA - But there is suppose to be a substitute part available)
Needle Valve Detent - YS1115
Fuel Nipples - YS0420
Back Plate Screws - YS1070
Cylinder Head Screws - YS1015
Regulator Mounting Screws - YS1155

YS Parts and Service:
http://www.yspartsandservice.com/


One more Item I'd Highly Recommend...You will need an "Assembly Lube" when you put the thing back together..Plus it makes a great After Run/Storage Oil:
Ultra Oil:
http://www.pspec.com/details.asp?ProdID=40&category=7


I think dis-assembling the engine is pretty straight forward...If you look at the diagram in the manual it will give you a pretty decent idea of what the thing looks like...A couple of highlights I can think of:

I'd say my First Note would be you shouldn't ever have to use excessive force while working with these engines...No beating with a sledge hammer is required...Smoothness and Fineness would be the key...Not blunt force...If something is being stubborn then try heating in the oven (see below)...

Remove:
Drive washer, Key and Spacer
Remove Carburator and Regulator Assembly
Remove Engine Back Plate
Remove Cylinder Head (I mark for Orientation with a sharpie marker or a make a dot with a scribe if I'll be vatting the cylinder head)
Remove Piston Liner (Mark for orientation!!..Os Engines have an Index Pin...YS's do not) (If it's stubborn heat in oven: see below)
Remove Piston and Connecting Rod Assembly (No Force!! Patience)

Once you get the engine broke down to that point it's time to remove the crank and bearings...Sometimes they will come apart easily...Sometimes...Not so much..

In order to remove the bearings I put the engine in the oven and heat to about 225*f...Actually I "try" starting at 180* and see if it will come apart...If not I work my way up...I do my best to not exceed 250*f (Most all my engines have come apart pretty easily before 250)

The YS rear bearings usually come off the crank pretty easy...On my OS engines I usually have to put them in the freezer to get the rear bearings off the crank...(note: If there is a build up of "stuff" on the crank it may make dis-assembly difficult...I'll vat the crank to clean it up prior to removing the bearing..see disclaimer below [sm=tongue_smile.gif] )

(On occasion I've had to heat the engine in the oven to get the Piston Liner to come out too...)


Not sure I wanna recommend this to everyone else...This is just what I do...The following is at your own risk [X(]
**I Personally** have one of those 1 gallon Parts cleaning vats from the Auto Parts Store...Once I get the engine torn down I've found it to be a pretty decent way to clean parts...I drop them in the "vat' and let them soak for 30 minutes or so...(If stuff is really bad I've gone longer...)...Then with the particular brand I have you rinse with water to neutralize the solvent (I have a slop sink in my basement..Not sure I'd do it in the kitchen sink??)...I'm only putting the metal or brass parts in there...No plastic ect..I oil the parts with Ultra Oil as soon as I've rinsed and dried them (Especially the Crank!! It will begin to rust almost immediately)

To "Dry" my parts after flushing I use my air compressor...I also take this opportunity to blow compressed air through all of the oil/fuel passages located in the case, regulator body, carburetor body, needle socket and throttle barrel...

Notice
I have had this solution remove a little of the black anodizing off a YS 60 cylinder head...Other than that I havn't had any trouble...I had no trouble with the YS 61AR parts at all...Only the YS 60?? Huh..Wierd..Oh well..


There may be better alternatives for cleaning parts?? I dunno...This is just what I do...

Thats about all I can think of right now...Obviously re-assembly will go about the same..Just backwards ...And Remember..Fineness Not Force!! Use a *Not Petroleum* based oil for assembly...Highly recommend Ultra Oil...

Chuck

You really have to be careful concerning which auto shop solvent you soak your glow engine in. A friend of mine's solvent bath turned my Enya 60-4C a very deep black color. I was not a happy camper.


Ed Cregger