So its time to rebuild your Honda s600 engine.

 

The first question one should ask is "do I have the skills patience and knowledge to do this myself".  Most Honda s600 engines found in the market place are purchased in boxes, meaning many people answer "yes" to that patience and knowledge question, but in the end or usually sometime during the process, the answer becomes "no".  Why?  First and foremost is the availability of parts often dictates the schedule of the rebuild.  Simple things like the valve guides, a common wear part, are not availabe and you will have to wait to find it on Japanese Yahoo, eBay or through your netwrok, or have them made via a similar blank; surprises like an out of spec crank, are almost impossibe to address.  

 

The knowledge and patience aspects of any mechanic are tested thoroughly along the way with any rebuild.  I invite you to look in the restoration files and follow the engine rebuilds on the cars for more information.  Ortmann has reduced some of the hurdles of the rebuild process by supplying gasket sets, oversized reproduction pistons and pins, and a myriad of parts to make the job a little more smoothly.  A host of other suppliers in Japan are also very helpful, Ishii-san at Eurasia, Spread-tool, can help with parts.  Every engine, like a box of Cracker Jacks, has a surprise or two waiting inside.  Some of these surprises are the result of previous Rube Goldberg mechanics trying to make things work.  Many home mechanics quit out of frustration, or during the waiting time for parts, or find other priorities in their life that precide the Honda engine that they started.  You may not be one of these people, so if you have the skills patience and knowledge, go for it!

 

If your answer to the above question is no, than you must find a builder to restore the engine for you.  My experience is that most restoration shops, including shops that claim they have the provenance in honda engines, are even more overzelous than home mechanics in beleiveing they have the skills patience and knowledge to finish the rebuild.  Once you have placed the engine in their shop you are at their mercy as far as time and money spent, and often you still end up taking your engine home in box.  So you have basically over paid someone to come to reach the same conclusion as you could have done on your work bench.

 

Unfortunately, in the case of Honda s600 engine rebuilds, there are very few skilled rebuilders.  So how do you ensure you find the right person to entrust with your engine?  When it comes to a Honda s engine rebuild you are looking for a restorer or rebuilder, not an above average mechanic

 

1) Insist on and check References  red_flag

 

Ask the restorer for references of 2-3 RECENT rebuilds with the customers phone numbers and emails.  Check those references and ask how long the restoration took, were there major issues, did the restorer buy the parts or was that up to the individual?  If the references are from more than a few months ago, or from several years ago this is a red flag.  Restorers trying to gain your business will mention noted names and famous people in Honda s circles, as their former clients.  A great way to get to know some of the icons in the Honda s circles is by calling them to check the references.  Always look for recent rebuilds, and find out about the quality of work, length of time the restoratin took, who sourced and paid for the parts, were there any issues over runs or budget problems.

 

2) Tour the restoration shop red_flag

 

If the benches are cluttered, if there are mutiple projects going on that seem to blend into each other, view that as a sign of caution. Know who will be working on your engine, mechanics leave, circumstances change, the shop is a fluid entity, a well run restoration shop must have the underlying organization of the work to ensure continuity.   If there are boxes and parts strewn about, there is not likely an inventory management system that allows your newly ordered parts to find your engine.  It is the nature of the restoration that there will be starts and stops while waiting for parts or machining, you do not want parts disappearing or being misplaced during those periods of inactivity.  Look to see that all parts are labelled with the customer name, engine serial number and sub assemblies name (or parts book reference).  THIS IS A MUST!  there are hundreds of different fasteners involved in the Honda s600 engine, and a wrongly placed too long fastener can break an aluminum casting, or crack an important part.

 

3) Ask to see a restoration in progress red_flag

 

The Honda engines have many different moving parts and hundreds of distinct fasteners.  On teardown of the engine, the pieces should be boxed, labelled, bagged and tagged.  If you see coffee cans of bolts, and boxes with pieces that are not labelled it is a red flag.  Seeing a restoration in progress reveals a lot about the organizational skills of the shop.  Is the restorer doing the actual work on the engine an expert or a trainee?  If the restorer is assigning work to a trainee, are they closely supervised?  Have they received adequate training?  Working on a lawnmower or tractor, does not make a trainee qualified to work on a Honda s engine.  A restored engine in progress should be pristinely clean, small amounts of dirt, shavings or grime can ruin a rebuild very quickly.

 

4) Agree on a timeline red_flag

 

Some shops will tell you that an engine rebuild can take more than a year; or they will give you an indefinite timeline.  If the shop is telling you this, they are not rebuilding your engine, they are simply doing it as a hobby, or to fill their time between other jobs so they have a steady income stream.  Most rebuilds should take no more than six months.  Be very cautious of a shop that talks you into an indefinite timeline.  The more time in the shop, the more chances a mechanic quits, parts disappear, or your engine is damaged.  At the outset, you should agree on a timeline with milestones, and if possible how charges will be made against the timeline.  If during the restoration the timeline is not being met, set terms in the agreement that allow you to remove your goods from the shop without penalties to you.    If the restorer gives you references from more than a year or two old, it is a red flag!  A reputable restorer I have worked with prepared the rough rebuild outline below of the steps required in the engine build.

 

5) Ask for a Guarantee red_flag

 

Understand the performance criteria of the finished engine.  Does it have a guarantee?  Will repairs be preformed for free? 

 

6) Do Not Assume red_flag

 

These cautions apply to ALL restoration shops; even ones who claim they are specialists or have pedigree in this engine.   The investment in a rebuild is high, and good portion of that cost is in parts, so any failure due to a bad rebuild ends up being very costly.  Many gaskets can only be used once, so if the shop needs to make repairs there is duplicate costs.  

 

"One bitten twice shy", the six points above will definitely save you greif.  Unscrupulous mechanics live and breath in the Honda Circles, and they are waiting to take your money, waste your time, and ruin your investment.  Do your homework on any shop before you make the decision to entrust them on a rebuild.  The above guidlines should help you steer clear of the vultures who will pick your wallet clean! and leave you with a box of parts.

 


 


An overview of the steps of an engine rebuild:

 

 

S600 Engine Rebuild Guidlne   BY JP

Does the engine Turnover?  An engine that does not turn over may not be a good candidate for a rebuild if their has been an internal failure.  The engine will have to be torn down to determine why it seized and a determination made to the economics of the rebuild.

If the engine does turn over, motor/clutch function and compression and leak down test

Engine Block

1)      Teardown cleaning and tagging

i)        Generator, starter, undress head, front cover, rear cover, distributor, water pump

(a)    Mark cam chain link Marks

ii)       oil pan, oil pickup and pump, lower case

2)      Check crank endplay and bearing wear

3)      Remove crankshaft –true, bent, worn bearing spec

i)        Rebuild –remove and clean front and rear bearing holders

ii)       Connecting rod tilt, twist and big end clearance

iii)     Piston, wrist pins, rings inspect

4)      Remove liners – clean and check condition of block – corrosion?

i)        Spec sleeves best case hone , worst –re-bore (outside job)

5)      Clean old gasket material from aluminum mating surfaces...by far the most tedious part of the whole operation

6)      Reseat liners

7)      Oil pump parts spec

8)      Install crank – awkward process as crank, connecting rods, pistons all one

9)      Rear seal replace

10)   Water pump condition – seal kit ?

11)   Thermostat

12)   Cam chain inspection –stretch, rollers condition

13)   Starter chain, planetary gears spec

 

Head

1)      Camshaft, sprockets, lifters and tappet clearance spec

2)      Valves, guides, seats spec –best case lapping valves, worst case remove and replace

3)      Choke plates – re-machine -straight forward, I have material already sized for this.

 

Distributor

1)      Bearing,seal,advance test

2)      New points/condenser - source?

3)      Dwell

Carburetors

1)      Assumption is that all rubber gaskets leak and must be replaced. Do you have contacts at Honda? Most of these are available with a huge mark-up.

2)      Test floats and valves and seats

3)      Clean/inspect vacuum pistons and pots and check slide. Polish if necessary

4)      Inspect jet needle

5)      Clean passages

6)      Bolt hole threads on intake manifold are usually stripped from over tightening or repetitively removing the carbs. They will need to be machined to oversize, or better yet, heli-coil or the like.

7)      Intake manifold will not be touched unless leaking

 

Start-up –bench test

1)      Brought up to temperature

2)      Timing

3)      Distributor wire, replace only if necessary

4)      Synchronize pairs of carbs

5)      Throttle response, test for leaks

  

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Some S600 photography courtesty of Karin Johnston