tips on backyard rebuild , honing , piston cleaning etc

[steveo3002]

got a little vw engine that i plan to give it a quick back yard freshen up on a low budget

i will have a machine shop replace the valve guides and plan to fit new bearing shells and probably piston rings after inspection

what are your thoughts on home /diy glaze busting or honing , ive been reading the 3 legged stone ones arent the best , but the ball hones are expensive and hard to find here in the uk

also what about cleaning up the pistons , what can i use

 

[shed or dead]

When I was at college I honed a Honda XR600 cylinder using a 3 legger and we measured the cylinder before and then repeatedly during using a (don't know the name) 2 axis air-bearinged probe thingy which plotted the shape on computer. We achieved factory tolerences (for a 1 size over piston).

The honing was done using a decent pillar drill but can be done using a hand drill as the hone has a certain level of self centering built in.

One potential problem is that the stones aren't very well adhered to the hone so risk falling off. Give them a few gentle knocks to see if they need re-gluing before use. We also conditioned the hone in another cylinder first to take off the squared edges.

 

[Sean]

easy ive done many. if your visiting the machine shop take the crank and cases in for measuring - they have usually been hammered and rebuilt many times and getting the correct bearings to fit is fraught with difficulties. Double check the heads for cracking between the ports and plug hole. new valves? dont just fit old ones check the cam lobes and bearings for wear

For the price of a set of barrels Id not bother buying a hone and rings just get a decent set of pistons and barrels. if you really want then the 3 legged ones are ok hold the barrel horizontal in a vice and use a battery drill on slowest setting and move the whole thing in and out as it turnss so you get the 45* hones. Lube the barrel well with parrafin/ diesel/ oil cut with white spirit - has to be light or the stone clogs.
re assembly is just a reverse......as they say - keep it clean oil it and spin the crank a few times after every operation to make sure you havent done something stupid. Fill the oil pump rotor with vaseline or it can starve of oil when you first start it there is a whole procedure to starting a new engine but you're a bit off that just yet.

Check out the many thousands of pages on VZi ( VolksZone international)

 

[Robotstar5]

I did a bike cylinder using the 3 leg type in a battery drill using kerosene as a lube, worked fine.

 

[pedrobedro]

I use 3 in 1 type oil and don't hang about with the hone, move it in and out pretty quick while it's spinning. When the barrel wall looks dull it's had enough, if you keep at it too long it will be a rebore

 

[bill_gj]

I've used the 3-legged type hone with success. As already said, a battery drill, slowly, slowly. I use parafin as the lubricant and keep swilling the bore while honing - get someone to help. Don't ever let the hone stop in one place, keep it moving and get the 45° pattern.
I clean pistons with diesel or parafin. After an overnight soak give them a rub with one of those green nylon kitchen scourers and nearly all of the old deposits and carbon come off.

 

[dannyp]

I picked up a free old dishwasher.

double dose it with tablet things and duff in all the engine bits you want cleaning in.

if it's an aircooled vw motor id be tempeted to get a set of barrels and pistons, aircooled engines arnt exactly kind to there cylinders. but if they measure up and your happy using them cack on, 3 leg hone will be fine the aircooled lumps arnt exactly built to tight tolerances

 

[Shox Dr]

I've always been taught a rebore is better than a new set of cylinders as they had had time to heat cycle many times, relieving any stress: so making them a better long term

 

[Sean]

brake cleaner works on the pistons too dries out the oil varnish to a powdery residue which washes off easier. Dont use the broken ring to clean out the ring groves as you can gouge the lands
Id watch putting the mag alloy cases in a dishwasher with soda, they are pretty reactive youll end up with a white fluffy thing.

 

[lshigham]

I've always been taught a rebore is better than a new set of cylinders as they had had time to heat cycle many times, relieving any stress: so making them a better long term

A rebore done well will make it better or as good as new, cleaning up with a hone in your back garden is probably not in the same league.

 

[steveo3002]

yeah rebore wont be happening

its a used engine ..kinda looks ok to use as is , but id like to have a lookie inside and refresh it for something to do

 

[MrFluffy]

why are you honing it? just to glaze bust? then the 3 legged things will do the job and thats all it will do. It wont correct any inherit defects but sounds like that isnt what you are trying to achieve. You can take a ring and measure the end gap at various points with feeler gauges, use a ringless piston to push it square, and that will let you assess the extent of any wear on them without it getting expensive in tools. As someone else has hinted at, you cant glue material back on with a hone so either you live with increased piston skirt clearance and resulting noise after and try to correct it with new rings, or you take it the next oversize to restore fit. When your honing its worth remembering you need to pass the middle of the cylinder faster than the ends, as for each stroke you sweep the centre portion twice. And diesel drizzled down it while you do it helps.

The non springy hones are made for correcting geometric defects post rebore and giving a better final fit. I aim for 0.003" undersize with the boring bar and hone to a fit with my raybrook (delapena type) cylinder hone. Even they can't glue stuff back on if its worn out though.

 

[MrFluffy]

I've always been taught a rebore is better than a new set of cylinders as they had had time to heat cycle many times, relieving any stress: so making them a better long term

The use of seasoned blocks is well known about in race prep circles, chris barre going on about it for some program on tv :-

 

[steveo3002]

yeah just a deglaze for re ringing


rings are rather expensive , so are you saying i could carefully remove the old ones and measure if theyre worth re using ? would i still hone if reusing?

 

[the snooper]

have you seen this engine run properly and under load ? if not I would check how oval the cylinders are before spending a lot of cash on it, nothing worse then finding out an engine smokes when you have just spent a load of cash on it

 

[MrFluffy]

Id budget on re ringing it myself, rings loose tension with age and heat cycles. I am on a tight budget and run used pistons in new liners but always spring for new rings and gap them.
But first you need to assess what you have and if its worth spending on. The ring at various points will be better than guessing, but better a bore gauge which you can measure ovality etc.

 

[MrFluffy]

yeah just a deglaze for re ringing


rings are rather expensive , so are you saying i could carefully remove the old ones and measure if theyre worth re using ? would i still hone if reusing?

To be specific i am suggesting you remove one and use it as a measuring tool to assess wear on the cylinder at various points.

 

[Sean]

you can diagnose the wear in a bore using the hone - stick it in and give it a quick 5 second blast without going up and down too much, wash the barrel and have a look wear will be the shiny dark areas the light grey the less worn area you want to check the top 20mm of the swept area as that's where most wear occurs.

 

[bill_gj]

Aged blocks - once upon a time, in the long distant past, in a galaxy far, far away........manufacturers of 'quality', 'up-market' engines used to stack raw block castings up and leave them for a few months before machining them. The rationale was that the stresses induced during the post-casting cooling phase would settle out and any machining carried out would retain accuracy over time. It was always thought that this gave a better finished product.

 

[the snooper]

Aged blocks - once upon a time, in the long distant past, in a galaxy far, far away........manufacturers of 'quality', 'up-market' engines used to stack raw block castings up and leave them for a few months before machining them. The rationale was that the stresses induced during the post-casting cooling phase would settle out and any machining carried out would retain accuracy over time. It was always thought that this gave a better finished product.

with todays measuring technology it would be interesting to test that theory