A couple of weeks ago I completed the very simple task of removing the top end of the engine and after sourcing a clutch/flywheel holder and a flywheel puller I could carry on with the bottom end strip down.  By the way, the engine was working perfectly before I stripped the bike down, the reason for the engine strip down is to have the engine cases vapour blasted and painted.

The first item to be removed is the clutch basket, clutch plates and primary drive gear.

The first few steps were very straightforward but I knew that the next steps would be somewhat more difficult after reading various internet forum posts on the subject.  To remove the clutch boss you have to first flatten the retaining washer which locks the 30mm nut (centre of the clutch boss) in place.  You have to then hold the clutch boss in place whilst attempting to loosen the centre nut.  I made the mistake of not clamping onto the outside of the clutch boss but tried to lock it off using the threaded pillars inside the clutch boss.  I hadn’t thought this through and snapped off one of the pillars.  (Bottom left pillar in the picture below).

Using the clutch tool (photo later on in this blog post) on the outside of the clutch basket was much more successful but the 30mm centre nut still required some serious torque to loosen it.

Thanks to rubberfingers at the fantastic TDR250 Forum I now have a replacement clutch boss.  Thanks again Andy!

The next step is to remove the primary drive gear and the clutch housing.  The Yamaha service manual recommends jamming the 2 gears with a folded rag to allow you to loosen the nut holding the primary drive gear.  My first attempt at this used an old pillow case but this was too thin and simply passed  straight between the gear teeth.

My second attempt was with an old towel, but this time the gear teeth simply cut through the towel material.

So in the search for something tough yet thin enough to jam the gears I spotted an old boiler suit which is made of a denim-like material.  This worked and the gears were jammed sufficiently to allow me to loosen the primary drive gear.  This also required significant torque to loosen.

It took me a while to figure out how to get the rag back out of the jammed gears until I figured out that I needed to nip up the primary drive gear nut just enough to turn the assembly in the opposite direction used to jam the rag originally.

To remove the primary drive gear nut I slotted a socket set extension bar through the piston rods to lock them in place.  I’m not entirely sure that this is the recommended method but as the nut was not torqued up it seemed to work well.

The next stage was to remove the gear shift shaft.  The end opposite to the actual foot lever is shown below.

I had already removed the gear lever so the shift shaft could be pushed through from that side.  To get clear access to it I first had to remove the sprocket cover.  As I could sit down in comfort when removing the sprocket cover I also took off the flywheel cover.

The shift shaft could now be knocked thorough (using a rubber mallet) the bottom end of the engine.  I think the fact that it was very cold did not make it any easier to knock it through.

I should point out that the shift shaft did not require an unreasonable level of force to get it moving out but after my previous experiences I took it very steadily.

Now it was back to the flywheel side to remove the flywheel and stator.  Without the prescribed holding tool (Yambits link) I am not sure quite how you can remove the flywheel as it will spin when you try to loosen the centre nut.

Once you have removed the centre nut you then have to use another specialised tool.  A flywheel puller (Yambits link).  You start by screwing in the larger (outer) part of the tool into the flywheel and then screwing in the smaller centre piece which pulls the flywheel away from the stator.

Now the stator and associated cable can be removed.

The crankcase was now almost ready to split open.  The final pieces to be removed were the carburetor joints and intake reeds.

The crankcase could now be separated.  There are a series of numbered fasteners on the top and bottom of the crankcase which (like the head) should be loosened by a 1/4 turn in turn (starting with the lowest number first).  When splitting the crankcase you should start with the lower (higher numbered) fasteners first.

With a little gentle percussive persuasion the crankcase then split into its upper and lower halves which in turn exposed the gearbox and crank shaft.

The gearbox could then simply be lifted out of the bottom half of the crankcase and a couple of retaining rings required lifting out of the case.

Once a retaining washer was removed the gear selector arms could be slid off the mounting bar and the selector cam could be lifted out of the case.

Finally, the crankcase could be lifted out of the case and that was it.  The engine has now been stripped down.

All that remains is to de-grease and clean up the cases ready for vapour blasting and possibly painting.  While the cases are away being vapour blasted I shall measure all of the components for their service limits and order replacement parts where necessary.

My first attempt at aluminium polishing was pretty good but there were still small (but still visible) horizontal scratches in the finished item.  My first thoughts were that this was a “grain” in the sheet aluminium used to make the exhaust end can.  With this in mind, I decided to try the process again but this time start with the coarsest sanding grade at right angles (vertically or up and down) to the aluminium “grain”.

In the close-up photo (below) you see the vertical or up and down direction of the first sanding grade.

I then proceeded to sand using the 120, 240 and 360 grades in alternating horizontal/vertical directions.  Each time I changed down a grade I ensured that I removed all traces of the previous grade’s sanding marks.  The photo (below) shows the 40 grade (vertical) sanding on the lower half of the piece and the 120 grade sanding (horizontally) on the upper half.

The final sanding grade (320) finish can be seen in the photo below (sanded horizontally):

I then moved to the white/blue polishing compound and the stitched mop and finished off with the felt mop and the green polishing compound.  The polishing was completed with some metal poilsh and a cloth to remove the black aluminium residue.  I was rather dissapointed to find that the exhaust still had some scratch marks in the final finish, however they were not as visible as the ones found after my first attempt.

I then remembered that I had gone from the 320 grade sanding straight to the stitched mop and white/blue compound.  I had not used the coarser “string” mop and the grey polishing compound.  To correct this I then used the “string” mop and grey compound in the opposite direction to the small scratches and then repeated the polishing steps with the sticthed mop and felt mop (in the opposite direction to the “string” mop).

This worked!  After giving it a final rub down with the metal polish there it was: a beautiful mirror polished finish without the grainy/scratched appearance!

The method clearly requires you to change between every grade of sanding/polishing.  Don’t be tempted to skip any, there are no clear shortcuts (I think).

I’ve only done this for one small strip of the exhaust can, so there’s still some work to do to complete both end cans and the swingarm…..  The process requires patience but if you are in the right state of mind it can be very relaxing, therapeutic and rewarding.

I have a number of aluminium parts for this project that I want to polish but I have never actually done any polishing.  Last Sunday I made my first attempt at aluminium polishing on one of my exhaust end cans.  This blog post describes the method and equipment used.

This is how the exhaust can looked before I started the polishing:

I have read quite a few articles on the internet and watched several videos on YouTube about aluminium poilshing so it felt like I had done my homework over the last 2 weeks.

Here’s a list of tools and consumables that I’ve purchased for aluminium polishing:

• Cheap corded drill.
• Mr. Fastner polishing kit.  Link to product at M&P
• A number of aluminium abrasive flap wheels.  Link to product at MSC/JL Industrial Supply
• Latex gloves.
• Dust mask.
• Eye protection.

The end can did not appear to be heavily scratched or pitted so after reading the instructions that came with the polishing kit I decided to try the coarsest (brown) polishing compound with the hardest polishing mop first.

You can see the yellow string in the mop which will give a mild abrasion.

It soon became clear that this was not abrasive enough as it really wasn’t removing the scratches, pits and grainy appearance of the aluminium.

As the shortcut route had not worked I had to bite the bullet and do things the right way.  I have 4 different aluminium flap wheel grades: 40, 120, 240 and 320.  Starting with the lowest number (coarsest) flap wheel, the whole exhaust was sanded.  The 40 grade was used from left to right (horizontally), the 120 grade was used up and down (vertically), the 240 grade was used from left to right and finally the 320 grade was used up and down.  You get the idea?  You should sand in the opposite direction with each different grade.

The result of the 40 grade sanding can be a little worrying as it removes any shine that the item may of previously had.  Don’t panic though, honestly.  The 40 grade removes any scratches and leaves a satin finish.  You can see this in the photo below: the bottom half has not been sanded and the top half has been sanded.

As you work through the sanding grades the finish becomes less “scratched” and more polished.  It can be difficult to see where you have sanded with the next grade though so good light is essential when you are doing this.

Now it’s time to go back to your polishing mops and compounds.  As the 320 grade had left a fairly smooth finish I did not bother with the brown compound and harder “string” mop.  The first polishing stage used the blue compound and a stitched mop.  The polishing stages are much quicker and satisfying than the sanding stages but it seems that like all jobs preparation is the key.  Without a decent sanding job you will not get the polished finish you want.

The second (and final) polishing stage uses a felt mop and the green compound.  Just a quick note: when you are using the polishing mops and compounds the aluminium will become blackened by the removed aluminium particles mixing with the polishing compound, just keep going and it will disappear. There is also a pot of lime powder (included in the polishing kit) that can be dusted onto the aluminium and rubbed off to remove any grease.

For a first attempt at aluminium polishing I was very happy with the results but I had made one mistake which only became apparent at the very end.  The aluminium used in the exhaust can has a “grain” which goes from left to right (horizontally).  This grain could still be seen after the final polishing stage (see photo below).  I think this was a result of using the first sanding grade in the same direction as the “grain”.  I’m going to have another go on this exhaust can but will start with the 40 grade in the opposite direction to the “grain”.

One final tip to end this blog post: after sanding with the 40 grade wheel it became difficult to see where I had sanded with the different grades (120, 24 and 320) so next time I will sand the whole piece with 40 grade but then sand and polish one area completely before moving onto the next area.  Hopefully this will mean that I can clearly see where I have sanded and result in a more thorough sanding stage which in turn will result in a more polished finish.

That is all for now, thanks for reading and good luck if you are trying some aluminium polishing.

Just to clarify, Mildred’s previous owner had replaced the original TDR250 engine with a TZR250 (2MA I think) engine.  Even though it was running well before the start of this project I need to strip it down to have the cases vapour blasted. Once vapour blasted I am not sure whether I will paint the cases black, grey or clear coat them.  I guess I’ll decide once I get the cases back from vapour blasting.

This is the first time I have ever stripped a 2-stroke engine and I’m sure that I will learn a lot along the way.

Here is how the engine looked with it removed from the frame:

The aim for this stage was to remove the head cover, barrels and pistons but the first task was to drain the transmission oil and any remaining coolant from the engine.  The fact that it was -1C outside did not help as ideally you would have a warm engine before draining the oil but as the engine is out of the frame there was no option but to do it cold.  I carefully positioned the engine on my cheap Wickes “workmate” and left it to drain whilst I went for a cup of tea.

The following steps were taken to strip down the top-end:

A. Remove spark plugs.  Note to self: I really must buy a spark plug spanner.

B. Remove water pump.

C. Remove head bolts/nuts in order.  Start with the highest numbered fastener and loosen each one in turn by a 1/4 turn before removing all of them.  4 of the nuts were dome headed and these were fitted with copper washers.  I’m not sure why this is done but I will replace these with new copper washers when I put it all back together.  One of the studs came out completely but as they all need to come out this is not a problem.

D. Carefully remove the head to expose the barrels and head gasket which is sheet metal.  It also has a handy marking indicating which side should be in contact with the head.

With the head off it became apparent that the left cylinder had let go at some point in its history.  The head was pitted as you can see in the 2 photos below:

E. Remove the power valve link between the barrels.

F. Remove the barrels.  The lower right (right barrel) and lower left (left barrel) nuts required careful removal as they are tight to the barrels.

G. Remove the pistons.  These are secured by circlips which should be removed with caution to ensure that they do not drop into the crankcase.  With the pistons removed I could see that the left cylinder has definitely had some repair work in the past.  The piston crown is marked with “0.50″ which I am assuming means that the barrel has been re-bored and an oversize piston has been fitted.  The right piston is marked with “0.25″.

And here’s how the engine looked at the end of the day.

I will carefully measure all of the top end components to see what needs repair or replacement.  I will have to consult people who know far more than me regarding the fact that the left and right cylinders have different bores/piston sizes and it may end up requiring some machining to make them the same, complete with new pistons/rings.

The last few parts attached to the frame should have been removed today.  The following parts were left attached to frame:

• Rear brake light switch.
• Rear suspension relay arm.
• Frame identity tag.
• Helmet lock.

The rear brake switch spring is looking a little slack and tired but the switch itself seems to be in very good condition and was easily removed.  Note again some more interesting electrical work by a previous owner….

The suspension relay arm was a different matter altogether.  The bolt will not come out, it just turns in the relay arm.

After consulting the better informed folks at the TDR Forum, it appears that this is a common problem where the bolt corrodes and seizes in a sleeve within the relay arm.  The only course of action is to carefully hacksaw either end of the bolt to free the relay arm.  I skipped that and will attempt it in a few days.

This just left the frame identity tag and the helmet lock to be removed.  The frame tag rivets are very hard and I could not easily centre-punch and drill them so I just ended up chiseling the rivets to snap the heads off.

When I saw the frame mount for the helmet lock I feared the worst but thankfully some of Halford’s finest freeze and free spray freed it up no problem.

It was just a case of making sure that the star drive bit was properly engaged (with some percussive persuasion) before attempting to loosen the bolt.

Again, I had not been able to make a return visit to the project as soon as I would have liked but I braved the cold and cracked on the day after Boxing Day.  Here’s where I started the day:

The plan for the day was to remove the headstock and bottom yoke, remove the engine, drill out the rear brake master cylinder (after rounding a bolt) and removing the frame rubbers.

Removing the headstock and bottom yoke is a very simple job and just requires the removal of the top nut.

Upon removal and inspection of the bearings and races, they all looked to be in very good condition with no noticeable wear.  I’m not sure how much of the current steering I will be re-using as I have some parts from a TZR125 Belgarda for the front end.  If I don’t re-use any of the TDR parts then they will find a good home via eBay, along with quite a few other parts.

The longest job of the day was the removal of the carbs.  This took much longer than I had expected due to the choke, throttle and various other tubes and cables that are attached to them.  Some of the removal process required a bit of improvisation as seen below when removing the power valve pulley.

With the carbs and the two-stroke oil pump removed, the engine was clear to come out of the frame.

The engine came out much easier than I had expected and it really feels that I am making progress now it is separated from the frame.

The final task was to go back to the frame and remove the rear brake caliper and assorted frame rubbers.

Earlier in the strip-down, one of the rear master cylinder’s bolts had rounded and my metal drill bits were worse than useless.  I had sourced a much more suitable set of drill bits and a tap and die set in the meantime and having the right tools really made a difference.

The thread in the frame will need re-tapping but the master cylinder came out very cleanly in the end.  I will run a tap through all of the threaded frame parts before I send it away for powder coating.

There are around half a dozen frame rubbers that needed removal and I have been very careful to record the location of each one as it was removed.  If the rubbers are available as genuine Yamaha parts then I shall order new ones but if needed all the old ones are in a reasonable condition and can be re-used.

Here’s how Mildred looked at the end of Day 4 of this project:

The next job will be to check that everything that can be is removed from the frame and then prepare it for powder coating.

I’d been away with work for just over a week so the strip down process was delayed  a little longer than I had planned.  The plan for last Sunday was to remove the cooling system, swingarm, rear brake system and the wiring loom.

Here’s where I started the day:

The first task was to remove the rear brake system, I had already drained all of the brake fluid from it.  I’ve been quite lucky so far and most fasteners have come out with no major issues however the top mounting bolt of the master cylinder was an exception to this.  The socket head had already been rounded by a previous owner so it would not come out.

I started to drill it out but soon discovered that my HSS drill bits were not the sharpest tools on the box.  I guess the back-end of the bike must get the worst of the road crud as the rear brake reservoir was also seized (and slightly bent I think but hard to tell with the state it was in).  So I now have 2 fasteners that need drilling out and the hole re-tapping.

I then had to remove the airbox so that I could remove the rear shock and then in turn the swingarm.  Removing the airbox cover revealed a rather tired/rotten air filter element.  I don’t know how long it had been in there but I had never actually checked it.

I will be replacing this with a new aftermarket filter from a guy on the excellent TDR250 Forum

The shock and the swingarm were then removed with no real drama.  I had expected some issues with both/either of these but thankfully there were none.  I have a replacement aluminum swingarm (from a Japanese TDR250) which needs polishing and the original shock is rather tired and I shall probably replace it with a new Hagon shock.

The footpegs and rear brake lever were then removed and I found that the right footpeg bracket was a little out of shape:

A slight adjustment with a rubber mallet soon straightened it out without any damage or cracking to the bracket:

The rear brake switch spring was also looking rather tired and soon to fail,  I would not have fancied trying to fault find that with the bike intact.

The engine coolant was then drained and the radiator and associated hoses stripped off Mildred.  Note to self: when draining the coolant, hold your bucket level with the coolant drain plug as the coolant comes straight out at you (horizontally) not downwards.

The final task of the day was to remove the tacho, clutch lever/cable and the wiring loom.  There are some interesting repairs and modifications to the wiring loom and electrics:

Some genius really had a blinder with the repair shown above…..

Another point of interest was the replacement coil which appears to be from a TDM850.  As original parts can be rare and expensive for TDR250s this is useful information.

On the whole and considering its age, Mildred’s wiring loom is in reasonable condition and easily repairable.

And that was that for the 3rd day of the strip down.  Here’s where I started and ended the day:

It only remains for me to remove the head stock and the engine now.

I didn’t get as much done as I had planned on Sunday as removing and draining the fuel/oil tank was more of a pain than I had expected.  I had planned to drain the fuel/2T oil, coolant, gearbox oil and rear brake fluid but did not quite achieve this.

I had heard tales about how tricky it was to remove and drain the TDR’s fuel/2T tank and I soon learned this for myself.  As soon as I lifted the tank away from the frame the two stroke oil tube came off the bottom of the tank.  I did not see this happen and the first indication of it was a pool of two stroke oil on the floor.  Thankfully I had some cloth nearby to stem the flow while I grabbed the waiting oil drain container and pulled off the tube which connects the 2T oil tank to the TDR’s auto-lube pump.

After a couple of minutes I spotted an old coffee jat that I could wedge into the frame so that the last of the oil could drain without me holding the receptacle while it drained.

Next time I do this I will drain the 2T oil before removing the tank by disconnecting the auto-lube tube from the auto-lube pump and draining it from there.

While the last of the oil was draining I decided to drain the rear brake fluid.  One of the bleed nipples on the rear caliper had seized and nothing I tried (or used) would shift it.  In the end the predictable outcome was reached – snapped off bleed nipple.

This is the first fastener that has refused to come out during the strip-down and ended up damaged, so I guess that’s not too bad.

My MityVac was again used to make very short and clean work of draining the brake fluid from the rear brake system (I sound like I’m a MityVac salesman but I’m not, honest).  By this time the two stroke oil had drained completely so I could remove the tank and then spend the next 20 minutes draining the petrol into every petrol can I could lay my hands on, it’s amazing how far a few litres can go.  The last of the fuel in the tank was a pig to drain as you need to swirl the tank around to trap the fuel in one corner then tip it up to drain it through the fuel tap.  The fuel tank looks like a real cock of a job to replace, I fear for my knuckles.

By this time I had had enough of draining fluids so chose a simpler task and removed the rear light and mudguard from Mildred’s rear subframe.

By the time I had finished my few hours labour I had bought a TZR125RR Belgarda front end, front brake and front mudguard for this project.  I just can’t resist the USD fork option but this has added more money and much more time to the project.  Am I getting in too deep?  When will it all end?

I’ve finally managed to get round to starting the strip down of my TDR250, a combination of traveling with work and watching Cheltenham Town has delayed things by a month or so.

I have big plans for this project but I’m not really sure how long it will take to complete but it will never get finished if I don’t start.  I reckon I will have done well to get it finished by June 2010 but will be happy just to finish at some point next year.  Let’s see what the reality turns out to be…..

Here’s what she looked like before I started the strip down:

I’ve got a huge list of things to change/refurbish; body work, wheels, frame, front end (would love to fit USD forks), seat, tank, dash, swingarm, rear end.  Enough of that and on with the stripdown.  Every fastener is being tagged and bagged as I go along and I have a load of storage boxes for everything that comes off.

I’m also obsessively taking as many photos as possible.  I do I have a full workshop manual but photos also help when it comes to a rebuild in another 6 months (probably).

The first thing to come off was the exhaust as I cannot use my bike lift while they are fitted.  Once up on the bike lift it was off with the plastic body panels.  I have some excellent condition replacements so the panels from here will end up on eBay or sold to a member of the most excellent TDR250 Forum

The first strip down day was spent working on the front end of Mildred.  Dash, headlight, forks, yokes, bars and levers being removed.

The bulk of Mildred’s electrical wiring is contained in the front end and the stripdown has revealed a number of repairs and other issues that need resolving unless I want long-term electrical problems.  The indicator wiring has been repaired a number of times and the headlight connector has a terminal that has broken free from the connector housing it.

Once the headlight, dash and temperature gauge were removed I could then drop the front forks out and remove the radiator guard.

Next the front brake system fluid was drained so that the parts could be stripped down.  My excellent MityVac again made short work of this job.  It quickly and cleanly drained the brake system.

The bars and associated levers/switches could then be removed.  This was quickly followed by the top yokes and rev counter and that was that for day 1.  Front end stripped down and no parts damaged, result.

I shall be cracking on with the tank and draining the oil/water/rear brake fluid from Mildred later today.  At this rate, the strip down should be complete by the end of next weekend.

In my last TDR post (about fitting the underslung exhaust system) you may have seen that I thought the exhausts sounded like they were blowing from the manifold.

I spoke to the guy who actually designed and made the underslung exhaust system (martin77 at TDR250 Forum) and he recommended using some Permatex Ultra Grey gasket paste and a new set of exhaust gaskets as I had not replaced the original gaskets (or used any additional paste) when I fitted the exhausts last week.

So it was off with the exahusts which is a 5 minute job as there are only 2 springs and one bolt holding on the exhaust and 2 nuts securing the manifold.

With the exahust (and manifold) removed, I could see exactly what gaskets were fitted.  The answer was only the paper(ish) one and not the metal gasket that should sit behind it.  I had assumed that the metal gaskets were in place when I fitted the exhausts.  Never assume anything (I guess).

I then cleaned and degreased the manifolds, mating surface of the engine and the ends of the exhaust pipes.  When using gasket paste it is always wise to have the cleanest application surface you possibly can.

Next, the manifolds were re-fitted this time with the the correct gaskets (copper and paper gasket).  I could now actually feel the copper gasket compressing as I torqued up the manifold nuts although I was incredibly conscious of shearing off a stud (Which I didn’t).

Then 2 beads of the gasket paste were applied to the exhaust pipe (where it mates with the manifold).

The pipes are made to be a close (almost interference) fit with the manifold and this ensures that the paste will provide an excellent seal.  When the pipe was pushed home there was a small amount of gasket paste that needed cleaning off and this comes off very easily with a clean cloth.

The initial curing time of the Plastex Ultra Grey is 1 hour and full curing after 24 hours.  I’m writing this as they are curing, so hopefully they don’t sound quite as blowy when I next start her up.

I had been advised to leave the paste to cure for an hour then start the bike and use the exhaust gas heat to finish the curing, so that’s what I shall do.

I will report back here on how she sounds after I’ve given it a while to cure.