A forum for owners of Yamaha TTR250 trail and enduro bikes!

Lin · Senior Member

RE: DROWNED

Lin · Senior Member

Time has been hard to find, but a little more was achieved last Monday....

The primary drive gear, oil pump and clutch was fitted. I coated the clutch plates in fresh oil. The red stuff on the end of the crankshaft is grease to pre-lube the oil seal fitted into the side case. To the right of the oil pump is a very important seal that seals the oil coming from the pump to the relief valve and oil filter in the side case. I have put a generous amount of engine building lube into the oil pump to seal it's internal clearances and encourage it to suck oil from start-up.

The service manual shows a special tool to hold the clutch drum to allow the retaining nut to be tightened. However if one rotates the shift cam and selects 2nd gear, the output shaft can be held and the clutch retaining nut tightened without any problems. This pic shows the output shaft being held.

Inside the clutch side side case. Note the oil seal (black semi-circular object) It is vital this seal is installed with the sealing lip facing inwards. It transfers oil from the oil filter to the crankshaft. The cylindrical object above is the oil pressure relief valve. Above it is the retaining bracket secured by a small bolt; the oil transfer seal is secured similarly. To ensure these bolts remain tight a drop of Locktite was used.

The appropriate Locktite 243. It is a threadlocking grade and will not allow most threads to undo of their own accord yet will allow disassembly without difficulty. Don't be tempted to use the stronger grades (bearing mounting grade etc) in the mistaken belief that "stronger is better". What will result is bolts pulling the thread clean out of the aluminium when disassembly is attempted.

Side case fitted, Locktite was not used on the side case fasteners. A new oil seal was inserted gingerly over the kick start spline and tapped into place.

A new oil filter was fitted and the oil filter cavity filled with fresh oil. Two filters can be used, HF142 which is a fine mesh bronze wire filter (which is really a debris screen) and HF141 which is a paper filter. For the initial run-in period I will use the finer paper filter.

Turning to the other side. The starter gear was fitted on a new pre-lubed bearing.

A little drop of 243 on the bolt that holds the starter clutch and flywheel on.

Locking the crankshaft with a piece of hardwood the bolt was torqued up.

-- Edited by Lin on Thursday 18th of October 2012 09:53:49 AM

-- Edited by Lin on Thursday 18th of October 2012 09:55:01 AM

-- Edited by Lin on Thursday 18th of October 2012 07:50:21 PM

-- Edited by Lin on Thursday 18th of October 2012 07:54:54 PM

Cubber · Super Guru

Wow - it's going to be better than brand new. smile

What a detailed and informative assembly thread - very impressive.

Such patience will be rewarded. Keep on in there, Lin. biggrin

Martyn

Lin · Senior Member

Thank you Martyn. It has been difficult to get a clear run at the job, other commitments etc get in the way. And the missus is not happy with an oily camera....
More to follow.

Lindsay

Lin · Senior Member

Another free Monday and a considerable amount was achieved....

A white dot was added over the TDC mark using the Pental white marker. This product is unaffected by hot oil.

Starter gears fitted and case fitted.

I don't apply Locktite to side case fasteners but this one is an exception and had a threadlocker applied in the factory. If it ever worked loose the starter gears would be damaged.

The TDC mark is clearly visible.

New seals fitted to gearshift and final drive.

The new Wiseco piston was fitted to the rod. The piston pin was a very tight fit in the piston, making installation difficult. I put the pin in the freezer for 30min and heated the piston to 70deg in the kitchen oven. This made pin fitting simple. The wire circlips that retain the pin were quite tricky to fit so patience required here. Ring end gaps were checked in the barrel before the piston was fitted.

Barrel fitted with the piston a BDC. Pre-oiled the piston, barrel and rings. The piston slid in easily with a slight side-to-side rocking of the barrel and some gentle finger pressure on the rings.

Turning to the head, the valves were removed. The correct spring compressor helps here.

The stem oil seals were removed with a hook tool.

The head was cleaned up and the valves lightly lapped in. As the engine had only done 3000km the valves and seats were unmarked.

New stem seals were fitted by sliding them onto an oiled Phillips screwdriver. The valves are 5mm stem size, the screwdriver is 4.90mm. The seals were seated on the guide with a gentle push on the screwdriver handle.

Valves refitted. A dab of grease on the collets assisted with keeping them in place during reassembly. Also of great assistance was my reading glasses....

TTRfan · Super Guru

Getting close to it running Lin - you may get there ahead of Jarrah unless he puts a spurt on wink

The photo sequence of fitting the timing chain tensioner is helpful as we have had a few issues with those lately. If it's tricky with the engine out, it is slightly worse with the engine in! After struggling a few times, I now use a small screwdriver (whose plastic head had broken off) and put a blob of resin on the end and it's possible to hold the screwdriver and the tensioner with one hand whilst putting in the Allen bolts. Best to make sure the Allen bolts are an easy fit first though.

Adapted screwdriver.jpg

Brian

barra8 · Guru

To be fair on Lin i did cheat & find a good bottom end to save the extra $$$ spent re-building the bottom end. Also got my local mechanic to do the valves as the tools to do it would have cost just as much. Atleast it's less i have to worry about though smile

........................

Jarrah.

Lin · Senior Member

Continuing with the cyl head...

The old intake side camshaft was corrosion damaged and barra had kindly provided me a replacement. This pic shows a method of holding the cam without damaging it while the sprocket bolts are removed and replaced.

The valve clearance shims were held in place with a little grease. Note the rags stuffed into the timing chain cavity. Dropping a shim down there would be very undesirable.

The sides of the cam followers were showing very light traces of abrasion scuffing from the silt so were polished with Scotchbright.

The timing mark was lined up, however...

The magnets in the stator refused to allow the crankshaft to rest at TDC, so a small screwdriver was lightly wedged in to hold against the magnets.

Cams were fitted. Pre-marked timing marks lined up.

MoS2 lubricant on the caps as per Yamaha manual.

Cam bearing caps fitted. The engine position is piston on TDC firing. As the TTR engine has no cam position sensor the ignition will fire every time the piston is at TDC. The spark on the TDC exhaust position causes no problem and is commonly referred to as "waste spark".

MoS2 lube on the cam lobes.

Chain tensioner in the extended position.

Small screwdriver inserted into the tensioner and rotated pulls the plunger back.

Holding the screwdiver while fitting the tensioner requires some juggling. Important not to allow the tensioner to extend before the mounting bolts are tightened or damage would result.

Checking the valve clearance. Luckily ok at 0.005" on the intakes and 0.008" on exhausts.

Lin · Senior Member

Continuing the saga...

The starter was stripped to check for contamination - found to be in good order.

A drop of oil applied to the bronze bush. The brushes are free in their holders and in good nick.

Armature re-inserted after cleaning the slots in the commutator and a little high melting point grease on the end float shims.

Note the alignment marks and locating notch on the yoke body.

Fit the notched end of the yoke body so it aligns with the tag on the brush end-frame. Reversing the yoke body will result in a starter that runs backwards.

New genuine Yamaha square section O rings replaced the old ones that had swollen. Fitting circular section O rings doesn't work, they expand out of the groove when the through bolts are tightened. The Yamaha O rings are extortionately expensive.

A little high melting point grease on the drive end bearing.

New O rings on the through bolts.

Tested on a 12v battery and ready to refit.

Refitted with a drop of Locktite.

Starter refitted, last job is to refit the oil feed pipe.

Job finished, now ready for crating and shipping back to the Philippines.

To anybody thinking of undertaking a similar project:

1. First and foremost, a copy of the service manual at hand will prevent hours of head scratching and damaged parts. Can't emphasise this enough.

2. Correct hand tools, preferably a 1/4 drive and a 3/8 drive socket set, a 30mm socket to loosen the sprocket nut. Undo it before you remove the engine from the frame by putting the transmission in top gear and holding the rear brake. A range of metric Allan keys or equivalent hex square drive sockets. A torque wrench. A clean dust free workspace.

3. A small universal puller to remove the left crankcase, although some gentle rubber hammer work may do the trick. An M18 x 1.5 bolt to pull the flywheel.

4. An indelible marker pen such as Pental for marking part orientation, location etc and a camera to record it just in case....

5. Access to various bits of pipe, heavy washers, bolts etc to make up bearing removal tools as described. Or better yet - proper bearing removal tools.

6. A friendly wife that will allow you to chill bearings in the freezer and heat crankcases in the oven.

7. Never, never hurry. Take your time, and have many parts containers on hand. Each section of the motor has it's own box. Head, left side, right side, clutch, starter gears etc. Make up cardboard crankcase bolt location templates as shown, it will save huge grief.

8. A refrigerator containing cold ale. As Haggis Hunter said, this will allow inspiration, gentle reflection on what has been achieved so far, and what is yet to be done.

Thanks to barra for the inlet cam.

Cheers

Lindsay

-- Edited by Lin on Saturday 24th of November 2012 10:12:45 PM

Cubber · Super Guru

I read on someone's previous thread that the motor can run backwards if the rebuild isn't done carefully. confuse biggrin biggrin biggrin

It's looking good Lin. The "better than Haynes" pictures and description are well worth a sticky for this posting.

Won't be long now and I hope your floods don't return.

By the look of our Southwest weather over the past few days I'm thinking of parking my bikes in the bedroom. smile

Martyn

TTRfan · Super Guru

A geat end to your "story" Lin.

I hope your engine arrives back in the Philippines safely and that you soon have the opportunity to run it in and reap the reward for your efforts.

I am not very good at stopping to take pics as I get too engrossed in the job so appreciate what you have done in documenting it so patiently for us all

Brian

barra8 · Guru

Good work lin....hope it goes like new for you. You deserve it after all that detailed effort

................

Jarrah.

Lin · Senior Member

The Sequel:

Here I am in the Philippines on the island of Siquijor. Yesterday I refitted the engine in 35deg and high humidity. A lot of ale was drank last night to replenish fluid loss. Today all final adjustments were done and after figuring out we didn't refit the negative ground lead to the engine, it started first pop. Done 100km this afternoon and it responds to the slightest throttle input, really feels like it wants to go. Some running in to be done, an oil change and then away we go on another adventure!

TTRfan · Super Guru

Brilliant news Lin - enjoy your holiday biggrin biggrin

Brian

Cubber · Super Guru

Definitely good news Lin - most pleasing and welcome.

It's funny how your TTR didn't like too much liquid, yet the rider does. confuse

Take it easy and please enjoy yourself.

Martyn

TTRfan · Super Guru

I respect your engineering skills Lin so what will be your running in routine?

How many miles before first oil change and what sort of use - also, how many miles on it before you try WOT?

Brian

Lin · Senior Member

Thank you for the kind wishes Brian and Martyn. Last nights intake of liquid inspired me to ride around the island today, so the total km on the clock is now 150km (90ml)

Concerning running in, one can listen to many pub-talk theories and for all I know some of it may be valid. However a lot of original research on running in was done by Rolls Royce Aircraft Engineering and the Allison Aircraft Engine company during WW2 when they were building ginourmous piston engines for long range bombers. It's interesting reading and valid today. However we cannot normally run in our bike engines on a dyno...

Concerning my TTR. I have filled it with 4T 10w-40 SG mineral oil and fitted a paper element filter. For the first 200km I use about 25% throttle and less than 40% of max rpm. A couple of brief 50% throttle applications to knock the asperites off, and some down-hill closed throttle over-runs to get some oil washing around the ring pack. After 200km will increase to 50% throttle and 50% max rpm to about 500km, then 75% throttle and 75% max rpm to 700km when I'll change the oil and filter, this time 4T 10-40 SH or better synthetic oil and a mesh filter. Will continue until about 1200km, then I'll use WOT/high rpm judiciously for another 300km or so.

I think it's important to understand that piston and ring temperature is almost proportional to the volume of air/fuel being burned. A new piston, rings and bore surface are initially going to generate heat from friction until the bed down and stabilise, so adding too much throttle too early may raise the temperature beyond the oil additives ability to lubricate and do some mischief.

But then again, there are plenty of websites that would dispute the above and advocate WOT from the outset....

TT-R250M · Super Guru

Hey Lin, glad to hear all went well for you.

Your running in method sounds a lot like mine and would be good for any air-cooled steel bore engine to ''run in'' like that.

Good work, take it easy and have fun!

Jarrah

Lin · Senior Member

Update.
My brother and I left the island of Siquijor 0600 Sunday morning (both on our TTRs) with the intention of riding to Cebu City via the island of Negros and the city of Dumaguete. About 160km and a good start to the running in process. Arriving at Dumaguete off the ferry around 0800 the speedo promptly failed. So noting the speedo reading on my brothers TTR we continued from Dumaguete up the coast and caught the ferry over to the southern end of Cebu island and rode up to Cebu City.

The engine performed flawlessly and was instantly responsive to the slightest throttle command. I had fitted the short exhaust front pipe and at that stage retained the original muffler. On reaching Cebu city we did a couple of short trail rides out back of Cebu city, then called it a day. Yesterday morning fixed the speedo, dropped the front forks 20mm (to match the Kouba link already installed) and fitted the handlebar riser kit. The bikes handling was transformed - much better steering entering corners and generally more "chuckable". We also fitted the FMQ muffler I had stored here for the last couple of years.

Now done about 500km and no complaints, carburation is spot-on, front pipe a nice deep blue and not a sign of pinging (unless one gets lazy with gearshifts) Considering fuel quality here (and the fact the carb spend 24urs under 2m of floodwater) it speaks volumes for the TTR engine design.

Today we have about 100km of trail riding planned, at 700km I'll change the oil to a 15W-50 SL full synthetic.

Oh. For those of us that are classed as "senior riders" I can vouch for the AirHawk seat cushion. Cradles the posterior and delicately protects it from the horrors of monkey butt. Best damn thing I ever bought.

Aussie Paul · Veteran Member

I just got on the Airhawk seat cushion site.
which size do you use that fits the TTR ??

They advertise small, medium and large cruiser seats in neoprene or polyurethane and small and large pillion size.

thanks Paul

Lin · Senior Member

Hi Paul

The 11" x 9" cushion is what we use. Important to follow the inflation directions exactly to get max comfort. They don't entirely eliminate discomfort and a small towel added on top also helps. They make a huge difference and extend the riding range of the butt by about 100%.

Haggis Hunter · Veteran Member

Well Lin, it's good to see that you are out on the bike doing with it what Mr Yamaha intended smile

A reward for your thorough rebuild!

Peter

Lin · Senior Member

Thank you Peter. Currently we are in the town of Bogo near the northern tip of the island of Cebu in the Philippines. Got here yesterday from the town of Toledo which is about halfway up the west coast having crossed the island the day before from Cebu City. As I don't normally ride much in New Zealand my riding skills are a bit rusty and had a couple of opps moments plus had forgotten the unpredictable character of Philippine dogs....

Bike is running very nicely, now done nearly 1000km and have given it a couple of brief WOT in 3rd and 4th gear. I must say it really gets into it and seems to be developing more torque in the midrange than before. After about 1500km I will put it back-to-back with my brother's TTR, which has the same exhaust system but standard piston, albeit has done about 22,000km so will have much less mechanical friction.