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The TTR250 FAQ web pages -> TTR250 -> Repair and maintenance "stickies" -> Engine removal and strip down - hints and tips
Post Info TOPIC: Engine removal and strip down - hints and tips
TTRfan


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Engine removal and strip down - hints and tips
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I have just started to strip the engine for my next project.

When I bought the TTR a couple of years ago, I couldn't start it and suspected low compression so it needs investigating.

There is already a "show and tell" for removing the cylinder head here so I am trying to think of any hints or tips that I haven't previously mentioned. Apologies if some of the following is "stating the bleedin' obvious" biggrin

First off make sure you start with as clean an engine as you can get it. My engine is out of the frame so a lot easier to power wash and scrub.

1 - cleaned engine.jpg

 

I use a pair of OE rubber tank supports as bungs to stop water getting in the inlet and exhaust ports.

3 - inlet plug.jpg

4 - leaking decomp plug and bung in exhaust port.jpg

 

Once clean, go around the engine and inspect it carefully for any issues. 

There are two obvious issues on this engine:

1. I need to get the clutch cover off to adjust the clutch as the actuating lever is not lining up with the casting mark on the crankcase. I will show how to do this later.

2 - clutch needs adjustment.jpg

 

2. The decompressor plug has been leaking so will need to be replaced.

Once the engine was dry, I loosened the sump plug (easier to crack it open with the engine on its side!) and then mounted the engine in the stand which was raised on blocks to allow room to drain the oil.

5 - drain oil.jpg

 

Before starting to remove the cylinder head I set the engine at TDC. To save chewing up the plugs on the generator cover, I use a large washer to undo them and it works very well.

6 - use large washer to undo crank plugs.jpg

 

Another tip is to loosen the bolt on the end of the cam chain tensioner before removing the tensioner as it can be difficult when the tensioner is off.

7 - cam chain tensioner.jpg

 

I am lucky so far with this engine as the cams and journals are in excellent condition.

8 - cam journals in excellent condition.jpg

 

The cylinder head bolts may not have ever been off before as they were VERY tight. I had to use an old pair of handlebars as an extension to my socket wrench to get them to budge!

9 - handlebar extension to socket wrench.jpg

 

Once the head and barrel were off it was evident the engine had been burning oil and was showing a bit of wear on the barrel.

10 - carboned combustion chamber.jpg

11 - carboned piston.jpg

12 - Wear ridge in barrel.jpg

Next stage is to strip out the head, sort the valves out and refit with new valve stem oil seals in case worn VSOs had contributed to the oil burning and consequent carbon build up on the piston and valves. 



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buffalo4


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Once again very interesting Brian thanks
Ian

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TTRfan


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Thank you Ian!

Another tip to keep costs down and make life easier is to use non-caustic TFR to help with power washing.

After a trail ride there is usually at least two TTRs to power wash, mine and my bro's, plus I use the power washer quite a lot in my restos.

Buying the 1 litre bottles of Muc Off or whatever was expensive so I now buy a 25 litre container of TFR and decant it into a smaller (4 litre I think)  container whose top takes a sprayer unit.

If I lift the small container just a bit higher than the sprayer it starts spraying almost instantly instead of having to work up some pressure as used to be the case with the 1 litre bottles.

I use the TFR neat rather than dilute it as suggested so I don't leave it on long, especially on aluminium.

I wash the loose dirt off first, give the bike an all over spray with TFR and then almost immediately rinse it off.Works good.

When cleaning the engine this morning, I sprayed on the TFR and then used a variety of brushes (bought in Home Depot when on my States holiday) to get into the nooks and crannies to help get the dirt off. Takes a while but the TFR really helps.

Brian

TFR and sprayer.jpg



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04TTR250


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thanks Brian, its great that you share your hints and tips with us all, keep up the good work mate!

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TTRfan


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Thanks Tyler smile

It was minus 3 degrees C outside this morning so the heater is on in the workshop!

I have stripped out the valves and cleaned them up.

To remove the valves I use thumb pressure on the valve tool (middle bottom of pic) and hoik the collets out with a magnetised screwdriver. To stop the valves dropping when I apply pressure, I put the head on a block of wood with a rag on top (bottom right of pic) that sits up against the valve heads.

To keep all the parts in their right order, I made up a little foam tray with cut outs for valves and buckets and a top of an old milk container to hold the collets - also in picture.

I start off cleaning the valves by putting them in the drill and use a paint scraper to get the majority of the crud off and then finish off with sandpaper. Gets quite hot so best to wear gloves!

Valves and head.jpg

Next up isn't my favourite job - lapping in the valves cry

Just stopped for a cuppa and choc chip cookies to keep my strength up!

I got a feeling that I am going to be diverted by Mrs TTR to help her decorating so may not get much more done for a while no

Brian



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TTRfan


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Engine removal and strip down - hints and tips
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I was lucky and the decorating didn't happen!

So, the next job is to grind the valves in. I have a reciprocating valve grinding tool that fits in the electric drill. New ones are available such as here and make the job a lot quicker.

Valves 001.jpg

 

Although an obvious point, make sure you remove all traces of the valve grinding paste when the job is finished!

Once everything was cleaned up it was time to replace the valve stem oil seals (VSOs). The exhaust VSOs always fare worst and these were looking a bit black and, once removed, it was possible to feel that the rubber had hardened and couldn't have been working effectively. The pic below shows a new VSO next to its new home.

Valves 004.jpg

 

There may be an easier way but I use a pair of long-nosed pliers to pull off the old VSOs. They can need a bit of wiggling to loosen them off.

Valves 006.jpg

 

It is obvious from the pic which are the exhaust VSOs. I replace all VSOs whilst I have the chance.

Valves 007.jpg

 

It can be tricky to fit the new VSOs square on so I pop the valves up through the stems and slide the new VSOs over the valve and then its easy to push them down square. Make sure they are pushed fully home.

Valves 009.jpg

 

Once the valves are all back in I adjust the valve clearances. It's a lot easier to do it with the head on the bench.

I think my guess that this engine hadn't been apart since new was correct as the valve shims were all the genuine Yamaha originals which have increments of 0.01mm. After-market shims are only available in increments of 0.05mm i.e. 1.80, 1.85, 1.90. 1.95, etc.

Valves 010.jpg

To check the valve clearances properly you need a good set of feeler gauges with the smaller (up to 0.10mm) ones in single 0.01mm increments. I have printed off and laminated a pic of the correct camshaft positioning and the inlet and exhaust valve clearance specifications.

Valves 012.jpg

 

Now the head is finished, the next job is to sort out the barrel and piston.

Brian



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TTRfan


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Having once dropped a gudgeon pin circlip into the sump and spending ages trying to fish it out, I now make sure that I cover the holes with something!

Piston and barrel 001.jpg

 

It's easier to locate the base gasket and stop it moving by fitting the dowels.

Piston and barrel 002.jpg

 

Don't forget to fit a new cylinder base O ring if the old one is at all suspect.

Piston and barrel 003.jpg

 

Don't be in a hurry fitting the barrel over the piston. It is easy enough to do it by hand but ease the rings into the piston and slowly "rock" the piston up into the barrel. If there is a lot of resistance then stop, remove the piston and check that all the rings are still in their grooves.

Turn the engine over being careful not to snag the cam chain to make sure it moves freely. I have fitted a first oversize (+.50mm) rebored barrel and new piston on this engine to give it a new lease of life.

I use lots of oil in my rebuilds and have found the cleanest way to get it on the engine parts (rather than on me and the workshop floor!) is to put some in a bottle and apply it with a paint brush.

Piston and barrel 004.jpg

 

Having removed the clutch cover to check on the internals, I used the opportunity to adjust the clutch actuating arm before re-fitting it. A very simple job using a 10mm spanner and a cross head screwdriver.

Piston and barrel 011.jpg

 

The pointer on the clutch actuating arm now lines up exactly with the bar cast in the crankcase.

Piston and barrel 012a.jpg

 

I nearly forgot to replace the leaking decompressor plug such was my enthusiasm to finish the engine rebuild disbelief

It was fairly obvious the previous owner had realised the oil leak problem and had fitted a new plug using Red Hermetite - unsightly and unsuccessfully!

Decomp plug.jpg

 

I remove the old plug by punching a hole in it and levering it out whilst being very careful not to scratch the aluminium sides in the head casting. Having got the old plug out, it was clear from the marks that the previous owner (or his mechanic) hadn't been so careful!

Decomp plug (1).jpg

 

Clean up the hole ready for the new plug and next remove the bolt on the side.

Decomp plug (2).jpg

 

Notice how little thread there is on the bolt so be careful that you don't overtighten it when replacing it. To give it the best chance of being oil tight without overtightening, I anneal the copper washer.

Decomp plug (3).jpg

 

The new plug ready to go in. Manufactured by Scott in Australia and available here. Great job Scott wink

Decomp plug (4).jpg

 

Plug oiled and fitted along with its retaining bolt  

Decomp plug (5).jpg

 

Next up is to look at the starter gears as the starter pinion is looking a bit "worn" cry

 

 

 



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buffalo4


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I Love reading these updates whilst waiting at delivery points
Thanks Brian

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Dullthud


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This is brilliant, Brian.

3 Questions.
What is TFR?
How did you refit the valves, springs and gubbins? Surely trickier than getting them out.
Did you get the same bore re-bored or did you have bored barrel waiting?

Andy

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Cubber


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Engine removal and strip down - hints and tips
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TFR = Traffic Film Remover

One of many suppliers' WEB SITE HERE

Martyn



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TTRfan


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Dullthud wrote:

This is brilliant, Brian.

3 Questions.
What is TFR?
How did you refit the valves, springs and gubbins? Surely trickier than getting them out.
Did you get the same bore re-bored or did you have bored barrel waiting?

Andy

Thank you for the compliment Andy - surprising how a few words can make recording this stuff worthwhile biggrin

Martyn has answered the TFR question. I buy mine in a 25l container from a local motor factor and it works out to be about £1 per litre.

Re-fitting the valves is a reversal of removal and usually goes quite smoothly. I use the business end of a valve spring compressor as using the whole thing can be a bit cumbersome. I have strong thumbs and am able to compress the springs enough to fit the colletts (see pic below) which saves a lot of time. This time I did get some assistance from Trish (aka Mrs TTR) who fiddled the collets in whilst I held down the spring as they weren't just dropping into place as they usually do! I didn't want to duplicate too much of the info here.

Engine build 030.jpg

 

You spotted that I couldn't have got my barrel rebored so quickly. I have a couple of barrels on the shelf ready to fit and used one of them wink

It's quite a trip out to where I get my "machine shop" work done so I tend to get jobs done in a batch. When I have a few barrels and cranks needing attention I will take them to be done. Can't afford the fuel and time to do them one at a time no

It's nice to be asked questions so if you or anyone else has any more please just ask away!

Brian

 



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TTRfan


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I am very pleased to say that, despite being hauled off by Mrs TTR to some some shelf fitting for a couple of hours, I have finished the engine and it's ready to fit to the frame biggrin

However, there was a bit more work to do this morning before finishing off. 

The starter pinion was worn so I needed to check the large idler gear which necessitated removing its cover. The snag with this is that if the original Allen headed "button" style bolts are still fitted then they are a swine to get out no

I tried the impact screwdriver with the appropriate head fitted but no go. I tried to shift them with Vice grips and then a hammer and cold chisel but they weren't having any of it evileye

I had to resort to cutting a slot in each of the bolts with the Dremel so that I had something for the cold chisel to purchase on.

This worked well and the bolts were soon removed. They will be replaced with proper hex-headed bolts!

Starter and gears 001.jpg

 

As I suspected the teeth on the large starter gear were looking a bit sorry for themselves. It may not be obvious in the picture but each of the teeth had been "nibbled" by the starter pinion.

Starter and gears 004.jpg

 

So a new large idler gear has been fitted. The bearings, shaft and housings were all fine thank goodness. That reminds me I either have to fit a replacement starter or have a go at Steve's Fazer fix - see here

I can think about that tomorrow but, for now, the engine is now all back together and sprayed ready for fitting.

Engine complete 001.jpg

Engine complete 002.jpg



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ERBS


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Hello Brian, do you know what sort mileage this engine had done before you took the it apart?

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Dullthud


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Cubber wrote:

TFR = Traffic Film Remover

 Totally Freakin' Reasonable.

 Cheers, Martyn.

 

Brian. Do you have oversize pistons on the shelf?

I wondered about the valve fitting as I've only ever taken them out of a knackered head and there was no point putting them back. A mate showed me a way of tapping them with a socket and a hitting device. It worked very well but I suspect less so as a re-fitting procedure.

 

Andy



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TTRfan


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Engine removal and strip down - hints and tips
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Dullthud wrote:
Brian. Do you have oversize pistons on the shelf?

I wondered about the valve fitting as I've only ever taken them out of a knackered head and there was no point putting them back. A mate showed me a way of tapping them with a socket and a hitting device. It worked very well but I suspect less so as a re-fitting procedure.

Andy

Yep - we keep all the oversizes in stock - see http://totallyttrs.com/epages/699105d9-e4cc-4b32-b236-84e72cd67f84.sf/en_GB/?ObjectID=1655063&ViewAction=FacetedSearchProducts&SearchString=piston

The technique to pop the collets out works as I have used it before now wink

Doesn't work in reverse though cry

If you use the valve spring compressor as intended the collets are easy to get back in. I try and shortcut which can sometimes make things tougher disbelief

Brian



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TTRfan


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ERBS wrote:

Hello Brian, do you know what sort mileage this engine had done before you took the it apart?

Nope! The TTR came to me with no speedo.



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TTRfan


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I decided to shortcut and fitted a good used starter, instead of doing a "Steve" fix on the old one, as I wanted to get the engine in before the weekend.

Also, a reminder to either use new copper washers on the oil feed pipe or to anneal (heat to cherry red and douse immediately in cold water).  I made a mistake this morning and tried doing all six washers at once which meant the wire I put through them for the exercise got very hot and bent such that all 6 hot washers dropped on the carpet.  Much smell and carpet stuck to the washers. So that actually added work rather than saving time. I also managed to burn my fingers grabbing the wire. My shortcuts usually bite me back disbelief

 I know it isn't to do with the engine strip but just to repeat a tip to make engine fitting easier, wire up the clutch actuating arm as it can otherwise get the wrong side of a frame tab and require lifting the engine partially out again to get it on the right side.

Engine fitting 001.jpg

At least the engine dropped in nicely biggrinbiggrin

Engine fitting 003.jpg

Job done!

Brian



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Kenny R


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TTRfan wrote:

 

Also, a reminder to either use new copper washers on the oil feed pipe or to anneal (heat to cherry red and douse immediately in cold water).  I made a mistake this morning and tried doing all six washers at once which meant the wire I put through them for the exercise got very hot and bent such that all 6 hot washers dropped on the carpet.  Much smell and carpet stuck to the washers. So that actually added work rather than saving time. I also managed to burn my fingers grabbing the wire. My shortcuts usually bite me back disbelief

 Cheered me up, thanks Brian. 



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j180


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Stoopid question Brian, in the laminated picture is this the engine at tdc. When doing mine tonight everything has moved so will need to set up the timing blind so to speak

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TTRfan


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Hi John

Thanks for resurrecting that thread - I had forgotten about it!

Yes, engine at TDC.

This may be a better guide for you - see here

Is this your spare project engine that you are working on that was in pieces?

Brian



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j180


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That's brilliant Brian. Many thanks

John

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TTRfan


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Working on an engine today reminded me of a couple more tips.

1. I have always had difficulty in fitting the oil control rings. I have found the best way is to fit the wavy ring first followed by the two plain rings.

2. Make sure all the threaded bolt holes in the crankcase for the cylinder bolts are clean and that the bolts easily thread in. The front left bolt and thread in particular can get rusty and tight so needs to be cleaned so that the bolt tightens up against the cylinder head rather than jams in a dirty thread and give a false torque setting. I learnt this the hard way and the result was a blown head gasket disbelief

Brian



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massamia


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HI, very useful info, but i seem to remember a while ago that you had a series of photographs and information about a complete stripdown and rebuild including fitting main bearings etc. I have looked everywhere??? but cannot seem to find it. Do you have a link to it if still available please?
Many thanks. Mike

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TTRfan


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This one maybe?  http://ttr250.activeboard.com/t58927535/new-325-project/

or this one? http://ttr250.activeboard.com/t43731716/modernising-a-1993-yamaha-ttr250-open-enduro/?sort=oldestFirst&page=2

 

 



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