Yet another Lc engine rebuild !!

[dusty350]

This will be the last one I do a thread on. There are already 2 other threads on the forum and I did wonder whether it's needed, but as there is never anything on the telly...
This is a 250 engine I picked up late last year. Complete, semi stripped down, only missing pistons. This will get rebuilt as a 250 and go in the "Plan B " rolling chassis.
Sat for many years, it was a little bit challenged, cosmetically;

20231016_174621 by dusty miller, on Flickr

20231208_083603 by dusty miller, on Flickr

20231208_083653 by dusty miller, on Flickr

20231019_120156 by dusty miller, on Flickr

As I was stripping the engine down I was expecting a fight from every fastener and bolt/screw, but amazingly they all came out with the rattle gun with no dramas. The condition outside made me think the gearbox could be toast, but I was pleasantly surprised;

20231019_111648 by dusty miller, on Flickr

All seems good with the gear clusters. Crank was obviously open to the elements and didn't fair too well, but it's not seized and will get rebuilt or replaced anyway
I felt a bit embarrassed when I dropped it off to Jamie for vapour blasting - I usually clean them up a bit first - but he did a stirling job as always. The last pic shows a welded repair to the casing behind the sprocket, evidence I expect of a fairly big chain failure. Not only did it damage the case but also took the lower casting out. Amazingly it didn't damage the top part of the casing where they normally break. After being vapoured it was easier to assess the cases;

20231230_184409 by dusty miller, on Flickr

20240429_063001 by dusty miller, on Flickr

20240429_062945 by dusty miller, on Flickr

It's not pretty but I'm loathed to dress it back in case I expose the damage it's there to fix. Plus, it's not seen and doesn't interfere with the operation of the engine. I did think it prudent to "test" the repair though as I have no proof it's oil tight, so I tipped the case on it's side and puddled some WD40 over the weld, then left it for a few hours to see if the oil would seep through to the outside;

20240429_063221 by dusty miller, on Flickr

Pleased to say it's completely oil tight with no weeps on the outside of the case.
Just put a first parts order into Fowlers today, so hopefully start a slow build this week

[JonW]

Brilliant, even as one who has built his fair share of these, its always nice to see Dusty do a thread on one

Also that transmission goes to prove the adage that you cant judge a book by its cover!

[dusty350]

Gotta say I was very happy when the top case came off. The fact the engine had sat for many years without oil in the case had me fearing the worst, and there comes a point when a rebuild doesn't make financial sense. Happily this isn't that rebuild ! I will include part numbers as before, and current prices. Last engine was rebuilt in 2022 I think so it will be interesting to see how/if parts prices have changed. I'm also planning on raiding my supply of used engine parts to keep costs down, so rather than just buying everything new, if have a good used part I will use it, although there is only one or 2 small parts that I will change.

[dusty350]

First parts have arrived from Fowlers.
45 quid for that little lot !!

20240430_111915 by dusty miller, on Flickr

[oldbritguy]

Start a spreadsheet and watch the cash disappear.

I have been gathering bits and pieces for a Suzuki project I have on the go just now and quite shocked at the prices of the usual bolts and rubbers etc

At the point where I am hiding it from the boss 😂

Always look forward to a Dusty build.

John

[JonW]

It will be interesting to see what this costs compared to previous times youve done it Dusty.

(ok, it will be scary.. but it'd still be interesting to know what % extra the past few years have added to a full build)

[dusty350]

Prices go up every time I do one. That's to be expected, but it would be interesting to know if Yamaha increase their prices in line with other manufacturers, or are the more/less than the others ?
For example, the ali sump washer gasket is actually a Honda part. In 2018 it cost 59p. In 2022 it cost 1.00. 2024 it costs 1.09
The correct Yamaha sump bolt washer was £6.00 in 2018, £8.83 in 2022 and now £10.20 !! At the end of the day it's not something I'm gonna get hung up about - the prices are included in this thread just to help guys realise the cost of parts and the budget needed. There are alternatives to a lot of the parts in the form of good pattern, which are often ( a lot) cheaper then genuine of course so you dont have to buy Yamaha parts all the time.

Something I've not done before was to test the 2 ali plugs that seal the ends of the selector fork rods. I've always been lucky with Lc's and Pv's that I have never had them leak, but have had weeps from aircooled engines in the past. They were sealed with rubber seals though, and easily removed and replaced, but these ali plugs would be harder to deal with if they were leaky. I know some guys have given them a tap with a drift to seat them, but I thought I would test them first, so I tipped the case on its side and sprayed Wd40 in and left it for a few hours;

20240430_115113 by dusty miller, on Flickr

Thankfully no leaks evident on the outer faces of the plugs, so I can move on. As said the sump plug washer is a Honda part, and a lot cheaper than the Yamaha Lc part. 94109 14000 will now cost you £1.09, as opposed to Yams £10.20 !! Save it where you can. I found a better sump bolt in my spares that wasn't as chewed up as the one that came with the engine. I had to get some light rust off the head, but will give it some enamel paint once fitted to protect it;

20240501_064906 by dusty miller, on Flickr

[steve63]

Excellent. Always enjoy seeing nice engines emerging from the crud. Thanks for taking the time and effort to document it again.


If I was a betting man I would have  put 50p on that weld leaking myself so good result. They're not in the Premier League of nice looking welds are they?

[abar121]

May 1, 2024 13:02:29 GMT 1 steve63 said:

Excellent. Always enjoy seeing nice engines emerging from the crud. Thanks for taking the time and effort to document it again.


If I was a betting man I would have  put 50p on that weld leaking myself so good result. They're not in the Premier League of nice looking welds are they?

Hey, that looks like one of my welds

I've found Dusty's previous threads super useful when rebuilding. Always time for another one

[lcmarky]

Another resurrection. There'll be more & more LCs on the road for sure.. Great work!

[dusty350]

Sump bolt and washer now fitted, so it's time for the first gearbox component.
The selector drum is pretty basic, and runs a bearing at the right hand end. To replace the bearing you need to remove the shift star which is retained by a central JIS head screw. I use a rattle gun to loosen this screw, usually when the drum is still in the engine at stripdown stage. It can be quite tight so the rattle gun - a cheapy from Lidl - gets it undone easily. I have had to drill the head off in the past when they've been really tight, but that was before I had the gun. The screw sits in a cupped washer, and once removed the star can be coaxed off - again, they can be tight;

20240430_160239 by dusty miller, on Flickr

You can see a locating pin on the underside of the star that sits into a corresponding hole on the drum. Sometimes they are loose and easily lost so keep it safe
Then there is a large circlip that needs to be removed, and then the bearing just slides off;

20240430_160423 by dusty miller, on Flickr

The drum now gets a wash in clean petrol and I check the surface the bearing acts upon is nice and smooth. The only other part to check is the neutral switch plunger at the opposite end to the bearing. Just make sure it springs back out when it's pushed in. You can remove the end plate to expose the plunger and the spring that sits behind it if there is a problem, but I've never had a duff one.
Once happy, you can fit a new bearing and circlip;

20240501_170104 by dusty miller, on Flickr

The bearing is now £16.90, up from £15.11 in 2022, and the circlip is now £4.61, an increase of 61p ! Bearing gets a bath in fresh gear oil and slides on to the drum, followed by the circlip that retains it. The bearing isn't a close tolerance fit, so it always feels a bit "baggy", but they are all the same;

20240501_170243 by dusty miller, on Flickr

Shift star then goes back on, with it's retaining pin, then the cup washer and a new central screw (old one is easily reusable). I use some blue Loctite on the screw.
The drum can now go back into the engine, Simply fit from the right hand side with some gear oil on each end of the drum;

20240501_170859 by dusty miller, on Flickr

20240501_170958 by dusty miller, on Flickr

We dont fit the retaining plate yet as we need to fit the selector fork rods first

[dusty350]

Selector forks are next. There is one selector fork rod shorter than the other;


20240501_171708 by dusty miller, on Flickr

The shorter one fits at the front of the gearbox and carries just one fork, the longer rear rod carries the 2 forks. Both rods have a circlip groove at one end, and that is the end that goes into the engine case first when fitting. Of the 3 selector forks, 2 are identical - the front single fork and the rear right side fork (engine facing forward). You can see the difference here;

20240501_171812 by dusty miller, on Flickr

I fit the front rod first, grooved end into the case, and sit the fork in the middle of the drum;

20240501_171922 by dusty miller, on Flickr

Some gear oil aids fitting. Slide the rod through the fork and push all the way in so the grooved end is just visible in the casing;

20240501_172147 by dusty miller, on Flickr

A circlip then locates into the groove on the rod. You'll need 2 of these;

20240501_172832 by dusty miller, on Flickr

£1.58 each, up from £1.37 a couple of years ago. I dab a little grease on the case above the rod so it's easy to stick the circlip above the groove, then you can gently push the circlip down into place with a drift;

20240501_173025 by dusty miller, on Flickr

[steve63]

May 1, 2024 13:45:26 GMT 1 abar121 said:

May 1, 2024 13:02:29 GMT 1 steve63 said:

Excellent. Always enjoy seeing nice engines emerging from the crud. Thanks for taking the time and effort to document it again.


If I was a betting man I would have  put 50p on that weld leaking myself so good result. They're not in the Premier League of nice looking welds are they?

Hey, that looks like one of my welds

I've found Dusty's previous threads super useful when rebuilding. Always time for another one

It's been many years since I did any aluminium welding. There was always a rumour knocking about that Japanese aluminium was full of crap which made it difficult to weld properly. It was probably just people who were not any good at welding and had a dislike of Japanese bikes.

When I was just a smoothed chinned apprentice the older guys would enjoy examining my RD200 and slagging off the frame welding. They'd also tell me that Japanese bikes were rubbish and wouldn't last long so they'd be worthless and scrapped in two or three years.

 

[dusty350]

It probably doesn't help that the area of the cases damaged by the chain is always covered in grease, oil and any crud picked up by the chain. I know when I've had Jap ali welded in the past by Glenn, the welder I use, it spits and burns and is generally a pig to get a nice weld on due to the contamination from oils and chain lube etc. If it was visible I would take the cases to him for a better job, but as it's not seen and oil tight, it's a battle scar that can stay !!
I know when I used to polish engine cases years back, it was very difficult to get a flawless finish. I took one set to a pro polisher, and although he got them a lot better, there were still areas that looked like "bloom", and he did comment on the poor quality of the metal. I spose mass produced parts that are destined for a coat of paint dont have to be the best quality in the first place.

[donkeychomp]

Shame you didn't pop to the pub every time you finished a build Dusty. First time £2 a pint. Now £6. Makes Yamaha price inflation seem quite tame by comparison!

Alex

[dusty350]

The longer rear rod goes in next;

20240501_173256 by dusty miller, on Flickr

The first fork, on the right of the pic matches the shape of the front one, so the rear fork n the left is the odd one of the 3 ! Again, push the rod all the way in so the circlip grove is just visible, dab of grease on the case and push the circlip into the groove. These circlips will prevent the rods moving to the left in use.


That's the selector drum and forks done, and it will now look like this;

20240501_173419 by dusty miller, on Flickr

20240501_173628 by dusty miller, on Flickr

[mouse]

This is brilliant!

Mouse

[zip2112]

Apr 29, 2024 11:18:30 GMT 1 dusty350 said:

This will be the last one I do a thread on. There are already 2 other threads on the forum and I did wonder whether it's needed, but as there is never anything on the telly...
This is a 250 engine I picked up late last year. Complete, semi stripped down, only missing pistons. This will get rebuilt as a 250 and go in the "Plan B " rolling chassis.
Sat for many years, it was a little bit challenged, cosmetically;

20231016_174621 by dusty miller, on Flickr

20231208_083603 by dusty miller, on Flickr

20231208_083653 by dusty miller, on Flickr

20231019_120156 by dusty miller, on Flickr

As I was stripping the engine down I was expecting a fight from every fastener and bolt/screw, but amazingly they all came out with the rattle gun with no dramas. The condition outside made me think the gearbox could be toast, but I was pleasantly surprised;

20231019_111648 by dusty miller, on Flickr

All seems good with the gear clusters. Crank was obviously open to the elements and didn't fair too well, but it's not seized and will get rebuilt or replaced anyway
I felt a bit embarrassed when I dropped it off to Jamie for vapour blasting - I usually clean them up a bit first - but he did a stirling job as always. The last pic shows a welded repair to the casing behind the sprocket, evidence I expect of a fairly big chain failure. Not only did it damage the case but also took the lower casting out. Amazingly it didn't damage the top part of the casing where they normally break. After being vapoured it was easier to assess the cases;

20231230_184409 by dusty miller, on Flickr

20240429_063001 by dusty miller, on Flickr

20240429_062945 by dusty miller, on Flickr

It's not pretty but I'm loathed to dress it back in case I expose the damage it's there to fix. Plus, it's not seen and doesn't interfere with the operation of the engine. I did think it prudent to "test" the repair though as I have no proof it's oil tight, so I tipped the case on it's side and puddled some WD40 over the weld, then left it for a few hours to see if the oil would seep through to the outside;

20240429_063221 by dusty miller, on Flickr

Pleased to say it's completely oil tight with no weeps on the outside of the case.
Just put a first parts order into Fowlers today, so hopefully start a slow build this week

[JonW]

Great work Dusty, on the comprehensiveness of the thread as well as the engine.

[dusty350]

Cheers Jon. I'm trying to write it in a way so that a complete newbie could easily follow it and do their own . Hopefully the pics, coupled with some text show how simple these engines are to rebuild

[Yogi]

Doing a great job Dusty 👌

[dusty350]

Cheers Matt

[dusty350]

The drum retaining plate can now be fitted. The plate sits in the groove on the drum, and it also stops the front selector fork rod from moving out to the right side;

20240501_174851 by dusty miller, on Flickr

Note the drum was fitted with the cut out on the star facing downwards;

20240504_065446 by dusty miller, on Flickr

This cut out is your neutral position for the drum, and although it's not perfect at the moment, it needs to be in this position. It means the brass plunger at the other end of the drum is in the right place to contact the brass pin in the neutral switch too.
You can fit the neutral switch at this point. The current Yamaha price for the switch is £26.59, and the O ring that goes with it is £3.24. Two years ago they were £23.03 and £2.89 respectively. I often use Fowlers for parts but I also use Norbo, Ebay, MBD and Mutts, as well as Pjme, so you have lots of options for parts and prices. I bought my neutral switch from "Bikeandquadparts" via ebay, and it was £19.00 delivered, so saving £7.59 over the Fowlers price (would be more with postage) so a significant difference. Do watch out though - there are Chinese copies on there so be careful.

20240503_082119 by dusty miller, on Flickr

Some red rubber grease on the O ring means easy fitment to the neutral switch, and a bit more grease allows the switch to push into position without chaffing the O ring;

20240503_195830 by dusty miller, on Flickr

The positioning of the 3 mounting holes means the switch can only be fitted a certain way. Dont overtighten the 3 bolts as the switch will crack if they are done up too tight;

20240503_201101 by dusty miller, on Flickr

[dusty350]

The next component to deal with is the shift drum stopper arm. This has a simple washer rivetted on the end and is tensioned by a spring;

20240504_085640 by dusty miller, on Flickr

This part is often cited as being part of the issue with finding neutral on a running engine. Various modifications are available, one being to reduce the points on the star itself, fit a lighter spring behind the stopper arm, and change the rivetted washer for a bearing that has a larger contact area than the washer. On this engine I'm leaving the star and the spring standard, but will fit a bearing on the end of the stopper arm. First thing to do is drill out the rivet that holds the washer in place;

20240504_085648 by dusty miller, on Flickr

20240506_112248 by dusty miller, on Flickr

I thought I had a spare bearing but must have used it on the last engine build, so I've ordered another which should be here in a few days, an SKF W605 2RS1. Cant do much else now till that arrives, apart from fit the spring into place;

20240506_112919 by dusty miller, on Flickr

[dex46]

Good thread Dusty following 👍as shameful as it sounds I’ve never had to rebuild a Lc bottom end must of been lucky over the years 🤷‍♂️
Will be stripping my engine over winter so this will be very helpful 👍👍
Dex