Inconsequential ramblings of an Old Git

[Nobby]

Looking at the damage to the piston, I'd give the barrel a go with hydrochloric acid and tooth brush.
The unknown is what has the lack of oil done to the crank bearings ?

[Le_Fromage_Grande]

The crank is probably okay, it doesn't need a lot of oil and there's usually enough coating the bearing surfaces from when it was rebuilt, he also ran it on pre mix for a while, so there'll be oil on the crank.

I've had LCs seize worse than that and the crank has been fine, but it's not difficult to get the crank out of he wants to get it checked, one of the joys of a simple engine.

[mangocrazy]

There's plenty of oil on and around the crank and little ends, so I'm not too concerned now I've had a good look.There's certainly no overheating around the gudgeon pin. I've taken the barrels and pistons to Pete at RTT Moto in Hoyland and he seemed to think there was a chance it won't need a rebore. If it's marginal I'll go for a rebore. It will need 2 new pistons anyway, so the cost of a rebore won't be that much more, and it's only(!) on +0.75mm at present.

[mangocrazy]

Pete rang me earlier today with the good news that a light hone of the barrels has done the trick and means that a rebore (and corresponding oversize pistons) will not be necessary. I will obviously need a new pair of +0.75mm pistons and rings, but that was always going to be the case. So the week ends with me a lot happier than it began...

[mangocrazy]

My plans to re-spray the barrels and head and then rebuild the top end of the LC have neen dealt a mortal blow by me failing to listen to my wife. It's a common occurrence. My over-zealous trivia filters can sometimes miss important pieces of information - I'm sure most on here can relate to this.

The important piece of information was that she was taking this current week as holiday. This means that she's been busying herself about the house and (more importantly) I don't have unmonitored access to the oven and airing cupboard to a) warm the components up prior to spraying and b) have a small, contained area to spray said parts.

How inconsiderate.

And I can't even make a start on Monday, as it's a Bank Holiday. I feel thwarted.

[Scuffmark]

My better half works in the evenings so I get 3 hours of me time, so I know exactly what your talking about when suddenly their on holiday

[mangocrazy]

As mentioned elsewhere I managed to use the household facilities to get the barrels and head re-sprayed on Friday. After letting the barrels cool down after their gentle (gas mark 0) post-spray bake in the oven, I removed all the masking tape and ferried all the bits out to the shed. I'd make the point that using proper 3M masking tape, not some cheap generic alternative, was instrumental in all the masking tape coming off cleanly and without leaving any residue on the mating surfaces. False economy is a terrible thing... I'm hoping to begin the rebuild on Monday.

A week or so ago, seeing that the short to medium term weather forecast looked resolutely crap, I decided to have another go at the KTM Duke 690 forks. I'd had an excellent ride around some of Derbyshire's finest a few weeks back (before the weather turned shite) and was pissed off to discover that my earlier spanner twirling hadn't really made any substantial difference. The Duke was still only using 100mm of its supposed 150mm fork travel and it was hitting a hard stop at that point. Going round one bend I hit a big pothole and instead of the front suspension soaking it up, it bottomed out and stood the bike upright. Something was clearly amiss...

One of my major gripes with the forks was how difficult it was to reassemble them without using somewhat ridiculous techniques. Photos earlier in this thread show how I had to basically invert the forks in order to reassemble them. Having thought about it, I decided I needed to tap an internal thread on the damper rod so I had a way of extracting the damper rod with the spring and spring guide sleeve in place. After measuring up it became apparent that there was enough meat for an M7 x 1.0 thread to be tapped, which would allow me to use a length of threaded rod to screw into the tapped thread and pull the damper rod up from the bowels of the fork. The components I'm talking about are part numbers 6 and 7 in the diagram below.

Duke_690_R_fork_internals.JPG (140.58 KiB) Viewed 927 times

I'd also decided that one of the culprits for the lack of fork travel was likely to be the sleeve that held the spring in place. Desperate times need desperate measures, so I lopped off 25 mm from both sleeves (they're a weird hard plastic material, a bit like bakelite) using my trusty hacksaw. There's definitely no going back with that particular modification... Reassembly was a breeze now that I could retrieve the damper rod, and both legs were filled with a reduced amount of oil compared to KTM's spec (480ml compared to the recommended 534ml). Go large or go home is my motto...

One last little rant... What on earth were KTM thinking of when they specified 4w weight fork oil? What's wrong with the 5w oil that the rest of the world uses in cartridge forks? Would the average rider actually be able to tell the difference? Or are they just trying to boost sales of Motorex 4w fork oil at the expense of the competition? Thankfully Putoline also do a 4w fork oil that's available at my local bike emporium, so that was used instead of the overpriced Swiss stuff.

As soon as Winter Mk II has finished I'll report back on results.

[weeksy]

Having owned and ridden many 690s, both with standard and R forks, i'd be really curious to ride yours.

I didn't notice ANY of the issues you describe in honesty on mine.

[Scuffmark]

You can get a damper rod bleeding tool ......

https://www.ebay.co.uk/itm/254295458552 ... SwX61ZCw7D

Not exactly cheap but if your servicing forks on a regular basis a handy tool.

I've always set the air gap rather than the quantity of oil. You can get a tool for that too

https://www.ebay.co.uk/itm/371903046054 ... SwYUpdzQrr

Even though I have the correct tool I still prefer spray bottle tops cut to the length.

The service I carried out on my SMC forks has helped but like your forks there an ongoing project

[mangocrazy]

Having owned and ridden many 690s, both with standard and R forks, i'd be really curious to ride yours.

I didn't notice ANY of the issues you describe in honesty on mine.

I know for a fact that I'm fussy when it comes to suspension. I think I'm also a little on the light side (70kg) of the rider weight that the bike is set up for out of the factory. And if I hadn't put a cable tie round the fork leg to measure fork travel I'd have been unaware of the unused travel and would probably have just accepted it, instead of heading off down this rabbit hole...

As and when we meet up I'd be delighted to hand you the bike and get your impressions.

How much (if any) difference did you notice between the R and non-R forks and suspension in general?

[mangocrazy]

You can get a damper rod bleeding tool ......

https://www.ebay.co.uk/itm/254295458552 ... SwX61ZCw7D

Not exactly cheap but if your servicing forks on a regular basis a handy tool.

I've always set the air gap rather than the quantity of oil. You can get a tool for that too

https://www.ebay.co.uk/itm/371903046054 ... SwYUpdzQrr

Even though I have the correct tool I still prefer spray bottle tops cut to the length.

The service I carried out on my SMC forks has helped but like your forks there an ongoing project

I did actually make up a fork bleeding tool for the WP forks (M12 x 1.0), but the problem comes when trying to retrieve the damper rod once the fork spring and its guide are in place. If the damper rod tool is screwed into the damper rod, the spring guide/sleeve won't go past it, as the hole in the sleeve is 12mm diameter... So that's why I internally tapped the damper rod with an M7 thread, so I could hold the damper rod up with M7 threaded bar and slide all the bits (spring, sleeve, washer, M12 nut) over it while stopping the damper rod disappearing into the depths of the fork. The threaded bar also serves as a bleeding tool, I'm glad to report.

I do have one of those air gap measuring tools and agree that it's the correct way to go about setting the forks up. Now I've got the damper rod retention sorted out I could use the air gap tool, but I was being lazy and decided to go with oil quantity. The forks were completely stripped and drained of oil so I was comfortable doing that. Next time I'll use the proper tool...

And the reason why I felt bold enough to attack the spring sleeve with a hacksaw is that I've finally tracked down a manufacturer who sells a complete cartridge kit for the Duke 690 R and they have confirmed in writing that their cartridge has 150mm of fork travel. So if I've cocked it up irredeemably I have a Plan B. And their kit has the major advantage that spring preload is externally adjustable, not the ridiculous plastic washer inside the fork arrangement that KTM use. This is the kit:

https://www.emc-suspensions.fr/en/690-d ... uke-r.html

And here's the (Google) translation...

The cartridge kit is intended to replace the internal parts of the fork in order to improve its performance. This kit contains two cartridges, two springs, two plugs with adjustments and assembly instructions. This assembly allows the front axle to be adjusted on 3 points:

Spring preload

Compression hydraulics

The relaxation hydraulics

The cartridge kit has the particularity of being adjustable on one side in hydraulic rebound and on the other in compression since a fork arm controls the rebound (R for Rebound) and the other arm the compression (C for Compression ).

The 3mm CHC footprint on the fork caps includes 4 turns of adjustments and allows you to adjust the speed of movement of the fork in compression and rebound.

The spring preload adjustment on the cartridge kit is done by the hexagonal recess with a 17 spanner. Changing the spring preload influences the height of the vehicle and therefore its ground clearance. We can thus push back tailgating or even gain maneuverability.

The springs are selected by EMC based on the general state of charge indicated by the customer.

The installation of the kit can be done by our technicians.

[mangocrazy]

Well, it's all back together again now so hopefully I can dodge the rain showers next week and get out for a blat to see if I've managed to improve it with my tinkering.

Fingers crossed...

[mangocrazy]

The LC fired up pretty much first kick after reassembly and also managed to contain all its fluids whikle doing so. I just about managed to bleed the oil delivery pipes before rain stopped play (again). It was running on premix while I was pulling the oil pump cable taut to deliver maximum output to the carb stubs.

There was a degree of smoke involved.

I'll see if I can get photographic proof tomorrow (or whenever the rain stops).

[mangocrazy]

The LC got its first 50 miles of running in under its belt yesterday. Initially it was threatening to foul its plugs whenever the revs dropped below about 2000, doubtless due to a) the amount of lube used in reassembly b) a 'strong' pre-mix ration and c) bleeding the oil delivery pipes by pulling the oil pump cable so the pump was at max delivery. Once I'd fully bled the delivery pipes, the ratio of premix was diluted by bunging in a gallon or two of straight unleaded, and then diluted some more by filling the tank up at my local Esso dispensary.

To try and avoid any further unpleasant oil pipe/exhaust flange adjacency I enclosed the one large and 2 small oil pipes in some spiral wrap to ensure everything stayed where it should. I'd also greatly reduced the amount of slack in the smaller oil delivery pipes for the same reason.

DSC_5363.JPG (685.91 KiB) Viewed 830 times

I'm also going to try and stay on top of keeping the newly refurbished wheels shiny and spangly, as the bare ali can turn furry with very little provocation. Half an hour with some 'Mothers' ali polish brought them and the fork legs up a treat. The real chore will be cleaning the 'spokes'. Perhaps tomorrow...

DSC_5372.JPG (739.05 KiB) Viewed 830 times

At first sight the bike doesn't look that much different to the one I posted at the start of this thread, but a fair bit has been done. All paintwork is original as is the frame and swingarm. Grab rail has been re-chromed, the bars and top yoke have been powder coated satin black and the spannies have been ceramic coated, but that's about it.

DSC_5367.JPG (737.46 KiB) Viewed 830 times

[Yorick]

I had a white one

20210529_152618.jpg (868.64 KiB) Viewed 825 times

[mangocrazy]

But only a 250... Did you get the choice of colour scheme? Mine was one of the first batch in the country and basically you got what arrived at the dealers (after a nine month wait from paying the deposit). I think at the time I would have preferred the white/red one but it wasn't a deal breaker.

[demographic]

You've likely mentioned it on the thread somewhere but I've dipped in and out of it so missed it so...
Where did you get the spannies ceramic coated? Happy with the finish/cost?

I'm askin for a mate like

[Yorick]

But only a 250... Did you get the choice of colour scheme? Mine was one of the first batch in the country and basically you got what arrived at the dealers (after a nine month wait from paying the deposit). I think at the time I would have preferred the white/red one but it wasn't a deal breaker.

I had a black 350.

[mangocrazy]

You've likely mentioned it on the thread somewhere but I've dipped in and out of it so missed it so...
Where did you get the spannies ceramic coated? Happy with the finish/cost?

I'm askin for a mate like

I got them done at Shropshire Powdercoating near Tern Hill. They did all the powder coat work for Project Binky. You do have to be reasonably careful with the finish, it will mark if you're not careful with the spanners, but it looks really good and is about as close to original as I could find. Andy charged me £150 (cash), but indicated it should have been more than that. The stuff comes from the USA and costs about £400 a pint (when import taxes etc. are added in). Camcoat in Warrington offer a similar service but are more expensive.

[mangocrazy]

But only a 250... Did you get the choice of colour scheme? Mine was one of the first batch in the country and basically you got what arrived at the dealers (after a nine month wait from paying the deposit). I think at the time I would have preferred the white/red one but it wasn't a deal breaker.

I had a black 350.

Pictures?