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Topics - cee-b

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Singles / C15T gearbox oil quantity
« on: 13 June, 2021, 18:37:05 »
I have just changed the gear oil on my C15T.

I was expecting to put in half a pint, but the oil started running out of the level plug at approx 150mls - roughly quarter of a pint.

This seems like a piddling amount of gear oil (particularly in a bike not exactly renowned for hanging on to every drop of oil that is put into it!)

Any ideas on why it might take so little? The level/drain plug was fitted by the previous owner - does anyone know whether there are plugs that fit, but are set to a different level?


Singles / Pulling a dent from fuel tank
« on: 08 May, 2020, 16:08:18 »
I was playing around on my trialler and dropped it (not unusual ::)) putting a dent in the fuel tank. It is not bad, but I'd prefer to pull it as the bike is quite tidy (it won't let me post a pic as they are too many MB).

I've got a hot-glue dent puller which has taken a far worse dent out of my Landie Defender door, but the glue just doesn't hold on the bare ali tank well enough to get a decent pull.

Has anyone come across this problem before and found a solution? I know I could send the tank away to get 'fettled' but it is a simple enough job if only I can find a way to get the hot glue to stick - or a better glue?

Edit: A bit more on what I did to prep before glueing:

I rubbed the area down with fine emery to de-gloss it. I then cleaned it with acetone - acetone actually removes hot-glue, so I finished it by cleaning with isopropanol.

Singles / Does anyone recognise these forks?
« on: 02 June, 2018, 12:44:10 »
The forks are fitted to a 1961 B40/C15T, but they are clearly of a later origin.

I'm trying to identify them so I have an idea of how much oil they should contain and what length of spring ought to be fitted. In the meantime, I'm just experimenting by 'feel'.

If anyone recognises what they are, I would appreciate any info you may have.


Singles / What oil to use in forks?
« on: 23 May, 2018, 16:07:22 »
What type and weight of oil would you recommend using in front forks please?

I have a C15T with non-standard front forks (I'm not sure what they are I'm afraid).

The previous owner had used 20W50 engine oil, but I feel that isn't giving sufficient damping. I used the bike on a long-distance trial at the w/e; I could feel the fork banging off the stops in extension while riding the trails between sections, so the rebound damping would appear to be insufficient.

From the dents in the mudguard caused by contact with the bottom yoke, the suspension evidently bottomed out as well, though I did take a pretty big 'hit' dropping out of a section into a gully.

I was going to replace the oil with a known weight - which is why I'm asking for advice - make sure the forks are properly bled, and then experiment with gradually increasing the oil quantity

Singles / C15T rear shocks - also chain slider?
« on: 28 December, 2017, 16:29:56 »
My rear shocks are a bit pogo-ish so I'm after new ones.

The existing ones are 12'5", but all the info I can get (not much) points to the correct shock being 11.9". This is the length given for both the C15 and B40, but no mention mention is made of Trials. Is it the same for the T? Can anyone knowledgeable please confirm?

Also, the chain currently runs directly over/on the swing arm pivot and is wearing slight slots into it. Is this correct or should there be some manner of chain slider to protect the frame from wear?

Singles / C15T crankcase breather oil leak - but only some times!
« on: 14 November, 2017, 19:38:17 »
I know that the subject of oil leaks has been covered countless times and apologise for raising it again. However, I can't find a previous answer for this particular set of circumstances.

When I leave the bike parked, it leaks oil from the RH side of the engine (nothing unusual about that, I know).

Removing the outer timing cover shows oil pooling and weeping out through the join; it actually drips from the rear RH stud of the sump, but this is only because it tracked to that low point.

The oil is entering that cover through the small breather hole low down in the gearbox inner cover - presumably this is the timed crankcase breather?

On some occasions this leak is barely more than a drip, on others however, it makes a fairly massive puddle. I can only surmise that the difference is due to whether the breather is timed open or not.

So, I have a two-part request.

1. Can anyone suggest a method of curing the leak?
2. If not, is there a method of determining whether the breather is open or closed without waiting for the puddle to form?

Any insights will be gratefully received.


Singles / C15 primary drive oil level - question rephrased
« on: 20 August, 2017, 13:38:25 »
To put it slightly differently than my first post about this, as there were no responses.

I have followed the directions from the Service Sheets regarding primary drive oil level.

If I remove screw M (the second screw back) which is identified as serving as the level plug, no oil comes out even if I overfill it.

If I remove the screw behind that, it drains pretty much the entire amount that I put in.

Other than draining the case and then putting in a measured amount (1/4 pint) every time, I am unable to check the level.

Can anyone advise please?

Singles / To polish, or not to polish - that is the question
« on: 03 August, 2017, 18:07:36 »
In among the proper oily-bits problems I am trying to sort out, I have a slightly more 'fluffy' question.

The C15/B40 trials bike that I have just bought is mainly raw aluminium - fuel tank, oil tank, both mudguards, engine casings.

The finish at present is not so much 'brushed' as 'scratched to buggery'; it looks like paint may have been sanded off in the past.

The question is, what finish should I be trying to achieve?

I have got a polishing kit that is capable of finishing the items to a fairly good gloss shine, but is this what I should be trying to achieve on a '61 trials bike? What was the the original state of ali finish please?

Singles / C15 - another oil feed problem
« on: 01 August, 2017, 21:33:43 »
I have a recurring (and very baffling) oil feed problem and would appreciate any help please.

The story so far:

I have checked that the oil flows freely (though surprisingly slowly) from the oil tank. The filter is clear and there are no blockages. The tank vent is fully functioning. I have changed to 15W30 fully synth oil as it is the thinnest (therefore fastest flowing) oil that I have.

I have primed the pump by removing the spark plug and turning the engine over on the kick start while pushing oil under pressure down the pipe from a syringe. Oil flows into the pump on cranking and oil returns through the scavenge line to the tank (all pipes are clear plastic so I can see the flow).

On starting the engine, oil can be seen feeding up the scavenge line to the tank return and to the rockers etc. Because this oil is slightly aerated, it is easy to see that it is flowing. I cannot see whether the oil in the supply line is actually moving as it is quite clear and un-aerated.

This continues for a short period - possibly up to a couple of minutes. After this period, the scavenge line begins to show large air bubbles in the oil flow and the supply line has large air bubbles appear from the pump end and float up toward the oil tank. Oil clearly stops flowing to the pump at this point and the pump becomes airlocked.

Following this, the pump will not work until the priming process is repeated.

I don't really want to have to split the engine and start investigating the pump unless I really have to (and the pump appears to be working when I turn it by hand.

Any thoughts please guys?

Singles / C15 oil feed problem
« on: 25 July, 2017, 19:16:13 »
I have recently bought s 1961 C15T and have a problem with the oil feed.

The oil pipes are routed according to the w/shop manual. The pipe from the return pump goes to a to a T piece, with one line leading to the tank and the other to the top end of the engine.

The problem is that all the oil is being scavenged to the tank and none is going to the top end. I cannot see why it should. Despite this being the way the manual says it should be 'plumbed', I can't see why the oil would continue uphill to get to the rockers etc, when it has an easier route to just return to the oil tank.

What am I missing here??


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