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Navigator engine in the shed

Submitted by dan_field on Mon, 01/05/2017
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Light Twins

Ok as you know I bought a navigator engine from gumtree a couple of weeks ago partly because I have a whole bunch of Navi bits that I could make into a complete bike. I had intended to fiddle around with my jubilee and see what I could do to improve it, but it turned out to be in better shape than I thought so that has gone together pretty much standard.

So I intend to build a bike around the navi engine using what ever I have to hand to make a usable street scrambler or bike for the MCC trials. I have a couple of other projects and two race bikes to maintain so it won't be quick!

Anyway I made a start today and took off the chaincase, the clutch looks good and the PO had made a nylon chain tensioner ( better than the wooden one in the jubilee!) but I wasn't happy with the lateral movement of the clutch or the way that gearbox sprocket moved down when I lifted the clutch! Being an early bike I was going to check the layshaft bush anyway so continued to dismantle, everything came apart easily.... a pleasure to work on. The gearbox had little oil in it .... worrying! And had a lot of black goo at the bottom, as if it had been contaminated by the clutch? The gearbox clusters came out ok and everything is serviceable except the kickstart rachet but I have a spare. But when I took out the sleeve gear I was surprised to see this (although it explained the wobbling!) Cont..

Submitted by dan_field on Mon, 01/05/2017

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A couple of questions: I'm going to replace the sleeve gear bearing given the beating it will have taken, is this a simple case of taping it out into the gearbox? And I want to clean befind the blind bushes in the gearbox if I tap out the plugs will they go back in again?! Also one of them sits proud of the cases, see below, is that normal, my spare has them both flush? Thanks

photo IMG_0646_zps5r4vg6lc.jpg

Submitted by andrew_wibmer on Mon, 01/05/2017

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Previously Dan Field wrote:

A couple of questions: I'm going to replace the sleeve gear bearing given the beating it will have taken, is this a simple case of taping it out into the gearbox? And I want to clean befind the blind bushes in the gearbox if I tap out the plugs will they go back in again?! Also one of them sits proud of the cases, see below, is that normal, my spare has them both flush? Thanks

photo IMG_0646_zps5r4vg6lc.jpg

Hi Dan,

mine fell out when I heated the crankcase to get my camshaft bushes out, figured I would put it back when reinserting the bush. Heated at gas 6 for 1/2 hour. I was going to push them in from inside the case.

Submitted by patrick_mullen on Tue, 02/05/2017

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Hello Dan,

You possibly already know more than me on the Jubilee gearbox and in general they seemed simple to work on. On all the boxes I have known there were TWO bushes in the sleeve gear, not the three you were expecting. I don't think it mentions these at all in the Maintenance Manual and I don't know if any new spares are available.

I can't remember having any problem in replacing the sleeve gear bearing so it must have been pretty simple to do as I have replaced a couple in the past. Again the Manual says nothing on the subject. I think the NOCshop still do replacements.

All the plugs I have seen sit flush to the case and I assume are a sort of core plug i.e you simply push in (when new) and give a tap with a hammer to lock in place. I don't think there were intended to be removed and re-used but I never thought of Andrew's method of heating ! I once used a coin of some description to replace a missing one!. And it worked as well.

Patrick

Submitted by peter_holland1 on Tue, 02/05/2017

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Previously Dan Field wrote:

As you can see two bushes are missing, heaven knows where they went, it's not like the blighters can fall out!

photo IMG_0645_zpsykepc8fa.jpg

Hi Dan,

I went to a bearing/transmission stockist and asked for Oilite bushes with the same OD and wall thickness. The one offered was a little longer than the original, so no problem there.

The bearings pressed in OK, but you will find the compression nips the ID up. They will need reaming to get the mainshaft to fit through. Don't use abrasives as these will contaminate the Oilite and continue abrading after assembly.An adjustable reamer is very useful.

One surviving bearing only is, sadly, quite normal. The other bearing has progressively fed itself into the clutch and been machined away.

It always seems to be the clutch side bearing that does this.

I fitted a third bearing between the inner and outer on my Electra. You just need to make sure the lube gets there, or else the mainshaft drags the bearing round in the sleeve gear.

Cheers

Peter

Submitted by dan_field on Wed, 03/05/2017

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This is my spare sleeve gear and is why I thought it had 3 bushes!

photo IMG_0650_zpsneb76z7y.jpg I also found this in the bottom of the gearbox, it's pretty small, but couldn't find anything obvious it came from? photo IMG_0651_zpstpabgtdv.jpg

Submitted by patrick_mullen on Wed, 03/05/2017

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Hi Dan,

You are in luck with your spares!

Uli will recognise the circlip. It is off the gear change cam plate - it holds the ratchet shaft into the cam plate.

Patrick

Submitted by dan_field on Thu, 04/05/2017

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Thanks Patrick, I'm actually going to fit my spare gearbox, complete with sleeve gear as it seems to be in better condition than this one, the kickstart rachet is very worn on the original. But I'll check the circlip is fitted before I do!

Dan

Submitted by dan_field on Wed, 17/05/2017

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Parts have arrived and I've been out start to give it an internal clean, sadly the layshaft bush fell out all too easily, it's obviously been spinning a bit there is some visible play but hopefully it will loctite in, I'm assuming that the box isn't sensititve to a bit of play! I'll peg the bush while I'm in there.

 



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