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Restoration 4 - Matchless G3 Panel Tank


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Hi Ron, though I’d share with you an image of the original fuel tank, you can still see it attached to the fuel tap🙈😂

Hi All. After recently completing my James ML restoration idle hands set in again. I said to myself no more projects, but after the opportunity of an early Matchless G3 panel tank came up I

Oil tank on and newly renovated battery carrier fitted....slowly starting to look like a bike with the 8” headlamp. I am having a little trouble finding a 1” throttle barrel compatible with my tw

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1 hour ago, flyingfleasteve said:

Different in height to Ron? 
I assume they accepted the same battery?

I never noticed any difference in height on the bikes. They both take the same standard Lucas WD battery and the mountings are the same. It's probably just a slight variation to the top bend.  Ron 

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My engine really clattered at the top end!   When I stripped it for a rebuild, I found that one of the rocker shafts had too much sideways movement. There was no up and down movement in the bushes that I could feel, so I just added a thrust washer to the offending shaft to the end that still aligned it up over the valve.

All some years ago so a bit vague now. I'm trying to think though, surely you wouldn't have to rely on the ends of the bushes to reduce end float?   

Steve can you add pictures of your progress please.  Ron  

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As Rod said, a thrust washer or shim would help, I perhaps incorrectly assumed the bush had become ovalised. 
 

Perhaps a new bush, then checking for excess end float and shimming/thrust washer is required. Could be a satisfying fix!

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The bushes are in fact used to set endfloat, and there is a special tool to be made to replace/adjust them, and while you're at it, also replace the felt washers inbetween them! (you will get more oil to the Big-end) you will need a special tool for that too, there is a very informatiuve video on Youtube where we learned all this, I did this process to several rockerboxes 2 years ago.

Lex

PS be carefull, the nuts are very tight sometimes!!!

7B3AA0~1.JPE

01670A~1.JPE

95885C~1.JPE

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Be interesting to see what you do Steve.

I've completed the correction swap of my battery trays and while I was at it, I made a new pivot pin for the stupid side stand on my G3L as the original was badly worn which made the stand even more stupid😝

The battery tray trunnions on my G3L are bronze after market or home made and were 2" long with  flat ends. The drawing shows them at 1 7/16" so I sawed at least 1/4" off all ends and rounded them off. I also took the opportunity while the trays were on the bench, to glue the rear trunnions in their channels with clear silicon.......Another silly idea by Matchless🥴 Ron 

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So I have dropped off the last of the engine parts to be vapour blasted and cleaned. The newly refurbed barrel is also being bored to +20 with a NOS piston to be fitted.

Remind me gents, what are the figures/tolerances the barrel should be bored to, please?

 

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Yes the machinist will always work from the piston being used! 

Strangely the Triumph SV data quotes 7-8 thou piston skirt clearance which by the standards of all the other makes I've dealt with....Is worn out!!??  Maybe Triumph pistons were designed or prone to expand more than others when hot?

Ron  

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Yep my engineer has winced at that instruction. But would do you do? Follow the book or make a calculated guess?? The 3HW OHV spec is as as you would expect... 4-4.5 thou. Ron

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Hi Ron,

I have been rebuilding engines of all shapes and sizes for over 50 years. I think that each make of piston should be considered independently. The manual would refer to using factory supplied pistons. As years go on different manufacturers will be making pistons for replacement. Usually there is a leaflet in the package giving clearance per inch, I know Hepolite and Wellworthy did this. Things can go wrong though and I will give an example, not a motorcycle, but was related to military vehicles. I was working in a MoD Workshop rebuilding engines for vehicles and was given a small batch of Commer engines to build, all done to the manual, block was already bored and prepared. I checked the gap on the rings, put it all together and it went in to the test house. Not long after I was told the engine had tightened up and I had to dismantle it for inspection. It revealed that the pistons had nipped up. On examination it was found that the pistons were not of the make of the original specification and that the originals were, if I remember correctly a 'wire wound' type working on a tighter clearance. Luckily the pistons were not damaged and the block was honed out to the correct clearance and all was well.

I am also aware that during the war period there were inconsistencies with the alloys used for pistons and there were problems with expansion. I had my WM20 seize once and on removing the piston (STD bore) I measured it against the REME Inspection Standards and it was larger than plan size, which bore out what I had learnt.

Regarding this Triumph piston I would ascertain the manufacturer of it and see what info can be found.

regards, Richard

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Interesting Richard! Wire wound pistons, Matchless used those from 1949 to 1952 or so, very good pistons, but unobtainable now.

Here a link to the MoD Inspection Standards book for wartime Matchless engines, it's a very good book!! (there's one for BSA too) Note though, some pages in the beginning are mixed up.

1953_Army_G3L_Technical_handbook_and_inspection_standards.pdf (jampot.dk)

I should have posted this earlier, but thought everybody knew about it,

Lex

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16 minutes ago, welbike said:

Interesting Richard! Wire wound pistons, Matchless used those from 1949 to 1952 or so, very good pistons, but unobtainable now.

 

Thanks Lex,

The original wire wound pistons for the Commer were made by BHB as were those for the c.1950 Matchless. It was a Matchless owner in the Workshops who realised the difference in pistons and the clearance differences!

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Lex I have the Matchless standards book and like the data in their manual, they don't give you a straight forward figure for the skirt clearance😣...You have to deduct the skirt size from the bore size to deduce a measurement of .0044"  

Here is the Triumph 3SW & 5SW data. (7-8 thou) As you say Richard, an after market piston could well have a different expansion rate, but if you don't have the instruction from the manufacturer.....It's guesswork.

Lex did you order a pile of hand books (just arrived here)??   Ron

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Things have been a little slow this week whilst work remains crazy busy. I am slowly buying a few last parts for the engine build but cannot for the life of me find the exhaust value dimensions, I think the head should be approx. 40mm in diameter, but I am not sure of the length, can anyone varify, please?

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