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Which 2T oil after rebore?
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Stephen
Great Yarmouth
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May 19, 2020 - 9:24 pm
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Hi again everyone,

Decided to carry on this conversation here rather than in the "introduce yourself" section which i started a few days ago!

So, all parts ordered and dimensions/measurements/recommendations obtained regarding the +40" rebore on my D1; just one more question!

What are your thoughts on 2T oil to use after a rebore with new piston/rings etc? Should i stick with the Shell Advance VSX I just started to use before strip dowm, or go with a general 2T oil like good old 'Morris Oil' vintage model 2T oil?

I'm thinking; brand new parts and a rebore then the shell oil should  be OK? (i know 2T oil is always a contensious issue)!

Thanks again in advance guys....and gals!

Stephen...

D1 Bantam 1963

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Blue Heeler
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May 19, 2020 - 10:38 pm
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Either will be fine. More importantly, after the quality of parts which you`ve got covered, is machining bore to correct tolerances for the piston and that ports are radiused, both of which a decent motorcycle engineer will have covered. Some don`t bother...Burdett Engineering, P`bro didn`t radius mine in 1976...I have a long memory, haha.  I`m sure you`ve got the rebuild quality and running-in covered....& the usual suspects, carb set-up, plug grade, ign timing and a freewheeling bike 🙂

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Stephen
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May 20, 2020 - 7:17 am
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Blue,

That was going to be my next dicussion; "& the usual suspects, carb set-up, plug grade, ign timing and a freewheeling bike 🙂"

I may need some help and recommendations with this also!! I've just signed up as paying Member so hopefully that will open me up to more technical documents and manuals on the site. But I guess you're talking carb jets, iridium type plug etc?

Hopefully I haven't bitten off more than I can chew regarding this rebuild....frownembarassed!!

D1 Bantam 1963

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cocorico
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May 20, 2020 - 7:21 am
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D1 bantam, any 2T oil, any multigrade oil in the gearbox, stick to standard plug (B6HS?), same with carb. Don't expect much in the way of performance but lots of fun and frustration getting there.

1956 D3 running, lights to sort. 7 other bikes in the Barn. 1950 D1 engine now running.

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Stephen
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May 20, 2020 - 8:51 am
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Thanks for that Cocorico! Performance is not really my concern or an issue, I just want to do the right things so I can get out and enjoy this little beauty....thumbs-up

D1 Bantam 1963

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Sponge
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May 20, 2020 - 9:14 am
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Just to add some depth to this thread - once you have settled on a suitable type of 2T oil - stick with it if you can.  Buy a big can and carry a bottle when you go on a long journey.  I have experienced overheating probs in the past with chopping from mineral to synthetic etc as they don't always mix.  Also check that the 2T oil is recommended for pre-mix useage.  Not all of them are. 

Theoretically synthetic 2T oil is better able to handle higher engine temperatures and runs cleaner - but mineral oil is what the engines were designed to run on.   I, therefore, use semi-synthetic and walk the middle path. 

Sponge

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Stephen
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May 20, 2020 - 6:25 pm
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Appreciate that Sponge.

If all goes well after start up and run-in and no issues are encountered, I'll stick with the Shell Advance VSX 2T oil (pre-mix approved). I'll also go with the manuals recommendations, 2 petrol cap measures of oil (200ml) to 1 imperial gallon of fuel (4.546ml) which works out to just over 1:22 mix.

I'd rather it runs on this ratio during the first few hundred miles before thinking about going to either 1:30 or higher (if at all)! 

D1 Bantam 1963

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mcafee
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May 21, 2020 - 6:04 am
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Morning Stephen ,Any good quality 2T premix oil will be fine but the biggest factors are not the oil, but as Blue Heeler says the qualiy of the rebore and also the way you run the engine in.My B175 was rebored by a local company who did a great job and the running in only took about 350 miles using a semisynthetic oil.Good luck with your running in dont forget be patient,let the engine rev a bit and lighty load it.

David

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Stephen
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May 21, 2020 - 4:28 pm
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David...appreciate the advice.

Here's one for everyone; when i stripped down the engine on the D1 I'm a bit anal about marking everything up so after removing the head I used a permanent marker to put an arrow on top of the piston showing 'front'.

After pulling the barrel off and seeing the pitting and wear inside I was more concerned about getting someone to rebore the barrel than I was about looking at the piston, more importantly the position of the pegs in the ring grooves!

When I was looking through my original BSA Instruction manual earlier today I came across this statement under 'Piston Rings' page 13; "The piston must be replaced in it's original position-i.e. with piston ring gaps towards the rear on D1 and the front on D5 engines."

I just went and checked my piston and based on the arrow I marked on the piston crown before stripping down, the 2 pegs in the grooves were facing forward and not towards the rear!!!

I guess this was fitted wrong by 'whoever' before I purchased the Bantam!! And could it be the cause of some of my problems with wear and a badly smoking engine when it was previously running????

D1 Bantam 1963

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Unitminor
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May 21, 2020 - 4:51 pm
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How I understand 2st is the pegs are there to stop the rings from turning also they are in a position so the piston gap does not catch in a transfer port 

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Number6
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May 21, 2020 - 5:00 pm
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http://livinginthepast-audioweb.co.uk/imagex/misc/hand-point-up.gif this

Seems like Stephen's was lucky and the rings didn't break! freaked-out_gif

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

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Stephen
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May 21, 2020 - 5:11 pm
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So am I right Number 6; Was the piston fitted wrong??

D1 Bantam 1963

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cocorico
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May 21, 2020 - 8:51 pm
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Service sheet 504 specifys ring pegs facing rear on the D1 (ie ring gap to rear), facing front for D3, D3, D7.

1956 D3 running, lights to sort. 7 other bikes in the Barn. 1950 D1 engine now running.

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Stephen
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May 21, 2020 - 10:21 pm
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Wow.....so it was installed wrong!!! Thank God for the amazing resources on this forum and the kind replies from the dedicated members here too!

As a newbie, I'm learning more every day....clap

D1 Bantam 1963

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Stephen
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May 25, 2020 - 3:50 pm
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So I've received the new +.040" piston and rings for the D1 rebuild and the new piston is stamped with an arrow on the crown still in the direction of the ring groove pegs. Common sense would suggest the piston should be fitted with the arrow pointing forwards but I'm going to fit it pointing rearwards so the piston ring pegs are facing the back of the barrel......unsurefingers-crossed  

D1 Bantam 1963

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Unitminor
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May 25, 2020 - 4:05 pm
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It may pay you to just give it a quick check before fitting offer the piston to the barrel and Mark where the pins are and they do clear the ports a minute or 2 checking could save a lot of trouble later as you have to assume that pattern parts are made to the same as original

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cocorico
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May 25, 2020 - 5:02 pm
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I also have a nagging doubt about the orientation. I seem to remember reading 'somewhere' that early D1s had rear facing gaps whereas later ones were towards the front. Anyone else shed any light - or is it a figment of my imagination???

1956 D3 running, lights to sort. 7 other bikes in the Barn. 1950 D1 engine now running.

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Stephen
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May 26, 2020 - 11:43 am
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I'm sure we're right Cocorico, but I will definitely offer up the piston with the barrel first as you suggested; you never know, either way it faces it still may not expose the ring gaps over or even near to the transfer ports! I will certainly let you and all those interested know when I do.

This from the manual; "The piston must be replaced in it's original position-i.e. with piston ring gaps towards the rear on D1 and the front on D3 and D5 engines."

D1 Bantam 1963

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Ringting
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June 1, 2020 - 1:11 pm
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Hi Stephen. All the above but also check that the piston skirt cut outs and transfer port cutouts at the bottom of the cylinder line up with the piston at bdc. 

Enjoy, Alan.

D1, D14/4, Guzzi LeMans, Triumph Trident 900, Maserati 160 t4. Mk1 Mini Traveller, Berkeley T60.

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Stephen
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June 1, 2020 - 8:34 pm
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Ok everyone.....without going into too much detail the engine is back together with no issues. Piston ring groove pegs and clearances in relation to transfer ports etc. all good. I must thank Damico Engines Ltd in Snetterton (Roudham Ind Est) for doing a great job on the rebore.

Here's a picture of the bike. I also have a short video (10 Secs) of the bike running after rebuild but i dont know if (or how) i can upload the video based on the file size and upload limitations......help please??

    

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