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Bruce's D1
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Piquet
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November 26, 2018 - 2:20 pm
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Have a look here

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There appears to be 3 different arrangements for the oils seals on 3-speed engines. This is my understanding of the different systems.

Very early engines (D1) had only an outer seal on the generator side and a seal between the bearings on the drive side, inner main bearings lubricated by petroil mix from drillings at the bottom of the transfer ports.

The next engines (D1, D3), from about 1954 still used only an outer seal on the generator side and the drive side seal was moved to between the crank and bearings. Drive side bearings were lubricated by gearbox/primary drive oil and the generator side was lubricated by petroil mix supplied by a transfer drilling and the fan drawing the petroil mix through. There also appears to be two different arrangements to position the generator side seal, earlier engines used a distance piece and no fan, later engines used a fan to assist with lubrication and the seal was positioned by a circlip to avoid covering the transfer drilling.

Later still, 1958 perhaps? (D1, D5, D7), the arrangement stayed the same on the drive side but the generator side now used 2 oil seals either side of the main bearing which was now lubricated by gearbox oil the same as the drive side.

Information seems to be confusing to say the least and the Parts books don't help as I'm sure they don't list all the seals in all cases!

Further information/confirmation gratefully received will be added to the above FAQ section.

I'm not a complete idiot ............................................ some parts are missing.

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thornebt
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November 26, 2018 - 3:10 pm
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Thank you Blue Heeler and Piquet.  I removed the oil seal and the engine is now back together and the crankshaft, as you would expect, now rotates perfectly.

I didn't even have any bits left over!  I must be getting better at this engine rebuild stuff.

The fiddliest bit was when the kickstart return spring managed to escape its proper location (twice!) after I had fitted the clutch.  I managed to get it fitted correctly but it's a lot harder with the clutch fitted isn't it!

Cheers.  Bruce.

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GCOBBY
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November 27, 2018 - 12:17 pm
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I have replaced small end bushes, extraction was fairly easy, used junior hacksaw to cut through the old bush in the con rod. This made the extraction easier, still used bolt and washers to remove bush, and to refit new one .

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thornebt
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November 27, 2018 - 12:57 pm
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I think the best way to do it is to extract the old bush before fitting the new one - instead of trying to use the new bush to wind the old bush out. That's how I tried to do it and it didn't go well.  There's a good chamfer on the conrod which helps when fitting the new bush.  Cheers.  Bruce.

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Blue Heeler
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November 28, 2018 - 12:09 pm
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Gawd yeah,never use the new bush as an extractor...too soft a material....and dealing with drag of old and new bush simultaneously,not good.

Are you sorted now?

Blue

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thornebt
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November 28, 2018 - 1:57 pm
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Yes, the bush is installed, oil holes drilled and reamed.  I got the idea of using the new bush to push out the old bush with a bolt and spacer in a magazine article.  Of well, I guess we learn by our mistakes.  Just need to find some time now to fit the barrel and a dry day to get the engine refitted.

Cheers.  Bruce.

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thornebt
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December 1, 2018 - 7:09 pm
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I appreciate that torque wrenches weren't around much in the 1950s but has anyone got a torque setting for the cylinder head nuts please?  I've done mine to 15lb/ft and it seems tight enough to me.  I'm using a standard composite head gasket.  I've carefully tightened them slightly in a diagonal fashion.

Cheers.  Bruce.

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BonesCDI
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December 1, 2018 - 7:29 pm
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18-20 ft/lbs

Running and project bikes from 1912 -2005..........She hasn't said stop yet.........

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cocorico
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December 1, 2018 - 8:53 pm
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Don't forget to re-check when the engine is nicely warmed up, too.

1956 D3 running, lights to sort. 7 other bikes in the Barn, 6 runners (when I get time!) and a still in progress Morini 250

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thornebt
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December 21, 2018 - 6:06 pm
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I'm just getting my D1 back on the road after the engine rebuild. The rear wheel is stiff to turn but I've read in the Haynes manual that the bearings are non-adjustable. I've greased them via the grease nipple in the hub.

If I were to back off the large 'inner' spindle nuts that are adjacent to the speedo gearbox and the rear sprocket is that likely to make the wheel turn more freely please? Or should I just take the bike for a run and let the newly injected grease work its way in?

I've tried loosening the main wheelnuts but that doesn't seem to make the wheel turn any more easily.  The drive chain is correctly adjusted.

Cheers. Bruce.

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swalsh58
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December 21, 2018 - 6:27 pm
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The wheel should spin reasonably freely, check its in neutral, check the brake isn’t binding, check the tyre isn’t rubbing on the mudguard. Ease of the inner bolts and see if it spins freely with them slackened. If it does, perhaps you have missed a washer or spacer? Or just overtightened? Is the speedo drive free and not binding, is it located properly?If all those are ok, the only other option is the wheel bearings.

Current bikes......1958 D5, a 77 Suzuki GT250 and a 77 Honda CB125S. I have a 74 Kawasaki S3 400 and a B175 waiting for restoration. A 1980 Honda CB400N waiting for MOT.  Everyday ride is a 2011 Harley Davidson Sportster. 

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thornebt
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December 21, 2018 - 7:25 pm
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Thanks for your reply.  I checked those things and then discovered that the wheel turns fine when the drive chain is removed.  So the stiffness must be in the gearbox.  I replaced the bearings, oil seals and layshaft bushes.  I'm confident that the layshaft bushes were inserted as far as they could go.  Anyway, there's no way I'm taking it apart now so I'll just have to hope that when the bike is run that the stiffness frees up.

Cheers.  Bruce.

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swalsh58
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December 21, 2018 - 8:08 pm
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Not necessarily. Is the chain new? Is it the right size? I am not demeaning your abilities at all, but some chains sold for the Bantam aren’t always the right size. Are the sprockets in line? If the chain is running slightly diagonally across the sprockets it will make the wheel stiff to turn. Can you turn the engine sprocket freely without the chain attached?

Current bikes......1958 D5, a 77 Suzuki GT250 and a 77 Honda CB125S. I have a 74 Kawasaki S3 400 and a B175 waiting for restoration. A 1980 Honda CB400N waiting for MOT.  Everyday ride is a 2011 Harley Davidson Sportster. 

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thornebt
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December 21, 2018 - 8:51 pm
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The chain is quite stretched.  There is no visible thread on the front part of the adjusters so it is almost at the end of its life.  However, the stiffness is certainly in the gearbox sprocket.  Everything seemed fine when I put the gearbox cluster in so I think it can only be that the shoulders on the layshaft became tight against the layshaft bushes when I screwed the crankcases back together.  I didn't pay any attention to the gearbox as I was more concerned about the crankshaft rotation.  The gears do seem to select OK though.

Hopefully the gearbox should quite quickly loosen up.  I need to think about a new chain once it's back on the road.  My Haynes manual shows the chain size as 1/2" x .205".  I've checked my current chain and it's certainly 1/2".  The internal measurement is .250" but it's obviously impossible to measure the roller length with a micrometer.  

A chain of this size can't be too expensive.  I'll probably buy one from Rex Caunt as I know it will be good quality and the correct spec.  I just looked in his Ebay shop but could only find the primary drive chains.  I'll email him.

Cheers.  Bruce.

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BASIL
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December 22, 2018 - 10:39 am
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Hi, I have to ask the question did you ream out the layshaft bushes to the correct diameter before you reassembled the gearbox? Regards Basil. 

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thornebt
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December 22, 2018 - 10:57 am
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Hi Basil

Yes, I reamed the layshaft bushes.  It seems my problem is resolved as I got the bike started and took it for a run of a few miles and the rear wheel now turns much more easily.  I've now got a separate problem which I'll start a new post for!  Cheers.  Bruce.

MOD EDIT - I've merged all of your D1 questions, so that the work on your D1 is easier to follow.

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thornebt
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December 22, 2018 - 11:04 am
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DSCN0961.JPGMy newly rebuilt D1 engine is pulsing a fuel mixture from the small hole in carb as indicated by the screwdriver in the photo.  It does this when I turn it over on the kickstart and presumably when the engine is running.  Can anyone shed some light on this please?  Cheers.  Bruce.

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johnsullivan
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December 22, 2018 - 11:58 am
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I think the float is stuck or set too low.

67 D10. and a D7    2007 Honda Hornet FA. Honda CD200 81 93 Yamaha TTR 250 Raid, Sinnis SC 125.   75 Montesa Cota 247 an electric scooter of Famous make.

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thornebt
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December 22, 2018 - 12:53 pm
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Thank you John.  You are right, the carb was flooding.  It seems OK now but it has done this several times before.  I removed the top of the carb and blew down the fuel line whilst pushing the float upwards and it seems to seal fine.  The taper on top of the float spindle looks good to the naked eye.  Cheers.  Bruce.

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Blue Heeler
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December 22, 2018 - 4:54 pm
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Quick tap on the float bowl with a decent-sized screwdriver handle sometimes settles things down.

Have you an external inline fuel filter fitted? The one in the tank isn`t always up to the job,after all those years having to face up to the grit and rust that has found its way into the fuel mix.

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