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FGF

Thanks Momus .

almost 0.03 '' , 0.8 mm with cold engine .

is this the BSA B25 value '?

FGF

sorry , i've forgotten ...

third solution : is it a problem to ride with a little offset between the valve stem and the tappet adjuster screw ?
the previous owner of my B50 rode like that , i don't really trust him .

FGF

Thanks Beat . i was curious to know if this problem was very usual on the unit singles . my second photo comes from the Web by a rider wich had this problem too. i 've taken a bit from the rocker arm , a little , for the rocker bore it 's not easy Momus , may be necessary. To choice shims , what abo...

FGF

Hello , removing the B50 rocker box , i find a wrong position for the Exhaust tappet adjuster : the end of the screw '' overcome the chamfer '' . rock_echap.jpg i wanted to fit a larger thrustwasher but the gap is very thin : there is a risk for the rocker to reach the housing. and the gap for the t...

FGF

Hello ,

After a few advises, i 've tightened the head stud nuts with oiled threads , torque wrench 40 Nm .
Obviously all seem to be OK .
i 'll try to start like that

i wait for my oil pump sent to PES for two weeks .
Bushes seemed to be necessary .
Francois

FGF

Hello Beat ,

Thanks for all , very sorry for having disturbed you with these mechanical problems .

Best wishes for your health .

FGF

Hello Beat , you needed some housings welds on your project. for the crankshaft bearings, you had to weld on the crankcase. i have a little fissure to repair on my B50SS crankcase . ( wrong tightening stud ) can you give me some advise about aluminium welding especially about the oil wich enter in t...

FGF

Hello , i understand now. a french B50 rider has told me that these threads are tapered ( about 1 % ) and so the stud is not tightened to reach the end of the thread like on every stud usually. i had never heard such a fitting for studs. too late for me ... the fissure is short but there are many co...

FGF

Hello Momus , could you explain me what your answer means ? my english is not accurate enough ... it 's a little fissure but this place receive a lot of constraints . i hesitate between loctite 271 alone and loctite 271 after a little TIG weld... many riders seem to have welded the B50 crankcase wit...

FGF

Hello the thread is in good condition . the stud is stopped by it's bottom instead of the end of it's thread : it 's unusual. I had a fear that the bottom hole was broken but there is a lot of material around it and it's depth is only 22 mm. the fissure don't cross the fixing bolt hole below. i 'm g...

FGF

for instance , i don't understand what has happened.

i see a little fissure on the crankcase near the red arrows and in the bottom of the thread
i don't feel any hole .

the stud was too long for the hole ?
if yes , usually it 's the thread which is broken not the crankcase .

FGF

The crash ! i decide to tighten the stud wich is about 3 mm higher than the three others. it turns slowly , 1 mm , 1.5 mm . i use a torque wrench fitted on 22 Nm , it 's not high . the nut can support 46 Nm dry ... and a big noise '' crac '' the left crankcase is broken . black oil is flowing from t...

FGF

Hello , a new surprise : one of my cylinder studs is not fully tightened . I can see two or three threads at the base of the stud near the crankcase. This stud didn't turn when i removed the nuts and the nuts seem to have been correctly tightened . two solutions : 1 -there is a machining mistake : t...

FGF

Thanks again for helping. All the bike engines i have worked on had head nuts to be oiled . It 's à wellnown solution to make a uniform tightening. BSA don't wrote it on the torque wrench settings for the head nuts.... I 'm going to tighten With the lower torque and With lightly oiled nuts. It would...

FGF

Hello ,

we have the torque wrench settings in the workshop manual.
for the head nuts , i think they are tightened with oiled threads .

but what is the tightening sequence ?
the six about 26 Nm with 1-3-6 et 2-4 -5 and after 1-3 -2 - 4 with about 43 Nm

FGF

Thanks for your help , Gerry , Momus , Gerry , i understand and my big end is a new one . I do want to fix my oil pump cases and it 's not very easy to find a 3 studs B50 oil pump now. My pump is not worn out , there is a little wear of course : i can see a little step on the upper plate but don't f...

FGF

Hello the work progress slowly : big end conrod and piston changed by a French machinist ( philippe Huron , goldstar French specialist ..) HP-bielle.jpg HP_culasse.jpg waiting for it : frame tank petrol cleaned and new paint for all the frame. peinture_cadre.jpg now beginning the engine rebuilding :...

FGF

hello ,

do you know the spider limit of wear : i 've read rickard 's advice

: rickard.jpg (10.7 KiB) Viewed 397 times

: spider chamfered

the rear plate chamfer create a new one on the spider edge .
So the axial clearance is about 1 mm betwen the spider and the centre.

is it too much for the spider ?

FGF

Sorry , it was a special shim the previous owner had fitted when he worked on the clutch . shim.jpg he had a big alignment problem ( 1.6 mm ) with the primary chain i guess ... i 'll see that later. nut slowly tightened , the crankshaft rotate freely with it's new bearings. Now , oil pump , gearbox ...

FGF

Hello , my B50SS has its crankshaft removed by my French machinist and we find a surplus washer !!!!!!!!!! if it was this one , it would be a nightmare : ( W on inner race ) Vilo.jpg can you give me some details about it ? this washer have OD 31.8 mm ID 22.2 width 1.6 the OD is close to the inner ra...

FGF

Hello Phil ,

if you don't want to worry about it , Peter Quick ( BSA unit Single ) sell all the parts and even a little bush
with all the advises to fit it . ( new O rings ...)

the thickness of your rocker box must have the same value than the others , nearly sure ...

FGF

Hello Tom Thanks for your answer about the crank assembly balancing. With a bigger piston ( 86mm ) and heavier alpha crankpin and carillo , where can be drilled the holes ? BSA has taken the whole place near the big end with it's two holes : B50_crank.jpg the B50 crank design is not easy to drill ex...

FGF

Thanks JB , it 's clear . But i was looking for an advise wich is to balance the flywheels separately before the crank assembly work. this way would be choosen by a machinist which make a static work with no modern machine like my French machinist today. the separate flywheel static balancing is not...

FGF

Thanks Tom. I 've read your old post about it and now i understand better the details of this way. It 's really accurate with a dynamic machine . At the beginning , i was looking to have a better comprehension of the static way working with the flywheel separately wich is something i never had liste...

FGF

Hello , Thanks for your advises . Jeff , you are talking about the crank assembly balancing with this factory weight replacement ? don't you ? B25_weight.jpg i 'd like to see a pattern of a '' separate flywheel balancing '' , if possible . Some think it to be a good thing before the crank assembly w...

FGF

Hello , i 've read many posts about the crank balancing and some talk about the flywheel separate balancing . i understand the sludge trap problem which cause a big dissymmetry . i know the dynamic flywheel balancing wich is made on an electronic machine but what is the static separate flywheel bala...

FGF

Thanks mlb50, yes it 's a B50SS and the supplier provide two NTN roller bearing Ok but a LJ7/8ZZ for the ball bearing . i agree with that choice for the 6206 metric in the gearbox on the sleeve gear to limit leaks and , only one seal would be enough. For the crankshaft it could be useful to limit th...

FGF

Hello , re-building the crankshaft , i 've received from a serious supplier an encapsulated ball bearing (LJ7/8ZZ) to remove the 65-5883. it's not a real sealed bearing , is it really a better design than the original one ? i think it would be better to strip the conrod side cover to let the engine ...

FGF

Hello , My sleeve gear ball bearing seem to be in good condition but the engine is fully stripped and the seal has to be changed. The bearing rotate freely with the gearbox sprocket. If i remove this bearing , do you advise me to fit a C3 bearing or a normal class bearing on the sleevegear ? sleeve....

FGF

Thanks for all. i 've found a 3/16 BSC at RGM Norton by Gerry but for the oil pump , it 's difficult to have a little diameter (3/16) and a long thread ( 1 -5/16 ) with BSC. Middleton and Custom fastener are interesting too , but for the 3/16 BSC i 've not found screws. Draganfly propose the breathe...

FGF

Hello ,

Rebuilding the B50 engine , it 's very difficult to find BSC screws like the 4 oil pump screws . 3/16 '' BSC
i 've looked over the classic suppliers and only one today.

Does someone know an English supplier for CEI or BSC screws ?

FGF

Hello , I was looking for the oil pump screws (41-0609) which are made with a BSC thread. A supplier change them by the breather head screw ( 40-0309 ) with a BA thread and a larger slotted head. These two threads are very close ... but does someone has used any BA in a BSC thread with a good fortun...

FGF

Hello , '' Re-building '' the oil pump , i see two little problems to solve : - no gasket : just oiling the plates and fully tightening the screws ? - worn screws ; the screw 's round cylinder head has been chewed by the screwdriver . I only find one at Draganfly store but they supersede it with the...

FGF

Thanks riders ,

3 hours bathing in unleaded gasoline and 3 hours with a cutter slowly and then acetone with a brush .

this B50SS will be ready to fire in a few weeks ...many weeks maybe, but it will !

FGF

Hello

the pump faces are covered with very old '' bond gasket '' .
How to remove it ?

i 've tried brake cleaner , white spirit , gas oil , white vinegar , acetone ...no real result .

FGF

Right , Beat
i thought it to be so tightened than the pinion.
it 's nearly free slipping , just pull with the fingers .

sorry for a useless mail. i take the opportunity to ask another question :

is it possible to use a '' brake cleaner '' to clean head , oil pump , aluminium alloy cases ?

FGF

Hello , now the oil pump : the case was fitted with gasket sealant and the scavenge hole nearly clogged... surprise : no feed gear thrust washer on this B50-1971 . the main case has the S mark and the upper one the V mark. someone gave me a blue print of the 2 studs oil pump but there is no note abo...

FGF

Hello , now the worm gear removal , i read two posts about it : a two legs puller with thin finger at the end. but , '' Ruppert'' said to pull behind the pinion, after taking off '' the tapered washer '' from the bearing with a special screwdriver ... the post wrote : pull from the end teeth of the ...

FGF

Hello
on the two sleeve gear bushes , we can see a slight groove where the seal scrub :

i don't see it on the pictures showed by the part suppliers.
are the bushes made with a rolled sheet of metal ? it 's not broken ...?

FGF

Hello , with a B50 stock conrod ( 41-550 for B50-B44 ) is it usual to machine the cylinder liner like this ? liner.jpg Gerry answered me quickly and i thank him but i 'd like to understand why the factory didn't design a suitable liner for it 's conrod .. Changing conrod is not a '' plug and play ''...

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