Ariel

[morrag]

An adjustable reamer is the only way to go.....Morrag

[Firery Fred]

YES remember Malcom and the frosted glass ha ha ha

[blair]

been working on another project a street fighter thingy may stick it on once im further ahead , cause i is a little slow at building stuff , finally had a go at sizing the bronze bushes , attempt 1 i used a honing tool as there wasnt much adjustment required or so i thought . turned out i had taken too much out of the main bearing and when my mate appeared with some adjustable reamers it was apparent that i had buggered it up , so i ordered another set , this tiime i used the reamer and also done them before they were pressed in. not sure if its true but i was told that when they are fitted they compress. will find out when they are fitted .

Ariel

[morrag]

Bushes should always be reamed after fitting, as they will compress the bore when fitted, the degree being dependant of fit, wall thickness of the bush, and expansion rate of the enclosure, Morrag

[blair]

thats ok though Morrag as i have left the reamer set , so if it does shrink a degree then i can run it through again . i have never used a reamer before but i think it when ok , i actually put some fine valve paste onto the shaft and spun it a couple of times and you could see high spots within the reamed bush .

ahahahaha reamed bush 

[blair]

finally got a bit more done to the ariel , used a reamer on the bushes and my mate pressed them into the crank cases . they did shrink a little but a wee dab of fine valve paste on the shaft and a spin opened it out to allow for the oil to get were it needs too , should have the bottom end back together soon enough
i may not have got it to withing .001" but im sure itll be ok for me , i have actually put other engine together and worked out that the parts have all been crossed between them , i replaced the needle bearings and pivot nuts as the ones that were on was thicker  so i guess that they came from the bsa engine

crank with home made alignment tool

Ariel

dry build of engine

Ariel

[blair]

different nuts , the ones that were fitted were hitting the inside of the crank cases ??

Ariel

[Manky Monkey]

Ooh, shiney cases!

[morrag]

I have had a 'home made', "Alpha" jig for setting cranks up for many years, but prior to that , and originally, under my old Dad's instruction! I aligned Brit. cranks using a heavy straight edge and feeler gauges on the rims of the flywheels, as British full circle flywheels were usually machined to excellent tolerances, with regard to crank pin relationship. so might be worth giving your crank a check using that method Blair, assuming you haven't already done so, of course! Morrag

[blair]

Hi Morrag

yes we did just that , well i didnt but one of the lads at my work did .

but this is the sort of advice thats short on the ground so thanks

cheers

[blair]

Hi Morrag

got a bit of a odd question , or maybe not . i rebuild the crank up and fitted it into the cases . all is well but if you spin the crank every third rotation is stiffens up a little and then frees off again , i could understand if it was a tight spot on every rotation, i have got oil in the sump and the pump is working as i got oil coming out of the return pipe.

any ideas ?

cheers for any advice

[morrag]

Well, a few things come to mind. If you have thrust washers fitted either side of the crank pin, they may not be concentric, but that's unlikely. You trued the wheels priors to building the bottom end, and sometimes, when the crancases are pulled up they "pinch" the wheels opposite the crankpin, which will give you the sort of tight spot you are getting. When I trialed Bultacos and Montessas, years ago, I made a "T" bar with a lower flat to give a cam action, so that once the bottom end was assembled, you could put it between the wheels, via the crankase neck, and "tweek" them back to true, after assebly. Put a dial guage on each shaft to check.Finally check the rod to flywheel &/or thrusts, to ensure equal clearance is maintained over 360 degrees of rotation. It will likely be sumat simple though!! Morrag

[hunter]

Yep I'll go with Morrag on the flywheels needing a tweak.

[blair]

ok i get what you are saying , i shall split the cases open again and remeasure the crank . i spoke to an old school mechanic today and he asked about my use of the reamer and thinks i may not have left enough clearance . but will check the crank first

cheers guys

[Olds]

Not quite understanding the every third revolution part though. Every rev I'd suspect the crank. Every other rev and I'd be looking at the cam or timing gears. How is the oil pump driven on this engine?