B50 at Bonneville Salt Flats

[HPbyStan]

I just bought a Sifton "High Turnover" cam off eBay from the Appleton, Wi. bunch. They thought it was a standard TR25W cam, LOL. Somebody cut the crapp out of the cam gear but I can throw that away and install a weighted one in its place.

[koncretekid]

Interesting, Stan, what can you tell me about the Sifton High Turnover cam? Does it use flat tappets or radused ones? I could install it in my spare cases and profile it if you want to send it / sell it to me. Not sure about the cam gear; is it wide key or narrow key? Wide gear or B50 narrow gear?
Tom
Is this it? Looks like radius tappets, lots of overlap!

[HPbyStan]

Yes, it is. It uses the C15 / B40 type lifters and is a top end cam. I'm not sure which gear is on it. Easy to tell it's all carved up but not sure from the pic what it started as. Better idea when it gets here.

[HPbyStan]

Wide woodfiff key. Looks like the gear was turned around to get a higher area around the lifters to keep them straight with the high lift cam and a bunch of rpm and then the teeth narrowed to miss the boss of the lifter area in the cases as well as lose weight. I dug through my cam stuff box and found a handful of newer gears and 2 old style gears that must have been here forever as they were lightened back before I learned what a bad idea that is from the S.A.E cam design book. Inexplicably I hadn't thrown them away but that has been taken care of now along with the latest one. A farther look around found one old style gear that hadn't been ruined so I put that on for now. ...Stan

[HPbyStan]

Found this B25 info from an old Sifton dealer price sheet. I don't have later Sifton stuff, that I can find at least ,so I don't know if this is for all unit singles from C25 on or not. 104 degree intake centerline and 111 degree exhaust centerline.

For those non mechanics amongst us, Lobe centerline is the highest point on the cam lobe in crankshaft degrees away from the piston at T.D.C.
in this case;
add 15.5 * intake opening to
.....180* to
.....45* intake closing for total of;
240.5
divide by 2 for;
.....120.25
subtract the smallest number, in this case 15.5 to get;
104.75 degrees lobe centerline

[koncretekid]

Interesting, Stan. I found some data I had taken on the Megacycle X4 which compares closely although you didn't say what the lift is on the Sifton cam. The numbers are as follows, measured at the pushrod with B40 tappets, extrapolated to .113" lift (my data was measured at .100" lift and .150" lift)

Inlet opens: 17º BTC
Inlet closes: 50º ABC

Exhaust opens: 47.5º BBC
Exhaust closes: 14º ATC

Lobe center at this lift (.113") calculated to be around 106.5º

Are you sure you didn't design the X40 cam after this cam, Stan????

[koncretekid]

Forensic Analysis after 14 runs at Loring, Maine
For those who didn't read my posts under "Tales of Woe", I had some good runs at Loring, Maine, after a complete rebuild with new cases. I managed a speed of 150.8, within .5 mph of my own record, but had clutch engagement problems on the 14th and final run. Here's the analysis:


Clutch plates looked fine, as did the steels, but the basket was totally grooved up so the clutch engagement was an issue.



This bracket holds the carburetor up and one end was broken allowing some major shaking of the carb.



The shifting rod is made of 1/2" steel tube with a turned down 5/16" bolt fitted within. It broke loose so that.................................

it had at least 1/2" of excess movement before moving the lever. No wonder I was having trouble shifting.





I found these 2 bolts in the fairing as well as the nut off one end of the lower motor mount rod. The 2 bolts and spacers held the oil filter bracket onto the rear motor mount. The bottom of the oil filter was bouncing on top of the clutch lever and nearly punctured.



The good news is the a leak-down test showed no more leak-down than immediately after the last time I checked it at 7%. Some people say that it should be less than 7%, but I've never seen it less. The leaks are partially around the intake valve and partially blow-by.

On a lighter note, my blueberries are the best we've ever had!



Tom

[HPbyStan]

I use steel solid plates and alloy fiber plates because while their tabs wear more quickly than the steel ones but they are cheaper than wearing baskets so fast.

[beat]

, I know - but just to make you jealous as well:

the best and most Apricots ever....

just out of my window....

beat

about the clutch: it seams as with your HP it comes to the edge of what it is built for....

[Barry Creary]

v

even more off topic these are what I catch at my back yard 5 this year from 900 grams to 2.1 kgs but I like blueberries and apricots looking for Mintey and I have used the same as in my clutch with the same thoughts as you Stan

[beat]

[b50root]

I use steel solid plates and alloy fiber plates because while their tabs wear more quickly than the steel ones but they are cheaper than wearing baskets so fast.

And where do you get those?


Rickard

[Barry Creary]

eBay Rickard not sure were but that's were I got mine and I bought a aluminium basket to so will see how it goes

[beat]

I bought a aluminium basket to so will see how it goes

wonders me two.....
beat

[HPbyStan]

http://s296.photobucket.com/user/HPbySt ... ort=6&o=85
This alloy basket served several years on one of my B50s before getting switched to the B25. Still going strong.

[Mark Cook]

We did start making a high quality version many years ago, but then abandoned them as there is just no point in using the BSA clutch when we make a better option. Sadly cheaper too now.

[beat]

This alloy basket served several years

was it " anodized " after machining ?

beat

[Barry Creary]

Yes Beat it is anodised and has a hardened steel ring for the roller bearings

[beat]

thanks barry...

beat

[Barry Creary]

Beat and Rickard the aluminium clutch basket is from montysclassicmotorcycles on eBay and they have the aluminium plates as well

[Sly Dixon]

Yes I got one from them and it seems to be a nice bit of kit. Got alloy friction plates as well but kept the steel driven plates. Clutch is very smooth and progressive with good clearance.

[koncretekid]

Just back from a great week at Bonneville with Andy, John, Mark, and Paul. Here is a photo of the crowd, including my friend Doug with his beautifully build Buell Blast powered open bike.


I took issue with a flagpole just after the timed mile at 149.33 mph which ended my quest to up the APS-PG (special build, partially streamlined, pushrod motor on gasoline) record over my previous record of 149.894 mph. I then had to strip off the fairing and run the open bike class where I reached a best of 125.6 on a 133 mph record.

Photos of my bike with the fairing and without with my pit crew Ed from Pennsylvania. Also, the broken windshield which kept me from pursuing the old record.




I'm already thinking about how to get a few more mph for next year. The open bike record is a bigger challenge.

Tom

[HPbyStan]

R40 ??

[AJ CCM]

R40 ??