BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
JWood Auctions JRC Engineering dealers JWood Auctions
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
DPO
DPO
Douglasville (Atlanta) Georgia
Posts: 1,649
Joined: June 2007
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
47 registered members (Allan Gill), 296 guests, and 454 spiders.
Key: Admin, Global Mod, Mod
Newest Members
Dan1818, Konaflyer, Begbie, Andrew Fallo, Zack Banks
10419 Registered Users
Top Posters(30 Days)
btour 84
Rohan 77
Triless 70
reverb 68
Popular Topics(Views)
713,728 mail-order LSR
Forum Statistics
Forums34
Topics68,328
Posts665,199
Members10,419
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate Thread
Sidevalve decompression setup #724224
02/04/18 5:58 am
02/04/18 5:58 am
Joined: Dec 2014
Posts: 160
Perth, Western Australia
H
Howley Online content OP
BritBike Forum member
Howley  Online Content OP
BritBike Forum member
H

Joined: Dec 2014
Posts: 160
Perth, Western Australia
Hi all,

I'm looking at my decompression setup. I've set the tappet clearance to the specified 0.012. The service sheet says to maintain a gap between the Lifter cam and the tappet head, but pulling the decompression lever only lifts the pushrod by less than 0.012 so the valve doesn't actually lift.

Is it ok to take up most of the tappet clearance with the Lifter?

Thanks

Support your #1 BSA Forum and our favorite sponsors

Check out BSA on e-bay: BSA Parts in UK, BSA Motorcycles in UK, BSA Parts in North America, BSA Motorcycles in North America

 
Re: Sidevalve decompression setup [Re: Howley] #724239
02/04/18 12:45 pm
02/04/18 12:45 pm
Joined: May 2004
Posts: 3,862
Sydney Australia
B
BSA_WM20 Online content
BritBike Forum member
BSA_WM20  Online Content
BritBike Forum member
B

Joined: May 2004
Posts: 3,862
Sydney Australia
No.
There is near 1/4" of travel in the pin of an M series decompressor.
It rotates round in circles with no stop.
So set the clearence on the valve, tripple check it.
Then remove the decompression lever and rotate it till the pin is almost touching the cam follower then replace the lever on the spline so it points down at around 45 deg.

IF you still can not get enough lift then the valve guide has most likely shifted in the barrel.


Bike Beesa
Trevor
Re: Sidevalve decompression setup [Re: Howley] #724245
02/04/18 2:02 pm
02/04/18 2:02 pm
Joined: Dec 2014
Posts: 160
Perth, Western Australia
H
Howley Online content OP
BritBike Forum member
Howley  Online Content OP
BritBike Forum member
H

Joined: Dec 2014
Posts: 160
Perth, Western Australia
To clarify.
There is plenty of lift in the lever on the case, but the lever on the handlebar pulls so little cable that it only actuates a tiny bit.
Have I got the wrong decompression lever for the bar? It bottoms out after moving the lever on the case literally a few millimetres.

Re: Sidevalve decompression setup [Re: Howley] #724276
02/04/18 7:37 pm
02/04/18 7:37 pm
Joined: May 2009
Posts: 99
Australia
M
MattL Offline
BritBike Forum member
MattL  Offline
BritBike Forum member
M

Joined: May 2009
Posts: 99
Australia
Hi Howley,

Post a photo of the bar lever. Is the inner cable too long?

Last edited by MattL; 02/04/18 7:38 pm.
Re: Sidevalve decompression setup [Re: Howley] #724303
02/04/18 11:10 pm
02/04/18 11:10 pm
Joined: Dec 2014
Posts: 160
Perth, Western Australia
H
Howley Online content OP
BritBike Forum member
Howley  Online Content OP
BritBike Forum member
H

Joined: Dec 2014
Posts: 160
Perth, Western Australia
Pics below. I can adjust the slack out of the cable no problem, although the curve in the cable at the engine end would contribute a little.
Note that the blob on the cable doesn't exactly fit in the lever but it is seated.
[Linked Image]

[Linked Image]

Re: Sidevalve decompression setup [Re: Howley] #724309
02/05/18 1:02 am
02/05/18 1:02 am
Joined: May 2004
Posts: 3,862
Sydney Australia
B
BSA_WM20 Online content
BritBike Forum member
BSA_WM20  Online Content
BritBike Forum member
B

Joined: May 2004
Posts: 3,862
Sydney Australia
You are missing the ferrule that sits on the end of the cable at the handlebar end,
With this fitted you will be able to back out the adjuster on the engine at least 1/2" if not more and that will give you enough pull to raise the valve.
Note it only goes up a few thou.


Bike Beesa
Trevor
Re: Sidevalve decompression setup [Re: Howley] #724319
02/05/18 3:20 am
02/05/18 3:20 am
Joined: Dec 2014
Posts: 160
Perth, Western Australia
H
Howley Online content OP
BritBike Forum member
Howley  Online Content OP
BritBike Forum member
H

Joined: Dec 2014
Posts: 160
Perth, Western Australia
I've got the ferrule, it's recessed into the lever. I can raise the valve now, but only if the Lifter in its relaxed state is taking out 9 of the 12 thou of tappet clearance.

Re: Sidevalve decompression setup [Re: Howley] #724331
02/05/18 4:25 am
02/05/18 4:25 am
Joined: Dec 2014
Posts: 160
Perth, Western Australia
H
Howley Online content OP
BritBike Forum member
Howley  Online Content OP
BritBike Forum member
H

Joined: Dec 2014
Posts: 160
Perth, Western Australia
This is approximately what I had after setting it up the first time.

[Linked Image]

Re: Sidevalve decompression setup [Re: Howley] #724336
02/05/18 5:04 am
02/05/18 5:04 am
Joined: May 2004
Posts: 3,862
Sydney Australia
B
BSA_WM20 Online content
BritBike Forum member
BSA_WM20  Online Content
BritBike Forum member
B

Joined: May 2004
Posts: 3,862
Sydney Australia
The outer should be almost level with the mouth of the lever, not 1/4" to 1/2" inside
Also try moving the lever arm up one place on the spline.
From what I can see your inner is too short as well.
can you pull the lever all the way back to the handlebars ?


Bike Beesa
Trevor
Re: Sidevalve decompression setup [Re: Howley] #724341
02/05/18 6:28 am
02/05/18 6:28 am
Joined: Dec 2014
Posts: 160
Perth, Western Australia
H
Howley Online content OP
BritBike Forum member
Howley  Online Content OP
BritBike Forum member
H

Joined: Dec 2014
Posts: 160
Perth, Western Australia
I think this lever must be a different design, because all is normal at the lever, despite appearances in the pics. I can adjust any slack out of the cable no worries, and the lever pulls all the way to the bar.
I'm not discounting the lever being the wrong type though, although according to the vendor listing it is the correct one.

Last edited by Howley; 02/05/18 10:20 am.
Re: Sidevalve decompression setup [Re: Howley] #724346
02/05/18 8:26 am
02/05/18 8:26 am
Joined: May 2009
Posts: 99
Australia
M
MattL Offline
BritBike Forum member
MattL  Offline
BritBike Forum member
M

Joined: May 2009
Posts: 99
Australia
My bar lever looks to be shorter and sticks out at a sharper angle (I mount mine below the clutch lever). Having said that the lever at the tappet chest only moves about 30 deg, say 2 o'clock to 3 o'clock.

[Linked Image]20180205_184057 by Matthew Leahy, on Flickr

[Linked Image]20180205_184136 by Matthew Leahy, on Flickr

[Linked Image]20180205_184151 by Matthew Leahy, on Flickr

[Linked Image]20180205_184206 by Matthew Leahy, on Flickr

Re: Sidevalve decompression setup [Re: Howley] #724824
02/08/18 11:36 pm
02/08/18 11:36 pm
Joined: Dec 2014
Posts: 160
Perth, Western Australia
H
Howley Online content OP
BritBike Forum member
Howley  Online Content OP
BritBike Forum member
H

Joined: Dec 2014
Posts: 160
Perth, Western Australia
Thanks for your help guys. I'm on top of it now. The problem was a combination of:

1. Slop in the pivot of the handlebar lever (fixed by increasing the pivot screw size).
2. Inadequate travel of the handlebar lever (fixed with a bit of careful grinding, don't worry it was a pattern lever).
3. Poor lighting in my shed resulting in me not noticing that the tapped head was dished, meaning the clearance I was setting was in reality far greater than 0.012.

I'm going to grind the tappet heads flat again and re-set the clearances, I'm pretty sure I'll be good after that.

Re: Sidevalve decompression setup [Re: Howley] #724835
02/09/18 2:31 am
02/09/18 2:31 am
Joined: Aug 2016
Posts: 55
Canterbury, New Zealand
B
BevanC Offline
BritBike Forum member
BevanC  Offline
BritBike Forum member
B

Joined: Aug 2016
Posts: 55
Canterbury, New Zealand
I don't have an s.v., but wouldn't the tappet heads be hardened, so grinding could remove the hardened surface ?

Re: Sidevalve decompression setup [Re: Howley] #724846
02/09/18 4:30 am
02/09/18 4:30 am
Joined: Dec 2014
Posts: 160
Perth, Western Australia
H
Howley Online content OP
BritBike Forum member
Howley  Online Content OP
BritBike Forum member
H

Joined: Dec 2014
Posts: 160
Perth, Western Australia
Interesting comment, although I'd just be grinding the flared edges and only licking the contact face.

Re: Sidevalve decompression setup [Re: Howley] #724991
02/10/18 10:39 am
02/10/18 10:39 am
Joined: Dec 2014
Posts: 160
Perth, Western Australia
H
Howley Online content OP
BritBike Forum member
Howley  Online Content OP
BritBike Forum member
H

Joined: Dec 2014
Posts: 160
Perth, Western Australia
So it's all sorted. It turns out that most of the issue was due to the shape and orientation of the Lifter 'cam'. Where it needed to be set for clearance was around the bottom of its circle, meaning that for the first bit of cable movement it was moving sideways instead of up. I ground the cam a little so it starts at 6 o'clock or so. I also gave it a more aggressive cammy profile so it goes straight into max vertical movement.

I ground the tappet heads flat too, using a temporary fixture to keep it square to the side of the bench grinder wheel, so I've got heaps of lift now.

I fired the bike up today for the first time since I bought it three years ago. My leg is hurting, carb is leaking like a sieve, and flooding itself, and the fuel tap is leaking and not fully shutting off, so I'll be servicing all that next.

Good to hear it run finally!


Moderated by  Allan Gill, Jon W. Whitley 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.6.2