Britbike forum

Classic British SparesKlempf British PartsBaxter CycleThe Bonneville ShopLowbrow CustomsGirling Classic MotorcycleLucas Classic MotorcycleHepolite PistonsIndustrial tec supplyJob Cycle

Upgrade your membership to Premium Membership or Gold Membership or even Benefactor


New Sponsor post
Triumph 650/750 High-Output Alternator Kit
by The Bonneville Shop - 01/13/23 11:29 pm
New FAQ post
Missing edit button
by wrench136 - 05/30/22 2:57 pm
News & Announcements
Premium members! 🌟
by Morgan aka admin - 01/31/23 2:14 pm
Buy BritBike staff a coffee ☕️ or pint 🍺
by Morgan aka admin - 01/15/23 9:29 am
Benefactor ✅
by Morgan aka admin - 01/08/23 8:38 pm
Gold members! ⭐️ ⭐️ ⭐️
by Morgan aka admin - 01/03/23 6:30 pm
How to guides - Technical articles
British Fasteners Specs
by Morgan aka admin - 01/03/23 1:29 pm
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Member Spotlight
AussieDerek
AussieDerek
Wangi Wangi, NSW, Australia
Posts: 25
Joined: November 2022
Top Posters(30 Days)
Lannis 77
DavidP 74
Top Likes Received (30 Days)
Kev. 36
DavidP 25
Newest Members
BSA A65 rebuild, Dan Haggard, Padsdad, sam keller, Raz
12,386 Registered Users
Forum Statistics
Forums35
Topics76,525
Posts783,968
Members12,386
Most Online204
Jul 10th, 2022
Random Gallery photo
Photo posting tutorial

Previous Thread
Next Thread
Print Thread
#886532 07/26/22 1:32 am
Joined: Mar 2015
Posts: 97
Likes: 2
alibaba Offline OP
Britbike forum member
OP Offline
Britbike forum member
Joined: Mar 2015
Posts: 97
Likes: 2
I have timed a lot of motorcycle cams with an engine on the bench - head off - using two dial indicators.
I want to avoid that to check cam timing on a problem bike.

Suggestions on how to check cam timing without pulling the head?
I have Keith Johnson 1/2 mile cams so any markings on the cams may no be correct.
I have the settings so just want an easy way to see if the cams are correct.

British motorcycles on eBay
Joined: Dec 2016
Posts: 37
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2016
Posts: 37
This can be done....as long as you have an accurate valve lift profile graph. Using the graph, pick an appropriate checking lift, a common one is 040". Calculate the "lift" at the lifter (where you check clearance on a DBD). Set the clearance to the checking lift clearance plus standard tappet clearance. Now set the engine position to overlap where each lifter is at 0 clearance and 0 lift. Compare that position to the graph. It's not as accurate as checking with dial indicators, but it's better than not checking.

Joined: Feb 2007
Posts: 1,174
Likes: 114
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2007
Posts: 1,174
Likes: 114
I have an A65 that I wanted to check the valve timing on. With a degree wheel hooked up and a buddy rotating the crank with a socket on the nut at the end, after a couple of tries, we were able to get repeatable results as to when the pushrods would start to get tight and were able to determine that, yes indeed, I had a bad cam (20 degrees late on intake opening and 30 degrees early on closing on one cylinder). I wouldn't use that method for precision work, but if you are just trying to verify that the timing is approximately where it ought to be, it should work for you.

Ed from NJ

Joined: Aug 2015
Posts: 1,985
Likes: 108
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2015
Posts: 1,985
Likes: 108
You can make the above 100% accurate.
Pick a wide tappet clearance say 0.040" as above but then check at both ends of the opening and closing where the push rod can just be rotated and note the numbers on the degree disc. Exactly half way between these 2 numbers is the lobe angle and is usually in the vicinity of 100 degrees
The lobe angle can be calculated from the camshaft spec opening and closing points
eg The cam opening point is 60 BBDC and closing point is 40 ATDC so total duration is 60 + 40 + 180 = 280, the mid point will be 140 which is 100 degrees BTDC lobe angle


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
GM500 sprint bike "Deofol"
Rickman Jawa 500 "Llareggub"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro No Senshi"
Kawasaki Ninja H2 "Fujin"

Moderated by  Rich B 

Link Copied to Clipboard
British Cycle SupplyMorries PlaceKlempf British PartsBSA Unit SinglesPodtronicVintage MagazineBritBike SponsorBritish Tools & FastenersBritBike Sponsor






© 1996-2023 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5