Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesSRM EngineeringLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade your membership to: Premium Membership | Gold Membership | Life Membership | Vendor Membership | Site Sponsor Membership
Welcome to BritBike Forum!
Britbike forum logo
Member Spotlight
Denis J
Denis J
Sacramento, CA
Posts: 396
Joined: November 2012
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Previous Thread
Next Thread
Print Thread
Joined: Jan 2014
Posts: 3,372
Likes: 19
R
reverb Offline OP
Britbike forum member
OP Offline
Britbike forum member
R
Joined: Jan 2014
Posts: 3,372
Likes: 19
Hello;
Possibilities:

T140

-70-9989 ex at factory mark with intake at factory mark.
-70-9989 ex at factory mark with advanced intake like Mr Russell suggested at some point but is a bit unclear for me.
-709989 ex at another mark and factory intake mark. Something that I do not know if can work.

Support Your #1 BritBike Forum!

Check out British motorcycles for sale: British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Joined: Jan 2006
Posts: 2,279
Likes: 38
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Jan 2006
Posts: 2,279
Likes: 38
Do you have the cases split? A 650 exhaust cam will make a noticeable difference.
My go to cam timing is around 101 degree lobe center intake and 105 degree exhaust. Seems to make good power where needed most. Unless you check, you will not know what you have. Just moving gears around could be an exercise in frustration.
Most 650 ex cams I've checked clock in at about 98 degrees stock marks. Most 750 ex cams are more like 92. Either would benefit from moving to 105 more or less in my opinion.
My 650 desert sled was assembled on the stock cam marks. Put down a whopping 29 hp. Ex cam was 98*. Moving it to 104 saw an increase to 34 hp on the same dyno. The power is in there somewhere, you just have to find it

1 member likes this: Nick H
Joined: Jan 2014
Posts: 3,372
Likes: 19
R
reverb Offline OP
Britbike forum member
OP Offline
Britbike forum member
R
Joined: Jan 2014
Posts: 3,372
Likes: 19
...Hi Mike; the engine is assembled but not used yet. I would remove the rockers, head and timing cover. I do not have the right extractor for the gears so I need to figure out something with the universal extractors.
I assembled it with an stock intake and 9989 ex.
I understand about that frustration but the times that I tried to find the lobe center were impossible for me. There is no any detailed information. I mean, all the information is from the perspective of people that just are in the known (gearheads to gearheads) so I did not obtained any good number at all hence I used the "teeth counting" but long time ago so I am unsure right now.

Joined: Aug 2016
Posts: 209
Likes: 17
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Aug 2016
Posts: 209
Likes: 17
You really MUST have the extractor/assembly tools, particularly the assembly one, or you will damage the camshaft bush with the camshaft key. Send me an email, and I'll send you a reasonably simple procedure for setting the cams using lobe centres. Usually the inlet cam will be about right with the standard marks, but not the exhaust, but best to check mickbarratt@talktalk.net

1 member likes this: Tigernuts
Joined: Jan 2004
Posts: 5,016
Likes: 81
D
Britbike forum member
Offline
Britbike forum member
D
Joined: Jan 2004
Posts: 5,016
Likes: 81
Lobe centre is found using a dial gauge. Easiest with the rockerboxes off so you can put the dial gauge in the end of the pushrod. Trying to do it whilst fighting the valve springs is not worth the trouble.
With the intermediate gear out you can rotate the crank around to the lobe centre for that cam then rotate the cam back and forth and find the lift equal distance down from maximum lift then split the difference. Put the intermediate gear in. You only have to pull the gear and realign to another keyway if the teeth are too far off.
Rotate the crank back to TDC, hold the cam gear and crank in place, pull the intermediate gear and replace the intermediate gear with the alignment mark at the crank. Mark the cam gear and intermediate gear alignment with a pen.
Then do the same with the other cam.
Now you can put in the intermediate gear with both cams in the correct position and the crank at TDC.
If you only have cam open/close degrees the lobe centre is (open degree + 180 + close degree) / 2 - open degree after XDC.
Example: Intake open 30 BTDC, close 60 ABDC
Lobe centre angle = (30 + 180 + 60) / 2 - 30 = 105 ATDC

Joined: Jan 2014
Posts: 3,372
Likes: 19
R
reverb Offline OP
Britbike forum member
OP Offline
Britbike forum member
R
Joined: Jan 2014
Posts: 3,372
Likes: 19
Hi TinkererToo thanks; I assembled few Triumph engines in these past years but never had the factory extractor. I think that I used an universal extractor and then a aid with a socket to push them in.
I will send you the email.

Hi DMadigan; thanks but there are many details about that method that I cannot understand to obtain the numbers.

In theory I put the timing like number 2.
9989 aligned with factory mark and inlet advanced 4.8º in a new mark "C" at 16 + 1 teeth
Also I do not remember if I used the right key or did not.

Joined: Aug 2016
Posts: 209
Likes: 17
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Aug 2016
Posts: 209
Likes: 17
For DMadigan, my method does not require removal of the rocker boxes, nor does it need a dial gauge, and you don't "fight" the valve springs. Drop me an email and I'll send you my procedure - feel free to pick holes in it, but it has worked for me! I have seen some of the work you do - far in advance of anything I do, but I do get repeatable results on cam timing, and it requires less mechanical aptitude (and equipment).
Cheers,
Mick

Joined: Feb 2005
Posts: 877
Likes: 10
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Feb 2005
Posts: 877
Likes: 10
Originally Posted by reverb
Hi TinkererToo thanks; I assembled few Triumph engines in these past years but never had the factory extractor. I think that I used an universal extractor and then a aid with a socket to push them in.
I will send you the email.

Hi DMadigan; thanks but there are many details about that method that I cannot understand to obtain the numbers.

In theory I put the timing like number 2.
9989 aligned with factory mark and inlet advanced 4.8º in a new mark "C" at 16 + 1 teeth
Also I do not remember if I used the right key or did not.

Reverb, in VB John Healy has stated that later twins had slip fit cam gears and that he reams the earlier gears with a 13/16" ream for ease of cam timing, I plan to do this for my current builds even though I have the factory tools...why not? Mark R.

Joined: Sep 2008
Posts: 1,685
Likes: 38
S
Britbike forum member
Offline
Britbike forum member
S
Joined: Sep 2008
Posts: 1,685
Likes: 38
It would appear that our experiences differ somewhat. In my experience Triumph 650 sports cams usually come up within a few degrees of spec, which is 100.5 degrees. On the 750's the exhaust cams clock in at around 99-101, but the last one I did averaged 98 deg exhaust and 106 deg inlet.
I ended up with these numbers reversed, that is 98 inlet and 106 exhaust. The engine, as far as I know, hasn't been run yet, so who knows how it goes, but I find 100-102 inlet and around 105 exh usually works well on T140 cams, and on 650 cams too.

SR

Joined: Oct 2012
Posts: 5,768
Likes: 126
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 5,768
Likes: 126
Many here have changed T140 intake timing...Stock timing for most is 92 to 94 degrees intake lobe center.There are some with 106 degrees....the early timing kills off the top end and increases the possibility of detonation. The later timing costs power on low and midrange rpm. As said aove, about 100 degrees intake lobe center makes the best overall power for road use


79 T140D, 96 900M Ducati ,61 A10 .On a bike you can out run the demons.."I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Aug 2016
Posts: 209
Likes: 17
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Aug 2016
Posts: 209
Likes: 17
I go for 98 and 105, as this cross checked fine with the "lift at TDC" method for the factory Spitfire production race figures. I use the T140 intake spec on exhaust as well, on convered pre-unit engines I can use a second inlet cam, though Harris make a 71-7017R for this (both to be used with 3/4" followers). There's no point it getting too anal about this, as you can only get +/- 2.4 degrees, each step of keyway is 4.8 degrees. Unless you have a sack of timing wheels, that's the best you'll achieve! I realise that this cam choice is a bit agressive, but that's how I like it! Opinions differ, shall we say.

Joined: Sep 2008
Posts: 1,685
Likes: 38
S
Britbike forum member
Offline
Britbike forum member
S
Joined: Sep 2008
Posts: 1,685
Likes: 38
Originally Posted by Hillbilly bike
Many here have changed T140 intake timing...Stock timing for most is 92 to 94 degrees intake lobe center.There are some with 106 degrees....the early timing kills off the top end and increases the possibility of detonation. The later timing costs power on low and midrange rpm. As said aove, about 100 degrees intake lobe center makes the best overall power for road use
I too have found more T140 inlets at around 92 plus or minus, than 105-107. The worst was at 90, in a wonderfully original 79 T140E, which wouldn't go well at any rpm. With the cam retarded to 100 LC it went so much better I could hardly believe it. However, with these long duration cams combined with a low compression ratio, they're still a bit soft low down. I find higher compression perk them up nicely, if you have the fuel for it. Other than that, I much prefer the 650 camming for road use. You and others knows more about hi performance camming, but I find an E3134 useful on the exhaust, and only tried a Hyde 1/2 race exhaust cam once, and it was great.

SR

Joined: Jan 2014
Posts: 3,372
Likes: 19
R
reverb Offline OP
Britbike forum member
OP Offline
Britbike forum member
R
Joined: Jan 2014
Posts: 3,372
Likes: 19
...I said "advance" because seems Mr Russell found always the inlet at 105 or more.

Joined: Sep 2014
Posts: 1,228
Likes: 10
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Sep 2014
Posts: 1,228
Likes: 10
I'm interested in your valve timing method Mick - I'll drop you an email.


If anything other than a blank space is visible here, something's wrong.
Joined: Dec 2004
Posts: 11,220
Likes: 131
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2004
Posts: 11,220
Likes: 131
Or feed your opening and closing figures into

https://www.blocklayer.com/degree-wheel.aspx

and it will calculate the lobe centre for you.

Joined: Aug 2016
Posts: 209
Likes: 17
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Aug 2016
Posts: 209
Likes: 17
Nice one!

Joined: Jan 2004
Posts: 5,016
Likes: 81
D
Britbike forum member
Offline
Britbike forum member
D
Joined: Jan 2004
Posts: 5,016
Likes: 81
Mick, I do not want to pick apart whatever method you have.
If you have symmetric lobes you can rock the cam between the two cylinder lobes and split the difference. then you are 90 cm degrees from lobe centre. By counting pinion teeth you can figure how far the crank has to be turned before inserting the intermediate gear. Or leave the crank gear at TDC and rotate the cam gear the required number of teeth.

1 member likes this: Allan G
Joined: Oct 2012
Posts: 5,768
Likes: 126
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 5,768
Likes: 126
I have used this for years. It's the standard used by high performane cam grinders. The formulas are easy to do with pencil, paper and a calculator if needed..

http://www.webcamshafts.com/pages_misc/degreeing.html


79 T140D, 96 900M Ducati ,61 A10 .On a bike you can out run the demons.."I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Jan 2014
Posts: 3,372
Likes: 19
R
reverb Offline OP
Britbike forum member
OP Offline
Britbike forum member
R
Joined: Jan 2014
Posts: 3,372
Likes: 19
...I read it but lack of plenty of details for a motorcycle application. Still looks a bit of Chinese for me. There are all types of videos regarding Triumph and other motorcycles. but no video of this important task.


Moderated by  John Healy 

Link Copied to Clipboard
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor






© 1996-2021 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5