Woody2000 Posted July 23, 2020 Report Share Posted July 23, 2020 Hi am starting to get my project up and running have got the engine running after 10-12 years in a garage it has a high lift cam fitted so wondered if anyone knew what the timing should be ??? Have it set at about 25 degrees BTDC at the moment runs ok ?? thanks Mark Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 23, 2020 Report Share Posted July 23, 2020 mk1 or mk2 ???? certainly not 25 deg more like 10deg static vacuum off. with a slow idle pete Link to comment Share on other sites More sharing options...
Woody2000 Posted July 23, 2020 Author Report Share Posted July 23, 2020 Sorry 1973 Mark 2 Link to comment Share on other sites More sharing options...
Nigel Clark Posted July 23, 2020 Report Share Posted July 23, 2020 Would expect static timing of 10-12 btdc. The best way is a test drive, if the engine pinks at around 2,000rpm on full throttle, retard the ignition timing slightly. If it doesn't pink, advance in small steps until it does, then retard just enough to prevent pinking. Nigel Link to comment Share on other sites More sharing options...
Nick Jones Posted July 23, 2020 Report Share Posted July 23, 2020 Any idea what cam? 25º static / idle is definitely too much. TBH I'm surprised it starts - I'd expect it to be stopping the starter in it's tracks as it tries to run backwards. It will also be getting extremely advanced as the revs get up - potentially as much as 40º at 4000 - which is easily enough to cause detonation and engine damage at big throttle openings. Might be worth bearing in mind that the timing marks on these sometimes move as they are marked on the harmonic balancer weight, which sometimes becomes unbonded and moves on the pulley assembly. Having said all that, if it's a fairly wild cam, it will respond well to lots of timing at idle/low rpm (25º is still alot!), but in order to safely run lots of advance you need to limit the the total mechanical advance timing to somewhere in the 30 - 32º region. Nick Link to comment Share on other sites More sharing options...
Woody2000 Posted July 24, 2020 Author Report Share Posted July 24, 2020 Ok thanks guys for all your help Link to comment Share on other sites More sharing options...
NonMember Posted July 24, 2020 Report Share Posted July 24, 2020 10 hours ago, Nick Jones said: 25º static / idle is definitely too much. TBH I'm surprised it starts - I'm not. I had a Mk1 Vitesse where the mechanical advance seized in the fully advanced position. It still started and ran. I had a Stag which got set up (by a well-known Triumph specialist) off the wrong cylinder and by a nick in the pulley - was almost 30 degrees out and still started. Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 24, 2020 Report Share Posted July 24, 2020 the rotating loose damper is a good call , happens more than many realise. JohnD has a engine rig to measure the effects of harmonic dampers ,,, it might ??? be at Duxford this year worth a watch , you will be amazed Pete Link to comment Share on other sites More sharing options...
Nick Jones Posted July 24, 2020 Report Share Posted July 24, 2020 4 hours ago, NonMember said: I'm not. I had a Mk1 Vitesse where the mechanical advance seized in the fully advanced position. It still started and ran. Similar on my 2.5PI. Dizzy advance mech not fully seized but very sticky and hanging up intermittently. I was having problems with that slowing the starter and it sometimes "knocked" as it started. Also problems getting the idle speed down though that was partly poorly sealing butterflies. Took me way to long to clock the dizzy problem.......... Nick Link to comment Share on other sites More sharing options...
Nigel Clark Posted July 24, 2020 Report Share Posted July 24, 2020 I've had engines almost refuse to start when there's too much static advance. The starter struggled to turn it over as the premature sparks try to push the pistons back down the bores. It's worse on classic bikes, the kick back on the kick start lever can really hurt your leg! Nigel Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 24, 2020 Report Share Posted July 24, 2020 isnt that an Up and Over kick start. pete Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now