Topic: CB750 - Will not run without full advance - WHY?

[PeWe]

I have my timed cams in an Excel sheet were loob centers will be calclated when open close are filled in.
I made it once it was fresh in my brain without need to think too much.

I tested some values on IN. LC 101 when advanced more. From my setting of open IN 25* to around 28*. Maybe not exact but in that direction.

[Tracksnblades1]

I have my timed cams in an Excel sheet were loob centers will be calclated when open close are filled in.
I made it once it was fresh in my brain without need to think too much.

I tested some values on IN. LC 101 when advanced more. From my setting of open IN 25* to around 28*. Maybe not exact but in that direction.

Indeed, Ive seen a video of one of your engine idling and it had a very good idle and a responsive throttle response…blue Honda I’m thinking…

How do you verify Dyna S 2/3 timing….?
Whats the Allen wrench used for that some talked about…?

[PeWe]

I have my timed cams in an Excel sheet were loob centers will be calclated when open close are filled in.
I made it once it was fresh in my brain without need to think too much.

I tested some values on IN. LC 101 when advanced more. From my setting of open IN 25* to around 28*. Maybe not exact but in that direction.

Indeed, Ive seen a video of one of your engine idling and it had a very good idle and a responsive throttle response…blue Honda I’m thinking…

How do you verify Dyna S 2/3 timing….?
Whats the Allen wrench used for that some talked about…?

I check with a timing lamp.
1-4 and 2-3.
Usually on 4 wire and 3.

2-3 was a little different, not much so I had to use the allen tool I got with the Dyna-S. Moved it just a very little. That was a few years ago.

[Don R]

 I had a 383 small block with apparently, less than optimal big pistons, it wanted 41* of total timing. Flame travel took some time. It did make 684 hp.
 I didn't see much discussion about fuel, is it fresh and what grade?  My gl1000 despises premium pump gas, it spits out the carbs and bogs off idle, when I top off with regular it gets happy again.

[Tracksnblades1]

I had a 383 small block with apparently, less than optimal big pistons, it wanted 41* of total timing. Flame travel took some time. It did make 684 hp.
 I didn't see much discussion about fuel, is it fresh and what grade?  My gl1000 despises premium pump gas, it spits out the carbs and bogs off idle, when I top off with regular it gets happy again.

Interesting about the fuel….Old premium was said to burn slower in low compression applications, but closer to normal in high compression applications….talking flame front….

My 1966 SuperSport 327 Big Fuelie 461x heads w/forged 11.25:1 Chevrolet / TRW TSlot oil drain back hole pistons (allowed tight clearances) loved 43* BTDC. 18-20* BTDC initial with a 23* or more mechanical advance in by 2500 and a z28 12* vacuum advance that dropped out with anything under 8” of manifold/vacuum and wouldn’t pull in until it had at least 12” of vacuum…all right out of Old Smokey’s play book…

Now days with better combustion chambers and piston top designs, timing lead is alot lower when using modern gasolines.. under 36* total for the better cylinder heads…

[Don R]

 My 40 Chev has 355", the double hump 71 heads, less compression than yours though, I built it for the street when good gas was hard to come by. Steel crank, pink rods, forged pistons, 9.5 or so comp. I had the old points distributor dialed in from a Hot Rod article. It's always run OK on whatever fuel it gets.
 My gl may have low cylinder pressure, it's got 59K on it and sat for at least 20 years. I call it an "attached garage" find. That could be the cause of it's finicky tastes as far as fuel goes.

[Tracksnblades1]

My 40 Chev has 355", the double hump 71 heads, less compression than yours though, I built it for the street when good gas was hard to come by. Steel crank, pink rods, forged pistons, 9.5 or so comp. I had the old points distributor dialed in from a Hot Rod article. It's always run OK on whatever fuel it gets.
 My gl may have low cylinder pressure, it's got 59K on it and sat for at least 20 years. I call it an "attached garage" find. That could be the cause of it's finicky tastes as far as fuel goes.

Yeh, but I haven’t seen my 66SS since 79 when I sold it to buy a 78 k1500 GMC..your 40 has to burn todays blend..

Back then you could still buy leaded 95 octane at Shell or go to a Gulf station to get the extra kick high octane premium and get the magnetic horse shoes for your bumper..😁