TOPIC:

the info I gave was off the top of my head that's why I suggested looking in the shop manual to make sure.

Ok thanks, off to do some more on it now,,

I've been going through this but my cause is/was most definitely carb related.

First double check your intake boots. I did this several times. First I sprayed WD40 around the inlets while running. Then I tried ether, Then I used a propane torch so I could direct the gas right around the edges. If the RPMS climb while doing this you have an air leak. If not, you should be good.

It could be timing related so I would double triple check before getting into the carbs.

Have you cleaned/rebuilt or adjusted your carbs lately? What are the settings on your air mixture screws? Main jet size?

I'm inclined to think its carb related and you are running lean. If you have changed your displacement and cleaned up the head, then you've changed the flow of your motor and how your carbs will interact with it. You now have more vacuum so the air/fuel mixture has changed. With the throttle hanging like that it points to lean.

I had the same problem but I've rebuilt and readjusted my carbs and it is almost perfect except mine leans out when hot. At first I was backfiring on deceleration and throttle hanging until I rebuilt and reset everything. My jets were filthy as was everything else. Now, my pilot jets are too small so I am not getting enough fuel and too much air at idle. I have no problems under load.

I think like you, it must be pointing towards a carb problem and too lean, also side affect of running hot, what I find strange is I haven't touched them in the 2 weeks it's taken to rebuild the engine. As you mentioned maybe after the rebore and head job I might have to reset them ( and clean )
I've just finished checking what everyone says to do which is, Valves timing ok, valve gaps ok ignition timing ok, also have full flow of petrol from the tap.
Correct me if I'm wrong but to get a richer mix I screw out? Is it an idea to also raise the needle by one notch?

To get a richer mix, turn the screws out.

Start by screwing them all the way in, not super tight, just snug. Try to count how many turns you were out and try to see if all the carbs were even.

Manual recommends a start point of 1.75 turns out. Max adjustment is 4.5 turns out. Any more and you will have to change the needle height or you may need to change the main jets.

My problem is different. I too have flow changes in my motor compounded by my new header. Under throttle I am fine but my idle and off throttle condition is lean. My pilot jets are too small.

Before I cleaned/rebuilt my carbs I had all kinds of other issues but they all went away except my idle when hot issue.

Last night I cleaned the carbs and took the mixture screws out to the max of 4.5 turns, and raised the needles by one notch.
The revs seem to drop a bit better now and
Not over heating like before. I must have touched something as the carbs are really out of balance, so much so that the exhaust presures on the left side is almost double to that of the right side.
This will be the first time that I will use my new vac gauges, any tips with this?
Cheers Pete.