Dellortos bolted on but very fast idle

[warrenz]

Hi

 

Finally got the Dellorto's and the extractors bolted on. Initially it would not start, but 4 of the 6 pump jets where blocked, that solved still no go. Sulio finally convinced me to change the plugs, even though they had only done about 500km's and now it starts.

 

But it idles at 4000rpm, with the idle mixture screws fully in. Butterflies are fully closed, fuel level in the float chamber is OK.

 

Cannot figure where it is getting all the fuel from.

 

Has anyone else experienced this problem?

 

Warren

[JP240z]

The idle mixture screws are fully in, but have you touched the idle speed screw that controls all three carbs?

[zr240]

Whats your fuel pressure running at??

 

Sound like you might have to much and thats why they are flooding. from memory you need something like 4psi nut do a search on hte net to be sure.

 

Ash

[warrenz]

The idle mixture screws are fully in, but have you touched the idle speed screw that controls all three carbs?

 

Not sure what you mean here, the linkage is such that the butterflies are fully closed.

 

Whats your fuel pressure running at??

I am not able to check the fuel pressure, but I only have the standard 240 mechanical fuel pump. I am using the standard 240 fuel rail and 5/16" fuel hose

 

I checked the height of the fuel in the float chamber and they were all 30mm below the top and when we checked Sulio's his was 25mm from the top, so I assumed it is not getting too much fuel.

 

Warren

[Scoota G]

At the end of the throttle shaft is a stop which is a washer with a little tab sticking out and a locking tab washer bent over the nut. These can be set so it seems that the throttle will not close anymore but are still open a few degrees which is all it takes. Try loosening them as i had the same problem.

[Toecutter]

We checked with a mirror and all butterflies were closed but the engine still "idled" at 4000rpm!?

[zr240]

Must be getting air from somewhere???

 

You may have done this but check your seal between manifold and head, carbies and monifold. double check that the line to brake booster is not leaking. Also check the chokes on the dellautos are definatly closed as I think they can stick and even if the lever is all the way back it can still not be at zero(internal sticking)

 

Also are the plugs really wet if you take them out after running it. Is it backfiring?.

 

Thats all I can come up with of the top of my head.

 

Ash

[Toecutter]

Must be getting air from somewhere???

 

You may have done this but check your seal between manifold and head, carbies and monifold. double check that the line to brake booster is not leaking. Also check the chokes on the dellautos are definatly closed as I think they can stick and even if the lever is all the way back it can still not be at zero(internal sticking)

 

Also are the plugs really wet if you take them out after running it. Is it backfiring?.

 

Hi Ash, yer we looked all ove for air leaks inc soft mounts etc. checked chokes and cleaned em up. break booster vacuum line is a good point.

 

Warren, you know come to think of it you did have some issues with the SU's and I do recall it was only on the one SU, ie three cylinders. If it is that vacuum line it would have been connected to the last three cyclinders only on the old SU manifold!? Something to think about.

 

Sulio

[warrenz]

Fixed, thanks for the tips

 

All is not what it seems when you are looking through the chokes with a mirror. Scoota's suggestion to slacken the butterfly shaft nuts did the trick. It was actually the centre carby that was the culprit, amazing what a very small gap can do as far as airflow goes.

 

OK now to get flanges welded to the extractors and exhaust and the linkage set up correctly to do some drive testing and final jet sizing

 

Thanks again

Warren

 

 

[Scoota G]

I RoCk WoooOOooo

[Toecutter]

Great looking forward to seeing more progress.

 

Sulio