E: Engine Egli 500 Special Carburation

Ben Langton

Active Forum User
Non-VOC Member
So I'm back in the garage trying to get the Egli riding well out on the road (where I am desperate to be). With school holidays rolling (I'm a teacher) I'm pleased and ready to get this sorted (when not so busy with my two sons). The great news is thanks to the help here in the club the oil system is sorted and running as it should with special thanks to Marcus. The not so good news the bike simply doesn't go as it should and is an absolute pig to start. I spent over an hour getting started yesterday.
I took the NGK plugs out and replaced with new brisk LOR17,s which I had hoped would be better, well I ended up putting the NGK's back in amongst other checks and a lot of kicks!
The running symptoms are (once started)!
Idles fine after a minute or so
Pulls away fine if a little lumpy
Acceleration is fine
Absolute pinned full throttle seems fine
Part throttle any position other than flat out terrible, surges forward, drops to nothing then surges again, it's like flicking the throttle or running out of fuel but plenty of fuel (50/50 avgas and super plus) and steady part throttle.
For normal cruising/riding it is terrible

In my limited knowledge I feel it's a problem with the carb Dellorto PHBE 34. I have taken it apart several times to clean it out but been unable to remove the float bowl pin to clean parts beneath. Jets are clean.
The picture below shows carb and jet sizes, do the sizes look right? Any ideas please?
image.jpeg
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Is the pump working ?,Is it faulty and letting fuel through, Take the pin out to test.
Is the slide too rich.
Use Champion N9y plug.
Is there an air leak on the manifold.
Cheers Bill.
 

Ben Langton

Active Forum User
Non-VOC Member
Hi Bill, hope your well?
Where is the pump? I haven't a clue how this carb works. Pin?
Keen to learn though.
Needle is on the highest notch.
Manifold connections look good.

I've popped a pic of plug on thread too.

Thanks for tip on Champions.

Kind Regards

Ben
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Sorry Ben, I have just seen yours does not have a pump.
Does yours have a choke ?.
The slide might be too rich.
 

Dave Hulstone

Well Known and Active Forum User
VOC Member
Hello Ben. I see you are running twin spark. Are you 500 or 600cc? I run a 36mm Dellorto on my 600 and have recently spent a lot of time setting it up, only to find it was an ignition problem (thanks Greg)
Phone any Dellorto supplier up and they will give you a basic set up for your carb that should only need tweeking from there on in, providing everything is working fine. Did you set the needle on top notch? (lean) Are you coil or magy?
 

stu spalding

Well Known and Active Forum User
VOC Member
Hello Ben. I see you are running twin spark. Are you 500 or 600cc? I run a 36mm Dellorto on my 600 and have recently spent a lot of time setting it up, only to find it was an ignition problem (thanks Greg)
Phone any Dellorto supplier up and they will give you a basic set up for your carb that should only need tweeking from there on in, providing everything is working fine. Did you set the needle on top notch? (lean) Are you coil or magy?
That rings a bell. It sounds like my twin when I first started with twin plugs. I was under the impression that I could run 1 twin lead coil per pot. Not so! I had to split the leads on each coil between each pot. If you're on 12V running two 6V coils in series would sort it, it depends on the ignition set up. Cheers, Stu.
 

greg brillus

Well Known and Active Forum User
VOC Member
I think he has a newer model BTH on there, which as a twin spark magneto will not work. The advance range is the same as a single spark version. If you have the timing set right for twin plug operation, the retarded position will be too far retarded. This for one will definitely make it hard to start, but if you advance the timing for better starting the engine will detonate. My advice Ben is to disconnect one of the spark plugs, and disconnect the small coil that runs that plug. Either tape up or simply chop off the extra blue and brown wires, they are in parallel to the other coils wires, so no big deal. This way you can run it at say 34 to 35 degrees full advance, the retarded position will be better for starting, and you will not suffer any detonation. The low speed/part throttle performance is in the slide cut away, if it is too small the engine will run rich and vice versa is it is too large. You can buy slides with different cut away sizes, I modify my own. But the ignition is the best place for you to start, for ease of starting and perhaps part throttle behavior as well. Cheers...........Greg.
 

Jez Nemeth

Well Known and Active Forum User
Non-VOC Member
Bonkers thought, sure you've considered it -what's the state of the inside of your tank- If you've not run the bike for a while, could there be blockage or restriction of debris around the fuel tap gauze? Probably not an issue with an alloy tank -but an old steel one...
 
Last edited:

Dave Hulstone

Well Known and Active Forum User
VOC Member
He says it goes well flat out though? I think Gregs onto it with the whole ignition/twin spark issue. I practically needed rollers to start my comet on twin spark with an electronic BTH. It was embarrassing. "Nice bike mate, pity you can't start it" ?
 
Top