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E: Engine Egli 500 Special Carburation

Ben Langton

Website User
VOC Member
#1
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 Website User
VOC Member
#2
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

Website User
VOC Member
#3
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
 

Dave Hulstone

New Website User
VOC Member
#6
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 Website User
VOC Member
#7
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 Website User
VOC Member
#8
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

New Website User
VOC Member
#9
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...
 
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Dave Hulstone

New Website User
VOC Member
#10
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" ๐Ÿ˜’
 

vibrac

Well Known and Active Website User
VOC Member
#12
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" ๐Ÿ˜’
Have you checked your compession ratio? Nothing is more able to prevent a pleasant start and ride than a high ratio it wasn't just poor petrol that kept new Vincent's in the sevens. While I was taking the bikes to Cadwell for VOC races I needed relatively high ratio I say relatively because often we had to still bump start but if you are not racing and opportunities to give it stick are vanishingly small what is 10:1 or 9:1 for?
 

Ben Langton

Website User
VOC Member
#14
Ok, had a minute to pop back in the garage to check a few things.
Fuel tank, taps and lines are clean and work as they should (the first thing I did was to clean that out when I got it)
Checked the choke, rubber at base looks fine. However I will hold my hands up and say I have not been putting the choke correctly on, ie up in the locked verticals position which is proberbly why I have needed to cover the velocity stack to start, could this be the problem? I doubt it as the next thing I checked is the coils.
I have the BTH red label which I understood was a very good type? And do have two coils, see pics. Slide pic too.
I'm still thinking the bike was built and run very few times if at all, it seems to have the "right" bits but maybe was never dialled in correctly then again it was on the road and I had heard it had been hill climbed???
image.jpeg image.jpeg image.jpeg
 

Bill Thomas

Well Known and Active Website User
VOC Member
#15
The chokes on my 36mm pumpers, Works as a fast idle, So wants no throttle !, Throttle would mess it up,
They work well on mine, If it plays up, Even hot, A bit of choke and shes away most times.
I put the chokes off almost as soon as it has started, Because it's a bit fast.
My chokes are cable.
I would try a weaker slide, I just filed a bit off mine !.
Once the plug is your colour, I would put it in the bin.
That plug gap look too big ??, Not sure what BTH say but I would try 20 thou.
Cheers Bill.
 
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Nigel Spaxman

Well Known and Active Website User
VOC Member
#16
If your plugs are blackened from running with a rich mixture there is no need to throw them out (bin them) You can clean them off by heating them with a propane torch to burn off the oil and gas, or if they are really carboned from a lot of oil burning you can sandblast them.
 

Ben Langton

Website User
VOC Member
#18
i don't know how to time the engine or have tools to do it, how is it done. I'll give it a go if I know what to do. BUT
I'm a bit surprised that the twin head, BTH coils were put on and don't work as they should. Who has the same setup (well similar) that works? The builder was knowledgable and a very good engineer.
Why do you think it's the ignition, can I test it?
I would like to use what I have, just need to test things to find the problem, one thing at a time.
As a complete novice to this I'm afraid I'll need some tips please.
 

greg brillus

Well Known and Active Website User
VOC Member
#20
The bloke at BTH hasn't got a clue, He told me half the mag's he sells are twin spark, and no one has any problems. That must mean there are a lot of bikes that are not used. You can not run a twin spark ignition that has the same advance curve as a single spark set up, the range of ignition will be too much. A stock BTH you set up will have 4 degrees retard and 34 degrees full advance. On a twin spark, the full advance needs to be 28 at the most probably less, so the retarded position is 2 degrees after TDC this will make the engine hard to start. The only way this would work is if you had a fixed timing BTH and used an original ATD with the travel reduced to 12 to 14 degrees of movement. You will need to check the ignition timing to see what you have, but the easiest and cheapest fix is to run it as a single plug. I have done exactly this to a 600 Comet engine here that has a twin spark BTH now only running one plug, ignition set at 34 degrees, engine starts very well.
 
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