Atlas Questions

Yeah, I'm thinking the same as PB2. A bit of crap in the tank has found its way into a carby jet.

On a bike that hasn't been used for a while, a good flush-out of the tank can pay dividends. It's also a good idea to install some in-line fuel filters. Get the biggest filters that you have room for. They might look crap, but larger filters have more surface area for the filter media, which allows a finer mesh to catch small particles. You might be surprised how much shit they catch.
 
I have a couple of metal-bodied in-line cleanable filters, they have this stone-like filter medium. I thought I did, I have one with no internals but MX Super Stories have them for $17. I snapped an end off a plastic one once, which made it very hard to do a roadside fix. Obviously, I have a full fuel tank which doesn't help. I will do the easy stuff first, at least I now know how to get easy access to the carb jets.
www.mxstore.com.au

Ballards Silver Alloy Fuel Filter at MXstore

Buy your Ballards Silver Alloy Fuel Filter online at MXstore. Australian owned, amazing service & fast free shipping* on over 100,000 products.
www.mxstore.com.au www.mxstore.com.au
 
My Mk 3 Atlas had a tantrum today as well, probably in sympathy with Vince’s.
Other than the usual necessity to coax it into life from cold, and warm it up before it settles down, it ran fine yesterday on my trip to visit my demented mother. This morning I followed the usual starting procedure but once fired up it wouldn’t behave itself. I had to rev it and slip the clutch to get it moving and not stall. I knew the fuel level was getting down to near reserve so headed off to the fuel station. It was a flat as a fart, fluffing and puffing and barely made it to the petrol station under it is own steam. To my annoyance and everyone behind me, it stalled as I went to pull away from the lights adjacent to the fuel station. Fortunately, it started again on the second attempt and I made it onto the forecourt.
With three fresh gallons of fuel on board I set off again, but after half a mile or so, and no improvement I decided to head back home. About a mile from home it started to cough and fart, and generally lurch forward and then semi die before repeating the antics. Sensing it might be a blockage that was in the process of possibly clearing itself I carried on a bit further and to my relief it at last settled down and started to run fine again. After I had made the stop at the care home, rather than head straight home I took it for a slightly longer run and it ran as it should.
Bloody bikes, don’t you just love them……
 
While I was investigating the carb parts people I found a place in Oz that built off-road race VWs and sold Twin Choke Delordo parts including a gadget called a j Jet Dr It apparently was designed to prevent idle jets getting blocked with crap, sounds familiar. The Oz bunch had run out of stock so I inquired with the USA manufacturer and got this exchange. So they only fit downdraft carbs, but I found it interesting that getting blocked idle jets apparently is familiar enough in these carbs to warranty someone making a mod to sell. Plus no built-in fuel filter like Delordo bike carbs. And maybe smaller orifices that block easier, I need to check for that. I might buy one of these Jet Dr and see whats up,

Hello Vince,

We don’t make jet doctors for the DHLA...

Only the DRLA and the Weber IDF.

-David@CB



-----Original Message-----
From: Vincent Glenn Stokes <vstokes@bigpond.com>
Sent: Tuesday, December 27, 2022 9:19 PM
To: susie@cbperformance.com
Subject: Jet Doctor

Hi I am after one of your Jet Doctors to suit a DellOrto DHLA 40 carb.
Are these avalable to buy

Thanks Vince Stokes
 
Just remembered Andy that red bike has bike carbs and not the Twin Choke car carb so that's really odd. Are you going in line fuel filter too?
 
I had a little play around today, drained a cup full of fuel into a glass container out of both the taps. Found nothing in the glass of concern but I did get a big rust-coloured stain on my hand from the rear of one of the fuel taps, that's really odd considering the fuel tank is I think made out of Nylon. It's made by Aserbus and has a very smooth surface feel. So next is draining the tank and pulling the taps to see where the hell this rust is coming from and what and how the I suspect idle jet got clogged.
 
Any tiny impurity in fuel from the servo or a speck of fuel line could find its way into the system.

Was driving a Toyota Hiace from Adelaide to Melbourne and it suddenly decided it would only run on the main jet - so flat to the boards, revs, back off, repeat continually until I made it to Strathalbyn. The roadside assist guy reversed two plug leads and forced it to pop back through the carby. The reverse pressure through the jets cleared the blockage and i was away. Clever bush mechanics! Who knows what blocked the jet/s but it sounded a lot like your ill-fated ride, Vince.
 
Just as a test I tried starting the bike, nope, it idles for 2 or 3 seconds won't take throttle and dies. Just a quick test to prove the issue isn't heat related. I have drained half the tank into a jerry can and will pull the taps tomorrow for a look-see. I spent some time googling drain plugs for that Carb, there is buggar all info.
 
Nothing in the fuel tap filters, they were unscrewed from the tap and separated but still in position just above the tap but that might have happened when I unscrewed the taps and maybe the filters unscrewed at the same time. They both were slightly stuck in the spigot that also unscrews between the tank and the taps. So I think these filters were doing their job. The next port of call is trying to find a carb float bowl drain plug, check what comes out and pull the jets and check them out, I hope to hell I don't need to pull the carby again. It's a lot of work doing that. The bowl was really clean last time, maybe that expressway run for 20 minutes doing 120ks @5k dislodged some crap, while the tanks off I probably should do a valve clearance check while I am at it.
 
I just pulled the jets, the idle jets are absolutely tiny. Think the thinnest sewing needle you have seen, a grain of sand would easily block them. They didn't pass light on first inspection but that could have been fuel remanence, anyway there now clear. I also found a very fine mesh screen in the main fuel connection point of the carb. So no crap has been found anywhere in the fuel system from the tank taps carb filter or in the bowl last time it came apart. If I add an inline filter that would make 3 filters, that's nuts. It's also got a brand-new oiled foam air filter. So I will give the tank a flush add some fuel and see what happens. Cleaning the jets is easy enough, 45 minutes but I wouldn't want to do it on the side of the road.
 
Could be a port and not a jet (one of the holes feeding the jets or air to the system), Vince. If you can blow compressed ait through every visible hole without removing the carb that sounds a lot easier.
 
From what I have read there are multiple tiny holes just after the butterfly in the carby throat, anywhere from 3 to 6. You cannot get to them without pulling the carb, so I blew out under where the jets sit. You have to be careful as there are permanent plugs used to blank off manufacturing drillings and if you blow out one of those plugs it's a giant pain. Latest headache had me find a large O ring sitting beside the bike on the floor, it's from where the spigot meets the fuel tank and screws into the taps. I didn't notice them pulling the taps and one was either missing completely or had gone to another dimension. Will replace them with Vitron ones.
 
Its mostly back together and goes well AGAIN. As a test I did the Trials Ride into my shed and it pulls off idle just as well as before the apparent blockage. Now the Snake Oil bit, I did some googling to learn about in fuel tank cleaners, lots of PR bullshitting and buggar all data, so I bought some that came in a Nice bottle, which reminds me of HP Sauce. So I will dose it up till the bottle runs out, it treats 100 litres, Mark Larkum says it's PRO strength and Advanced so it MUST be fantastic.

PRO SERIES PETROL COMPLETE CLEAN + | Penrite Oil

Petrol Complete Clean+ is a professional strength, petrol fuel additive that effectively cleans the entire fuel system from fuel tank to engine. It uses a powerful and proven additive technology that cleans stubborn deposits and inhibits new contaminant build ups forming. Application Petrol...
penriteoil.com.au penriteoil.com.au
 
I'm a sceptic with any sort of fuel additive. Most of them do bugger-all.
If it actually does what it says on the bottle, where does all the dirt from the tank and fuel lines go? Answer - Through the carby.
 
I am hoping it all goes to the same place as all the bits I keep losing go, like the O ring under the left fuel tap, into another dimension of Space-Time never to be seen by me again. It's where all my 10mm sockets apparently are as well.
 
Did something dumb yesterday, wanted to test the power off idle so I rolled the bike out of the shed without placing the sheet of ply on the grass I use for the side stand. The ground is quite hard or so I thought. Stand down I try a Horse mount and the side stand sinks in so I put the stand-up and swing a leg over. Big mistake, I get it up on the seat approx nipple height and the bike wobbled, so I use some strength to stabilize it while standing on one leg with the other way way up. I just got on and rode it into the shed fine. But today I am getting back spasms and a bit of pain. Why the fuck do I need to on every fucken bike I own weld on a plate twice the size of the stand foot so I can use the bike on the ground it typically gets parked on. Fucken stupid shit.
 
Just pull the tank off vince, wash it out vigorously with water and detergent, rinse, rinse again, dry it in the sun.
If you like you can slosh some two stroke oil around it.

Or am I the only one who does this....
 
It's a pretty transparent tank, you can see inside through the cap to just about everywhere and being white it's easy to pick out any crap. It's pretty spotless inside. There was no issue till I did that 20-minute run up the expressway at 120kph @5k, so maybe that dislodged some crap. As I said it's a huge carb on a small engine so that I suppose results in tiny jet orifices that block easily. Like I also said a grain of sand would easily block these tiny idle jets. The Big KTM Adventure Bike accessory people sell a filter I think called a Gogglemonster that you sit over the tank when you fill up to strain out crap. Slows filling by a lot though, they are notorious for having blocked in-tank fuel pump filters. So this is still an issue on modern bikes.
 
You must log in or register to reply here.
Back
Top