Mini Vac

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Vince

Hero member
I have an idea that needs some input. I am having an ongoing issue with blocked idle jets in my Atlas. I have pulled and cleaned the Carb, Twin Throat Delordo and found said blocked idle jets. There was no stockpile of crap that I could see in the bowl or anywhere else in the fuel system, it's got 3 separate filters and there all clean. That fixed it for approx 100ks and but it has done it again. The cleaning I did to the carb involved pulling the jets and spraying Nulon Carb Cleaner into the passages below those jets and then hitting those passages with compressed air. I have been doing some reading on Italian Cars sites, only places that have that Carb info and they mention those passages have the usual 90 deg bends and blind galleries ext. These carbs are notorious for having blocked idle jets. I don't want to pull the carb again, it's a nightmare job but there is relatively easy assess to the jets via a panel just above them in the top of the carb. So I was thinking instead of blasting compressed air into these passages with the jets removed and driving any crap deeper into the carbs I thought maybe one of those Electric brake bleeders might suck the carb cleaner and any crap out of the system. I have never used one, only seen them used. So anyone have an opinion on where this might work? Can you use them on petrol? The recommended idle jet size from Multiple Sorses is a 58 up from a 52 as std plus there is a later designed much shorter style jet that's coming and hopefully won't block as easily.
 
Having had a bit to do with twin throat Dellorto carbs on a Z900. The issues are forever ongoing.

I found the best results were found on a shelf in the garage, and there they should remain.

Refer modify thread. A pair of Lectron carbs will have you out of the garage and on the road, scrub or track of your choice.
 
Yes, I have a compressor, this looks doable but I expect I need to spend maybe $100oz to get a gadget that produces enough vacuum to work. This bike has the Series 3 Atlas exhaust that allows enough space to fit typical bike carbs. Earlier Atlas models had exhausts that ran where std bike carbs did. Read some interesting stuff on Lectron Carbs over the years. Actually rode a very early model KTM 250 2 stroke with one of those Carbs. It ran very smoothly but lacked a hit from the pipe for some odd reason. The makers of those Carbs are very helpful so I hear. Without the blocked idle jets it carburates very well and starts really easily. I haven't checked fuel consumption though.
 
Repco has a 25% off sale so I bought one of their vax bleeders for $60ish bucks and a needle attachment that I hope will get deep into the carb. I also bought another can of Nulon Carb Cleaner that will give me enough to flood the carb passages, so hopefully with some compressed air and vacuum I will clear this out once and for all.
 
Do I have this right, does it work like a carby? You plug in a compressed air line and that air passing across causes a Venturi effect and suction is formed as that air column passes by. More than on the brake bleeder I just bought? Will work on fuel and carby cleaner safely? It's cheap enough to buy it anyway.
 
Yep. It's a venturi. Just the same as the brake bleeder.
Dunno about how much suck you can get. You'd have to check the specs. Those little vacuum generators vary in size and price from a few bucks to around $100. I think the more expensive ones have sensors and control valves and stuff in them to control the vacuum. They're typically used on things like those big industrial suction cups that are used to pick up glass panels and lift them up by crane.

I reckon for cleaning out carbs you want high volume of air flow rather than high suction vacuum. It's an area I haven't put any thought into, so your guess is as good as mine re the vacuum generators.

BTW, it wouldn't be difficult to make a venturi sucker. It's just a tube with a narrow throat that you blow air through. I reckon you could make the one by heating a bit of PVC electrical conduit with a heat gun and rolling it into shape so it has a narrow throat in the middle. Put a compressor hose connection on one end and drill a hole in the throat to connect your sucker pipe to connect into. I guess you'll need a shut-off valve too. Might take a bit of trial and error to create something useful.

Another possibility is a vacuum pick-up nozzle like this gadget:

Handy Air Vacuum Suction Lifter & Air Blow Gun (0.1kgs,10mm,10cm) - Air Angle Vacuum Sction Pen, Air Angle Vacuum Sucking Pen Air Angle Punch Press Vacuum Suction Lifters Air Angle Vacuum Pick-Up Hand Tools, Air Vacuum Picker Air Vacuum Sucking Tools

The TAIWAN GISON's GP-SA10 has 10 mm Suction Cup and its max suction capacity is 0.1 kgs. It can Pick up & Place quickly for any flat rough surface small object. GISON is a high-quality Handy Air Vacuum Suction Lifter & Air Blow Gun (0.1kgs,10mm,10cm), Handy Air Vacuum Suction Lifter & Air Blow...
www.gison.com.tw www.gison.com.tw

Come to think of it, the old blow gun that I use for blowing dust and shit away has a vacuum port on it that you can connect a hose to. The vacuum is adjustable via some kind of valve (needle valve?). I've had it for donkey's years and can't remember where I got it. Just had a bit of a browse online and couldn't find anything like it. Closest thing I could find is one of these:
www.ebay.com.au

Sandblaster Air Siphon Feed Blast Gun Metal Ceramic Tip Sand Blasting Tool Kit | eBay

Find many great new & used options and get the best deals for Sandblaster Air Siphon Feed Blast Gun Metal Ceramic Tip Sand Blasting Tool Kit at the best online prices at eBay!
www.ebay.com.au
 
I worked to unblock an accelerator pump jet in my Keihin FCRs yesterday. The jet is fixed into the inlet venturi and not that easy to get at, and the hole is at 90 deg to the jet 'shaft' and so small I don't think any wire made would fit into it. I decided that trying to blast air into the inlet end of it was simply going to wedge any contaminants further and tighter into the thing, so I jigged and rigged my air compressor air gun to attack it from the reverse end (the tiny hole end). Also sprayed Si into it with the thin tube then compressed air - seemed to shift it - it now pumps perfectly, like the left hand one - and as a result I could start a very special engine.
 
Yer, makes sense but as I said I don't want to pull and strip it again. I was thinking back washing it with compressed air via the fuel hose connections but I think that would not be good on the needle and seat or the float adjustment. The jet access is via a small removable panel at the top of the carb where you can pull the 2 idle jets and main jets plus the emulsion tubes that connect to these jets. First I will try the brake bleeder on the cavity where the jets were, gently add some carb cleaner via its supplied tiny tube, go the brake bleeder again, add some compressed air, and brake bleeder again. And finally, flood it with brake clearer and suck that out with the brake bleeder. In other words, suck and blow its brains out. I got it cleared just by squirting carb cleaner and compressed air before so that implies the crap was either driven deeper or there is access into the carb from the outside so crap can get back in. So I hope this has some permanent effect. I have heard so many stories about these bikes running like crap under 3k and that's exactly what happens with blocked idle jets, On a couple of occasions after clearing them it's been really great to ride at low revs. Very smooth and controllable. This needs fixing permanently.
 
As I don't want to pull and strip the carb again the ultrasonic would need to fit the whole bike in it. A bunch of people in the club have them. I know I am half arsing this, and if it doesn't work then I will end up going there but I am NOT looking forward to it.
 
Vince, it really sounds like you could have a much better solution by replacing the carbs. There must be plenty of options that won't leave you worried every time you head off about a fuel blockage. There's obviously a design flaw in what you have.
 
I like its oddness, I did notice 2 things when I was working on it. It's got a big hose connected to the carb top as I think a float bowl breather that runs slightly up and back and is open to the atmosphere just above the airbox snorkel. I was tempted to have it go inside the airbox to be inside the filtered air part but was advised not a good idea, pressure variation issues. On the other side of the carby adjacent to that breather, there is an open hole to again I think the float bowl. To be honest I don't like the idea of either of these holes being open, there are both index finger size. I will take a pic and post it for comments.
 
Vince said:
I like its oddness, I did notice 2 things when I was working on it. It's got a big hose connected to the carb top as I think a float bowl breather that runs slightly up and back and is open to the atmosphere just above the airbox snorkel. I was tempted to have it go inside the airbox to be inside the filtered air part but was advised not a good idea, pressure variation issues. On the other side of the carby adjacent to that breather, there is an open hole to again I think the float bowl. To be honest I don't like the idea of either of these holes being open, there are both index finger size. I will take a pic and post it for comments.
Click to expand...
Stick a little air filter on it.
 
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