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Forum Home > Technical > 3800 needs more fuel?

Rustman
Member
Posts: 61

Hello and greetings from Finland!

Just gave my swedish 3800 first ride for this year. After a while I noticed something I now remember from last summer. The engine starts fine and everything is otherwise okay except when I turn the choke on normal (right) the engine doesn't want to run well (hardly 20 km/h). If I back the lever halfway it runs happily (around 30 km/h). The membrane is new and I have cleaned the carburettor and fuel pump twice, on the second time with ultrasound. I have also checked the fuel and carburettor filters.

Do I need a bigger jet/s? The air jet is 551 and the main jet is 28.

Regards, Matti

--

"Rust never sleeps!"

April 14, 2013 at 3:07 PM Flag Quote & Reply

lowflyer
Member
Posts: 43

If you have the facilities it is well worth the effort to make a variable main jet. I made the body of the jet from a piece of brass and used the needle from a model aircraft engine. It is then possible to fine tune the engine even as you ride the machine. If making a variable jet is not possible then try either a 30 or 32 jet (check on the Brian Solex site as I recall that he recommends a particular size). As the engine runs better with a little choke that clearly indicates that either there is a blockage or the jet is too small. As you have cleaned the carb' the latter would seem to be the case.

April 14, 2013 at 5:33 PM Flag Quote & Reply

Rustman
Member
Posts: 61

Thanks! Any idea where to find a suitable variable aircraft jet? I tried the ebay with little luck.

--

"Rust never sleeps!"

April 15, 2013 at 5:06 AM Flag Quote & Reply

dave 411
Site Owner
Posts: 593

You can buy a complete adjustable jet from Bertrand on French e Bay.See our suppliers list.

April 15, 2013 at 8:25 AM Flag Quote & Reply

dave 411
Site Owner
Posts: 593

Hes not on there.try this http://www.ebay.fr/itm/SPECIAL-COMPETITION-GICLEUR-VARIABLE-SOLEX-DU-330-AU-5000-SUPER-QUALITE-/360636576045?pt=FR_JG_Moto_Pi%C3%A8ces&hash=item53f79d712d

April 15, 2013 at 8:30 AM Flag Quote & Reply

BrianSolex
Member
Posts: 1656

Before playing with the jets, I recommend that you completely check for air leaks in the fuel circuit, and for restricitions in the fuel circuit, both of which can make it necessary to keep the START lever positioned somewhere left of full-right.

Common places for air leaks into the fuel circuit:

- crankcase bearing and crankshaft seal

- fuel pipes, especially at the unions...cracks in pipes or flares

- fuel pump...unions, front cap, top stud... plastic seat deformed...bolt(s) loose

- manifold...gasket worn, bolts loose

- carb/manifold union nut...loose or worn/missing ring seal

- carburetor...fuel jet seat

- crankcase side cover gasket...or cover bolts loose/missing

- cylinder base gasket...or nuts loose

 

Common places for fuel restrictions:

- dirty fuel jet...twisted/damaged fuel jet...corrosion inside fuel jet

- carburetor...dirty/corroded diffuser passageway

- fuel pipes...dirty...build-up inside pipes

- fuel filters (carb & tank)

 

It is not a total catastrophe or unusual to have to run the Solex with the START lever somewhere left of full-right. After the engine is started, think of the START lever as a fuel/air mixture screw. After the engine is warm, move the lever left and right to find the best running. If it is right of middle, and you've made all of the checks mentioned above, you can ride with no problem. But, if you must keep the lever left of center, you definitely have a problem that can be fixed by going through the above checks.

 

Check videos and photos of Solexes...you'll see the START lever in a variety of positions.

http://www.youtube.com/user/Rickbrendan

 

Dealers were equipped with sets of air and fuel jets to fine tune the engines, but rarely did so. Fuel jets for the Cyclomoteur 3800 came in sizes from 26 cc to 32 cc. Normal is 28 cc. Air jets came in 100, 150, 115,125, 120, 551, 601, 651, 701, 951. Normal is 551

 

If you are 100% sure that you have no fuel restrictions or air leaks, and you want to be able to move the lever full-right, you can try to fine tune with different size jets, or a variable fuel jet:

http://home.swiftdsl.com.au/~thetinkerer/solex/fueljet/index.html

 

http://www.paacsolex.com/moteur.htm#lien_7

 

http://www.ebay.fr/itm/SPECIAL-COMPETITION-GICLEUR-VARIABLE-SOLEX-DU-330-AU-5000-SUPER-QUALITE-/360636576045?pt=FR_JG_Moto_Pi%C3%A8ces&hash=item53f79d712d

 

--

The bicycle with the motor...SOLEX.

April 15, 2013 at 8:55 AM Flag Quote & Reply

BrianSolex
Member
Posts: 1656

ps Hei Matti!

 

--

The bicycle with the motor...SOLEX.

April 15, 2013 at 9:00 AM Flag Quote & Reply

Rustman
Member
Posts: 61

Oh yeah! Thanks for the info. There is a chance that the main jet is somewhat clogged regardless my cleaning efforts. Actually it looks a bit suspicious. I cleaned the pipes and everything yesterday and there seems to be no visible leaks anywhere.

--

"Rust never sleeps!"

April 15, 2013 at 9:30 AM Flag Quote & Reply

Solex1961Manche
Member
Posts: 74

My 2200 was exactly the same as yours - would only run with half choke - I bought a variable jet and hey presto all ok now - 34kph on the flat... One thing I did was to shorten the bolt sticking out with the butterfly nut as it was hitting the metal behind the engine when I pulled the engine off the wheel. Als good thing you can tune it on the move - I have found that there is a very fine amount 1/2 turn around the sweet spot to make the thing run bad.

--

Citroen Dyane Turbo

S2200 1961

April 15, 2013 at 2:14 PM Flag Quote & Reply

Rustman
Member
Posts: 61

I cleaned the jet again twice with ultrasound in cleanig fluid. Tried again, and... It works! There must have been something blocking the jet. Whew! And the snow is almost gone! Happy, happy, happy! And my "new" 1962 2200 is on it's way from Hungary to me:D

--

"Rust never sleeps!"

April 16, 2013 at 1:05 PM Flag Quote & Reply

Paul G
Administrator
Posts: 746

Great news, Matti. Your persistance eventually paid off.  :D

--

Paul G

"Getting there ....... slowly"   

April 16, 2013 at 3:06 PM Flag Quote & Reply

lowflyer
Member
Posts: 43

Brilliant, It's often the simplest thing that we miss.

April 16, 2013 at 3:44 PM Flag Quote & Reply

BrianSolex
Member
Posts: 1656

Excellent! A restricted fuel jet is a very common cause of this problem...the passageway through the jet is so tiny that it is easily restricted...even a globule of oil can block the jet...the reason why oil should never be added directly to the fuel tank, and fuel should always be mixed in a clean, separate container. 

 

Hoping your S 2200 arrives safely from Hungary!

--

The bicycle with the motor...SOLEX.

April 16, 2013 at 4:26 PM Flag Quote & Reply

BrianSolex
Member
Posts: 1656

Matti, what type of cleaning fluid did you use in the ultrasound?

--

The bicycle with the motor...SOLEX.

April 17, 2013 at 10:15 AM Flag Quote & Reply

Rustman
Member
Posts: 61

It's Solmaster AS40 finnish biogradable natural oilbased washing liquid concentrate for all transport vechiles, farming machines, to boats, motor cleaning and overall cleaning for industrial housings. 3-10% for pressure wash,  10-20% for engine wash (works fine washing dirty engines, like 2CV :-).  Overall it's quite effective. Just added some to the water in my ultrasound washer. I just thought it might add something extra. Don't know if it did, but it didn't explode, either :-)

--

"Rust never sleeps!"

April 17, 2013 at 10:48 AM Flag Quote & Reply

BrianSolex
Member
Posts: 1656

Thanks. I will look for something similar to try. 

--

The bicycle with the motor...SOLEX.

April 17, 2013 at 1:55 PM Flag Quote & Reply

Stevosolex
Member
Posts: 302
I use a bit of liquid hand soap. probably totally wrong but seems to work!
--

Racing through life at 18.1 mph

April 18, 2013 at 9:07 AM Flag Quote & Reply

Rustman
Member
Posts: 61

Fairy liquid for hand dishes has been suggested also.

--

"Rust never sleeps!"

April 18, 2013 at 11:32 AM Flag Quote & Reply

BrianSolex
Member
Posts: 1656

Yes, I generally use DAWN dish-washing liquid.

--

The bicycle with the motor...SOLEX.

April 18, 2013 at 11:50 AM Flag Quote & Reply

Rustman
Member
Posts: 61

Same thing again. Runs poorly with the lever on the right. Yesterday it rode like hell and today it started to stall. Then the speed came back and soon it went away again. Cleaned everything again and there was very little something in the lower section of the plastic filter in the carburettor. I mean very little, like 1 mm x 4 mm thin cotton like piece. Could it have been the cause? Hope it's better now. I didn't have time to try it out today evening.

--

"Rust never sleeps!"

June 6, 2013 at 3:12 PM Flag Quote & Reply

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