Ryobi RLT26CDS - Not starting - Air bubbles in return

[rwiddowson]

Evening

Just stripped the carb off the Ryobi and needle valve, blew through all the holes and vents and the like and the damned thing still won't start.

Nice fresh fuel in it.

Taken out spark plug and spark looks OK'ish but a bit yellow. Apparently should be 0.050". It looked less than that so bent it open a little more and tried again. Still no luck.

When I press the primer, air bubbles are appearing in the line return back to fuel tank.

Any ideas or suggestions what could be up please?

Also, it says in the manual you should change the spark arrester every 25 hours of operation. What on earth is a spark arrester?

Any clues greatly appreciated.,

 

[Jackrae]

50thou seems quite wide for a spark-gap
Are you sure it's not 0.5mm (circa 20thou)
25thou used to be a fairly universal setting

1) Remove sparking plug and check it's dry
2) Attempt your usual start technique
3) Remove sparking plug and check if it's dry or wet

If it's dry you're not getting fuel
If it's wet you're either getting too much fuel or the spark system isn't firing

Why did you consider you needed to dismantle the carburettor

Spark arrestor is probably a piece of gauze inside the silencer system. This can become choked with coke

You also need to check the air filter to ensure it can actually pass air and isn't choked with either dust or oil. For trial purposes you could remove it and attempt a start.

 

[rwiddowson]

I agree.

I thought 0.63mm is average but manual states 0.050".

It seems to be getting fuel.

I stripped carb out of habit as last time it had an issue it was exactly that. Sure I drained it down though for winter so I wouldn't get a starting problem in the spring.

Bulb feels OK'ish but not really building up a good resistance. Maybe it's that. I can't say I've paid too much attention to it when it's working but the air bubbles in the return line do look excessive.

 

[joe-90]

Can you see a spark if you lay the plug across the engine and pull the cord?

 

[rwiddowson]

I can indeed. I do state that in the first post. Not happy about colour though.

 

[DaveHerns]

Any cracks in your fuel pipes ? Mine cracked up over the winter

 

[Burnerman]

After a few presses, the primer bulb should have visible fuel in it - about 3/4 full.
Do check for split fuel pipes, as suggested! Another cause of bubbles is a tiny hole in the carb pump diaphragm.
It's always wise to have a spare plug on any two stroke standing by.
If the plug comes out wet at any time, turn the engine so that the plug hole is down over, then pull the starter cord to expel any raw fuel that could be in the crankcase.
To clean out these carbs, you really need a can of carb cleaner and compressed air......
John

 

[rwiddowson]

Stripped carb last night and used compressed air.

Gaskets look fine but might buy a new set today. Plug is a nice colour.

Just wondering if the spark is failing under compression. I've heard strange things can happen.

Spark should surely be blue?

 

[rwiddowson]

Is it worth bending the needle valve lifter?

 

[Burnerman]

Ideally, the spark should be blue - hence my suggestion to have a spare on standby.....although it does rule out any igniter fault!
A couple of points re the carb - which I guess is a Zama?
You have to watch out not to blast out the two welch plugs (oval) when using compressed air, and likewise the very fine mesh filter that feeds the needle valve - so easily done!
Regarding the needle valve lifter - in it's resting position, it should be parallel with the carb body. I really wouldn't advise any adjustment here so long as the engine has ran well enough before.
Be lucky!
John

 

[rwiddowson]

Cheers John.

Can't see any oval plugs. Which face are they on?

Yes it is Ruixing. New carb is £25 so might try that. Could do without buying a carb unnecessarily. Money's tight at mo.

 

[Burnerman]

The Ruixing is a Chinese copy of the Zama cube carburettor.....I hope we are talking about the same type! Maybe you could post a picture of yours?
Obviously I don't know exactly how similar they are, but on the Zama, the welch plugs are under the 4 screw cover, in the same area as the needle valve. The fuel filter is under the single screw chamber, with the diaphragm and gasket removed.
The welch plugs cover channels which control idle speed metering - but if they are blown away the engine won't work at all!
It's ironic that a diaphragm set is half the price of a new carb.
You didn't lose the spring below the needle valve lever, did you?
Do try a plug first before diving in!
John

 

[rwiddowson]

Spring is in place. Will try plug before carb.

I haven't removed any gaskets other than one below primer and one under 4 screw cover.

Interesting you say Ruixing is copy of Zama as this is an original fitment carb!!! Ryobi!!!

 

[rwiddowson]

Spark plug indeed.

Gave it a brush off and it started so going to get a new one and some 2 stroke oil with fuel additive in.

Problem is I got that frustrated last night that I ended up putting fresh fuel in without adding oil.

There was probably a quarter tank left with proper mix in though.

Only ran it for a few seconds. Max. 5 secs so hope I have not done further damage?!!!

 

[Dave54]

Pretty unusual with modern fuel / oil mixes, but you can get "whiskering" a thin "hair" of deposit that shorts the electrodes on the plug, and is difficult to see.
Engine will probably be OK without oil if it was just for a few seconds off load. Assuming the engine didn't seize of course, and that it runs normally with the right mix in it.