It won’t start! EFNR44B7 (Solved)

[andrew]

Working to get an EFNR up and running but having some difficulties.

I ran this motor only once when I bought it a few years ago. Was very tough to start and ran rough. Motor otherwise in good condition.

Recently I cleaned up the carb (Amal 416 1A) and replaced the rings and head/base gaskets. Did not disassemble crank casing. Bright spark, 70psi, thought it would fire up well but no luck.

My first thought is that there could be a problem with the carb, though it does seem in fine condition. I don’t have any alternate 416/1A carbs to try, but wondering if a 416/2 carb from a forty would be an acceptable substitute? I couldn’t find any reference on the forum to the differences, so not sure if the 1A and 2 versions have different jets etc? I have a forty with a 2 version that starts first pull every time, so know that carb is good if it’s an acceptable alternate to try.

My other thought is that there’s a leak in the crank case causing loss of vacuum. Don’t see any leakage at the join from running in prior life though.

Looking for suggestions please!

[Collector Inspector]

Hi Andrew

If the only thing not really checked is the crankcase your problem may well be that. You are kinda thinking along those lines anyway.

The top bush may be dry especially if the motor has been dormant for an extended amount of time. I had that problem with an LS ages ago...oiled in the cases and stood it on its' head for a week...that worked in my case.

The case can leak around the tiller mount area as well.

Also check that the ignition can spark a gap (in air) at least 6mm. Sparking great on a plug gap does not mean a strong spark under compression.

Also the old chestnut of installing the piston upside down....that has been done before aye.

Cheers

B

[andrew]

Thanks Bruce for the tips! No luck so far, unfortunately for me.

Took the cases apart, they cleaned up easily and appear in good condition. Had a bit of that red silicone-like gasket sealer on the mating surfaces which I cleaned off, hoping that had degraded and was causing the issues. Alas no. Lightly cleaned mating surfaces on very fine grit paper on top of a flat glass table. Mating appears good, as good as or better than some other motors I have that run well.

Piston right side up. Good to check though as never know the history of some motors.

While I was at it, I swapped out the CDI with a new one I had handy for another project. No impact, so will swap it out again next time.

After pulling the starter cord several times the plug tip gets a bit wet, so I'm led to believe carb is working to some extent at least.

Bruce - is your 6mm spark gap number correct? I gapped a plug to triple normal size, 0.06" (1.5mm) and spark looks good. I can go further to 6mm but was concerned the D16 plug might not bend that far and back without damage. I guess better to sacrifice a plug than go insane.

Next I will try in order:
1) Carb - does anyone know if the AMAL 416 version 1A can be exchanged for a version 2? Are they same jet sizes despite coming from different cylinder sizes? Could I just swap out jet if different? Surprisingly couldn't find any discussion on this on the forum
2) Spark plug boot - its new but I'm not a fan, rubber a bit tight around the D16 so its hard to tell how good the connection inside is. I recall having this same problem last year on another motor: after pulling my hair out for a week turns out a brand new spark plug boot was the problem!
3) Oiling the bushes - hadn't thought about this before. I usually keep things oiled as I reassemble, but an extra squirt never hurt a seagull
4) tossing it off the porch then starting again

[Charles uk]

Plug gaps

White CDI smooth circumference flywheel, mk3 35 thou
Black CDI single groove circumference flywheel, mk4 25 thou

Do you have the right flywheels fitted.

If you think the crank case might be leaking brush a light coat of kids bubble mixture on all the joints & pull the starter a few times, if it leaks you'll see foam, saves a lot of work.

Remove the float bowl, on the side of the hex main jet, the size is stamped, probably a 95 or 100.

[Collector Inspector]

Throwing it off the porch is not a requirement but threats whispered may well get some results.

Without the spark plug...hold the HT lead 6mm from the head. A spark should jump.

Cranky old thing ain't it just?

B

[JERSEYMAN]

Flywheel woodruff key, is it in the correct slot in the flywheel? Has the ignition somehow shifted?

[andrew]

Thanks for the suggestions guys.

Black MK4 CDI, single groove flywheel, woodruff key in the right slot.

Tried all manners of plug gaps in small increments from way too tight to about 45 thou.

Still need to see if it can jump a big ie 5/6mm gap but given I’ve got a new coil on there and the original one also seemed fine I am hopeful that’s not the problem.

Starting to think it is either the carb or casings even though both look in good nick. Trial and error at this point.

Funny how the newest motor I own with probably the lowest hours is the one giving me the most grief!

I have a set of WSPC casings which I will clean up and try, last time I used them was years ago on a bitsa but never any problems with them. As for carb I’m still not sure if a 416 off a forty will work but will give one of those a try too. Also have a spare amal 2 jet which I have found to be a more reliable option a couple times now, will see if that helps too.

Hopefully carve out some time this week for another proper tinker.

[beerjam]

I hope I'm not stating the obvious here, but have you tried squirting a shot of fresh fuel straight into the air intake, to see if it will fire?

Cheers, Mark

[Horsley-Anarak]

I hope I'm not stating the obvious here, but have you tried squirting a shot of fresh fuel straight into the air intake, to see if it will fire?

Cheers, Mark

If they have a spark at the correct time and compression they will run on WD40, just give it a squirt down its intake and it will run.
https://youtu.be/LVij8U6el50

The fault finding process is very simple, spend a couple of hours (or days if needed) watching this guy https://www.youtube.com/c/mustie1/videos. Darren explains the process every time he has a new motor.
It is very simple compression spark fuel, it will run.

[andrew]

Tried a few more things tonight, still no luck:

WD40 and fresh gas in the intake, and Amal 2 jet carb.

Spark did indeed jump quite far from bare cable tip, several mm at least.

I feel ignition and compression are more likely OK than fuel. So will explore that some more. Could be contaminated (but expect wd40 would have fired if so), or maybe losing vacuum in/around the casings. Off with its head!

[never-outbored]

As Charles suggested previously, you could use bubble mixture to find out if it’s the casings without having to strip it.

[Charles uk]

It's starting to sound like H-A is closest to the answer, with his flywheel keyway suggestion.

[Horsley-Anarak]

It's starting to sound like H-A is closest to the answer, with his flywheel keyway suggestion.

not me

[andrew]

Flywheel key definitely in the century slot. But I will probably swap the entire ignition/flywheel/base assembly from another reliable forty just to be sure that isn’t the problem (keyway slot changed for the test of course). Then can at least tick that off the list. Need to grab some bubbles from the bubble store too.

Thanks for the continued support. These’s an answer here somewhere, just have to go one part at a time as everyone well knows!!

[Horsley-Anarak]

Pull the plug and squirt some petrol in the cylinder.
That will give you the petrol where it needs to be for ignition, it will be too rich initially to start but will soon lean out enough to give you a pop after a few pulls.

Crankcase issues are very low on my list of things to look for, flood the crankcase and it will run.

This type of 2 stroke is one of the easiest engines to get your head around.

The only other issue may be bent crank, that can stop them from running.