Got Spark, wet plug and compression but still wont run.

Hi all, had a few Vespa's and other assorted 2T bikes in the past but this is my first twist and go ped.

Piaggio NRG Power DD LC. 2007 Model, bought it as a non runner thinking...kicks over ok, anything else is normally cleanable/fixable (dirty carb, plug, air filter, etc) so lets have a go.

Firstly I fixed the starter bendix gear (sticky), changed the fuel (petrol and 2T oil), removed and cleaned the carb/air filter, cleaned, charged the battery and cleaned and gapped the plug, checked the spark, all good.

Still wouldn't start but turning over nicely so I removed the fuel tank and tap and cleaned both, fuel looks to be getting up to carb ok, removed plug and it is wet so pretty sure fuel is getting to cylinder as well, so... good spark, fuel in cylinder and when the plug is removed there seems to be plenty of compression, also cleaned reeds. thats when I looked inside the crankcase and when I kicked it over there was loads of fuel in the crankcase sloshing about. is this normal? I understand that the fuel is drawn into the cylinder this way but there was a lot in there and I thought the fuel drawn through from the carb would be atomised and more of a vapour than a liquid? Is this the result of "flooding"? I know a bit about engines but I'm not an expert and I wasn't expecting to see so much fuel in there so I don't know if its normal or not.

Also I should add that the cylinder head and reeds have "malossi" on them, are these aftermarket? The exhaust definately is as I have seen some pictures of the standard one and mine is one that doubles back on itself.

The last thing I want to say is that the electronic choke is not working, I checked it by connecting it directly to the battery and it didn't move so I stripped it and the electronic end (electro magnet??) was full of green deposit like when you leave batteries in something too long, so I cleaned it up but still doesn't work, will this matter much? I have tried manually choking the air flow with my hand, it used to work on older 2T bikes and go karts I have owned but cant tell with this one yet. Does any of this matter or should it at least give a cough or something, it wont even fire with easy start being sprayed into the carb or plug hole.

Any suggestions would be well appreciated, and any info on the crankcase full of fuel situation would greatly help.

Many thanks Don

 

Auto chokes as far as im aware are always on, so the bike will be flooding, i found this when i broke my auto choke on my sym jet 50cc, with a duff choke it wouldnt fire simply flooded.

A quick fix if you choke is like mine. Take the brass cylinder off the auto choke, pull the needle out from it so you now have a brass cylinder with a hole in it.

Now fill this with solder or jb weld etc so the cylinder no longer has a hole in it. Pop it back in the carb and fit the auto choke back over the top, use somthing under the auto choke to keep the cyclinder in place like a small bit of fuel tube.

You will now have a bike with no choke. It should fire up within a few kicks, i found my sym fired on the first kick without the choke!

 

Check the bore to see if it's been seized at some time, dry out all the petrol , you could try easi-start!

 

Cheers creamsodauk, sounds like sound advice, I was kind of experimenting with the choke by taking the whole slider/needle assy out but it never occured to me to just remove the needle, I suppose the slider keeps the air travelling through rather than escaping out somewhere? So just put some fuel pipe around the tiny spring behind the slider then? to stop it rising? I have read that I should drain the fuel from the crankcase on other threads so at least I have found out about that.

Thanks Marsh for confirming that as well, I dont think it has been siezed, the friend I got it from said it just cut out when riding home and wouldnt start after that, as if it had run out of fuel. It kicks over sweet and if I put my thumb over the plug hole it blows it off with quite some pressure, I'm sure my old Yamaha DT50 didn't have that much compression and that was brand new.

Stupid question maybe... would the fuel in the crankcase stop the motor firing completely? Just drowning the plug maybe?

 

Yes it would.

 

get rid of the fuel in the cases ...then new plug ..but maybe a bearing seal has gone

 

just to say, the needle need to be removed and the cylinder needs to be filled so it is solid, otherwise fuel will be allowed to pass and it will flood.

I dont have any pictures sadly of mine, but i just filled the cyclinder with solder to block it off and reinserted it

 

Thanks again for advice creamsodauk. I removed the needle today (cut it off) but didn't put the petrol pipe behind the cylinder like you said to and it flooded again, I will try again tomorrow with the pipe fitted to stop it rising, I hope my understanding is correct, wish I had taken a picture to be sure. I guessed that cutting off the needle would make soldering the cylinder unnecesary as the remaining part of the needle is still there and I managed to cut it off flush so pretty sure thats ok.

Also checked the reed petals again and they were sitting a little away from the block they sit on, so I stripped and cleaned them and they seem to be sitting better.

I tried turning the bike over without the manifold or reeds fitted to watch the crank turn and to try and see if there was still any fuel inside and I got a pop and flame out of the intake hole after about 3 or 4 cranks, only one but I still see it as progress as I guess it shows the engine has compression, tried spraying SAS spray (like easy start/wd 40) into the intake hole while turning over but it didn't fire but I'm not sure that would work anyway.

I'm ordering a new choke unit tonight but will try again with the petrol pipe fitted to the choke slider tomorrow, do you think this could be the reason it still flooded today, due to the cylinder rising and letting too much fuel through, I did think this only affected the air to be honest and I'm starting to think I may have a carb issue, maybe over fueling, jet too big? I know this bike did run with this config tho...well confused now, never thought a little 2T engine could give me so much trouble, must have been lucky in the past.

 

roxy boy, what makes you think a bearing seal might have gone? Do you mean the fuel might have damaged the crankshaft bearing seals? I suppose that is well possible if it has been sitting in there for a while, how can I check without stripping the whole engine down?

 

hey bud, a pop is certainly a good sighn, shows you have combustion.

You could leave the plug out overnight to let fuel evaporate. And yes you are correct with the needle etc, im not sure if it effects air or fuel im pretty sure its fuel, as my sym would fire once if left overnight then woult cough again. It was just flooding straight away. as soon as i blocked the choke cylinder it fired up after a few kicks (clearing its throat of fuel haha)

good luck

 

it wont run with a broken seal and a stuck open choke wont stop the bike running while you are running it i dont think or was it started then wouldnt start again ..but i dont think there is a way of checking seals

why dont u just empty the fuel disconnect the fuel line and empty the float bowl and insert about a lid of petrol into the cylinder and then heat a new spark plug up on a stove not a lighter because they will break it ..but it should start if it is going to start at all

 

Gutted.. opened the cylinder today, piston ring had gone and is embedded in the piston top, there is a lump of piston missing, some of which has travelled into the crankcase I think as there are some light scores in the bore, there is also damage to the head mainly lots of little dents in the bowl/combustion chamber, It's a malossi iron kit so I am thinking of buying a new piston and rings and having a go at repairing the damage to the head with a dremmel maybe just take the high spots down and generally clean up?, don't know if it will work but worth a go I reckon, I was wondering how I can check for damage to the crank and shells, bearings, etc without splitting the crankcase? Anyone know a good method to remove debris?

This all came about after I spent £25 quid on a new choke unit, and a fiver on a plug and was still wondering why the thing wouldnt start, then I had a little look in the plug hole with a torch and thought I could see a shadow that never noticed before, wish I had looked harder the first time eh.

 

Also.. and this is going to seem really stupid. How can I tell which NRG it is that I have got? It is a 2007 LC does that mean it is a "NRG Power DD" or "Mc3" is there a way to tell easily? Need to know now I need to buy parts.

 

on your log book it should say.

When you say repair the head with a dremel either way id say no, but if you man the barrel then its a definate no!

 

if parts have gone into the crankcase not good means splitting them

although from my experience the junk usialy gets threw out the exhaust port

the model type wont matter aslong as you choose the correct cooling method.

 

haven't got the logbook back from dvla yet, dvla and rac websites both just say nrg.

I was only talking about the head not the barrel, the score/groove in the barrel is very slight, you can just about feel it so might be ok as it is, I was only going to take down the high spots on the head where the pieces of ring have impacted and left not just an indentation but a small lump where the metal has pushed back, need to get a picture to show you what I mean, there are about 15-20 indents but only about 5 need grinding down and the overall shape looks ok, the lip that fits to the barrel and makes the seal isnt affected either so it should still have compression as long as the piston fits well.

New malossi piston is £40 or I could buy a standard piaggio 50cc cylinder kit for around £60.

 

thanks Sketchytom, when I turn it over I can't hear any grinding or rattling but it is a bit oily and wet in the crankcase so I'm a bit worried that there might be small fragments stuck somewhere and waiting to fly out and cause a similar situation, the piston had a lump missing out of the top on the underside and I was wondering if anyone has any ideas what may have caused this? Could it be the ring let go and took part of the piston with it? I don't really want to spend loads of money and end up with the same problem in 1000 miles or less

 

most likely the engine siezed at high rpm and the momentum just tore the piston apart. one of the most common thing to happen to a 2 stroke to be honest. i have a selection of pistons all from engines ive seized and some have some serious chunks out of them!

the crankcase should look oily and wet due to that being were the fuel and oil goes before into the cylinder

and regarding the cylinder head it is not wise to reuse with indents due to these parts can cause hot spots and can lead to a holed piston

 

Thanks tErr0 mine is exactly that: 2007 lc with rear disc brake. I thought it was a power dd but just wanted to be sure.

Bought a 2007 lc engine tonight with a 70 kit on it, i think it is a motorforce kit does anyone know about these?

Also do I need a standard exhaust to get an mot?