2018 Aprilia RS4 50 Euro 4 Upgrade Project

[kaldis12]

Bad spark plug can cause hard startup when the engine is hot. Lets say you have a BR7ES(lets say this is the hot) and when the engine warms up, you cannot start up again just hardly. You put a colder plug in there in NGK it should be BR8ES(colder) and when the engine is hot its easier to start up but harder to start in cold weather. But you should be fine. In NGK spark plugs the higher the number the colder the plug is. But you should be fine with the BR8ES. Try it out and lets see if your problem has been solved or not.

[Berkeley]

If it idles fine for a while, and then dies, usually that means there is a fuel delivery problem like a plugged fuel filter or gas tank vent.

Cheers thanks for the Advice.. When i installed the 'fog horn' it came with a lot of extra wires, so this bunched up could have been the cause of the tank vent getting blocked.

I changed the spark plug back to the original champion RN2C, ran the bike for a bit ( before the heavens opened up) and it didnt stall. Got back to the garage and left it running and it didnt cut off. so it may just be fixed.

Tonight ill sort out the wiring properly so we can cross this one off

BTW the champion RN2C is cross referenced with the NGK BR8ES and BR9ES. I found this spark plug online and thought it would be an improvement.. Had it in from the very beginning and had no problems so wasnt convinced it was that??

[kaldis12]

Dont buy champion ones. They are shit. Ngk BR8ES should be the best for your bike. For a mild 70cc would be BR9ES, in my experience. For a derestricted 50cc BR8ES is the best. Just buy NGK. Nothing else.

[Berkeley]

Yeah..I know that's why I changed it.. this was in there when I got it. I did change it for the BR8.. then for that new spark plug..couldnt seem to find it.. just the box.. will order them in.
cheers

[toratora]

Indeed that plug looks sketchy. I think even Rin chan would say "ないは."

If she's going to be doing city riding with lots of stops, then go with a 9. If she's going to be wide open throttle a lot then go with a 10. I usually run 10s or 10.5s in my bikes. The one way I would run an 8 would be if the bike had to spend a lot of time at idle. These are NGK numbers. Champion runs the other way where higher is hotter. NGK higher numbers are cooler. I've had the best luck with NGK plugs with these bikes.

As for getting it running properly before you swap everything out, well it wont really matter unless the crank is fubared. You can check the crank with feeler gauges when you open it up. Shouldn't be an issue. All of the other elements (except the pipe) are going away, so it really doesn't matter what condition they are in. The one possible exception being the ignition.

[kaldis12]

10 for a 50cc? Thats kinda seems too cold to me. I ran 10 on 80cc, on bigger 10,5. On my metrakit 50cc I ran 8, was perfect.

[toratora]

He's switching to a BBK, so he might as well buy plugs for it, rather than for the stock 50. But even then I'd probably run at least a 9. Again it depends on how you ride. I spend a lot of time with the bike at high RPM. For instance the PMPR doesn't even get on the pipe until 10K so that bikes is always revving high.

[Berkeley]

Hi Guys glad to say that the issue is resolved. It must have been the tank vent tubes getting caught and the flow restricted. Its a bit of bad design but the tubes are just long enough so that the tank is in the vertical position. Any big amount of fuel in there then it falls down. So this leads to having long tubes that can get caught.
All the other cables tied away so no chance of getting caught. Thanks for the advise in finding the problem

[jkv357]

I agree on the Champion or E3 plugs - stay away.

NGK is the way to go for any cycle engine IMO.

Glad to hear you are getting it all sorted out!

[Berkeley]

Hey Guys, Tora.
With just replacing the top end will i need to do a leak test?

Installing the Metakit 70cc , with the gaskets they provide do you have to still measure the squish clearance? If so does that come from aprilia, or metrakit, if its in the instructions? or if not can someone advise what the clearance should be?
The same goes for the torque setting for the head nuts, where do i get these from? if these are the same settings as the derbi activation project at 10-12 Nm?

Cheers