2018 Aprilia RS4 50 Euro 4 Upgrade Project

[jkv357]

Is there any way to tell if the electrical plug-in on the original carb is a Throttle Position Sensor (TPS)? If it is, I don't think it will run without jumping it or adding a resistor.

I have an '08 Honda CRF150R with a carb that uses a TPS. Surprised me - thought a TPS was only on Fuel Injection systems.

[Berkeley]

Don't think so.. I believe it went in a nipple on top of the engine side port of the carb.. maybe smog/ nox. Will take a closer look.

Changed the plug to br8 as was a 9 before to see if that made a difference, sparking fine. Checked float bowl ..full of petrol . Float was free not stuck. Air fuel mix 2 turns out. Idle 8 turns out. Tried a few times and nothing. Put starter spray in the head and another in the carb.. nothing

What happens if the squish clearance is wrong and is too big? I'm thinking that it was 0.85mm before I added a layer of copper seal to each side of the gasket?? Would that make it not fire? Clutching at straws here.

Tomorrow will take it for a bump start to see if that works.

Any other ideas more than welcome cheers

[kaldis12]

Squish has nothing to do with it. The squish is good from 0.75 to like about 0.95 it really just depends on your setup. Try GP start it. If the electronic what you pulled down from the carb is a TPS cable then that should be a problem. TPS advances ignition based on throttle position. Which could cause to not start up. At least on a well built bigger bike TPS works like this. I have no Idea what the heck did they put in this euro4 bike.

[jkv357]

Put starter spray in the head and another in the carb.. nothing

Usually, if you have spark, you will get brief running from a spray of Starting Fluid.

Did you open the throttle all the way when you sprayed it in the carb?

[toratora]

The electric starters on this bikes are well knows for being anemic. It's quite likely that if you GP start the bike it would run. As K emoted your squish should be fine. If the plug was wet when you pulled it then should should be enough fuel to start it. A hotter plug will just make it less likely to foul, and if it hasn't run it's unlikely to be fouled.

[Berkeley]

Hi guys yes throttle was open when I sprayed. Tried to no avail. Then took the reeds off to check. Sprayed in there also,Tried no luck. I'll check the cable and send pics. I'll send a pic to the dealer also to find out what that is as he has the oem book

[toratora]

If you can get a PDF of the workshop manual for this bike that would be great. I have them for several of the older bikes so I'm confident that they made one for the new bike. This would be a boon for trouble shooting issues like these.

[Berkeley]

OK I will Try and ask the dealer.
So far all I found were the older ones online that go up to 2016.. maybe 2017.. this must be the euros 3 engine.

I know the dealer has the latest , but hes accessing it via a dealer link via the piaggio website so doubt this is available for the public yet.. but can ask. thanks

[kaldis12]

First of all try GP starting. We will see what it does. Sometimes it helps a lot in finding the problem.

[Berkeley]

Ok, some progress.

I bumped it down the road.. took a long time before anything happened but it fired up and started. managed to keep it going until either I let the throttle off or pulled the clutch in, then it stalled.. did this twice. choke in. then let it off. afterwards tried starting it via the starter switch and nothing happened.. same as before.

This morning I asked a dealer in the uk to send me any info of this electric device on the carb as mine was closed today.
so thoughts after this ??? most welcome cheers