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2018 Aprilia RS4 50 Euro 4 Upgrade Project

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Jaxx
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Jaxx » Wed Oct 14, 2020 12:17 pm

Are you sure that hose from radiator was empty? There should be coolant in every pipe of the system. On my RX is expansion tank so stupidly positioned even if empty the system there is still coolant inside tank to the min. mark! Outlet hole is not leveled with tank bottom...

I don't know for RS4, does it have temp gauge or just overheat lamp, like SX/RX?
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Berkeley
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Berkeley » Wed Oct 14, 2020 11:31 pm

yes 100 % empty. when i had the oil leak from the water pump seal i didn't see any come out. was expecting to piss out when i took the hose off. I assumed that when the pump was working then it was drawing up water below the hose up and around.. then any imbalance would be topped up using the expansion chamber. when the bike was running it felt like fluid was circulating inside.

As for the temp sensor, I changed this out and put a koso gauge on. over the past few months it wasnt working hence not catching the problem sooner . all before that was always keeping an eye on the temp gauge.( ahh)

So as for the piston can I still reuse it , or get another one..?.. If it has had a heat problem then does that automatically mean the cylinder has to be replaced as well??

when looking at types of piston crown problems it seem like this was the closest example. although there are just two marks at the front end of the piston.

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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade

Post by Berkeley » Thu Oct 22, 2020 10:37 pm

Hi Guys,

I would like to be posting about little upgrades I have planned for the bike.. not trying to fix it so heres a little recap and update.

The bike was stalling as it was going round corners , possible air leak. reseated the carb . serviced the bike and noted heat damage to the piston so replaced it with a new cylinder head.

It was working ok if not a little rough but before riding it another time I started it up and let it run to check it was still ok. Came back 15 mins later and the bike was dead. couldn't even bump it .

Checked the cylinder head and it had overheating marks., noticed the coolant was extremely low. filled it up from the radiator full .. So just replaced the cylinder head again, replaced the carb manifold as it had a small split in it ( not sure if it was penetrating the outside).checked the reed valves all look ok same as before,radiator full again.

It wouldn't start on the starter motor and almost showed signs when bumping it. At the bottom of the hill fuel was coming out of the top of the overflow pipe on the carb ( first time this has happened ever). tried it with the starter motor again and put some pilot start into the piston.. again almost sounds like its getting going but as soon as the pilot mix runs out it sound dead as before.

Took the carb apart, no signs of clogged jets etc etc.. seems fine. however petrol pissed out of the fuel line from the tank when i took it off from the carb.. normally it flows but not that much.

Now when going to inspect the carb again I take the fuel line off and NO fuel runs out ( as far as i can remember every time ive taken the the fuel line off in the past it has). I take the breather off the carb and nothing.. only when i suck on the breather pipe does the fuel flow out of the fuel line.

Can anyone tell me if this is normal or there is an issue with the petcock or breather value? The spark plug looks a little dry when compared to past times of checking but its a brand new piston /cylinder so difficult to tell. also checked the spark plus and giving a good spark.

look forward to any pointers thanks

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Jaxx
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Jaxx » Fri Oct 23, 2020 4:45 am

When you remove fuel feed pipe, there should be just a small amount (volume of a pipe from carb to the vacuum valve) of fuel inside. Vacuum valve should be closed with engine off, obviously. However, it happend to me a couple of times, that fuel didn't stop 'pissing' out when I removed feed pipe and I have to 'clip' it to prevent losing all fuel! It looks like somehow valve stayed in opened position! I've read somewhere that rubber diaphragm inside can be damaged by a fuel with added ethanol which is common nowdays across Europe (even premium 100 octane fuels have it.) But on the other hand you have fairly new bike, I'm not sure if that damage shows that quickly.
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jkv357
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade

Post by jkv357 » Fri Oct 23, 2020 6:03 am

Berkeley wrote:
Thu Oct 22, 2020 10:37 pm
(SNIP)
Now when going to inspect the carb again I take the fuel line off and NO fuel runs out ( as far as i can remember every time ive taken the the fuel line off in the past it has). I take the breather off the carb and nothing.. only when i suck on the breather pipe does the fuel flow out of the fuel line.

Can anyone tell me if this is normal or there is an issue with the petcock or breather value? The spark plug looks a little dry when compared to past times of checking but its a brand new piston /cylinder so difficult to tell. also checked the spark plus and giving a good spark.

look forward to any pointers thanks
If I'm following correctly, there isn't a problem with the petcock.

What you refer to as a "breather" to the carb from the petcock is a vacuum line that opens the petcock only when the engine is running and providing vacuum.

It's a check-valve to prevent fuel from flowing into the engine if the float valve in the carb fails to seat.

As long as it flows when there's vacuum it's fine.
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Berkeley
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Berkeley » Fri Oct 23, 2020 6:28 am

Thanks Guys

Anyone have a suggestion as to what to check next on the bike?

Im thinking of draining all the fuel.. put new in it.. just to rule that out, plus a new spark plug...

As ive been using the same setup i didnt recheck the squish clearance .. if that could be a reason. still trying to think back to why would the bike just died then not start.. going back to the first encounter
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jkv357
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by jkv357 » Fri Oct 23, 2020 8:48 am

Starting with new fuel is a very good idea.

Confirming there are no vacuum leaks would be next.
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Berkeley
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Berkeley » Sun Nov 01, 2020 7:46 am

Changed the fuel,took the carb apart , new spark plug and can now get it to bump start which is a lot better than before.

Going to charge the battery and try again with the starter motor.. still dont think the carb setting are correct but its a step in the right direction.
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by jkv357 » Mon Nov 02, 2020 5:59 am

Just a battery without adequate voltage can cause odd running problems.

Definitely make sure you have a fully-charged good battery before moving on.
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Berkeley » Thu Nov 05, 2020 8:47 am

finally....... can log in again!!!

so took long to start, got going then stopped.

Anyway im looking for parts to build a pressure test kit but only seem available in the US with a long waiting time. Does anyone know where to buy the parts mentioned in the tutorial section? or a test kit in europe??
Even typing in the french translation on the packet for the expand tite plugs it comes up with items completely different.. even my french friend couldnt find the right words for it.. It surely must exist on this side of the pond. thanks
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