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2016 Aprilia RX 50

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Berkeley
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Re: 2016 Aprilia RX 50

Post by Berkeley » Fri Sep 25, 2020 1:37 pm

Jaxx wrote:
Fri Sep 25, 2020 1:27 pm
It's probably because it lacks compression because it seized previously. Since I fixed my air leak I have no problems with starting or idling, just trying to figure that scoring out.
Did you have an easy way to test for leaks? thinking of getting the bike running then putting smoke near the boot and see if that draws it in.. to me that seems like the only place.. Not sure why the bike would be running fine then not all of a sudden.. maybe vibrated loose or something?

We have the same engine.. can you take pics of your carb and boot how that is seated??? thanks
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Jaxx
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Re: 2016 Aprilia RX 50

Post by Jaxx » Sat Sep 26, 2020 7:51 am

Here you go:

Image

It should be like this - that metal part of carb (where this hand-written number 8491 is) touches rubber and that transparent vacuum hose is left to rubber protrusion (I had that protrusion directly on vacuum hose, so carb couldn't be inserted deep in enough...)
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jkv357
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Re: 2016 Aprilia RX 50

Post by jkv357 » Mon Sep 28, 2020 6:05 am

Berkeley wrote:
Fri Sep 25, 2020 1:37 pm
Did you have an easy way to test for leaks? thinking of getting the bike running then putting smoke near the boot and see if that draws it in.. to me that seems like the only place.. Not sure why the bike would be running fine then not all of a sudden.. maybe vibrated loose or something?
I usually use Carb Cleaner to check for leaks.

Get it to idle smoothly, then spray around the areas that may be leaking. If there is a leak you will hear a change in RPMs.
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Berkeley
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Re: 2016 Aprilia RX 50

Post by Berkeley » Mon Sep 28, 2020 6:40 am

jkv357 wrote:
Mon Sep 28, 2020 6:05 am
Berkeley wrote:
Fri Sep 25, 2020 1:37 pm
Did you have an easy way to test for leaks? thinking of getting the bike running then putting smoke near the boot and see if that draws it in.. to me that seems like the only place.. Not sure why the bike would be running fine then not all of a sudden.. maybe vibrated loose or something?
I usually use Carb Cleaner to check for leaks.

Get it to idle smoothly, then spray around the areas that may be leaking. If there is a leak you will hear a change in RPMs.
great, thanks will do !!
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Jaxx
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Re: 2016 Aprilia RX 50

Post by Jaxx » Thu Dec 17, 2020 2:19 am

Two months ago I've ordered Top Performaces TP 80cc cast 50mm bore/std stroke, this is the kit I wanted in the first place, but it was out of stock and I somehow ended up with Stage6 instead. Finish quality is quite better than Stage6 and all ports are factory chamfered!! Due to very little spare time I didn't have time to play with port maps, etc. but official timings are published as 186°/126°, which is very similar to Stage 6 Street Race 77cc.

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TP single piston ring came in un-sealed plastic bag, don't know for sure if that means ring gap was pre-adjusted in factory but I've checked it and it was just right. I didn't care about ring gap with previous kit, which I've later found as mistake (btw Stage6 instructions don't mention ring gap at all). And their rings came in sealed bag from piston manufacturer, so they definitely weren't adjusted.

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Checked squish gap and it was little over factory claimed 0.9mm. Interesting, Stage 6 has even much lower squish than claimed 0.8mm and you can feel the difference between two by turning kick starter. Now I assume that big compression of Stage 6 in combination with too tight (or none) ring gap caused that excessive wear marks around cylinder ports.

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TP on the other hand has a little less power at low (around 5000) rpm, Stage 6 was almost brutal, but it runs more smoothly through entire rev range and revs higher. Honestly, to get most of it I should use at least 21 carb. I've made some 250km with TP, checked cylinder recently with borescope and it is in a TOP shape:)
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