Hi all,

I've got my barrels off and thought I should do a leak test to be sure that when I put it back together the crankseal integrity is good so I don't have to pull it down again immediately after.

Question is, how far do I fill the top cylinder with petrol/oil mix? I've been told that if you fill it completely or too much, then yes, it will leak regardless, giving a false positive (it's leaking when it really isn't).
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MC21 Honda NSR250. TYGA 300 conversion.

I have always done the following :

1. Put bike on padlock stand
2. Pour petrol down top cylinder reed intake, fill to just under bottom edge reed valve square.

Remember that a proper leak down test would be the best since this test only shows you the the crank center seal is sealing from left to right and that the flywheel side crank seal is still OK.

The other side may still leak and you wouldn't know it. If it did however then your right hand side exhaust will smoke heavily because its now pulling the gearbox oil into the engine when running.

Bike will also be very difficult to start and when running, the one exhaust will run hotter than the other. ( Feel exhaust gasses with hand. )

If your bike starts 1st or second kick then I wouldn't worry too much....

Alzazorq wrote:If your bike starts 1st or second kick then I wouldn't worry too much....

This is probably the best real indication. Experience has shown that if the NSR is really hard to start (assuing jetting etc is all good) then the crank seals have probably hardened or failed. If it starts first couple of kicks, then the seals are good.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

I've never had a Honda that starts easily, as chance would have it. If mine has sat a while it generally takes five. I consider that lucky

How far can you fill it before it spills over?
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MC21 Honda NSR250. TYGA 300 conversion.

Dave Ett wrote:

Alzazorq wrote:
If your bike starts 1st or second kick then I wouldn't worry too much....

This is probably the best real indication. Experience has shown that if the NSR is really hard to start (assuing jetting etc is all good) then the crank seals have probably hardened or failed. If it starts first couple of kicks, then the seals are good.

Sorry Dave, I have to disagree! Mine has never been a good starter. Not when it was new, not when it was rebuilt crank-up! When it was rebuilt it also had a new battery and reg/rec... and doesn't even have to run lights!

I can see the bugger sniggering at me every time I walk up to it... especially if there's anyone around watching me!
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Andy.
NSR-WORLD.COM

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I can see the bugger sniggering at me every time I walk up to it... especially if there's anyone around watching me! Confused

- LOL I can just imagine that !

To put it plain - There's something wrong with your bike then Andy !

There probably is now... I expect the crank seals are rock hard as I've not used it for 18 months, and it's been sat outside!

However, I can assure you there was nothing wrong with it after it was rebuilt, as anyone who rode it will attest to. It just doesn't like to kick start. Bump it and it's fine, but just hates to kick.

I've seen people start NSR's by hand... mine would have your arm off if you tried that! And no, I don't run high compression, before anyone asks!
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Andy.
NSR-WORLD.COM

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I'm not saying it's the only way to tell the seals are gone Andy, but if it starts the first couple of kicks, I'll put money on the seals being good!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Yes, I agree when you put it that way. What I meant was if it doesn't start, I wouldn't personally immediately assume it was crank seals. Mine was, for all intent and purposes new, and it was still a nightmare to kick-start sometimes... usually when people were watching! F**ker!
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Andy.
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A good reason to put the kickstart mech in in bin and bump it.
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Yep!
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Andy.
NSR-WORLD.COM

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Do you have access to a low pressure gauge ? You can make up some adaptors to fit into your carb rubber with the gauge and a tyre valve .Plug off the exhaust port . Pump it to + - 7 psi and have a tea break ,
then check if the pressure has dropped .

Andy wrote:Mine was, for all intent and purposes new, and it was still a nightmare to kick-start sometimes... usually when people were watching! F**ker!

Andy, did you try opening and closing the throttle a few time before kicking it over???

Are you trying to catch me out Tom?!
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Andy.
NSR-WORLD.COM

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lol do you remember that at the dyno that time?
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If I have to take the carbs off once more...