Sorry for my ignorance, you might have already mentioned it, do you want to keep the water temp at 50 degrees or do you mean something else?Originally Posted by F5 Dave
How do you measure the loss through ring sealing by the way?
Ta
Sorry for my ignorance, you might have already mentioned it, do you want to keep the water temp at 50 degrees or do you mean something else?
How do you measure the loss through ring sealing by the way?
No8 Wire Extraordinaire
Yeah about 50 seems optimum but anything appreciably cooler than air cooled is worthwhile. Ring seal tester is two gauges and piston locked at top of bore. Feed compressed air in plug and 2nd gauge measures % difference. Should be about 8-10% so 35 is pants.
Don't you look at my accountant.
He's the only one I've got.
Ta
35% is bad for sure looking at what the aim is. I imagine there is untold fucking around to heat the piston and cylinder before testing, and trying to be consistant with timing of the test.
Think I'll repress the memory of this conversation, so it doesn't cross my mind as the GT gets assembled.
No8 Wire Extraordinaire
yeah I'm getting desperate so trying all sorts of things. If it seals properly I might get some decent power out of it.
Don't you look at my accountant.
He's the only one I've got.
Long Haired Yobbo
Looking Pro!
Heinz Varieties
Hardcore Biker
I know I'm jumping in here, and I haven't read the full thread, but leak downs need to be done on a hot engine, and it's a cylinder seal test, so includes valve seating if it's a four stroke.
Carry on..............
No8 Wire Extraordinaire
A 4 stroke?! Don't be ridiculous.
And no they don't 'have' to be.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
I leak down test every 2 stroke I build (even standard original stuff) and there is always a large difference between cold and hot, and, the smaller the engine, the larger the leak (when cold)
I am unsure of your method, but I assume that you are 100% confident that the leak is from the cylinder sealing rather than anywhere else (exhaust port is very common), and simply spraying soapy water is the method (I am sure you are aware of this)
I have personally never found an engine (yet) that hold the pressure for more than a few minutes (or less) particularly when cold, as it just eventually seeps past the rings, and have only done a few fast 50's myself, but I seem to remember that something like 10% was the norm in all cases (somewhat less than 35)
Have you tried an expander ring behind the piston ring? I use them when I have trouble with ring sealing (Suzuki RG 150's have them on the second ring, and you can cut them to suit for 125's no problem, but 50cc I suspect not..... Maybe some production 50's have them, but I am not sure.
I just had a look in some 50 kits and they all have expander rings, i don't think you woukd have much luck buying just the expander ring, but even a cheap Chinese ring kit (retail something like €5) would have the expander ring.
No8 Wire Extraordinaire
Your post confuses me. Leak down of cases vs leakdown of ring seem to be interchanged in places. This is ringseal with engine locked and you can hear air leak out the carb and pipe. This is my 100 with a KT piston.
anyway a successful night testing it stayed together. More power so must check seal again to compare. Temp gauge in rad reads way low compared to head temp, I'll have to move it. Thanks to Koba for helping out.
Finally getting somewhere
Don't you look at my accountant.
He's the only one I've got.
Forum whore
[QUOTE=F5 Dave;1130611297]Your post confuses me. Leak down of cases vs leakdown of ring seem to be interchanged in places. This is ringseal with engine locked and you can hear air leak out the carb and pipe. This is my 100 with a KT piston.
anyway a successful night testing it stayed together. More power so must check seal again to compare. Temp gauge in rad reads way low compared to head temp, I'll have to move it. Thanks to Koba for helping out.
Finally getting somewhere[/]
Unfortunately I was attempting to write via phone, and I edited it cack handily.
Does the cylinder hold pressure for any time, or leak immediately?
No8 Wire Extraordinaire
Well straight away, you're feeding pressure constantly from the compressor into the sparkplug hole with piston held at TDC. Ex port is wide open as is carb (apart from having to get past ring & piston).
I must retest it now I've honed it with torque plates, the power has come from somewhere.
Don't you look at my accountant.
He's the only one I've got.
Bucket Racer/Crasher
honing it out to 136cc would of helped.
No8 Wire Extraordinaire
I'm using the piston you suggested & assumed it was legal. but I had to water cool it to build up the material as the bore job went right through and exposed some gaps at the base of the fins.
Actually when I first fired it up last night the bike sounded notably different. More kind of gruff, & there were some new rattly sounds coming from the clutch area.
It hit me; its because its not ringing the fins - the noise is suppressed, so you can hear other stuff that was drowned out before.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
Interesting.... I use a modified blood pressure testing kit (similar to a Kart tilitson pop off tester) to hand pump, rather than a compressor, I have always felt that was too much pressure... How many bar do you run?
No8 Wire Extraordinaire
http://www.ebay.com/itm/Dual-Gauge-L...cessories&hashUm, google ring leak tester. My other crankcase
leakdown tester uses a bicycle pump at 8 psi, but this is a different test altogether.
Don't you look at my accountant.
He's the only one I've got.
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