[grahampaul]

are either really needed?and if so can someone give me link to one.

[AzCal Retred]

These will likely do fine. Most of my oil breather issues went away after installing a properly fitted modern piston with rings that actually sealed. As 2CV pointed out, the breather-auto-chain-lube feature is nice!

Feelers 1/2" (12MM) One Way Inline Check Valve Non-Return One-Way Air Water Gas Check Valve Ozone Resistance PVDF, Pack of 2 ; $6.58
https://www.amazon.com/Feelers-Inline-Non-Return-One-Way-Resistance/dp/B0B71FS1Z5/ref=asc_df_B0B71FS1Z5/

[grahampaul]

yes ,thanks.i was looking more in the uk market,am from uk.

[tooseevee]

are either really needed?and if so can someone give me link to one.

    You need one or the other or you don't have a crankcase breather "system". Just an open-to-the-air hose won't do it.

[stinkwheel]

According to my experiments, both work equally well in that the volume of gas they flow is not significantly different.

I think the valve works better if you have a closed capture/bunded system because you can put the valve between the crankcase and the bund/can. Two benefits, one will be a faster response to pressure pulses, the other is the bund/catch can is only dealing with residue flow and so doesn't need to be airtight.

[grahampaul]

i have a feeling am being told to stick the duck bill back on..do they act like a one way valve?,i can suck and blow through mine.

[AzCal Retred]

The duckbill is an early days Primitive Pete low-buck check valve attempt. Its operation is entirely dependent on materials condition. India rubber isn't the best. The actual cheap check valve and some automotive oil resistant tubing is a better fix. Amazon is world wide, they sell the same cheap Chinese sourced parts as the local boys, they just ship it to your house. Two valves for $7, tough to beat.

[Adrian II]

Here's the link for the one Henry Price sells in the UK. Just remember to fit it the right way round so it can blow out but not suck in!

A.

[AndyMcP]

My bike killed a couple of that type in very short order.  If you take one apart, the valve mechanism is very 'light' duty.

[tooseevee]

i have a feeling am being told to stick the duck bill back on..do they act like a one way valve?,i can suck and blow through mine.

     Yes. The rubber duck bill is a one-way valve. Works fine for this engine if supple.

     If you can both suck & blow through it it's probably dried up too much & it's not totally closing on the "suck stroke". Doesn't mean the piece itself is NFG. Just need a new one OR get a "modern" one.

     The duckbill works just fine for the pressures & vacuums involved here.

      I wonder what the actual numbers are here. Anybody know?

[Adrian II]

If the small one-way valves are too flimsy, you can get brass ones which are heavier duty.

A.

[grahampaul]

i have both the oneway valve and the duckbill coming soon.any disadvantage using both i wonder?.

[Adrian II]

Use one or the other, but choose the one with the best flow.

A.

[grahampaul]

i have fitted an alluminium one way valve,will see how it goes.have the duckbill as a spare.

[AzCal Retred]

Route it onto the chain, the lubrication is free!