How to make a leak down test kit

[jimblob]

Hi guys & gals,



I’m currently part way through the restoration of a rd350r YPVS (1995) Brazil built bike. It’s taking a loooong time but has started to progress quite quickly over the last few weeks. Hopefully when it’s finished it will look like something distantly related to an ‘N’ type model!!!



I’ve hassled a lot of people on this forum for their invaluable help and advice so I thought I’d post something that might help someone else for a change 😀



I wanted to try and make a leak down test kit but all the instructions I found involved cutting copper pipe, soldering, making blanking plates, rubber seals, etc. After watching a few you tube videos and searching through this forum i started searching flea bay for the parts I needed. I have no experience of soldering pipes etc so wanted it to be as simple as possible to put together.


I’ve tried to add the link for each eBay item at the bottom of the page. I hope they work.



To seal up the intake and exhaust ports (intake rubbers fitted) I used four ‘freeze expansion’ rubber plugs (31 - 34mm).



I then found a 30psi pressure gauge with a ‘1/8 BSP bottom entry’ (fnar fnar) whatever that means.



I then obtained the following fittings -



1/8 bsp x3 way female tee



1/8 bsp x 1/4” hose tail (x2)



1/4” brass hose tail connector



Soft rubber tubing (5mm x 8mm)



Rubber bungs (x2). One with hole and one without. I bought size 13 which worked ok but I think size 15 would be better.



A blood pressure bulb type pump



And some PTFE tape for sealing water/gas



I also obtained a 1/8 bsp Schrader valve so I could use a bicycle pump as well in case the blood pressure pump wasnt up to the job!!

905B174D-0EE5-4CE3-81A8-166263BADCC0 by James Smith, on Flickr


I used the ptfe tape to attach the pressure gauge to the top of the x3 way tee and to also attach the hose tails either side of the tee piece. I used a piece of the rubber tubing to attach the blood pressure pump to one side of the tee joint.

I then attached the rest of the rubber hose to the other side of the tee joint and then attached the double ended hose tail connector to the end of the tube. The rubber bung with the hole in it was then pushed over the end of the double hose tail connector. The attached rubber bung was inserted into one of the balance pipe joints and the solid rubber bung was placed in the other balance pipe joint to seal it.

After inserting the spark plugs and ensuring all bungs were a snug fit I finally pressure tested the engine.

Unfortunately the engine didn’t hold any pressure over 2-3 psi but after squirting soapy water everywhere I found x3 leaks around the intake rubbers where it meets the Reed valves. I had to keep pumping to keep the pressure at around 5 psi to test the rest of the engine but fingers crossed I couldn’t find any other leaks 😬

E978F495-5F85-4592-B951-C0B6FBA38AB9 by James Smith, on Flickr



I did test the equipment on its own and it worked perfectly with no leaks at all!!!



Total cost for all the bits is approx £50.00.



I’m hoping the above info may be of some use to someone in need of a leak down test kit. If I managed to put it all together anyone can.


Cheers



Jim



Freeze expansion rubber plugs

www.ebay.co.uk/itm/285308448583?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=JoSkOPTTSgG&sssrc=4429486&ssuid=&var=&widget_ver=artemis&media=COPY



30psi pressure gauge with a ‘1/8 BSP bottom entry’

www.ebay.co.uk/itm/133957973574?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=NixkHUICQ1K&sssrc=4429486&ssuid=&var=&widget_ver=artemis&media=COPY



1/8 bsp x3 way female tee

www.ebay.co.uk/itm/110897874412?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=NixkHUICQ1K&sssrc=4429486&ssuid=&var=&widget_ver=artemis&media=COPY



1/8 bsp x 1/4” hose tail (x2)

www.ebay.co.uk/itm/121132816124?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=NixkHUICQ1K&sssrc=4429486&ssuid=&var=&widget_ver=artemis&media=COPY



1/4” brass hose tail connector

www.ebay.co.uk/itm/121137623807?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=NixkHUICQ1K&sssrc=4429486&ssuid=&var=&widget_ver=artemis&media=COPY



Soft rubber tubing (5mm x 8mm)

www.ebay.co.uk/itm/265285771363?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ehjYaSnpSwS&sssrc=4429486&ssuid=x-kJgxS3TJ-&var=&widget_ver=artemis&media=COPY



Rubber bungs (x2). One with hole and one without. I bought size 13 which worked ok but I think size 15 would be better.

www.ebay.co.uk/itm/144648261255?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=YI5yZF5vTzy&sssrc=4429486&ssuid=x-kJgxS3TJ-&var=&widget_ver=artemis&media=COPY



A blood pressure bulb type pump

www.ebay.co.uk/itm/203758502130?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=vsPpxoifTze&sssrc=4429486&ssuid=x-kJgxS3TJ-&var=&widget_ver=artemis&media=COPY



PTFE tape for sealing water/gas

www.ebay.co.uk/itm/251466811320?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=dw9mkD0pQYS&sssrc=4429486&ssuid=x-kJgxS3TJ-&var=&widget_ver=artemis&media=COPY



1/8 bsp Schrader valve

www.ebay.co.uk/itm/254334745408?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=BmpHqVtnQD6&sssrc=4429486&ssuid=x-kJgxS3TJ-&var=&widget_ver=artemis&media=COPY

[JonW]

Great post.

Ive used plastic plumbing end cap fittings before for the intakes and drilled a hole in them and fitted schrader valves and brought my air in that way, in fact I did both sides and the gauge hangs out of one while air goes in the other.

I found cheap glass cleaner from Aldi to be very effective to show leaks and clear up streak free...

[dusty350]

Great info Jim
That is an essential kit in any 2 stroke owners toolbox. Thanks for the info

Dusty

[midlifecrisisrd]

Great Post, thanks

I still have one of the 3d printed ones someone did years ago

Mine is still intact but think a lot of people's went porous or broke up

Maybe keeping mine sealed in a jiffy bag has helped it

Steve

[stusco]

I bought one from racelab after my 3d printed one dissolved

[rigga]

Didn't know the printed ones dissolved over time, I need to check mine as it went into the tool box draw and not looked at it since.

[stusco]

I spent all my time repairing leaks on the test kit
this is the race lab one
share.icloud.com/photos/023P8GSsQ8kVWTvd_V7hc3K2Q

[JonW]

Yes sadly the 3D printed ones were made of cheese it seemed. I think the issue was they were printed with a lot of space inside as they were a honeycomb. If you did the parts up tight they failed and if you pulled on them the tabs would break off.

The maker didnt mean them to fall apart, its just how he made em and perhaps lacked the knowledge to make them stronger.

They were fine for one or two uses it seemed.

I started with that kit, had hassles and eventually added to it with a gauge and pool bungs (421 exhausts) and other things like plastic plumbing pipe end caps (take an inlet rubber to a DIY shop and get creative!)

You defo need a leak down kit... Tho I also save time now and 'glue in' the inlet gaskets lol How did we not know they leaked like sieves back in the day :/

[dusty350]

I had the same kit, and the plastic exhaust clamps would bend and break when tightened.

[abar121]

Yep, also had the same problem with the kit. I ended up making some alloy plates with some rubber glued to them, to block the exhaust ports.

Worked fine then.

[steven]

Hi,
Here is the last time we all got into leak down test,s.
Still not reading of many doing the vaccum test too.
Its a lot of faffing about, but well worth the hastle, for peace of mind, imo.
Steven.
rdlccrazy.proboards.com/thread/30445/ypvs-lc250-350-leak-test

[JonW]

If you have a vac brake bleeder (or a big syringe maybe) you can easily attach that and do a vac test instead of using the pump. But agree not many do it, me included... maybe i should...

[alankelly]

Yes

No doubt the original kits were most likely printed in PLA which is easy to print but does breakdown overtime

I think if these were printed in something like PETG (plastic Coke bottle material) they would last forever just like coke bottles 😔

[midlifecrisisrd]

Jul 9, 2023 22:05:46 GMT 1 alankelly said:

Yes

No doubt the original kits were most likely printed in PLA which is easy to print but does breakdown overtime

I think if these were printed in something like PETG (plastic Coke bottle material) they would last forever just like coke bottles 😔

I'll send you a kit to copy 🤪🤣

Strve

[alankelly]

Jul 9, 2023 22:35:17 GMT 1 midlifecrisisrd said:

Jul 9, 2023 22:05:46 GMT 1 alankelly said:

Yes

No doubt the original kits were most likely printed in PLA which is easy to print but does breakdown overtime

I think if these were printed in something like PETG (plastic Coke bottle material) they would last forever just like coke bottles 😔

I'll send you a kit to copy 🤪🤣

Strve

Sounds good to me👍

Best wishes Al

[urbantangleweed]

Jul 4, 2023 23:05:59 GMT 1 jimblob said:

Unfortunately the engine didn’t hold any pressure over 2-3 psi but after squirting soapy water everywhere I found x3 leaks around the intake rubbers where it meets the Reed valves. I had to keep pumping to keep the pressure at around 5 psi to test the rest of the engine but fingers crossed I couldn’t find any other leaks 😬

If you used the metal gaskets with the grey sealer pre-applied, in my experience, they're sketchy at best...... I've found they leak more often than they don't and are mainly fit for the bin.

Gaskets made from regular gasket paper (I think Rob 4l04ever can supply machine cut ones) with a light coat each side of spray Hylomar works perfectly every time. A thin smear of the same Hylomar on the mating face of the inlet rubber also makes for an airtight joint.