Two Stroke Racelab

Mark(UK) performing a leak down test on a Lambretta TS1 238 cc engine with his custom tool. Many thanks Mark and I hope everything goes well with your project.

Leak Down tester kits for the Yamaha TZR250 1KT - 2MA & TDR250 bikes, can now be purchased via my  online store. The leak-down tester is an essential tool for any high performance two stroke engine. This kit is installed in place of your carburetor and by pressurizing the engine cases you can check for any air leakage due to worn mating surfaces, erratic torque values due to aged parts, worn crankshaft seals etc. It is a necessary evil that it will help prevent catastrophic damage to your engine and keep performance up. A very valuable tool for a two stroke engine, handmade with care. Directions of use:  Testing can take place after a newly assembled engine to verify that everything is leak free, on a bike you just bought and you need to check crank seals condition etc. Place the tool in the carb manifold, seal the cylinder head with a normal spark plug and seal the exhaust flange with the included CNC exhaust blank plug. Pump the en...

A few months back I made a custom leak down tester for Jason(UK) and here are some photos that I received and wanted to share. Jason owns a Banshee motor with Athena 421cc cylinders and used to have constant seizures on LH cylinder and needed to verify that there is no air leakage on crankcases, oil seals etc. Hi Nick, You did me a special leak down tester for my 421cc Athena Banshee last October. Your kit fitted perfectly and I had zero leakage - actually gaining a bit of pressure after 7 minutes due to a little air bleeding back from the second cylinder through the labyrinth seal after I had taken the pressure a little over 5psi and then used the needle valve to set it to 5psi exactly. Thanks again - I am delighted. Jason      And here is Jason's bike. 

I've just completed working on a custom made leak down tester to suit Nsr250 Mc16 Keihin 28mm carbs, for Karl(UK). I love working on a metal lathe.

Leak Down tester kits for the Yamaha TZ125 4JT bikes can now be purchased via my online store. The kit will fit all Yamaha Tz125 1994 - 1997 models. Most probably it will suit later TZ125 models as well though I haven't verified this yet. The leak-down tester is an essential tool for any high performance two stroke engine. This kit is installed in place of your carburetor and by pressurizing the engine cases you can check for any air leakage due to worn mating surfaces, erratic torque values due to aged parts, worn crankshaft seals etc. It is a necessary evil that it will help prevent catastrophic damage to your engine and keep performance up. A very valuable tool for a two stroke engine, handmade with care. Directions of use:  Testing can take place after a newly assembled engine to verify that everything is leak free, on a bike you just bought and you need to check crank seals condition etc. Place the tool in the carb manifold, seal the cylinder head with a normal spa...

Leak Down tester kits for the Suzuki Rgv250 and Aprilia Rs250 bikes can now be purchased via my  online store. The leak-down tester is an essential tool for any high performance two stroke engine. This kit is installed in place of your carburetor and by pressurizing the engine cases you can check for any air leakage due to worn mating surfaces, erratic torque values due to aged parts, worn crankshaft seals etc. It is a necessary evil that it will help prevent catastrophic damage to your engine and keep performance up. A very valuable tool for a two stroke engine, handmade with care.  Directions of use:  Testing can take place after a newly assembled engine to verify that everything is leak free, on a bike you just bought and you need to check crank seals condition etc. Place the tool in the carb manifold, seal the cylinder head with a normal spark plug and seal the exhaust flange with the included CNC exhaust blank plug. Pump the engin...

Leak Down tester kits for the Honda Nsr250 bikes can now be purchased via my online store. The tool will fit the following models :  MC18 MK2  MC21 (all) MC28 (all) The leak-down tester is an essential tool for any high performance two stroke engine. This kit is installed in place of your carburetor and by pressurizing the engine cases you can check for any air leakage due to worn mating surfaces, erratic torque values due to aged parts, worn crankshaft seals etc. It is a necessary evil that it will help prevent catastrophic damage to your engine and keep performance up. A very valuable tool for a two stroke engine, handmade with care.  Directions of use:  Testing can take place after a newly assembled engine to verify that everything is leak free, on a bike you just bought and you need to check crank seals condition etc. Place the tool in the carb manifold, seal the cylinder head with a normal spark plug and seal the exhaust flange with ...

Leak Down tester kits for the Honda Rs250 bikes can now be purchased via my online store. The kit will fit all Honda Rs250 from 1993 up to 2009 models. The NF5 model will be added in the future or upon request. Price is at 85 Euro (WW posting costs included).

I've just finished working on a custom leak down tester for Ryno(UK). The dimensions are the same as a Mikuni TMX38 carburetor, that Ryno uses in his Honda CR250 bike.

Leak Down tester kits for the Honda Rs125 bikes can now be purchased via my online store. You can find the link to the store, at the right hand side of this page. Leak Down Testers for other motorcycle models will be added in the near future or upon request. Price is at 65 Euro (WW posting costs included).

I've spent some time with the NF4 project and I believe the engine is now complete though still needs some minor work here and there. According to the porting theme, the cylinder is a '94 model and has a new nicasil plating from the last owner with the cross hatching markings still visible in there. After some chamfering work it's ready to be installed on the cases.  Piston to cylinder clearance is 0.09mm so it's out of spec and ring gap is 0.42mm hence really close to service limit as well but do not exceed it. I will still use it for the first start up as to verify any possible issues with the rest of the bike e.g electronics etc After a few minutes the engine is complete... ...thought the leak-down testing showed a major leak on the reed valve assy.  I'm really thankful I didn't had to split the cases and after a couple more tries to seal the reed valve the leak down test got a stable and healthy me...

Leak-down testing on a two stroke is another essential tool that can get you out from troubles. In contrary to the compression tester, this test measures pressure loss but both can be used in conjunction by an experienced user to reveal possible issues on an engine.  Testing can take place after a newly assembled engine to verify that everything is leak free, on a bike you just bought and you need to check crank seals condition etc. A leak down tester can be fabricated easily out of parts found on a hardware store but there also kits dedicated for this work at reasonable prices.  Procedure is pretty simple, you need to block all air passages out of the engine, like the carb and exhaust manifolds and the spark plug hole. For the later one, a simple spark plug will do the job fine but you will have to construct some bungs for the carburetor and exhaust manifolds and also acquire a pressure gauge and an air hand pump.  Here is a pic of a plumber pipe plug o...