Jog-Mania

[Raizer]

That's a Dunlop valve

[tsimi]

Another leak test done today, this time with soap water.
Very good news is the seals are holding and are not leaking at all. Yeah!
The reed block and exhaust port are also holding. This time I closed the exhaust port with a piece of MDF and Motoseal. Still it did not hold air inside. It was leaking but rather slowly and there was a hissing sound near the exhaust port. Looking closer I could see 2T oil & air coming out between the cylinder and the engine case. (see image for better understanding.) So I took apart the top end again and put some Motoseal at the bottom and top of the base gasket. I also looked at the Yamaha Jog Service Manual and there it says to torque the stock cylinder with 14Nm down so I did the same with this MHR Rep cylinder, ignoring Malossis recommended 11Nm.
Now I leave it to dry for a couple hours and then I give it another try. I kinda have a good feeling about this next coming try.
Stay tuned...

[Lucass2T]

I always put sealant on gaskets...but just a tiny little bit to only get a little sticky layer on it.

[spaz12]

[tsimi]

Did another test and it still won't hold air for "minutes". A few seconds yes, but not minutes. Crank seals OK, base gasket OK, intake OK, case halfs OK, exhaust port OK. So where else could air leak out? Head gasket maybe?

[spaz12]

Soapy water?

[spaz12]

I've seen head gaskets and spark plugs leak.

[spaz12]

Piston at BDC?

[tsimi]

I just applied Motoseal to the head and need to wait now till it dries.
If this should also fail...

Yes piston at BDC but now that you mention it forgot the spark plug! How should I seal that?

[spaz12]

I just snugged mine down a little more.

[Raizer]

May 2, 2016 19:14:04 GMT -5 tsimi said:

but now that you mention it forgot the spark plug! How should I seal that?

Tighten it?
Not using a plug you've cut the seal off for the CHT are you?

[tsimi]

I just use a regular spark plug with normal ring around it. I will connect the CHT later once the engine runs.

If I tighten the spark plug more then it is now it will break for sure.

Funny thing is my current red Jog engine with the Polini Sport on it never went through such a tidious check or leak test. I just used the thin base gasket that came with it never put any sealant on it same goes for the intake and head. Still it runs strong and with no issues thus far. Making me think why am I doing all this now for the MHR Rep? The main reason for the leak test was to check if the crank seals were installed right and they turned out to be OK.

[spaz12]

Apr 30, 2016 19:45:36 GMT -5 tsimi said:

Changed to this valve yesterday. Does a better job of keeping the air inside.

Did you use soapy water to test all of your fittings? From the looks of it, you leave it all attached while testing. It could be the cause of your leak.

[tsimi]

I tested the leak tester and it holds air for many, many minutes without the gauge needle even moving 1mm.
Anyone ever did a successful leak test on a 5BM engine? No video = it never happened

[tsimi]

I decided to continue with the engine assembly.
Went to the Monster Jog guy and asked him to get the gears and install the bearing but he didn't had time today so he just gave me this.



That's a 4t press, an engine with gears, OEM Yamaha replacement parts like gear bearing, clamps and so on..., a red racing CDI, a digital tacho, bushing installer and bearing puller.
A lot tools and plenty of time...
This is how far I got today; cleaned and installed the gears and rear brake. It is a PITA to install stuff if you need to find the missing parts and pieces.



The Jog guy said I can have these two here.
That's a digital, water proof tacho (max. 20000rpms) including memory feature to save highest rpm reached. And another red racing CDI. Now I have 2 of them neither is installed. lol
This couldn't have come at a better timing. My current tacho goes only until 10000 rpms and the MHR Rep engine will probably rev higher then that once a decent pipe is installed.