Base gasket

[Czakky]

I feel a bit petty even asking this.

Is it recommended to trim up the base gasket around the transfer ports? On my Dr Q cylinders it hangs in the breeze a bit.

[Jspooner]

I would. 

[1976RD400C]

The last thing you want is a restrictor plate on your tricked out cylinders. 

[teazer]

Get a one piece base gasket from Lyn Garland and do the best to match crankcases and barrels to that gasket.  That applies both to Air cooled separate cylinders or a monoblock like a TZ. For a TZ top end I'd use a TZ base gasket and Cometic supply those if you can't get one from yamaha.

[SUPERTUNE]

No, you didn't port the stock cases to 400 template! If you were to look at the gasket on your stock cases it won't do jack crap, but take away gasket strength.
Why are you asking the internet when they don't know enough information on it?
You always texted me before...just because of all this covid 19 crap I got slammed out and haven't been able to be on here much. Life took a turn on me!
Chuck

[Czakky]

Copy that Chuck. I was asking in a more discussion format. I'm just trying to learn and hear opinions. I never have an issue texting...

No gaskets have been harmed.

Ha!

This is what happens when I'm waiting on parts for two bikes.

[Yamaha 179]

As most of you know I sell two kinds of base gaskets in three thicknesses.  The two styles are standard RD and TZ style.  The RD style is made like the OEM with a thin inner section and a wider, rounded outer section.  This avoids gasket overlap of the two gaskets in the center of the assembly.  The TZ style gasket is just that; a TZ style not a TZ gasket.  The TZ gasket has a hour glass shaped center section with the thinnest portion about 5mm thick while my gaskets have a pillar shaped center section 8mm thick.  The reason for the difference is the monoblock TZ cylinder and the twin cylinders used on the RDs.  I do not recommend using a true (OEM) TZ base gasket on a twin cylinder engine as there isn't sufficient sealing surface, however my TZ style gaskets work very well; better than the RD style.

The only disadvantage is that if you happen to ruin a base gasket you have to pull both cylinders to replace the TZ style.  In the 25 to 30 years that I have been using these gaskets I have never had a gasket failure.  (I have had some dramatic and drastic engine failures though.)  The material is Tempon; it is cut by a professional shop owned by the family of my former racing associate.  We still use them in every engine we build.  I always grease both sides of the gasket before using.
Lyn Garland