I'm going to start tearing my 250R down sometime this week, and I need to know what gaskets to buy. I've heard that I should only go with Honda OEM gaskets, and that all the others leak. I already have a top end gasket kit, so all I need is the bottom. Does anyone know of a place to buy a bottom end kit? Where should I get the gaskets/seals from?

Basically I'm asking what all do I need to buy to put the motor back together.

Thanks,

 

It does not matter which gasket set that you use if you are going into the bottom. I have had good luck with them all. You can not just buy the a bottom end set, you must buy a complete set if you are doing the bottom. What people are saying that leak is the head gasket. Go with the 86 or 87 set because it comes with the fiber head gasket. Which will give you more compression than the metal one in the 88 and 89 set. While you are in the cases it is a good idea to change the seals, better now that latter if they leak.

 

Well, I ordered a K&S gasket set. My 250R has a CR head, with a metal CR250 head gasket. I'm thinking I can salvage it, and if not, I have an 86 ATC top end gasket kit I can use.

 

I just completely built my 250R engine, and for the bottom end, i would reccoment not using a gasket between the cases. Uses a sealant like Yamabond or something like that. It seals a whole lot better in cause there is some imperfection in the edges from where you split the cases.

 

Hondaman85, thanks for the tip, but I already have the gasket set. I plan on running a small amount of high temp silicon around the case seal, just to insure that it wont leak.

Thanks for your help,

 

You HAVE to use a center case gasket.

The gasket acts as a shim between the cases. If a gasket is not used, then the amount of free-play for the transmission shafts, crank, and counterbalancer will be too tight. There are many engines that do not use a center gasket, but they are designed as such, a 250R is designed to use one.

In all the engines I have rebuilt I have yet to have a center case gasket leak. The center case gasket can be purchased seperately.

THE best gasketing compound I have used to date is Loctite 518.
http://www.loctite.com/datasheets/tds/Product_5181.pdf

 

The mechanic that's helping me finish my motor said he never uses case gaskets on 250R's. And he has done a lot, including strokers, big bores, and stock ones. He's made some that outrun modded banshees. He said that yamalube works just as well. The 1 millimeter space should not make that much of a difference as of the transmission binding up.