hey guys, I am in the process of taking a 79 xs400and turning it into a bobber. First i took care of my carb problem but when i tested the compression it was extremely low so im wondering if anyone knows where i can find the torque needs to be for the various motor parts. I am also wondering if anyone knows where i might a quire a gasket set for it. Thanks Warkilt

hey guys, I am in the process of taking a 79 xs400and turning it into a bobber. First i took care of my carb problem but when i tested the compression it was extremely low so im wondering if anyone knows where i can find the torque needs to be for the various motor parts. I am also wondering if anyone knows where i might a quire a gasket set for it. Thanks Warkilt

download the workshop manuals in the sticky at the top of this section for the torque settings!

gasket kits are common, yam still supply them and athena make copy kits ( full and top end) get 'em evrywhere fleabay, motocycle shops etc!!

Ok Thanks i was able to find a new gasket set so i am ready to go for the rebuild. Thanks Again

tell us about your rebuild.... LOTS of pictures and posts!! please.

i have a 79 XS400 so i would like to know what you find and how you solve any problems

The 400 engine didn't have many problems. Occasional cylinder head issues if wrong oil used. The cam chain tensioner has a plastic receiver for the tensioner blade, these can break up letting go of all chain tension. rare though. On the whole just normal wear and tear items will need attention, this is normally limited to pistons and bores.

thanks for the replies, I'm having a little trouble getting the motor out off the frame but i'm hoping that i will get started on it this weekend. I bought a new camera so hopefully i can figure it out so that i can post pictures of my progress. Thanks Again!

partsnmore has cheapest gasket set @ $45.00 (ebay may have it, but i usu see it at a premium there):

https://www.partsnmore.com/cat_index.php?model=xs400&category=engine

Hey again I have been trying to get the motor out of the frame, i follow the service manual on what needed to come off before i removed it. Now i cant seem to pull it out is there any chance that there may be a hidden bolt or two that could be still holding the motor on?

Hey again I have been trying to get the motor out of the frame, i follow the service manual on what needed to come off before i removed it. Now i cant seem to pull it out is there any chance that there may be a hidden bolt or two that could be still holding the motor on?

top engine mount off?

2 rear mounts?

front lower mounts off?

sometimes the motor is reluctant to come off the frame as it tends to wedge in the front mounts. you can do a top end strip to lighten the engine and I suggest loosening the front sprocket nut as its tight (use the gears and drive chain/back brake)

just rock the front up to free it and take the engine out from the right hand side.

top engine mount off?

2 rear mounts?

front lower mounts off?

sometimes the motor is reluctant to come off the frame as it tends to wedge in the front mounts. you can do a top end strip to lighten the engine and I suggest loosening the front sprocket nut as its tight (use the gears and drive chain/back brake)

just rock the front up to free it and take the engine out from the right hand side.

Thanks a lot i finally got it out, I had one other question though, Could use one of those AGM batteries on a 79 xs 400 it says it can be used on the 1980 so i figure it could but i just wanted to check before i spent the money.

Thanks a lot i finally got it out, I had one other question though, Could use one of those AGM batteries on a 79 xs 400 it says it can be used on the 1980 so i figure it could but i just wanted to check before i spent the money.

battery will be smaller, so would need to pack a little to stop it moving! Also check dimesions and amperage

Thanks a lot i finally got it out, I had one other question though, Could use one of those AGM batteries on a 79 xs 400 it says it can be used on the 1980 so i figure it could but i just wanted to check before i spent the money.

I have an AGM part #61-2026 from mikesxs.net on an 78 XS400. works much better than one i had before.

here is what mikesxs said when i asked:

"If your bike had a 12n12a4a-1 battery then our battery will interchange ( check dimensions and post polarity positions and note the AGM battery has No vent.)"

Think i looked up and that was one of two batteries the late 70s XS could take (think other one was Yuasa YB12A-A) so i bought it and been using it since.

PS think that same part is also on partsnmore.com

I have an AGM part #61-2026 from mikesxs.net on an 78 XS400. works much better than one i had before.

here is what mikesxs said when i asked:

"If your bike had a 12n12a4a-1 battery then our battery will interchange ( check dimensions and post polarity positions and note the AGM battery has No vent.)"

Think i looked up and that was one of two batteries the late 70s XS could take (think other one was Yuasa YB12A-A) so i bought it and been using it since.

PS think that same part is also on partsnmore.com

thanks for the reply's i will do some checking tomorrow to make sure it will work.