Honda XL 350 engine [another one] 1 Poor compression cause revealed.

Not long ago, I had never worked on a Honda XL 350 engine, but now I have two, each with a different owner, on the go at the same time! This one was a runner with poor compression and it turns out it shouldn't be too difficult or expensive to put right, as seen here!

[@adrianbennett617]

Well done Paul, you have saved another engine for me, much appreciated mate.

[@TheNorfolkThunderbolt]

Well, that’s an odd looking thing! What do you think Honda were thinking when they designed that?

[@russparker71]

The little hole is a simple decompression system to assist with starting. All the XL350 K1 and K2 models had that feature.

[@paulhenshaw4514]

I will have to try and find out how it was supposed to work, if that's what it is, as it doesn't seem to connect unless the head gasket blows.

[@battlebbot]

The gasket has failed due to the cylinder head nut on the downward facing head stud being loose. Check the head is flat, change valve guide oil seals, and cam chain, then it will be fine. On the other 350 changing the rings wont help, unless the motor is smoking more when the throttle is being opened, and the motor is under load. If the smoke is worse when the throttle is closed on the overrun, that suggests oil getting in through the cylinder head, cylinder to head joint area.

[@ClassicTrialsChannel]

It will probably be to help with starting. at low speed. Ie when kicking over some compression leaks out. once running everything is moving so much faster that the little loss doesn't make much difference over all. the Beamish suzuki rl325 trials bike has a hole in the bore to the exhaust to help starting, which is why Im thinking this is a similar thing.

[@hermangibbs8163]

Great job as always. Thanks !

[@gusdogbrownlab435]

Hi Paul where do you get the piston rings from? I've had no luck so far

[@paulhenshaw4514]

I'm not sure, sorry, the owner sourced them and I think they came from the USA or Canada if I remember.

[@AlbertDongler]

How very an odd design. What"s the reasoning behind that void space and hole through to the exhaust? Seems weird!!

[@geoffreybennett2457]

Yes .... I wonder what it's purpose is ???

[@bananabrooks3836]

For more insight on the hole/crescent see my comment on the other engine video.

[@jernone3849]

got any videos on the transmission?

[@paulhenshaw4514]

No, sorry.

[@shug831]

Odd design, weld it up and smooth it off. Sorry, i must be a bodger at heart.

[@MegaTubescreamer]

those cunning tech`s at honda hey ?? watch this space !😅🙃