Classic Triumph Bonneville

[Mr. Dazzle]

He's not even started looking yet, I knew he wasn't going to start until this week at the earliest. He spanners for BSB so last week was all taken up by Cadwell aftercare.

[Mr. Dazzle]

He's got it down as far as the cylinders, can't find anything obviously wrong with the work I've done. He commented that one of the pistons is 'tight' on the con rod and the crank doesn't feel right. Still seems tight to turn over.

Only thing to do from here is to keep going, it's just a case if who splits it apart. Me or him.

[Mr. Dazzle]

Spoke to my wife about this - it's her bike after all - we're getting the mechanic to tear in to it. He's going to take the engine out and bring the bike back here (his workshop is filling up) then break into the bottom end and see what's what. I don't have a proper bench at home so I've not really got anywhere to take a bottom end apart. Also not sure I can be arsed!

With four bikes plus a load of other crap in my garage there's nowhere to lay an engine out in bits. The lack of garage working space is a convenient decision maker!

It's gonna cost a few pennies more than the non-trivial sum already spent. I will have potentially a 'new' engine at the end of it though.

[KungFooBob]

Your wife will have a 'new' engine :p

[Mr. Dazzle]

Maybe I should have asked her to try starting it.

[Taipan]

The bike has a lovely provenance to it. Its well worth getting done properly imo. Good on ya!

[Supermofo]

Wondering if I should get me one of these Wife bikes. MT10SP with all the extras.

"Course you want an Akro darling, I know you don't ride but I'll take one for the team and take it out for a nice blast for you. Don't really want to but for you my sweet"

[Cousin Jack]

Wondering if I should get me one of these Wife bikes. MT10SP with all the extras.

"Course you want an Akro darling, I know you don't ride but I'll take one for the team and take it out for a nice blast for you. Don't really want to but for you my sweet"

Somehow I cannot see that working, at least not with Mrs CJ. Good luck though, you will need it.

[Mr. Dazzle]

She's not even got a license

[weeksy]

Wondering if I should get me one of these Wife bikes. MT10SP with all the extras.

"Course you want an Akro darling, I know you don't ride but I'll take one for the team and take it out for a nice blast for you. Don't really want to but for you my sweet"

Don't do it... they'll make you own a bloody zx6r

[Mr. Dazzle]

The thing is, if there's something wrong with the bottom end if must have been that way for a long long time. I did manage to kick it and start it before I started on all this work, even that was reasonably difficult. At the time it was waaaay down on compression though, so maybe one cancelled the other. I also knew that it wasn't going to be easy to start - compared to anything I'd ridden before at least - so with no basis for comparison maybe I just didn't realise it was broken.

I've not touched the bottom end in the time I've had it, so the only thing I could have done is drop something in there. But that would do way more damage than just making it stiff I'd have thought.

AFAIK the bottom end has never been apart in 52 years.

[weeksy]

The thing is, if there's something wrong with the bottom end if must have been that way for a long long time. I did manage to kick it and start it before I started on all this work, even that was reasonably difficult. At the time it was waaaay down on compression though, so maybe one cancelled the other. I also knew that it wasn't going to be easy to start - compared to anything I'd ridden before at least - so with no basis for comparison maybe I just didn't realise it was broken.

I've not touched the bottom end in the time I've had it, so the only thing I could have done is drop something in there. But that would do way more damage than just making it stiff I'd have thought.

AFAIK the bottom end has never been apart in 52 years.

I guess we'll soon find out then

[Nidge]

The thing is, if there's something wrong with the bottom end if must have been that way for a long long time. I did manage to kick it and start it before I started on all this work, even that was reasonably difficult. At the time it was waaaay down on compression though, so maybe one cancelled the other. I also knew that it wasn't going to be easy to start - compared to anything I'd ridden before at least - so with no basis for comparison maybe I just didn't realise it was broken.

I've not touched the bottom end in the time I've had it, so the only thing I could have done is drop something in there. But that would do way more damage than just making it stiff I'd have thought.

AFAIK the bottom end has never been apart in 52 years.

Or...... you took it out, gave it a thrash, dropped a valve and buggered the bottom end

On the plus side if the sludge trap hasn't been cleaned in over fifty years it's about time to split the cases and do it so you haven't really lost anything....

[Mr. Dazzle]

There's still the question of why the valve dropped in the first place too....so maybe it's all related. Well it dropped 'cause the guide collapsed, but why did that happen?

[Le_Fromage_Grande]

There's still the question of why the valve dropped in the first place too....so maybe it's all related. Well it dropped 'cause the guide collapsed, but why did that happen?

Because the guide was worn out or got too hot, either could be caused by a lack of oil to the top end, but I suspect it's just down to high mileage.
What oil pressure does the Triumph engine normally have, is it a low pressure, high volume engine like the Kawasaki Z900 family, or is it a high oil pressure engine with plain metal big ends like most 4 strokes?

[Mr. Dazzle]

It's got plain bearings at the big and little ends. Pressure it about 70psi when it's hot, as far as I can tell it's getting that - although I have no proof the gauge is accurate. You can check to see if oil is returning to the tank when the engine is running (it is) which is normally a sign the pump is working.

The tops of the pistons had oil on them when I peered in through the plug holes. Not very much, only a tiny smear, but they were pristine clean when they went in so oil is obviously getting to the head and down between the valve and guide.

The oil pressure light also goes out briefly when you kick it. I also managed to get oil over the floor 'cause I had the rocker feed pipes disconnected when I was turning the engine over to fit stuff - turning the engine over turns the pump, which pushes oil out of the pipes.

Yes I did check I had oil left in it before trying to start

[Le_Fromage_Grande]

70psi, no wonder they have a reputation for leaking oil, my Kawasaki is about 3.

[Nidge]

I’m pretty sure hot oil pressure is about 40-50 psi (I think the pressure relief valve operates at 60psi on a T140)- helpfully the oil light illuminates at 5psi … more of a “your engine is fucked” light

[Mr. Dazzle]

Workshop manual says release valve pops at 60psi, but also says normal operating pressure is 60-80 It's a piston type pump, so it's going to fluctuate a lot. It's only 25psi at idle.

http://www.classicbike.biz/triumph/repa ... -63-70.pdf

[JackyJoll]

The 60 psi is only seen between the feed side of the pump and the big ends. That part isn’t prone to leak.

Hot oil pressure at idling rpm may only be 10 psi, without it being any problem.