Head rebuild - 450 Springer

[machten]

Hi all,

Thought I'd share a few photos and ask a few question about my 450 head rebuild.

After giving the 450 a bit of a hammering in the Alpine regions of France and Italy, I sent it back to Oz to adopt the role of a regular rider.The bottom end had already been dealt with, but when I got it back here it developed a sticking valve issue. On examination I arrived at the conclusion that I'd replace the valve guides and the seats. This pretty much would complete any engine work required post my life time.

After the machinst extracted the guides very gently by line boring them close to the parent alloy, and getting some guides from Nigel at Nigel Lacey Engineering, he fitted the new guides to suit. Very sweet, and a good solution.

The on to the seats...I think I recall at some stage, Nigel talking against "valve seats within seats". I may be wrong on this and it may be in an email between us, or I may be imagining it!....I just couldn't find the post. In any case, my machinist took that approach after consulting with some ex-VeeTwo people to embed the unleaded seats within the original valve seats. I'm not totally comfortable with it, but I'm happy to experiment with it. This approach involves putting the unleaded seats within the old phosphour bronze seats. Anyone have any experience of this?



I also wonder if my exhaust valve is not riding a little high? Thoughts? (bearing in mind the valve sealing is on the new unleaded seat and the old bronze seat is recessed through wear)



The rocker spindles were in pretty ordinary shape too. Ridged on the contact surfaces by 0.5mm+. They were replaced. Suprisingly, the bushes were pretty good.




Kev

[Jordan]

With luck, your new seats and guides should see you out, Kev. But as you asked, here are some thoughts.

Good idea to bore out the old guide to near OD, as it would help to safely remove it. I can't say I like the factory recommendation to knock them out cold as is, and I've suffered a loose guide after that treatment. I heat the head first now, to decrease the grip on the guide, and haven't had seats fall out during the process yet. Were your new guides installed hot or cold?

That's an interesting way to fit valve seats. If it works then OK, but it means an extra junction to potentially restrict heat flow?
I have, apart from my splendid Ducati motorbikes, some cruddy old British machines that I like just as much. One of them has a particularly cheaply made cylinder head of cast iron. It's really built down to a price. When concerns over lead-free fuels leading to valve seat recession came about, I did the sensible thing - nothing. May as well wear out the existing seats before spending money! Many years have passed, quite a few miles too, but the old seats are surviving happily.

The rocker spindle (but not bush) wear is very typical on Ducati singles, if mysterious. Not nice, but It doesn't seem to matter much, as valve adjustment takes up play. It's one reason I like running with no valve springs.

I think your "high" sitting valve is OK, if it doesn't hit the piston. You want some thickness around the edge of the valve head, so as to avoid a hot zone with a "sharp" edge, that could lead to valve burning.

Jordan

[machten]

Thanks Jordan. I don't know whether he used heat or not on the guides, but he's had many years experience on bikes other than old Ducati's and a good reputation. There are very limited options here now for expeienced bevel familiar machinists (both of who are very good - just very busy), so I've gone down this path to try and see if we can start building the local bevel community another option as waiting times for work can be months right now. I'll try this out for a wee while and if looks OK I'm going to give him some bevel twin heads to do. When I picked up the head I gave him my Sport footpegs and gear change and brake levers to sleeve as they are now annoyingly sloppy on the footpegs.

I confess, I was suprised at the degree of wear on the spindle. It's not something I've seen to that degree on a twin before and my 250 hasn't exibited any such signs (so far!)

Thanks for your reply.

Kev

[machten]

Well the head's back on and the 450 has had about 200km of use. I set the valve clearances fairly wide (it's a scew adjuster, so easy to change) at about 0.15mm on exhaust and intake just whilst I give it some initial running. I'll tension the head again tomorrow.

It is running and pulling beautifully.

I have to say though,...despite a new bottom end about 4000km ago and now new top end and oldhams lash removed, this is still what I would consider a noisy Ducati single engine. I've no doubt the bottom end is fine, the top is fine and everything in between is fine. It's just very noisy compared to my 250 desmo and all bevel twins that have.



I recall back in 2010 in Canne running the bike and asking Rich Lambrechts to have a listen to it for his opinion. (I know Rich reasonably well enough to know it wasn't just a vague effort on his part for someone he didn't know from a bar of soap)..he told me that it can be hard to tell the condition of a 450 because they were just "loud" because of a thinner barrel that caused noise to reverberate around - especially with a springer.

I'm hoping setting the valve clearances to tighter spec will help a bit, but I wonder how much the heavier screw rockers contribute to the noise (and also the spindle wear I found)

Kev

[graeme]

Hello Kev,
For what it's worth,,,
I have a 450 Desmo and a 450 RT, both are quieter that the 450 Scrambler (even allowing for the worn rocker bits in the SCR head)
Graeme

[Jordan]

this is still what I would consider a noisy Ducati single engine.
Kev

It might be interesting to use a mechanic's stethoscope on it, to try to identify the noisy area.
A large screwdriver can be used too, with the blade point touching the engine, and the ear pressed against the handle end.

Jordan

[machten]

I went back tonight to tension up the head and set the valve clearances to spec. I measured the clearances before re-adjusting them. The exhaust was still on 0.15mm, but the intake had moved out to 0.30mm, so either I screwed up setting the intake, or something has moved. The screw nut adjuster seemed solid, so it's a bit of a mystery. Anyway, I've set them down to 0.13mm and 0.1mm and I'll give it a bit of ride when weather improves and have another look.

Just running it cold after resetting them it seems to have quietend down enough that I'm not questioning my big end about to let go. Still noiser than the whirring and clicking of my 250 desmo, but not sounding like a time bomb any more. I used the old screwdriver approach Jordan and it certainly seems top end noise, but at least now it seems basically OK. I actually wonder if what I'm noticing is some difference between the valves hitting up against phosphour bronze vs the new unleaded seats. I did notice when I dropped the valves against the new seats they did produce a noticably different high pitched sound compared to the old seats. After a little riding, I might chuck in some valve lube and listen for a difference.

Time to do some ride tests!

Kev

[LaceyDucati]

Kev

Bent or distorted spindles can give the symptoms you describe. Some aftermarket spindles are centerless ground after heat treatment, problems occur if they are distorted in heat treatment. If they are bent entering a centerless grinder they can still be bent after grinding. Take the spindles out and roll them on a surface plate.

Just a thought!

Nigel

p.s. Seats within seats can work fine, not ideal, but then the original seat dimensions and seat undercutting is far from ideal either!!! My solution was to stick to bronze and just use an additive, works fine for me. Standard single seats are certainly less disturbing than SS bevel twin seats, which seam to me to defy engineering sense !!

[graeme]

"The exhaust was still on 0.15mm, but the intake had moved out to 0.30mm, so either I screwed up setting the intake, or something has moved. "

This is where I found the rocker pin holes in the head were worn and the rocker pins were also worn, combine the 2 and the clearance was different every time I checked my Scrambler.

Graeme

[machten]

Just a thought!

and

This is where I found the rocker pin holes in the head were worn and the rocker pins were also worn, combine the 2 and the clearance was different every time I checked my Scrambler.

Yes, and a good one too. That didn't occur to me. I did replace the spindles with new ones but I didn't check them for straight. I also didn't replace the bushes in either as they didn't seem too bad at all, but I should have had a more rigorous inspection, I think.

The spindle holes are actually very good and required the new pins to be tapped in. I'll run it for a wee while and go back in there. I think just to give me some peace of mind I'll replace the rocker bushes too. Should have done it in the first place. A rocker bushes order is heading your way shortly, Nigel!

Of course, I could have just screwed up the initial setting, and I kind of hope I did, but I always fully rotate the cam a couple of times after setting them and 0.3mm is kind of noticeable!

Thanks for the suggestions fellas. Fortunately removing the head is easy compared to the vertical one on a twin! (which I've recently had to do to fix an o-ring leak).

Thanks also for the seat info Nigel. That also puts my mind more at rest.

Kev