Cutting valve seats.

[Sidehacker]

Is it possible to machine UL cylinders out so you can have replaceable valve seats. If so is there anything I need to wach out for . I'm looking for some one who has actually done this. Thanks

[AZ pan]

Sorry, but I have never done them on a UL before but have done many ironhead sporty seats and see no reason why you cant as long as you use the guides as a pilot so you get the right angles and placement for your new bore.

[T. Cotten]

Sidehacker!

The problem with seat replacement on Flatties is entirely one of proper material for the new seat.
Because their optimum temperature is dangerously close to where modern hardened seats shrink, any mishap like advanced timing or a vacuum leak will make them come loose.

Traditionally, seat inserts were made of cast iron, of similar expansion character to the matrix casting. They were simple to install.
But today, after the fad of OHV "unleaded kits" and other BS has overwhelmed the industry , finding cast iron seats has become a task.

The major installation concern is keeping the insert margins as far from the bore as possible.

...Cotten

[Sidehacker]

Cotten , I under stood what you were saying but I want to do what corrector if I update it I don't want to screw it up. Are you saying I should look for cast iron seats or are you saying you wouldn't do it if you were me . Who ever own this bike before didn't ride it hard at all every thin including cams show very little wear . I need too fix the cylinders one i( the rear ) has got a standard piston the other cylinder is forty over and it looks like the front cylinder has had one more valve seat cutting. ( just a little deeper hardly noticeable . I want to even things out , should I bore or sleeve and don't forget the seats .

[koanes]

It 's not important to match the bores. You don't want to bore either cylinder any more than it needs to clean up. It sounds like your seats are in very good condition, no reason to do anything other than refinish to fit your new guides and valves. A quality manufacturer of guides and valves, Rowe, is no longer in business, but another source for first class parts is Kibblewhite Precision Machining.

[Sidehacker]

Now that's the exact information I wanted. I know math mathematically you can run two different bores but when I balance it where do I take off material so they will weigh the same cause there should be more material coming off the larger bore piston. Correct. Did I explain that correctly . Do you understand what I mean

[T. Cotten]

Sidehacker!

There is only one reciprocating mass, and one rotating mass in the balancing equation.
The motor doesn't know it has two different pistons or bore sizes, as it only has one crank throw.

Back to seats, cast iron would always be my choice for a Flatty.

....Cotten

[Rubone]

When I first built my UL I found one NOS cylinder and one at .020. That was thirty five years ago. They are still that way! Runs just fine like that!
Robbie

[Peter Cooke]

Reading this thread with interest as I'm about to pull the heads off my 31V and take a look. I was always under the impression that cast iron was to soft for use with valves and ULP hence the need for hardened seats.

The recommendation here seems to be replacing, only if neccessary, cast iron seats with cast iron seats. Won't the valves still hammer there way into the softer cast iron when using ULP without the hardened seats or is the concern of the hardened seats coming loose, due to the engine operating temp, more of a concern so it becomes a choice of the lesser of 2 evils?

[Steve Slocombe]

I used to have my VL cylinders fitted with unleaded seats, and had stainless steel valves made, but stopped doing it because of the cost. I now just have the seats recut and use the nitrided valves and have no problems reported in the last 5 years. As to balancing the engine, first thing is to think of a balance factor and I've heard numbers between 42% and 60%. There are none published for the VL, although the Uncle Frank book implies 50% for all old bikes. I've pulled down motors with one cylinder standard bore and the other +80, plus found them with different compression ratio heads still plugging away. Note that Shop Dope 112 of December 1934, introducing the new aluminium T-slot pistons, says it is not necessary to rebalance the engine when replacing one old ally or magnesium piston with the new ones, and not altogether necessary to rebalance the engine when replacing two cast iron pistons with two T-slot ones. Those bikes have serious flywheels.

[Peter Cooke]

Hi Steve,
Do you think that climate may come into the equation? Your in the UK where the air is cooler whereas most of the guys on the site are in the US where it gets hotter and mine will be running in Australia where it definately will be hotter. Being air cooled engines I'm wondering if your climate is working in your favour regarding the engine temp and hardened seats coming loose? Although, I guess the explosion inside the combustion chamber is pretty much the same temp regardless of the outside air temp.

I saw an old sidevalve v8 ford engine running with 1 cylinder head missing once. Old engines with big flywheels seem to be almost indestructable!

[Steve Slocombe]

Dear Peter, most of the engines I've pulled down have come from the US, so I don't think it is an ambient temperature thing. But running temperature is a concern, as the VL front cylinder runs hotter than the UL and WL models. The guy who did my unleaded valve seats was concerned enough to fit them very tight so they did not come loose. Maybe this is like weld repairing crankcase baffles, which I've also stopped doing, as you risk making things worse in trying to make them better.

[T. Cotten]

...The recommendation here seems to be replacing, only if neccessary, cast iron seats with cast iron seats...

Peter!
That is my personal recommendation, based upon my experience only, others will have their opinions, and we all need each others experiences.

... Won't the valves still hammer there way into the softer cast iron when using ULP without the hardened seats or is the concern of the hardened seats coming loose, due to the engine operating temp, more of a concern so it becomes a choice of the lesser of 2 evils?

I am not familiar with ULP, (a fuel?),
but if original seats are cast iron, a cast iron replacement should be nearly as serviceable.
(Any insert has a heat barrier, of course.)
Do original seats burn, erode, or beat away in your region?

No matter what, a seat insert unleashed is quite destructive.
Wilson Plank (American Indian Specialists)goes to the trouble to oven-sweat hardened seats (and sleeves, I think) with silversolder.
I applaude his effort!
However, at those temps, I would think the hardened steel seats would pre-shrink (no problem), but lose some of their hardness.
(doubtfully a problem, either.)

Which is "harder" to a slapping valve anyway: Cast iron, or annealed steel?

There is a need for cast iron seats once again.
Kibblewhite recognized a similar problem for Panheads, and has finally started producing extinct bronze seats.
Who will pick up the ball and make cast iron seats available?

I would in a heartbeat, if I had a lathe open with a skilled manager to operate it.
All I need is someone to take over.

....Cotten

[harleytoprock]

I know of a very good cast iron welder who welds up worn down seats and then the material is machined. What do think of this process verses pressed in seats?

[T. Cotten]

I know of a very good cast iron welder who welds up worn down seats and then the material is machined. What do think of this process verses pressed in seats?

harleytoprock!

I do not know if your question was addressed to me, but I have a feeble answer anyway.

Your welder is undoubtedly more skilled than I,..
Yet I, myself, would not hesitate to attempt to build up old seats, even with piston rings for filler rod, before I would install hardened seats in a Flatty.

I would have to build a bigger oven, however.

Just an opinion.

....Cotten