Valve springs and PW3 cam

In another tale of woe from my rebuild ( I found a damaged valve guide that the head "expert" had fitted apparently with a sledge hammer) I took the head to someone else who comes highly recommended. He's found that all the valves are slightly bent. There's tonnes of valve to piston clearance and there's no evidence of them hitting the pistons so they must be hitting each other so I've got valve float.

When I bought the cam I was told that it was designed to run with standard valve springs so that's what I fitted.

What valve springs does everyone else use with a PW3?

I'm tempted to put the old Axtel cam back in but it's with the grinder fixing a bit of rust damage from when it got wet in the shed. He's only had it a year.

Pj
The curse of the "expert". Watched mick h video with pw3 cam and he didn't saw anything special about the springs . What did the people you bought it off say?
And what did the expert say when you told him?
J

auldblue said:

Pj
The curse of the "expert". Watched mick h video with pw3 cam and he didn't saw anything special about the springs . What did the people you bought it off say?
And what did the expert say when you told him?
J

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Guy I bought the cam off says use standard valve springs. Current guy is going to measure spring pressure of current ( standard Norton ) springs and decide whether they are the cause of valve float.


Just wondered what everyone else does.

The only way to go is to do as much as possible yourself. If I get into trouble I do a re-engineering exercise. I use the ordinary auto engine repairers to do cylinder boring, and cutting valve seats. The best crank grinder I can find for that department. Then do the rest myself, except for any aluminium welding. I have about two engineering workshops near-by who are excellent for making the difficult stuff I cannot handle on my own machines. No experts - I don't have many heroes in my life.
I'm not too bad at making sketches for machine shops - been doing that for bike parts all of my life. My best machine shop usually charges only two prices $10 and $20, and his work looks like it is standard production from the Norton factory. If I drive 38 Km, there is the best machine shop in NE Victoria with capability of gear hobbing and a lot of other really good stuff. All top quality.
If you employ an expert, you might as well farm the work out to the subcontractors yourself, the result is always better and you learn more in the process. A bit of research goes a long way.

The best thing to do would be to call Mick Hemmings and speak to him. He supplied me with springs and titanium valve collars. To match my PW3 and the big valve head he had also done. The springs are not standard ones from AN but that's all I know. If you have standard size (an hence weight) valves and collars then you may need different spring to those he supplied to me. He knows what he's doing an his prices are very reasonable I would simply just go to him.

i fitted pw3cams to a few engines with std valve springs without any trouble
However what you said earlier about valve float IS the answer
here is how i do it
-assemble the engine and head ,
-put engine so cam lift is max
-measure the lenght of your compressed spring (write it down , and do the same for all 4 off course)
-put engin at tdc, compress valve spring more until it touches the pistonhead (write it down)you can do this also by measuring lift and multiply by ratio of rockerarm
-take head off and dismantle the spring-
-put spring under a press and on a scale(bathroom will do)
-compress until same lenght as in engine is found ,note how "heavy" it is
-add shimms untill you get near 90kg
-put shimms and spring again under press and put measured lenght again on , you should read 90kg ,of course
-check that you still have 2 mm before coilbound ,if not spring are crap

i did a guzzi lemans with brand new "sport" spring wich turned out to be crap ,and they were not cheap ones
so back in went the old ones(we had no spare and the bike had to ride)one spring had 4mm shimm under it ,but enough room so no coilbound-risk and it flew
the fact that 4mm had to be added meant ,i think'that the srings were tired and should be replaced

I would not install a pw3 without a spring kit.

Webcam and Megacycle both require spring kits when using their version of the pw3 cam. Jim

comnoz said:

I would not install a pw3 without a spring kit.

Webcam and Megacycle both require spring kits when using their version of the pw3 cam. Jim

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I have fitted JSM Beehives with my PW3.....and I fully understand your comment Jim, and agree, but it does say on the spec sheet supplied with my PW3......

'Standard Spings are best'

I ignored it, but....that is what it says....

I have heard back from the guy who has the head right now.

He's measured the current ( standard ) springs at 75lbs seat pressure when closed. His opinion is that if they are shimmed enough to get around 90lbs, they'll probably go coil bound on full lift.

Kibblewhite do a set of lightweight springs and retainers and they're in stock locally. Another invoice to hide from the wife

pommie john said:

I have heard back from the guy who has the head right now.

He's measured the current ( standard ) springs at 75lbs seat pressure when closed. His opinion is that if they are shimmed enough to get around 90lbs, they'll probably go coil bound on full lift.

Kibblewhite do a set of lightweight springs and retainers and they're in stock locally. Another invoice to hide from the wife

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I usually shoot for 95 to 100 with new springs on a pw3 racebike. After the first race they will be down to 90 - 95 lbs. Jim

comnoz said:

pommie john said:

I have heard back from the guy who has the head right now.

He's measured the current ( standard ) springs at 75lbs seat pressure when closed. His opinion is that if they are shimmed enough to get around 90lbs, they'll probably go coil bound on full lift.

Kibblewhite do a set of lightweight springs and retainers and they're in stock locally. Another invoice to hide from the wife

Click to expand...

I usually shoot for 95 to 100 with new springs on a pw3 racebike. After the first race they will be down to 90 - 95 lbs. Jim

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Thanks for the info Jim.

I noticed that it was much easier to kick over after a while. I assumed that the motor had loosened up but it was obviously the bent valves! I'll be fitting that 60 thou head gasket I bought from you to drop the compression. It's 10.5 with a 40 thou gasket. I'd expect what? 10.0 with a 60 thou gasket?


John

pommie john said:

comnoz said:

pommie john said:

I have heard back from the guy who has the head right now.

He's measured the current ( standard ) springs at 75lbs seat pressure when closed. His opinion is that if they are shimmed enough to get around 90lbs, they'll probably go coil bound on full lift.

Kibblewhite do a set of lightweight springs and retainers and they're in stock locally. Another invoice to hide from the wife

Click to expand...

I usually shoot for 95 to 100 with new springs on a pw3 racebike. After the first race they will be down to 90 - 95 lbs. Jim

Click to expand...

Thanks for the info Jim.

I noticed that it was much easier to kick over after a while. I assumed that the motor had loosened up but it was obviously the bent valves! I'll be fitting that 60 thou head gasket I bought from you to drop the compression. It's 10.5 with a 40 thou gasket. I'd expect what? 10.0 with a 60 thou gasket?


John

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John,
.020 will change the compression about 1/2 point.
By the way this is Jim Comstock, not Jim Schmidt. I don't have any .060 head gaskets. Jim

Ah sorry, wrong Jim.


Thanks anyway.

john

I have used a PW 3 cam for many years for racing. I set them up pretty much as described by lynznsu. For racing I set the pressure over the nose at around 220 lb (100 kg) but this is for racing and it will rev to over 8000 without any valve bounce. You will not get a standard spring to go this high before coil bind. Coil bind on the standard springs I have measured is at about 190 to 200 lb. 86 to 91 kg.

I use special springs from Mick Hemming for racing (they coil bind at about 250 lb) but actually I think the standard springs should work OK for normal street use and the 6800 rpm red line. You really dont want to use more pressure than you have to. It just wears out the valve train.

But the main comment I have is why do you think your valves are bent from colliding with each other ? Do you see signs of damage on the valve head ? If you get valve bounce you will hear it.

Where is the valve bent? Why isnt it stuck in the valve guide if it is bent? They must be bent just at the head not to be sticking in the guides - correct? If the guy who built the motor made mistakes with installing the guides then how do you know the valves were OK to begin with?

Unless you are really reving the engine way past the red line I would be surprised if the valves had actually hit each other. - unless the springs are really shot!

John
With regards to your Axtel cam being with the grinder for over 12 months. You have clearly taken it to the big cat. Do yourself a favour and collect it now before they bugger it. When the old tiger was there things were done promptly and correctly but since he has retired, more motorcycle cams have been buggered than have worked.
I borrowed a cam (Ariel Art Senior grind) to have copied, which they guaranteed would take less than a month. After 12 months of copping crap from the owner of the cam, who wanted it returned yesterday, and numerous phone calls from me to the grinder, I finally received my cam and the original back from the big cat. There were visual differences between cams and when I measured lifts the 2 cams of course were not even remotely similar. After getting no where as far as customer service was concerned I gave up and had to return the other cam to the owner any way. From there it just got worse. The cam performed poorly and when I removed it to replace it with another cam I was shocked by the wear. The cat did admit that the cam had not been properly hardened, but I am still waiting for my money back.
And I am not Robinson Crusoe. A friend set about restoring a New Hudson that was missing the camshaft. There are only 3 known bikes the same in oz and my friend was lucky enough to have an owner strip his engine to provide the cam for copying. Only the cat took 18 months to complete the job which again has not been hardened properly. I do not know anyone who has had satisfactory motorcycle cam work done there since the young tiger took over.
Recently I have had good service and first class work from Franklin Cams in New Zealand http://www.camshafts.co.nz/ . They have stellite welded several worn cams and reground for me to a sample cam and returned the cams within 3 weeks. When I checked lift every 5 degrees I found no more than .001” difference between the original and the reground cam.
Alternately try one of the US grinders and I am sure there should be recommendations on who to try but get your cam back now before it is too late.
Ando

ando said:

John
With regards to your Axtel cam being with the grinder for over 12 months. You have clearly taken it to the big cat. Do yourself a favour and collect it now before they bugger it.
Ando

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Who's the big cat?


I sent the cam back to the guy who made it in the UK. he does good work, but takes on too much and is slow. I'll give him a call right now .

When Noah was a Boy , And Norvil was Norvil - they used W&S spring sets .Norvil / Thruxton Race Shop that is .

W&S were JoMoCo developed Triumph Springs from LSR days . The yamawhore TX 750 / 550 set gets you two sets , with all the gubbins .

deleted by poster

deleted by poster

John
as you live in Brisbane I thought you were referring to a well known Brisbane cam grinder who built up an excellent reputation for good work, and has numerous cam profiles. Unfortunately the founder has retired, the son does not appear to be up to the task, and has no interest in motorcycles. PM sent.
Ando

ando said:

John
as you live in Brisbane I thought you were referring to a well known Brisbane cam grinder who built up an excellent reputation for good work, and has numerous cam profiles. Unfortunately the founder has retired, the son does not appear to be up to the task, and has no interest in motorcycles. PM sent.
Ando

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PM received and reply sent.