Valve timing issues 750 GT

motoddrob said:
I'd be more concerned with loctiting the flange to cam.
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Most probably quite contra-productive Rob!

The flange/chainwheel connection relies to 99+% on friction between the (hopefully!) dead flat surfaces. The key (in this case at least) counts for next to nothing when it comes to transmitting rotational forces while the studs provide clamping pressure alone, these shouldn't really be under shearing pressure at all. The flange/chainwheel connection should be assembled dry.

It is vital that the nuts are tight and cannot "give" in any way. The original star washers used by the factory usually crumble upon disassembly (meaning they've been hanging on by the skin of their teeth) and the nuts are almost always badly deformed by the washers. Any adhesive between flange and wheel may move/soften/crack under certain circumstances and is definitely a no-no.

Refacing the flanges and wheel on a flat surface with #320 emery is always a good idea seeing the amount of gouging and denting on these parts I often come across. Distortion and burrs are also quite common. A good test for the surface condition is to apply a drop of thin oil like WD40 and press the parts together, they should adhere to the point that the flange can hold the chainwheel indefinitely when lifted perpendicularly to the flat surfaces.

Loctiting the nuts is another no-no, a royal pita for future disassembly. I have vowed to take the angle grinder to the next set I come across thus "secured"!:mad: Checking the studs have not been stretched, new nuts and Schnoor washers are seemingly the most reliable of fixings.

piet
 
Is there any common place to use Loctite? I very rarely do, but its usualy the green stuff, not the red. Big fan of Nilocs, but they're not helpful if heat is about. I haven't used any of those metal nuts with that slight distortion clamping inbuilt. The only thing I have found loose lately was a couple of fairing bolts. I haven't lost anything ever really, Exhaust nuts for a while used to loosen but not for ades.
 
Vince said:
Is there any common place to use Loctite? I very rarely do, but its usualy the green stuff, not the red. Big fan of Nilocs, but they're not helpful if heat is about. I haven't used any of those metal nuts with that slight distortion clamping inbuilt. The only thing I have found loose lately was a couple of fairing bolts. I haven't lost anything ever really, Exhaust nuts for a while used to loosen but not for ades.
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Loctite bits that fall off and that left hand crank nut on our big Laverda.
Paul
 
Piet, I was referring to the fit of the flange onto the cam end as that seems to be the problem when both cams move independently of each other.
once happened to my old SF2 back in the 70s.
 
That is exactly what Piet is referring to Rob. Gijs van D sells flanges with pinch bolts, I used some on a set of cams with the flange shafts distorted. Laverdaparadies sell (sold?) flanges with different internal diameters.
 
OK Lee, re reading Piets post the first line is in reference to my thoughts.
Next line he mentioned chain wheel.
I just put the 2 together.
Like the idea of the pinch bolt
Been awhile since Ive had a 750 apart
Will be revisiting that at some stage when my 270 crank turns up.
 
Tippie said:
That is exactly what Piet is referring to Rob. Gijs van D sells flanges with pinch bolts, I used some on a set of cams with the flange shafts distorted. Laverdaparadies sell (sold?) flanges with different internal diameters.
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Phil Todd wrote about applying nickel to keep the flanges tight.
Paul
 
Paul Marx said:
Phil Todd wrote about applying nickel to keep the flanges tight.
Paul
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Electro-plating is a tried and tested method of taking up excessive clearances in an interferance fit. Nickel, copper, chrome, what have you, as long as it doesn't seperate from the base when pressing the components together it works fine. Problem is mainly attaining the correct thickness without needing additional machining (depending on application), reckon an experienced plater can come up with that easily.

Gijs' pinch-bolt flanges work nicely!

piet
 
motoddrob said:
Will be revisiting that at some stage when my 270 crank turns up.
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pressure is on now Rob, be next month for your 270 degree crank, have two more engines to finish first that I am doing right now
can install flanges on the 5C cams as well if you wish with right side offset drilled by 45 degrees to match the crank
we machine our flanges so they are a true press fit, will never move
 
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