Any advantage with a bigger oil pump?

[1200ts]

I will soon be opening up the primary on a 3CL. Time for a new chain, tensioner and clutch rubbers. While I am in there, is there any advantage with upgrading to the later big oil pump? Been riding the bike for 25 years with out problems but am wondering is this a worthwhile upgrade or a waste of money?

 

[sfcpiet]

A larger oil pump is an advantage when the engine has to work under extreme conditions, racing, very high ambient temps, etc. The additional oil volume pumped through the engine aids cooling to a degree. For normal tootling around, the stock pump is usually well up to the job. But do check the pump housing and the gear teeth for wear/damage while you're in there.

piet

 

[3crider]

'If it ain't broke don't fix it'. Maybe check to see if the oil pump is still in spec or for any undue wear. Why replace the chain? Is it noisy? A new tensioner will need to be run in producing quite a bit of rubber FOD in the oil. I've never changed my tensioner in 165,000 miles and I think my clutch rubbers are original also.
If the bike is running well, don't mess with it.

 

[sfcpiet]

'If it ain't broke don't fix it'. Maybe check to see if the oil pump is still in spec or for any undue wear. Why replace the chain? Is it noisy? A new tensioner will need to be run in producing quite a bit of rubber FOD in the oil. I've never changed my tensioner in 165,000 miles and I think my clutch rubbers are original also.
If the bike is running well, don't mess with it.

Chain renewal intervals weren't issued by the factory just for shits and giggles, the primary chain leads a hard life and should be replaced at specific intervals, if only for peace of mind if its history is unknown. It doesn't necessarily have to be noisy to warrant replacement, when it does become noisy it will be very, very worn. I'm pretty sure you would change your view if you saw what havoc a snapped chain can produce. Analogue to the old saying "oil is cheaper than bearings", a chain is also a lot cheaper than a crankcase, or even the primary cover which will suffer badly in case of a chain failure. I've seen quite a few results of a chain that was "OK the last time I looked, she'll be right"... not a pretty sight.

If the chain is tensioned correctly, the tensioner blade will sacrifice none of its rubber lining. The tensioner can even last indefinitely if not abused. The same cannot be said of the clutch cush rubbers, at 165k miles they're long past their "best by" date.

Depends a bit on how you define "running well" I guess. I noticed many bikes at the Breganze meeting that I'd personally wouldn't trust further than to the next village. Routine maintenance isn't "messing" with the bike, at least as long as you know what you're doing.

piet

 

[Paul Marx]

I noticed many bikes at the Breganze meeting that I'd personally wouldn't trust further than to the next village. Routine maintenance isn't "messing" with the bike, at least as long as you know what you're doing.

piet

Many probably did come from the next village.
That's where the vans were parked.
Paul

 

[Dellortoman]

Chain renewal intervals weren't issued by the factory just for shits and giggles

I'm not necessarily disagreeing, just proposing an alternative approach ...

Andychain (who used to post here) seemed to be quite knowledgeable about chains. His rule of thumb about replacing chains was that if the chain stretch was less than 1% it was OK to remain in service. I've never seen anything like 1% stretch on a Laverda primary chain, although I've only worked on a few. Guys like Piet who work on these bike all the time have probably seen some way worse examples.

Some time ago I calculated the relationship between chain stretch and the deflection at mid-span for a Laverda primary drive. I've attached it below as a chart. The datum used (for 0% elongation) is the calculated length of chain pitch multiplied by the number of links. If your chain has more than about 20mm sag (when pressed mid-span), it's time to start thinking about replacement. If you want to be more conservative, that's your choice. Just remember that even a brand new chain may have something like 5 to 10 mm sag from the theoretical length because of the cumulative effect of the small clearance between the pins and bushes.

I don't remember the recommended km between chain replacements, but I'm not too bothered about it. Basing maintenance decisions on measurable physical properties seems more logical to me than an arbitrary odometer reading or a date on the calendar. The distance travelled method doesn't account for how hard the engine has worked. For a given distance travelled, there would be a big difference in chain wear between a bike that's been flogged on a race track and one that's just been used to tootle around town on. A specified km limit therefore has to err on the side of caution and assume the bike has had a hard life, which most bikes don't.

As an example, my brother's 3C has done over 100,000km and still has the original regina primary chain which only has a fraction of the 1% stretch limit.



PS: I acknowledge that some chains have been known to break before they reach the 1% elongation. But I suspect most of those would have had some kind of inherent fault. The problem with chains is the weakest link theory. A roller chain is made up from a lot of components. I can count 24 components for each link pair of a Laverda triplex primary chain. There are 38 pairs of links (76 pitches), so 912 individual parts in the entire chain. If only one of those parts has a defect or a has not been fitted together properly, the chain could fail. Unfortunately there's no way to tell if there's a hidden defect lurking in your bit of chain. Such things are generally only found during a post-mortem of a busted chain. So there's no chain replacement regime that can protect against that kind of spontaneous failure. It can be logically argued that a known used chain that's still within its wear limit is less of a risk than a brand new chain, because you can be pretty confident that the proven chain has no weak links. Whereas the new chain is unknown.

Fortunately the quality control of reputable brand chains is pretty good, and such failures are rare.

 

[iis_iis]

Go for the engineered materials and known characteristics, add in long term practical hands on workshop outcomes... Cam and Piet by example demonstrated.

Somewhat similar all the guff i endured about SS poppet valves in steel guides. Test jigged the stem in head mounted guide, ramped the temperature and measured the valve stem expansion versus the steel guide expansion rates, at cold to about 200C ( best temp range i could manage with home workshop ).

Outcome was the diametrical clearance was ok for cold crank and ok at elevated temperature end, what the problem was the difference in expansion rates meant the diametrical closed to tight as the valve stem and guide transitioned to upper temperature. Was straight forward to then calculate the working diametrical for safe working SS valve to steel guide.... never seized a valve after that. Not quite on topic though pump wear and expansion may be part of the best operation of the pump body... maybe. j

 

[3crider]

Responding to Piet's comments. I will of course, always defer to the greater knowledge to those who work on these machines day in day out. I'm sure he sees some awfully abused basket cases!
However, for my 3C I tend to listen for any changes etc. I checked the valve clearances last winter, they were within 0.02mm of nominal and had been like that since Keith Nairn did my top end some 25,000 miles (40,000kms) ago. So I wont look again for another 10,000 or unless something changes. The same goes for my primary and cam chains, nothing has changed, it sounds the same as it did when first fitted.
I'm not in favour of always taking the thing apart just to check, I'm in favour of leaving a system alone until such time something changes.
Nick

 

[sfcpiet]

Nick,

Not everyone has the luxury of a freshly, expertly overhauled engine/cylinder head. That your valve clearances have not changed comes as no surprise to me, the modern materials that Keith, Red, I and others use offer far more reliability and longevity than the originals ever could.

There are more old beaters of dubious provenance out there than well-overhauled specimens with precise recent history, advising to leave everything well alone is a rather dangerous move imho. FYI, Laverda specified primary chain replacement at 25000km intervals, for the much-lauded thick-pin Regina chain of the time, at that! Of course wear and tear will vary across a wide spectrum, the wannabe boy-racer will manage to trash his bike far earlier than the sedate tourer. At an educated guess, the stated 25000km would be well on the safe side, but personally I wouldn't run a primary chain for much more than 35000-40000km (unless the bike is pampered of course, reckon a triplex primary can easily last up to 100000km if the bike is cared for and isn't pushed hard). At this stage, the primary chains become quite audible, irrespective of manufacturer, further use would only cause unnecessary wear on the sprockets on which the chain runs, making life harder for the next replacement chain. I replace my own timing chains at around 60000km, don't really feel the need to experience valve salad. The factory never specified replacement intervals for that, maybe they weren't expecting the bikes to last that long?

Out of interest, I have cut several old, tired primary chains apart to inspect actual wear. At around 30000km, distinct wear can be found at each and every pin/sideplate, it doesn't get any better with age. The surest indicator for wear is how far the chain can be "bent" when laid flat. This is a bit misleading in regard to the primary chain being endless, but the difference between a new and old chain can be startling. With the degreased chain laid flat, just pushing and pulling on the links of an old chain will reveal distinct movement between the links, a new chain, also degreased, will show next to no movement.

I'm also convinced that chain technology has progressed a bit since the original Regina chains were fitted. I have yet to see a sheared off pin, but lots of sideplates that have been ripped apart at the pin bore. This is most probably the reason that pins are a lot thinner these days, affording the sideplates the much needed increase in cross-section. This still doesn't make modern chains immune to wear.

piet