New Cams New Thread

So having my cam chain break, I thought I'd consolidate my work process in the right forum section.

Disclaimer: I will not be "telling all" about the Neville Special, suffice it to say it's bigger and longer. You want one, call Neville.

Here the cams I have on hand, from left to right:
Stock Intake, Neville Special, Megacycle Intake, Stock Exhaust, Megacycle Exhaust.



More to follow as I go.

Here's the first interesting find, 2006 chain on left, 2014 chain on right... see the difference?



Never mind, same number of plates on each chain, but, look where it broke. Right at the thinnest point of the cutback on the new chain. Certainly suggests the old one is stronger.




Possible advisory for big cam Roadsters?

Another find, I'm not sure what to make of yet. The left two are exhaust side, right two are intake side. The bolt holes are lined up, as you can see they are not only different length, but different contours, and the older ones have a whole lot more metal in them, quite a bit heavier. The new intake side one is pretty much all plastic. @Neville Lush @warp9.9 @R-III-R Turbo for any insight here, not an area I've ever paid attention to. Cam chain guides:

EDIT: Art Answered the question about the guides in the how to fit a Carpenter 240 kit thread. Guess I will, after all be needing new chain guides.



My interpretation is, the deep thin scoring visible is evidence the outer weaker plate was the first to snap and it lived long enough with an outer plate broken to score the guide.

While searching around the net for cam chains with these type of side plates, the one that broke, I started noticing a trend. That trend is China! I see cut down out plates on a lot of China made chains but none on OEM 4 cylinder liter bikes or hayabusas.

Being curious I hopped into ebay, a great source for part images, and found this, from a 2011 Roadster. I bought it to I can inspect it, was cheap, why not.


Same as the broken one.

At this point, I would advise all 240/265 kit bikes to, at a minimum pull the crank inspection plate and see which chain you have. I don't think it's an issue for stock bikes in any way, and may not be for built engines, but trends start somewhere and I seem to be #1.

Compression related numbers:
Bore - 101.6mm
Stroke - 94.3mm
Chamber Volume - 75cc
Gasket Diameter - 102.22mm
CP 11:1 Piston Dome Volume - 6.3cc
Gasket Thickness Crushed - 0.41mm
Cylinder Volume - 764.82
Gasket Volume - 3.364cc
Swept Volume - 836.88cc
Compressed Volume - 72.064cc
Comp Ratio - 11.61 Static CR

Valve Train Measurements (stock):
Intake Valve Length - 96mm
Exhaust Valve Length - 96.3mm
Valve Tip Distance - 4.575mm
Retainer Height - 6.85mm
Retainer Outer Diameter - 22.9mm
Retainer Inside Diameter - 7.4mm
Bottom of retainer to spring seat - 5.35mm
Bottom of retainer to bottom of keeper distance - 0mm
Spring Seat Diameter - 16.95mm
Top of Retainer to spring seat - 1.5mm
Spring ID - 17.5mm
Spring OD - 24.3mm
End of valve to retainer top - 2.4mm
Valve tip to Keeper top - 3.75mm
Keeper groove diameter - 1.75mm
Lower spring seat thickness - 1mm
Stock Tappet thickness (no shim) - 4mm
Stock assembled intake height without shim - 43mm
Stock assbled exhaust height without shim - 43.3mm
Intake Valve tip height from head - 39mm
Exhaust Valve tip height from head - 39.3mm
Carpenter retainer height - 13.3mm
Carpenter retainer spring perch diameter - 17.65mm
Carpenter Spring ID - 17.72mm
Carpenter Spring OD - 24.99mm
Carpenter retainer spring seat height from bottom of retainer - 6.5mm
31mm Tappet thickness - 3mm
28mm Tappet thickness - 2.5mm
Retainer top to valve top - 3.4mm
Bottom of retainer to bottom of keeper - 0.65mm
Stock installed height - 34.1mm
Carpenter installed height - 35.6mm
Titanium Intake valve - 97mm
Titanium Intake Valve height over head - 40mm

ARP Head Bolts Need 2 Packs
https://www.summitracing.com/parts/arp-675-1011?utm_source=bing&utm_medium=cpc&utm_term=+arp++675-1011&utm_content=ARP&utm_campaign=Part+Number+Ad+Groups
Rocket suitable valve test springs, 1lb rate:
https://www.lowes.com/pd/Hillman-Zinc-Gate-Spring/3115915
Cam gear bolts, m6x1x12, need 4:
BF6X12YLW - Flange Bolt 10.9 Yellow Zinc [BF6X12YLW] - $0.31 : Bel-Metric, Metric Hardware, Metric Fasteners, Metric Bolts, Metric Nuts & Time-Sert Thread Repair
Cam Ladder bolts to replace garbage triumph torx, m6x1x40, need 16:
BF6X40FCLZ - Flange Bolt 10.9 Zinc [BF6X40FCLZ] - $0.44 : Bel-Metric, Metric Hardware, Metric Fasteners, Metric Bolts, Metric Nuts & Time-Sert Thread Repair
Threaded Rod to mount degree wheel to crank snout:
https://www.amazon.com/gp/aw/d/B07H7P3HQW?psc=1&ref=ppx_pop_mob_b_asin_title
M8 nuts to hold crank 24mm nut in place and secure degree wheel while timing cams, need 3:
NNF8CLZ - Nylock Flange Nut Zinc [NNF8CLZ] - $0.29 : Bel-Metric, Metric Hardware, Metric Fasteners, Metric Bolts, Metric Nuts & Time-Sert Thread Repair
7" degree wheel, makes clearing clutch and oil filter easier:
Mr Gasket 1570: 7" Diameter Degree Wheel | JEGS

Easier to consume worksheet:


I am aware the stock clearances are different tolerances.

Based on this I'll be doing 5,000 mile valve clearance checks until they settle down from here on.

Here's the current blueprinting worksheet for the head, have some more measurements to get (some typos).


Stock Valve tip height: 39mm from seat (without 1mm spring seat)
Carpenter Ti Valve tip height: 40mm from seat (without 1mm spring seat)

Claviger said:

Disclaimer: I will not be "telling all" about the Neville Special. You want one, call Neville.

Click to expand...

No I expect forthrightness - Yes! have been drinking.

Are the chains made with the same material? bigger and beefier does not always mean stronger.

Absolutely true!! There's no way for me to know the metallurgy, I'm going with the bigger is better in this case.

As we know, Triumph gradually outsources to different vendors over the years, as is the business way. I would, and am, betting the older chain is closer to the engineers intent than the new one.

I see 9 plates per inner/outer segments in the 2006 chain with full cut plates. I see 7 plates per inner/outer segments in the 2014 chain with plates cut in the center. I would want a 2006 chain only.

Rob what do you think caused the chain to break ? Was the tensioner to tight or damaged ?

Nope, not that I'm aware of, I always back off the tension once finger tight a little since loose is better than tight to give it a tiny bit of play.

Initial guess? Angry engine and manufacturing defect or the new design didn't get along well.

I would offer, it's no coincidence I was on the Dyno for 3 hours the day prior to the break, but it was only a matter of time, either on the Dyno, on the street, or on the salt it was inevitable I think.

When adjusting the manual tensioner does the engine have to be turned over to a certain spot to find the loose/tight spot ?