At SMSP (Sydney) We have the Festival of Speed in February , the feature Race is Unchained Anything Goes , XR69s replicas , GSXR 200hp 1600 Irving Vincent 200hp , FZR1000 147hp , Last race very hot and humid , 7 laps ,Keo Watson on the FZR and Beau Beaton on the Irving , Strategy keep sticking it up the Irving it will Not like the Heat at 7 laps and it will Break , Entering T1 Keo sticks it under Beau at 260 kph , Beau returns the Favour up the hill out of T5 through T6 the Irving has incredible drive , T8 the Irving Breaks (around Lap 5 ) hence a DNF , the only mods to the FZR is YZF 750 Cams and a 6 speed G/box and it is Reliable , Keo wants to Ride the Irving ,He is sympathetic on the Machine , HP is one thing , having a Rider that can Corner is another , to Win 1st You have to Finish
Crank build for racing engine
- Thread starter chark_mandler
- Start date
With the classic racing, it is difficult to point any finger when describing if one is "Cheating " or not, as the rules vary from country to country. In Australia we can run "Any kind of drum brake so long as its drum diameter does not exceed 230 mm".......This would be seen as wrong in the UK or Usa......In reality it is a big "Limiter" in a way......I see it as a safety feature.......Given the bikes go much better than they did back in the day. Some items that seem incorrect, but totally over looked by many old school boys........I'm running a Keihin round slide racing carby.......most look at that as cheating because it is too modern this verses say an Amal TT or GP.......but in our rule books it is perfectly ok to use one, and it even mentions this carby to use.......Engine mods are pretty much open, so long as you cannot visually see it externally......I used to be a huge fan of the Irving Vincent's and still am to some degree.......But I would not like to compete against them......Despite what others might think, their bikes are really cheating at the highest level........If we all had a full CNC machine shop just think of the bikes we could create.......Ken and Barry are very smart guys who have built some amazing machines........but they show no interest in helping anyone or making anything Vincent related to help the Vincent world......It is for that very reason than a friend and I decided to make everything ourselves.......I have gone to some detail to explain what we have done, and will be happy to soon enough.......I just wanted some more actual run time to prove the engine some reliability and endurance......I know for a fact I am never going to be able to ride like Beau Beaton or Cam Donald.......But just building a big single that can hold its own against other Brit twins is more than enough fun for me.......The issue the Horners have is keeping a big HP engine cool.......When running certain fuels, there are types of micro detonation that sends shock waves through the connecting rods........these then ultimately fail.......I feel this might be part of their problem......It is one thing to carry out mods that could be seen as cheating.......I think it is just mankind trying to outdo each other anyway they can whilst getting away with it.........No one in the classic bike field really gives a toss these days.......the numbers of classic bikes racing is dropping off in big numbers all over the place.......Geoff Clatworthy's ES 4 Norton is anything but legal, but at over 60 RWHP and 107 kg's in weight with years of dedication to making a pushrod single quicker than a Manx.......his efforts are outstanding.......Its just a bit of fun.......madness but fun.
I wonder how many Vincent's are actively being raced around the world now.......can't be many.
on that note, having seen both authentic factory racing Pantah (TT1/F1, TT2) and beveldrive (NCR900) and modern era efi (851SP1/888SP4/955) Ducatis they all have the same browning on the top of the conrod; and I suspect its not brand related.
the 851SP1 and 955 with titanium conrods even had oil channels in the conrods to the small ends to minimalist friction and excessive heat build-up.
some useless information:
as all conrods no matter polished or forged or welded in combustion engines they are all exposed to the same: the heat produced form combustion. and the most modern pistons have the small ends very near the underside of the deck so more exposure.
given the heat exposed surface of the conrod I expect engines with long conrods to be more discoloured than short conrods as the conrods oscillate a larger angle and thus a larger exposed area; long conrods oscillate a smaller angle so the heat is concentrated to a smaller area.
before, engines had the crankshaft dictate where the small end is located in the piston and the gap between the piston bosses and the small end are large to accommodate the location of the conrod. that effectively meant, however small, the conrod centreline could be offset the piston centreline and impose a tilting force on the conrod, usually leading to the bigend/conrod running surface loaded on an edge rather than over a surface.
nowadays, with plain bearing bigends being the standard on almost any multicilinder combustion engine, the piston now dictates where the conrod will be: the conrod is much more confined to the inside of the gudgeon pin bosses, less than 1mm in fact, and the conrod is allowed to slide axially along the crankpin thus giving it a degree of freedom on the crankpin to find its position without the worry the crank may force it over to a side or rub shoulders with the conrod beside it. this is based on the last 1200 Panigale V2, and I suspect this design practice is common amongst many brands now.
coming back to greg's angle:
I think its not only the offsetting of centrelines piston/conrod, but also the longer conrods have the heat much more concentrated on the same area with the smaller oscillating angle it makes. a bit like aiming a flame torch on one spot of the conrod versus moving the torch sideways.
Vincent pistons have the gudgeon pin say halfway the piston, whereas the Royal Enfield piston has the gudgeon pin approx ¼ total piston height from the bottom.
and the running clearance between the gudgeon pin and small end and piston bosses is a balance between being free enough to get any oil mist between for cooling but confined enough to avoid hammering and gripping, over a range of temperatures but notably in the running temp range.
had a mate's Husqvarna SMS630 in the garage once for an overhaul, have titanium valves and very soft springs, and never ever do any lapping of titanium valves it said in the manual, because you will grind off the coating (mentioned earlier before?) and expensive shit happens very soon after running the engine. used dummy valves to lap off sharp edges after dressing the seats, clean properly and put in the titanium valves. engine still running 5 years later and close to 80.000kms now.
titanium is nice stuff to use for components subject to oscillations to get the reciprocating masses down.
using aluminium brons for valve guides is in my book a definite no-go! phosphor bronze and lead bronze and cast iron is fine, but no way aluminium bronze! have seen many valve guides being pulled out of heads and top-end components seriously deformed/destroyed due the guides sticking on the valves and things getting squashed into places they shouldn't go. also had a trial with alubronze plain bearings for 50mm mainline diameters, went fine as long as the revs did not exceed 3500rpm. its tough material with high load carrying capacity, but not high surface speed friendly and particle bedding friendly as the other PbBronze and PhosBronze. used them for Brons / Waukesha gas engines in the camshaft bearing caps not a problem in the world, then again these engines don't go above 1500rpm (750rpm camshaft speed) and the mechanical injectors and heavy springs and valve train components could wear out these cams and bearings. but 4000rpm on 50mm dia mains, yep that locked the engine on the dyno with an oil pump capacity (pressure and volume) on par with a tuned Ducati 1198S Corse race spec (200bhp and approx 160Nm torque at the wheel).
Yes the titanium valves are fine until you machine them.......however, its not disastrous so long as you catch it and do something about it as we have done.......When you modify them and clean up the surface of the stem it looks perfect so you are hopeful that nothing will happen......but it appears to be very abrasive not only the stems but the seat faces as well.......Some would ask.......why bother......well its all about reducing the reciprocating mass so you don't have to run massive valve springs which then can become destructive.......These valves came from NASCAR engines running near 10,000 rpm all day long with massive springs........so us running them to say 7000 max with less springs should be fine.......so why the big spring pressures........Roller cams.......it is these and modern spring technology that has allowed a V8 to put out 3 times the power it use to.......With a follower ratio of 1.2 and rocker ratio of 1.25 0.400" lift at the cam gives 0.600" at the valve........This amount of lift and holding it there much longer than a flat tappet cam is what gives you more power........and also reducing the massive duration normally used on high performance engines.......the sooner you close that inlet valve, then the compression builds much better.......big duration cams cause the inlet to close very late......Some about 70 or even 60 degrees before TDC.......this is why their power band is up high in the rev range.........We want massive torque out of the corners........Testing so far has given us just that......After more run time it will be interesting to see what the pin looks like........Often difficult to fully center the rods on a twin.......if the bore mouths are not right or the spacer between the rods is the same........They were never designed as a performance engine.......just a big lazy twin to ride for miles.
Hi there David, Does that crank have one piece flywheels and main shafts......?.......I'm guessing they must drill the holes larger to compensate for the heavier Carrillo Rod........Cheers.......Greg.
ive also got M&S flywheels and mainshafs pre-fit.
they're without mills pins as the they use much higher interference fit. JAWA has this too, now, with their latest 500cc pushing out 65-95hp at 13000rpm and no key or pin whatever holding the shafts in the flywheels!
the M&S wheels have the top holes drilled out already for Carrillo rods.
they're without mills pins as the they use much higher interference fit. JAWA has this too, now, with their latest 500cc pushing out 65-95hp at 13000rpm and no key or pin whatever holding the shafts in the flywheels!
the M&S wheels have the top holes drilled out already for Carrillo rods.
Wow, those flywheels are beautiful!
I've built up several cranks using Maughan's new wheel/shaft assemblies, plus their big ends to match.......generally with stock Vincent rods......We luckily have ARGO rods here in Australia that are the same beam shape and similar weights to the Vincent rods.......The Maughan products are magnificent to put together, and they true up very well........old flywheels that have badly worn or spun shafts I don't even bother with anymore.....not worth trying to reclaim them, and too risky as well if something goes wrong......Its more a "Cost effective thing" rather than me simply giving up on repairing the old ones.........Not unlike old wheel hubs or cylinder barrels.......If the bearing sockets are worn or if the barrel specs are too far out, I just scrap them........If you consider the time and effort to strip a wheel right down or an engine to the bare crank......you have to seriously think of this unless you are happy to do it all again........ The thing I like about dealing with Maughan's is they always ask questions about the sizing of rod big end bores and so on.....Many times they have supplied me with slightly over and sometimes way over sized rod liners to correct rods that are oval.......this is very common at least 50 % of rods the bore is not round.......This should be honed back to being round first and then measured to get the correct size of liner and interference fit........Both Steve and his son Lee are very helpful here.......Great guys to deal with........Cheers.