jon v8 Posted October 16, 2013 Report Share Posted October 16, 2013 I currently have my 350 Ajay motor in bits for a full rebuild,tis in a bit of a state after doing a lot of hard work.I also plan to rebuild my HT motor as a short stroke 500 as soon as the Ajay is back running. I want both motors to run as well as possible,be reliable and long lasting.So as much care as possible will be taken in building them... So my question is,what balance factor is best to use,Don Moreley suggests using a factor of 60%, is this still the sensible number ? Both bikes will be used for road based trials,but I'm not worried about vibration at higher engine speeds on the road,I'm happy just to pootle along between groups of sections and enjoy a smooth and docile motor in the sections. My well used copy of "Tuning for speed" has been out again ! Link to comment Share on other sites More sharing options...
ask greeves Posted October 16, 2013 Report Share Posted October 16, 2013 Sounds like your a fastidious dude, Don Morely 60%....why not ask Sammy Miller...maybe he'll be 61% or even Kieth Duckworth. Why not include an external counter balance shaft, also some guys use methanol on trials 'old timers'...the father of a famous trials rider definitley uses alky in his HT5. Probably your going to use a Carrillo with a super tick Piston..so's the combined weight would probably be nowhere near stock so you will need a balance factor....do the maths...work it out yourself, unless you want to add some providence, or name hinting to the speel, when you sell either machine, lets hope there's a scrap of bygone trials heritage, left to saviour. Link to comment Share on other sites More sharing options...
dadof2 Posted October 18, 2013 Report Share Posted October 18, 2013 Not something I have ever concerned myself with. However a bloke who used to build speedway and grasstrack engines back in the days of JAP and Weslake use to have holes in the crank wheels into which he could insert lead, steel, aluminium or plastic stuffers to minimise vibration at different RPM Link to comment Share on other sites More sharing options...
jon v8 Posted October 19, 2013 Author Report Share Posted October 19, 2013 So it looks like I'm on my own with this,two things come to mind....Either people just build engines without bothering to check or its all a big secret.With my Ajay I cant do anything until I get the new piston and can weigh it anyway,but I can work out what it was built to before. For how little extra trouble it is I cant see the point in not setting it to at least somewhere between 60 and 70 % to avoid riding a bloody jackhammer.... (Esp when you consider how much trouble the rest of it takes to build an engine that does what you want it to do.) Link to comment Share on other sites More sharing options...
madmostin Posted October 20, 2013 Report Share Posted October 20, 2013 Irving's tuning for speed has suggested balance factors for the differing disciplines. Link to comment Share on other sites More sharing options...
axulsuv Posted October 20, 2013 Report Share Posted October 20, 2013 (edited) Jon; I've never balanced a single cylinder engine before , but have balanced many a multi cylinder race car engine to the grain ... Wouldn't a 50/50 balance be the best starting point ? Or does it work out better with the crank weights just a bit heavier ? Glenn Edited October 20, 2013 by axulsuv Link to comment Share on other sites More sharing options...
jon v8 Posted October 21, 2013 Author Report Share Posted October 21, 2013 I had a chat this afternoon with someone who has some real knowledge and practical experience on this subject... The upshot of it is,when I have the new piston and a decent undamaged pair of flywheels - I'm going to have the crank dynamically balanced. It will be interesting to see what it runs like,esp when the Lucas mag gets a full rebuild.If its anything like other old motors I've rebuilt and run,the more effort and care you put in,the better the result is. Link to comment Share on other sites More sharing options...
axulsuv Posted October 22, 2013 Report Share Posted October 22, 2013 "the more effort and care you put in,the better the result is" Isn't that the way our line of work generally goes ? Glenn Link to comment Share on other sites More sharing options...
jon v8 Posted October 23, 2013 Author Report Share Posted October 23, 2013 "the more effort and care you put in,the better the result is" Isn't that the way our line of work generally goes ? Glenn Yep,its just not often you get customers willing to have the job done properly now.... I had an Alvis speed 25 hillclimb car in today,I've nearly convinced the owner to fit a pair of wideband Oxygen sensors to run dual AFR gauges so we can tune it properly - Now that will be an interesting job. Link to comment Share on other sites More sharing options...
ask greeves Posted January 8, 2014 Report Share Posted January 8, 2014 In bygone days there used to be machines called 'Krypton Tune' people would say 'i'm going to have my car Krypton Tuned' This was the start of taking away the 'human feel' to the mundane, low power, gas guzlers of the day. If you can't use a timing light and haven't got 'the touch' to be able to twist a distributor or adjust a carburettor...I think your lost. Or maybe all you need is a kick up the aristotle and read up on basic engine technology, or why 'uneven' engines and dual plane engines (modern V8's) need a balance factor. So your going to fit a pair of wide band oxy sensors, I assume its a 6 cylinder engine, why not fit 6, monitor each cylinder, or maybe just fit one further down the exhaust...2 carbs maybe, dual afr gauges...so then you'll need some kind of data aquisition gizomo, to record over the full rev range, to make your adjustments, otherwise your just going to 'get it right' over a very small part of the spectrum. Sounds like an excellent way to spend somebody elses money. Link to comment Share on other sites More sharing options...
jon v8 Posted January 8, 2014 Author Report Share Posted January 8, 2014 In bygone days there used to be machines called 'Krypton Tune' people would say 'i'm going to have my car Krypton Tuned' This was the start of taking away the 'human feel' to the mundane, low power, gas guzlers of the day. If you can't use a timing light and haven't got 'the touch' to be able to twist a distributor or adjust a carburettor...I think your lost. Or maybe all you need is a kick up the aristotle and read up on basic engine technology, or why 'uneven' engines and dual plane engines (modern V8's) need a balance factor. So your going to fit a pair of wide band oxy sensors, I assume its a 6 cylinder engine, why not fit 6, monitor each cylinder, or maybe just fit one further down the exhaust...2 carbs maybe, dual afr gauges...so then you'll need some kind of data aquisition gizomo, to record over the full rev range, to make your adjustments, otherwise your just going to 'get it right' over a very small part of the spectrum. Sounds like an excellent way to spend somebody elses money. I ignored your first answer to my question as it came across as rude,and offered little or no practical help.Seeing as you feel the need to have another shot at me I have to ask is this something personal - have I marked out a section you couldnt clean,do you not like "youngsters" riding "proper" bikes ? Perhaps you could enlighten us ? But to answer a couple of your comments,no I wont be using a Carillo rod in my AJS,it all as standard as it can be - just the piston is a modern,slightly different type.Secondly,fitting the wideband sensors to the Alvis is a VERY good way to spend money.The owner is currently paying for 2 dyno sessions a year where he has to go by what the garage do in terms of tuning.The cost of the kit including sensors etc is less than the 2 dyno sessions.With them fitted he can then do live tuning or data logging after each sprint or hillclimb.And guess what the bloke who keeps beating him has fitted to his car ? I cant see what you have against using "modern technology" on old engines,the way we can literally see whats going on in live data,then go back over it is reaping huge benefits in power AND reliability.In drag racing for instance, tuners are getting way more power from the same engines than they were 30 years ago.Nothing has changed in the engines,just the way they are monitored and then tuned.The Alvis has benefitted greatly from the use of an oscilliscope to sort out its igntion system.Why would you not want to make an engine run more smoothly,reliably or make more power ? Do you think Hugh Viney would have shunned test equipment like we now have ? You cant be too against modern technology or you wouldnt be on this forum in the first place. Looking around my workshop this morning,its pretty full of customers bikes and a 4.4v8 Discovery 3.The oldest bike is a 1938 Triumph Tiger 70.So plenty to do.I do no advertising - at all,not even business cards. Have I lost it,do I need a boot up the back side ? Tell me,what am I missing ? Some sensible crank balancing tips would be a start. 2 Link to comment Share on other sites More sharing options...
b40rt Posted January 8, 2014 Report Share Posted January 8, 2014 This is shaping up to be the best fight since Bridget Jones's Diary - who is Clever and what's Darcy? Link to comment Share on other sites More sharing options...
laird387 Posted January 8, 2014 Report Share Posted January 8, 2014 Hi, Not wanting to add fuel to any fires let me at least give you some actual historical facts. Firstly I never worried about the balance factor in any of my own Ariels or AMC machinery - or any of the various one's that I restored - but I did concentrate on getting the ignition timing set 'just so' to my own parameters developed by experience. I'm sure some members might recall my 'party trick' with my Ariel HT5 - which I could actually start quite easily by hand. Valve lifter set 'to my spec.' (that was purely by feel - not very much science) - ignition set to just off retard, rock the motor round on the kickstart to just past BDC on the ignition stroke. Then with the valve lifter acting, start the motor swinging by hand on the kickstart and let the valve lifter go just at the right moment and 'chuff, chuff' away went the motor. But remember - I had learned the hard way with my favourite road bike being the Velocette Venom that I had restored, and they need 'the Velocette knack' to get them started. For a long while our personal transport after we had married was a big Panther sidecar outfit - and they need a decent swing on a cold morning. Life was very different in those days gone by and it is very hard for someone who has no personal experience of life before mobile 'phones, etc., to understand why we oldies seemed to do such strange things......... Incidentally one of Hugh Viney's little ways - and he really was the Maestro in so many aspects of our sport, was to have an extended lever on his ignition control. If you watched him coaxing grip on a slippery climb you would see he had the ignition lever placed on his handlebar so that the long lever sat in the 'vee' between his thumb and fingers on his left hand. He would coax the bike up the section using both hands as though they were on throttles, the twisting of his left hand giving him very fine control of the ignition. I never saw anybody else doing it and when I tried it was beyond my skill level! Whatever you do - enjoy it! Link to comment Share on other sites More sharing options...
jon v8 Posted January 8, 2014 Author Report Share Posted January 8, 2014 Deryk, I wonder what Hugh Viney would make of the modern tyres we have now,the IRC ones we use give amazing levels of grip,even with the 8 or 9 psi in the back of my AJS,grip is hardly ever problem.In fact I can often get it to grip where modern pogo sticks fail.Does any film exist of Mr Viney in action - it would certainly be good to see. I'm too young to remember anything before about 1973 in terms of trials,but I can well remember Martin Lampkin riding the Knut and getting his autograph on a piece of old paper fertiliser sack.He and two other riders then did a 100 odd yard wheelie up a muddy bank away from the section - an amazing sight to me and my mates ! As others have said,please keep posting your stories and pictures,this forum is more interesting now than it has ever been. 2 Link to comment Share on other sites More sharing options...
axulsuv Posted January 8, 2014 Report Share Posted January 8, 2014 As a "tuner" ,engine builder , Licensed emission technician with about 40 years of twisting wrench's under my belt , I wouldn't think of taking someones money for tuning their motor for peak performance without my 4 gas analyzer hooked up and sniffing ... What comes out the tailpipe tells a amazing story if you understand how to interpret what you see . Glenn Link to comment Share on other sites More sharing options...
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