ESE's works engine tuner

[husaberg]

Would need to be matched with the chocolate valves in your GN

The origional honda Vf750 f and s had chocolate cams if that helps.

[Kickaha]

Would need to be matched with the chocolate valves in your GN

It's only happened twice and no one will let me forget

Now how many choclate FXR cranks have you killed?

[bucketracer]

Chocolate Pistons



Gudgeon pin damage seen when a circlip has been left out or come right out.



For what its worth, my guess is that a tang has broken off a circlip possibly by hammering from the pin due to a bent rod.

See page 10 http://www.mlcmotorfactors.co.uk/Tro...s/PistonTT.pdf

The damage is caused by the tang rattling around like a jack hammer at the ends of the stroke. The damage is both sides as the tang can rattle its way back and forth through the hollow little end pin. And the damage is wider than the gudgeon because the piston is relieved on the sides. Debris rattling around like this typically leave the piston pin hole looking melted.

Links to PDF's on Piston Damage.
http://www.boosttown.com/engine/piston_damage.pdf
http://www.ms-motor-service.es/ximag..._leseprobe.pdf

OK so its 4-stroke and I had posted it in another thread but has been posted again here to keep a copy of all the ESE tec posts in one place.

[wobbly]

All that balance stuff on the Twostrokeshop site I did 3 years ago when starting the TSS500 project.
I was amazed when checking the RZ balance factors,and then found that someone at Yamaha also did it properly when designing the RD400, as it is set at 55% in both the drilled and leaded crank versions.
The stroker cranks I have for the RZ/LC all have Peek big ends,with Mallory balance weights,and I have the roller mains in stock.
The roller mains do have slightly more friction but will handle over twice the loading
,and last forever.
No one has tried Peek on the small ends as far as I know - but I have special silver plated small end bearings for the RZ/LC/Banshee.

[husaberg]

All that balance stuff on the Twostrokeshop site I did 3 years ago when starting the TSS500 project.
I was amazed when checking the RZ balance factors,and then found that someone at Yamaha also did it properly when designing the RD400, as it is set at 55% in both the drilled and leaded crank versions.
The stroker cranks I have for the RZ/LC all have Peek big ends,with Mallory balance weights,and I have the roller mains in stock.
The roller mains do have slightly more friction but will handle over twice the loading
,and last forever.
No one has tried Peek on the small ends as far as I know - but I have special silver plated small end bearings for the RZ/LC/Banshee.

In this Pic you can see Benelli for thier 250cc 4 stroke 4 cylinder came up with an interesting crankshaft design . It was a built up design with cadged roller bearing and revved to over 16000rpm.(Carruthers went on to work with Team KR much later) did OK on it. The crankcase design was pretty unique for the time with a cassette gearbox.
Have a look at the internal cut outs in the big picture of the crankshaft .Note the flywheels appear removable from the crankpin's cum-mainshafts.
With regards to the Yamaha based twins.
A couple of the 250 single based twins. That were built up to go against the over-bored 350 yams in the 60's and 70's. These engines were arranged not as 180 degree twins but as 360 degrees so they fired together. I guess it was to reduce the rocking vibrations as the crankshafts would have been very long.The Yankee for dirt,from two Ossas, the Farhon was 2 x Greeves Silverstone( Spondon later) and the DMW typhoon was two Starmaker's or Enfield GP5's all, I believe used 360 degree cranks.The Suzuki T500 titan/Cobra and the Suzuki big triples I understand had offset transfers which overlapped between the cylinders to decrease the width.The TSS500 had an option for 90 degrees but Wob's but i think said fuel robbing occured?.PS spell check is now working.Just need the punctuation pixie now.

[wobbly]

The 90* crank versions I built for the TSS500 was an embarrassing nightmare.
The crank force simulation shows 31% less rocking couple and way less forces on the mains.
The first one I tested was absolutely fine vibration wise,but in reality it had,by shear chance an unbalanced prototype flywheel on it.
The two pistons rising to TDC close together create a vertical shake that vibes the bars like hell.
This can be offset by creating an opposite force in the flywheel,as I tested this by clamping a hose clip onto the ignition,with the screw positioned 1/2 way opposite between the two pistons at TDC.
But this "fix" creates a huge rotating out of balance force on one end of the crank - and the RZ case has enough trouble maintaining main bearing crush on a balanced assembly, without pounding it to death running an out of balance flywheel.
The carbs and bars vibrate enough to froth the fuel without soft manifolds - so the idea was dropped ( on my head).

[speedpro]

That's something lots of people don't understand. The huge forces don't go away, they are opposed, sometimes within the crank assembly and sometimes by a seperate rotating assembly. BMW of course used a seperate reciprocating assembly. The crank assembly counters reciprocating forces in one direction only and when there isn't any reciprocating force to counteract, at 90 degrees, it actually introduces an unopposed force. If a seperate rotating assembly is used for counterbalance then all the forces act through the crankcases and they can be large. The actual forces on bearings caused by the production of power are insignificant compared to the forces created by the movement of the parts whether reciprocating of rotating.
Any 90 degree engine with an even number of cylinders is great for this problem as there is forces acting at 90 degrees which balance out just sweet.

[husaberg]

The two pistons rising to TDC close together create a vertical shake that vibes the bars like hell.
This can be offset by creating an opposite force in the flywheel,as I tested this by clamping a hose clip onto the ignition,with the screw positioned 1/2 way opposite between the two pistons at TDC.

Balance with The hose clip innovative. These three engines I used were went to be like jackhamers until they were timed to fire as a single I have no idea why they ran smoother firing as a single I will try and find the articles as to why but I guess they didn't know why either other than the rocking.I understand it makes no sense.
In a single couldn't a narrow single couldn't experiments be carried out for balance factors on the ignition rotor as wobbly did. I am picturing something light a stealthy flywheel weight bolted on might not work on a a inner rotor type.
Attached is the Irving article on a 76 degree firing parallel twin crankshaft.

below is a exert from flashback fabrications on a Aemacchi Single balance.

I was concerned about the balance factor, as I had just added about 100 grams to the crankpin, rod, and piston... I talked to Rudolf about this. He said balance factor for an Aermacchi is all just theory. He said put it together and just use it. He talked about someone in Germany who went to great trouble to make a very beautiful, modern-style "pork chop" flywheel for an Aermacchi. It was very light, and promised more power! In reality, it vibrated terribly, and they tried every balance factor from 15% to 40%, and nothing worked. Finally, they went back to the stock flywheel, and it was a great improvement. Rudolf also spent 900 Euros on getting one of his flywheels balanced, and it wasn't any better than before.

This stuff relates to balance factors differing according to the frame thay are in.I do note the Commando and the Atlas were very much the same engine but the Commando is rubber mounted in its std frame and on a 20 odd degree angle in its std frame.

Featherbed Commando balanced to 52%
Having finally got the 750cc Commando engined Featherbed vintage racer finished, I have the following observations to state. The Featherbed handling is far superior to the Commando, (even with a Norvil headsteady). The vibration level is nearly intolerable at 6500 - 7000 r.p.m. but the engine still has the Commando balance factor of 52%, not the 84%[?] of the Atlas. The 90 degree crankshaft seems even more inviting now; the best of both worlds
Featherbed Commando balanced to 77%
I have a 750cc Commando motor in a Wideline Featherbed frame. The motor was rebalanced at 77% prior to buildup. I am running the bike in its 2nd. season, and last week ran the revs up to 6800 r.p.m.. Yes, it was a bit buzzy, but not much more than a standard Triumph twin in the same rev band. You will never get it to run as smooth as an isolastic setup, but hey, its a rigid mount!. I am not at all displeased with the motor performance!
Featherbed Commando should be balanced to ca. 70%
Go for a 70% balance factor à la 650SS. This recommendation is from John Hudson of the NOC. The 52% balance factor will likely break everything on the bike if you leave it that way. The best thing would be to have the crank dynamically balanced for smooth running at the speed you want to use it most; this may vary from the 70% quoted. If you can't afford that, then balance it statically.

[wobbly]

Irving got the math wrong - the best layout for a vertical twin is firing at 90* as one piston is stopped and the other is at full noise,1/2 stroke.
Several late model engines are built like this, and they achieve "big bang" as well to increase off corner grip and better rider feel of the contact patch.
They vibe way less than any variation of 2 cylinders on the same plane.
The best is Bartols parallel twin in the KTM250GP,it has a balance shaft to kill all the vibes ,and reverses the crank rotation to reduce gyro precession forces as well.
I will try,one day, to spread the opposing out of balance force needed, right across a crank, just to see what happens.

[jasonu]

[QUOTE=wobbly;
Several late model engines are built like this, and they achieve "big bang" as well to increase off corner grip and better rider feel of the contact patch.
[/QUOTE]

I recall Mic Doohan saying big bang engine was no better than the regular engine except no one else had one and it sent them all in a spin trying to replicate it and therefore distracted them from the real goal.

[husaberg]

Irving got the math wrong - the best layout for a vertical twin is firing at 90* as one piston is stopped and the other is at full noise,1/2 stroke.
Several late model engines are built like this, and they achieve "big bang" as well to increase off corner grip and better rider feel of the contact patch.
They vibe way less than any variation of 2 cylinders on the same plane.
The best is Bartols parallel twin in the KTM250GP,it has a balance shaft to kill all the vibes ,and reverses the crank rotation to reduce gyro precession forces as well.
I will try,one day, to spread the opposing out of balance force needed, right across a crank, just to see what happens.

Not convinced he got it wrong. He just came up with a different solution.That's the beauty of balance discussions, they have two sides,
British race twins Nourish and SRM's and many others had 90/270 cranks 25 years or more before the Yams. Plus plenty of people have done the 76 crank with the same results too. Personally I prefer Ducatis solution with the Supermono the best.A bit hard to accommodate on a two stroke though.Added the BMW version too. With the 180 degree crank Val Page's 6/1Triumph had one prewar.
My favorite twin was Ian Cramps (from FB) twin crank overlapping 90 degree twin.Just throw in a jack-shaft for contra-rotation of the second cylinder. Plus reverse his rear cylinder cause his inlets were ugly.
PS has anyone seen the twin to 8 design with the hinged outer cylinders, balance that one.http://thekneeslider.com/archives/20...ore-v8-update/

Re Jasons comments above I think that was Doohan's Physcological mind trick. Like going back to the pre big bang engine when no one left in GP's then had the skills to ride them.The big bang was less about outright speed, more drive-ability leading to better lap times and not getting spat off and injured.
Quote Alan Cathcart:

"Developments of the 91 NSR 500 focused around Doohan testing a number of designs as HRC shifted their main push behind the new up and comer... For some while Doohan had been asking engineers to replicate the wide power band characteristic of the RVF750 4 stroke endurance bike, which he and Gardner had used to lead the previous summer's Suzuka 8 Hours... HRC answer was the 2 stroke equivalent of the the 4 stroke Big Bang... technically speaking all four cylinders fried within 70 degrees toafford the tire more time to hook up...""Consider and instant success by Gardner "Jesus, this is amazing" but Doohan was a doubter... the 92 NSR droning big bang had a very flat exhaust note which made it sound slow to riders... It was onlyduring HRC's final preseason phase that Doohan began to believe in the Big Bang... He found little difference in lap times but the close firing order was easier on tires and set up..."Rainey and company were in for the shock as the season kicked off...Utilizing the Big Bangs ability to find traction where others could not... Doohan ran away with the first four races... winning by anything up to 28 seconds wet or dry... The Big Bang proved such a giant leap forward that rival factories Cagiva, Suzuki, Yamaha rush to build copies... having learned the NRS's secret by playing track side audio recording against an oscilloscope..."
"There could be no doubt now... Honda now had the best 500 on the grid by quite some margin... the big bang NRS proved to be a winner in a variety of hands... Since the 80 when engine HP dramaticallyoutstripped tire and chassis performance... GP teams had been hiring tail sliding dirt trackers form America and Australia because no one else could wrestle these monsters into submission..."

Chocolate fish question of the day. Why do the single carb Honda twins sound different from the twin carb per models? EG CD175 vs CB175.Write answer on a $5 dollar note and send to ......

[gav]

It's only happened twice and no one will let me forget

Now how many choclate FXR cranks have you killed?

Yeah, twice in the last few years, huh? How often has the bike been out in that time?
Twice, maybe?

[diesel pig]

Chocolate fish question of the day. Why do the single carb Honda twins sound different from the twin carb per models? EG CD175 vs CB175.Write answer on a $5 dollar note and send to ......

I am not going to give you $5 has we both know you will just buy more chocolate fish with it and would just make me a enabler. The single carb twins have a 360 cranks and the dual carb twin are 180 degree cranks.

[wobbly]

Here is the 90* side of the story.Interesting.

http://www.xs650.org.au/smoothness.htm

[Grumph]

Irving got the math wrong - the best layout for a vertical twin is firing at 90* as one piston is stopped and the other is at full noise,1/2 stroke.
Several late model engines are built like this, and they achieve "big bang" as well to increase off corner grip and better rider feel of the contact patch.
They vibe way less than any variation of 2 cylinders on the same plane.
The best is Bartols parallel twin in the KTM250GP,it has a balance shaft to kill all the vibes ,and reverses the crank rotation to reduce gyro precession forces as well.
I will try,one day, to spread the opposing out of balance force needed, right across a crank, just to see what happens.

Irving got the math right - when you factor in rod length and angularity, 72 deg is pretty much where the piston reaches max velocity.
Spreading opposing forces - have a look at a Laverda 180 deg triple. Outers are "up" and balanced like a normal 360 deg twin - inner is "down" and has enough counterweight to put the crank into acceptable balance - it'll never be in static balance as a bare crank because the counterweighting allows for the second bigend weight.
Did a Benelli 650 a while back - std balance factor worked out at 83% - shook like a bastard. Changed to 70% and it's quite acceptable. Rigid mountings and angled cylinders....
Aermacchis - as I said 25 to 28% is the right range for a horizontal cylinder and as I've built all the ones currently racing in NZ to this...well QED.
The dutchman Kempen is known for never giving answers......
External balance - a lot of Yank V8's have flywheels which are not in themselves balanced but which counterbalance the crank as an assembly - a trap for the unwary trying to lighten flywheels...