Centre of flywheels and lateral centre of weight for a twin engine.

[Monkeypants]

Yes< I've seen the youtube video, in fact it sold me on these TE kits. That's where the design of these latest top ends of Terry's comes from- Steve Hamel and Terry's collaboration with their two Bonneville bikes and all that Terry has learned over the years. Steve started with Terry Prince heads and opened them up more, changed combustion chamber shape etc. He got even more power from them so Terry incorporated Steve's results in this latest batch of Top ends . The only thing is Steve's bike is 998CC whereas the Kits are anywhere from 1200 to 1350 depending on the crank chosen.

I don't think many people are fully aware of what Terry Prince has been up to. Having met him , I can tell you he is not much on self promotion.

Steve's bike is 100+ RWHP from 998cc. Terry's sidecar rig is 140 RWHP from 1350 CC.

 

[roy the mechanic]

as Brian Chapman said to me a while ago-"be careful, one day you may be famous!" Regards, Roy.

 

[Monkeypants]

It will be interesting to see how it performs. The Godet 1330s are in are in a comparatively mild state of tune but still go very well by all accounts.

Right now tho, I'm still in the "prebasketcase" stage with this project. Hopefully in a year or two.....

 

[Howard]

Howard, I think the swing arm needs to be centred for the rear shocks to sit true. I could be wrong, but as long as the swinging arm is rigid enough, I don't see why. There's a 500 Kawasaki about with cantilever suspension, and ony shocker that fits alongside the engine, and that seems ok.

One other slight complication is the down tubes on the Egli Frame. They also attach to the engine and come off the frame at top. These would also need to be made extra wide and spacers used to allow for different engine postions. Yes, but if it's wider it should also be better at resisting the torsional stresses.

Hearing that Ken Horner's bike has the shifted engine has me thinking "just go ahead and build it that way, it will work just fine." I agree, if you know it works, copy it. I've never been one for re-inventing the wheel.

I've also been rethinking the rear suspension on the Egli and considering using an alternate method similar to a modern bike such as a Suzuki gsxr. In the end I nixxed this idea as it caused the rear wheel to move back and increase wheelbase by about 3"

Here is an interesting set of facts on the subject-

Rear travel on a swing arm Egli- 3.5- 4" depending on rear shock choice - Yes and it's bumpy as hell two up on British roads. I boosted mine to a huge 4" of travel, but the geometry somehow meant I had to run with the chain slacker than I wanted it, so I've put it back to standard. Egli geometry is built for racing, and it works well, if you're considering changing anything, consider the whole chassis, not just rear wheel travel in isolation, 7" of travel might cause havock with steering angles etc at the other end.
Rear travel on 04 GSXR 750 5.1"
Rear travel on 1949 Vincent Rapide 7"

Hmmmmmm

I had a bit more time to think, stuck in fog and traffic on the way home last night. All the talk of swinging arms instead of RFMs made me forget that the swinging arm is attached to the engine, not the frame, so you,d have to set the chain, then move the engine and s.a. to align the wheels. still possible, but a lot more thought and pesky spacers. Almost better to fix the back end with wider wheel options and move the steering head to suit .

I agree with the points raised about the tyre width, but there must be some reason race designers go for extra rubber, it could be argued that road bikes have wide tyres just for fashion/sales reasons.

I ride an Egli on the road with a Shadowish spec motor, and 130 back tyre. I also ride a Honda Fireblade with a 180 tyre, I don't have to adjust my riding style between them apart from being aware that even the excellent Laverda 2LS aren't in the same league as twin discs. But a few years ago I had a big Suzuki sports tourer with wide tyres, and changing from the Honda to the Suzi was like getting on a bike with 2 flat tyres, handling was iffy, and steering was sooooooooo slow. Big tyres are no good if the rest of the setup is wrong.

Interestingly, the most noticeable handling difference between the Egli and Honda is at very slow speeds. The Honda is much more stable. I originally put this down to the wide tyre, but a few months ago I read that in slow races (why on earth would anyone want to race slowly?) the better riders rev their engines more so that the engine gyrascopic action compensates for the lack of help from the slow turning wheels. So even that advantage might be down to the faster revving engine, not the wider tyres.

H

ps comments in red are so you can tell my comments from yours only - I've accidently offended people doing this in the past.

 

[TouringGodet]

Steve's bike is 100+ RWHP from 998cc. Terry's sidecar rig is 140 RWHP from 1350 CC.

Last I heard from Steve H., he is closer to 120 RWHP, 998cc on petrol, and thinks there is still more to be found with different cams. Terry has been running the sidecar on alcohol on the salt, but I don't know if the dyno figures quoted for him are with alcohol or petrol.

 

[Monkeypants]

thanks for all the input Howard, it is always good to bounce these ideas off other people with similar interests.

It is interesting to hear that the Egli doesn't ride all that well on rough roads.

Although this is very subjective, I find that my Rapides do ride quite well on rough roads, at least the rear suspension works great. The front end leaves a lot to be desired. The Norton Roadhandlers on both the Commando and the 650SS are much better at soaking up the bumps than the Vincent Girdraulics are.
But I think the back end on the Vincent does a better job at this than the back end of the Nortons do.
Neither of my rapides has anything special in there for suspension units either(Koni dampeners). With Thornton suspension I imagine they would be even better.

The thread has got me rethinking the rear suspension for this frame. I'm now inclined to build an RFM unit that copies the proven geometry of the Vincent RFM but will be made to suit the wide GSXR rim and disc brake setup plus use a modern monoshock unit.

This is what Ken Horner has done with his incredibly fast Irving-Vincents and also how Terry Prince builds frames now. It is interesting to note that Terry built a large number of the original Egli frames for Fritz Egli but has now gone away from the swingarm and back to an RFM with monoshock, much like a D vincent.

So the idea is to have;

-Front end off a 750 GSXR, 55 pounds complete with wheel, brake, fork bars and controls. This gives the bike great suspension , powerful double disc brakes and very light weight.

-Back end like an original Vincent but made to fit GSXR rear wheel and disc brake plus use a modern suspension unit

-1350CC engine with all of Terry's high performance parts and a five speed Surtees /Quaife gearbox that shifts nicely.


Here is a link to the Ken Horner bikes. Looks to me that he has used Japanese sport bike front ends and wheels on these bikes.

http://www.irvingvincent.com/bikes

 

[Pushrod Twin]

Have you considered the exhaust pipe clearance on right handers? Even a standard Vin with a determined rider can ground the pipes. You might have to rethink the exhaust layout as well as balance etc.

Note Timetravellers point here. And the other who suggested ground clearance issues with the clutch cover.
I built the Egli style replica you dont see clearly in my avatar. I humbly suggest you process could go like this;
Find the symmetrical centre line of the engine by sitting it sqaurely in a vee touching the widest points, clutch cover on left & g/box cover or whatever on right.
Mount engine under frame tube/ headstock assembly, with symetrical engine centre in line with headstock centre line.
Build swingarm with rear wheel centre matching front wheel centre line, shocks will line up with tubes above.
Adjust chain line by use of offset sprocket at front and/or same at back. Move sprocket carrier on wheel if needed. I moved a Water Bus sprocket a lot on the carrier.
If engine is not far enough to right, then move it that way, I suspect your symmetry will point you that way anyway, a la Horner Bros.
You will probably also end up with longer forks & shocks to raise engine for ground clearance.
If you use standard crankcases you are fixed to PCV's arrangement of swing arm pivot 1/2" above crank centreline, I wasnt because I fixed an AMC box behind cut cases, but I stuck with that anyway! Thats why Howard had issues with chain tension.
Remeber what Peter Williams said; "keep your foot pegs as narrow as possible"

 

[Pushrod Twin]

Gyro nonsense.

I think you'll find the reaction from the flywheels is in the wrong plane to cause a tankslapper (lots of chat about tankslapper causes on the forums).

At worst it will probably cause the bike to rock a la BMW Boxer, but since it's a turning moment, you'd need a large force at 9 mm radius to make a significant difference.

Why not make the frame/engine fittings wide enough so that you can move the engine off centre to suit various tyre widths including standard. A batch of spacers of varying thicknesses should allow quick adjustment, and if the offset causes problems you can simply go back to a standard wheel/tyre.

H

Howard & Tom, you are being mischeivious with this gyro nonsense! Refer to Tuning for Speed. I dont have my copy at hand to refer to, I'm working in the Middle East for the next few years so my Egli project is on hold again, but I recall PEI explained it well.
Monkeypants, just lighten your flywheels as much as you dare & take no notice of any wild stories of reduced top speed, they are bollocks! (if I may be allowed to use the expression?)
Those of us who have ridden Vee Twin Guzzii & sloppy R Series BMWs for 30 years lead factory attitudes and chewed every last gram off our flywheels for improved acceleration & engine braking. The principle applies to all engines, regardless of which way they point in the frame.
Roy.

 

[Monkeypants]

Pushrod twin said "Adjust chain line by use of offset sprocket at front "

I don't see much space for movement here, at least not to move the chain to the right in order to clear a big tire. The G50 plate is in the way.

 

[bmetcalf]

, it could be argued that road bikes have wide tyres just for fashion/sales reasons.

When I was in Bangkok in '95 or so, the big bikes were 250's with enormous rear tires, so I agree.