[Mustang (OP)]

I know of a couple of steamers that have busted their frames right where the outriggers come down from the backbone ............... :shock:

[coachgeo]

I know of a couple of steamers that have busted their frames right where the outriggers come down from the backbone :shock:

Thanks Mustang.

Outrigger?  are you refering to the larger tube or the smaller one that triangulates the larger one?

Do you know how they busted these?  Lay downs hard or soft?  How often, Metal or weld fatigue orrr?

[Nick Calne]

Think round the problem another way, you could look at it like this....

 A steamer with a diesel engine weighs at least 250kgs and probably more with fuel. A  small cradle frame to support the engine in steel will weigh say 5kgs. That's not much in the scheme of things.

You could design the cradle to provide crash protection and support the exhaust system.  You could also design the cradle to be able to be lifted into place with the engine in it, making fitting the engine a little easier.  I'm guessing that on a conversion job like this the engine is probably going to be in, then out, then in, then out etc and making this process easier might be a real help...

Having a cradle frame also allows you to jack up the bike easily - like you do with a motorcross bike.  

...and it will give you a chance resolve the vibration / torsion / bending issues that you will otherwise be transmitting through an engine (and it's fixings) that may or may not be designed to cope with it.

Perhaps.  Or something.

[Mustang (OP)]

you really need to get a frame at home so you can look closly at it .
they aint made that strong or with very thick steel either . the outriggers are the flat steel pcs. coming down from the horizontal steel tube that is at the bottom of the backbone tube .
the steamer motor is probably the strongest part of the equation in the frame strength.

also have seen/heard of frames breaking where the struts come down for the front cylinder head mounts. sidecar stress was the reason for the struts breaking , heavily loaded two up was the outrigger failures

have also seen/heard of subframes busting just below the seats towards the rear of subframe .just from rough roads and two up riders

you are gonna need trial and error as your friends . just build the damn thing and see what happens ...........just saying

[coachgeo]

...you could look at it like this....

 A steamer with a diesel engine weighs at least 250kgs and probably more with fuel. A  small cradle frame to support the engine in steel will weigh say 5kgs. That's not much in the scheme of things.

You could design the cradle to provide crash protection and support the exhaust system.  You could also design the cradle to be able to be lifted into place with the engine in it, making fitting the engine a little easier.  I'm guessing that on a conversion job like this the engine is probably going to be in, then out, then in, then out etc and making this process easier might be a real help...

Having a cradle frame also allows you to jack up the bike easily - like you do with a motorcross bike.  

...and it will give you a chance resolve the vibration / torsion / bending issues that you will otherwise be transmitting through an engine (and it's fixings) that may or may not be designed to cope with it....

We are on the same wavelength here.  Adding a removable cradle pretty much as you suggest was my first thought and for the reasons you outline.  The added weight concerned me thus my questions about using modified (isolated) OEM  like mountings

[2004Tiger]

I know of a couple of steamers that have busted their frames right where the outriggers come down from the backbone ............... :shock:

My faith in the Tiger design team was misplaced. Everyone keep their welders handy.

[JetdocX]

I'm with Nick.  Pick up the engine mount positions with a stressed "frame/engine cradle" and then shock mount your engine.

[2004Tiger]

... A steamer with a diesel engine weighs at least 250kgs and probably more with fuel. A  small cradle frame to support the engine in steel will weigh say 5 kgs. That's not much in the scheme of things...etc...

Yes, I like this approach. Such a cradle would be very useful, especially if it was rigid enough to replace the structural element provided by the original stressed engine. The diesel engine could be supported within the cradle by vibration isolators. Of course any engine other than the original will have such a difference in configuration that it could not serve as a stressed member without some cobbed up struts and fasteners. Better to build a rigid cradle to support both the frame and the engine. Or, you could fabricate a structural tube, about the same diameter as the backbone, to be welded in place. This tube could start at the steering head and end at the rear swingarm pivot, and encircle the new engine. Weld your motor mounts to the low section of the tube. Such a tube could be made rigid enough to provide a lot of support for the backbone.

Coachgeo, since you asked, my degree is in mechanical engineering with emphasis on machine design and stress analysis. Could I design a MC frame? No. I am not familiar with the modern methods of computer finite element analysis, and MC frames have evolved into very complicated shapes.

[oxnsox]

Coach...  Don't know if this helps, or if you have seen something similar already... Recently read an article on the TRACK Diesel bike   http://www.dieselmotorcycles.eu/ in a UK magazine (MSL September issue).
The article had a few good pix that showed some frame detail for their installation... which incidentally was a Triple...

[2004Tiger]

... TRACK Diesel bike   http://www.dieselmotorcycles.eu/ in a UK magazine (MSL September issue).
The article had a few good pix that showed some frame detail for their installation... which incidentally was a Triple...

Very cool bike.
Coachgeo, looking at the naked bike pic, you can see that the backbone is two girders which run around the very tall engine, and the engine hangs between, unstressed. They are very thrifty with their steel. The structural concept is the rigid triangle, and elegantly executed.
This bike must be very top heavy, but it looks to be well engineered. I like that the in-line cylinders are fore and aft, to minimize width.
Three radiators? Oil, water, and intercooler.
No gears, no clutch.
I want one, to match my diesel pickup truck.

[coachgeo]

Track uses diesel engine out of a Mercedes Smart Car.  Transmission is CVT.

I am rather familure with the bike.  Though I have not studied the frame. Will look closer at that aspect.

[coachgeo]

Track...rather familure with the bike.  Though I have not studied the frame. Will look closer at that aspect.

looked at frame closer.  Is not this skeletonish design becoming more popular these days?

[Sin_Tiger]

I'm with Nick and the others, an engine sub-frame could be so much more, maybe even the basis for a chair mounting  :D What struck me about the Track was how exposed the sump looked, although I love the styling of the rest of it. The centre stand is a really ugly POS though :lol:

I feel a bit more comfortable now having seen everybodies background. My background is Marine Engineering, everything to do with big ships, so I have a fair bit of experience with diesel engines. The NHV (noise / harshness / vibration) you are concerned about is what is termed "structure bourne" noise, i.e. what is transmitted through whatever supports the engine, you will know from your own experience a joint with a cartilage performs a similar function (one of them anyway) to an isolatic bush, you just need to find out a suitable size, run it with a steel bush and measure the frequency and any harmonics then choose a material that best suits your needs. Your measurements at speed are the ones that are important, vibration sitting at the lights doesn't matter. Got any friends with vibration analysis equipment? Try a bearing supplier, they usually have this kind of kit.

[coachgeo]

hey Im not near my bike.  As in it stored out of town.

Some of you may recall I planning to swap out a semi bad engine in my Tiger for a diesel 3cyl  (search youtube Diesel Tiger for sample).  Engine I "want" to use is hard to find and EXPENSIVE so Im looking at alternatives.

I stumbled upon a 3cyl Kubota engine on craigslist.  Dont know if it's dimensions are anywhere close to a Tiger 3.  Its a bastardized engine so there is not really a model number to look up and find a size on.  If any of you can do a general tape measure of your lump and let me know if the below dimensions are anywhere close?

Kubota  Height 20"  length 19"  width 12- 13"

lets not get into discussing my bastardization of a Tiger please.  

much appreciated.

[Mustang (OP)]

I will get some measurements for you tonite as I have a motor sitting on a lift and can easily measure .

what i can't understand is why you would want to go diesel, the fuel cost is more ,it is dirty and the power just aint gonna be there like the sweet 885 triple . :icon_scratch