GT550 / Lombardini Feasibilty Study

[jdaftra]

I just acquired a Lombardini 6LD260 with about 20 hours on it. Looking at the service manual at:

http://service.lombardinigroup.it/docum ... 02-387.pdf

I see this is only about 5 hp. Is this a feasible engine for my project? I know the HP isn't the same on a diesel engine and I am after economy not speed but I'd like to be able to get out of my own way. I am looking to cut off the drive of an old 2-stroke Suzuki GT550 and use the frame and transmission. I am wondering whether this little motor will cut it.

[Stuart]

Personally I'd say this engine is too small. If you want to build something to show and/or perhaps do small journeys on, something that will get you lots of attention (actually all these bikes get that) then I guess this would be ok.
If you are looking to build a usable and economic bike then you really need to get something nearer 10hp. You may bet up to 55mph out of that and about 150mpg (Imp Gal). Even with 10hp the bike will fade a bit on hills and against wind. Big grin factor though
I went from something like that to a bike which gave me a better balance of economy and power. It generates nearer 20hp and gives me 100-120mpg depending on about town or long runs. The limited revs mean I get about 68mph from her.

Hope that helps

[sbrumby]

Stuart is right wont go very fast

mine is 6hp does 225mpg (imp) 41mph. Great to go shopping on and riding round country lanes, but would be deadly on motorways.

[jdaftra]

Well, I have listen to the great advice here and I have modified my plans. I have a 1972 Yamaha AT 125 that I think I will use instead of the GT550. First, it weighs a lot less and is mostly there but rough. I know the 260 is not going to produce much power but this little transmission would not handle much probably anyway. My idea is to start small and see if I can actually do the fabrication and make a working bike. If so, I might move up to a bigger bike with more power next project. I got the engine (Lombardini 6LD260) off of a sign board and I got her running yesterday. The engine runs beautifully.

However, I do have a Lombardini question. This model seems to be a constant speed engine. I cannot find any "throttle" anywhere. It has a little pressure release that is spring loaded that seems to serve as a kill switch but that is all the controls I see of any kind. I looked at the manual and seems that it does have a governor that controls the injector output. Does anyone know if this could be modified to act as a throttle? If not the dream may be deferred once again and this maybe just a generator project instead.

Please, any Lombardini wise men out there? Thanks a million, JD

[IgorVigor]

Sorry to say but I had a look in the manual and the injection pump is opened and closed by the governor, and its all inside the engine, unless the pump from another model fits, I cant see anyway of modifying it...

Some of the older self governed engines (like the Petter AVA1 and PAZ1 I have in my back garden) basically used an external governor arm which moves the pump throttle plunger. Because of this method you could remove the arm and throttle the engine manually...

However, all is not lost...because of the low power of your engine you could set it up to drive a generator/alternator, which then powers an electric motor, for vehicle drive (have a look through or search for them).

One method that might works it to fit a tap between the fuel tank and the injector pump, and to throttle the engine down shut the tap partially.
Just don't shut it too much or you will get air bubbles in the fuel line...

Another option, which I thought about, but haven't ever had the chance to try is to modify the injector line between the pump and the injector...

Basically fit a Y shaped flow tap (have seen them around) into the line with one line travelling to the engines injector, the other to an injector fitted into the fuel tank.
Then use that as a throttle, so that when you try and throttle the engine down it doesnt allow all the fuel to the engine, instead some goes back to the fuel tank.
Less fuel = less power which means the engine will slow down...

No guarantee it would work, but its an idea...

Hope that gives you some fuel for thought

I am picking up an engine tomorrow (Lister LT1 - which were rated between 2.25 and 9hp depending on what governor was fitted). Its a fixed speed like your so once I can get it to run, I will experiment my self to see if either idea works. Then thats going in a bike