Is 6.8hp enough?

[Mouse]

Got a 315cc Lombnardini engine but I've the feeling that it is not enough to get a bike up to acceptable road speeds.

[Diesel Dave]

The granddaddy of all Diesel Enfields, the factory produced Taurus was just 325cc.

I ran mine as a 360cc for many years in the UK.

These were the Greaves unit's which are copies of the Lombardini 6LD series engines, I'm guessing your 315 is a later 15ld series which are slightly more powerful for the capacity.

As the Enfield is quite a heavy chassis for the smaller motor to push along (makes no difference to top speed but acceleration suffers and hill climbing gets killed).

My 360 would top out at 48mph, and although the factory state 38 for the 435 I know many top 45 on the flat.

One thing you do need on a smaller motor is closely spaced gears, especially between the two top ones as any incline will leave you struggling.

For inspiration take a look at Mike Sieberts minibike:
http://www.youtube.com/watch?v=YAy8DrojAuQ

Nice and light with a Comet CVT, from memory Mike said it hit 30 mph fairly quickly and this is evident on the video. He subsequently had a problem with the Chineese motor that sidelined the project which was a great shame - if I could get one through an SVA it would be a great addition onto the camper van tow hitch.

At the second Uk dieselbike rally was an excellent Honda RS250 conversion that had competed in the Lands End Trial; lots of engineering/Tig welding as it used the Honda gearbox but managed to join in the ride out 2 up. Sam Brumby had a 250 Superdream with a tiddler motor and hand change 3 speeder, I'm not sure of the size but 260cc springs to mind.

So long as your expectations fit the HP anythings possible

Mopeds are about 5hp so bear this in mind.

Cheers
Dave

[Numbutt]

Hello all,
Its been a while since I've had a chance to log up, I've been working crazy hours. I just met Mike Siebert in Portland, Oregon, and what a class act he is. I had answered an ad for a large minibike frame and found that it was Mike's. I bought the remnants of his diesel minibike with the intention of rebuilding or replacing the engine. I've watched the Youtube clip a few times over the past year with the intention of reverse engineering it. What a small world this dieselbike community is. I have a new Mellga diesel that may fit. The engine that Mike had on the minibike was a DEK, a Chinese Yanmar clone. It would probably be easier, and cheaper to replace the engine than finding a new crankshaft. Any ideas or leads would be appreciated.
Don

[andrewaust]

Hello all,
Its been a while since I've had a chance to log up, I've been working crazy hours. I just met Mike Siebert in Portland, Oregon, and what a class act he is. I had answered an ad for a large minibike frame and found that it was Mike's. I bought the remnants of his diesel minibike with the intention of rebuilding or replacing the engine. I've watched the Youtube clip a few times over the past year with the intention of reverse engineering it. What a small world this dieselbike community is. I have a new Mellga diesel that may fit. The engine that Mike had on the minibike was a DEK, a Chinese Yanmar clone. It would probably be easier, and cheaper to replace the engine than finding a new crankshaft. Any ideas or leads would be appreciated.
Don

Hi Numbutt


Do you know if the crankshaft is toast or just a bearing gone south, I just replaced the ball raced bearing in a clone yanmar myself https://www.dieselbikeforum.com/view ... ?f=3&t=963 .

There is a chap on ebay that sells bits for these L100 10hp clone yanmars "Parts Man Store", as well as the smaller cc variants. I don't know if he sells cranks though.

The yanclones are cheap for many of the parts, it cost me under $100, and I had the engine up and running again.



Cheers



Andrew

[Diesel Dave]

I think Mike said that the crank had actually snapped in two, in this case you would be lucky to keep the cases!

From memory I don't think it was a 10hp motor, prob a 6 or 7 and it was a tight fit in the minibike frame.

I loved the look of that little scoot, wheelbarrow wheels and everything just looked like lots of fun. If it could be scaled up by about 10% and stick in a 10-12hp single with a Comet and 2 speed box, swing arm, cage in the frame sides with steel mesh and strap a spare wheel on the side with a tractor type tyre it would make the ultimate survival scoot.

[balboa_71]

Guys,
I think Mikes engine was 4 or 6 hp, and I believe his gearing was a tad steep, which would have lugged the engine. While many will disagree, you need a 6 to 1 reduction on your final drive even when using a torque converter. These engines do not like to be run down on in their rpm range, they are made to run 3,000 rpm all day long. All minibikes from yesteryear, and I mean way back in the 60's had 6 to1 reduction (either 10 and 60 tooth sprockets or 12 and 72 for a normal bike). My very heavy GS850/10hp clone of a Kama clone, runs 5 to 1 rear reduction and it's too steep with me on board. Just my $.02 worth...

Cris

[Numbutt]

Diesel Dave,
Sounds like you just described a Pak Jak. It is used to pack out downed game in the Western U.S. It has a 3hp gas engine in it, but is geared 60:1. It is slow going. I have a small 4.2HP Yanmar diesel ready for the transplant. It will literally climb a tree, if you can hang on.

[Diesel Dave]

I'm a closet fan of the Tote Gote,

Favourite picture from Arnem's site:



It's difficult to contemplate wilderness in the UK as every inch of the land has been owned by somebody since the Norman conquest in 1066.

[balboa_71]

Dave,
The best riding in these parts is on private land. Darn near everything is bought up, and then the fed. government owns the rest and likes to keep motorized vehicals off it. If it were possible, the best riding would be under the sea or any large lake, as there is no one to cause your grief again, possible

We had tote goats when I was a teenager. We also had boonie bikes (large rear tire and 8hp briggs engine). But will all those designs, you had no suspension (except weak tire side walls) and no ground clearance. Mud (clay) made going impossible because the tires could not dig in deep and find the bottom to get a hold of. For practical reasons, gearing should be kept to 25mph max, or you will get hurt! Last, the engines of those days were real shakers....I remember having trouble holding on to the grips due to vibration.

Cris