British powered Dnepr

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stormcoat
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British powered Dnepr

Post by stormcoat »

My British powered Dnepr is on its way. I have successfully fitted the clutch to the flywheel and mated up the gearbox. These images, if they appear, will show it before I did this; gearbox is just in place for lining up in the frame.
I turned the engine over with the kick starter and found little resistance, so I am anticipating a top end service, valve grinding and gaskets etc before it fires up, but, just in case, I will give it a few turns on the starter before I do. It had plenty of compression last year, when | turned it on its starting handle, so perhaps it just needs some exercise!
The engine (an ebay opportunity purchase) is only 15hp, at 3600rpm, so I am not expecting much more than a steady trot, but would anyone like to suggest what final drive it might pull, with a sidecar. It has the standard 4.2 at present, but I have a new 3.89 in the drawer. I am wondering if it may just pull 3.5, as the Hatz 20hp pulls the 3.2, or am I flying with the fairies on that one?
I have been admiring Johnny Fireball's Daihatsu. I particularly like the tank. My frame is probably almost as tall, even more stretched and the manifold is bulky, leaving very little space to drop the original tank, if any. I am debating whether to make a dummy tank if I cannot make a saddle tank and put the fuel somewhere else. How did you do yours, Johnny?

For the record, I settled on the Petter engine for its appearance and for its ready made bell housing, which has proved quite easy to make up a conversion flange for and to have the flywheel machined up to accept the Dnepr clutch. The front end has a facility to fit a PTO shaft, which will be used to turn a Nippon Denso alternator of the same kind currently used on the new Urals. The governor has been fitted with a variable speed mechanism, cannibalized from another Petter, and a 3600rpm speeder spring.

Petter engines, especially this one, resemble an old fashioned industrial sewing machine in shape and form, so I have had to make very drastic alterations to the frame. I hope members will consider that the result is not too reminiscent of a piece of equipment that might have been found in the old gasworks (in contrast to the sleek integrity of some of the expertly crafted machines that we have seen on the site lately).

The cutting, fabricating and welding was done last year, with the valued assistance and expertise of a family friend, Craig, who was kind enough to put his workshop and three phase welder at my disposal, and carried out the more visible welds himself.

I will endeavour to further the progress this year, but cannot promise to be ready in time for the "Big Knock" in May. In the meantime, may I send my best wishes to those who will be there and hope the rally goes well.
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LocomotiveBreath
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Re: British powered Dnepr

Post by LocomotiveBreath »

I think that engine is way cute,will look really good polished.

Two thumbs up!
Dave
“Face piles and piles of trials with smiles. It riles them to believe that you perceive the web they weave, and keep on thinking free. "Moody Blues"
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Diesel Dave
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Re: British powered Dnepr

Post by Diesel Dave »

That's a nice looking motor, looks very like the early air cooled inline fours from the early part of the 20th century.

On the subject of gearing I would go for 70mph at 3600 and you won't be far out, my little Enfield is geared for 55 on 8hp and will hit this in favorable conditions.

Dave
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Diesel Dave
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Re: British powered Dnepr

Post by Diesel Dave »

I've had a little look at your available ratios:

rpm ratio kmh mph
2200 4.2 61 38
3000 4.2 84 52
3600 4.2 101 62
4000 4.2 112 69


2200 3.89 66 41
3000 3.89 90 56
3600 3.89 109 67
4000 3.89 121 75

2200 3.5 74 46
3000 3.5 101 62
3600 3.5 121 75
4000 3.5 134 83

2200 3.2 81 50
3000 3.2 110 68
3600 3.2 132 82
4000 3.2 147 91


The reason for the 2200 start figure is this is usually the max torque rpm so this is where you want the motor to be when changing up from another gear, 3000 will be the smoothest and between these two will be the most effecient in terms of fuel consumption.

Given it's a 15hp motor I'd plumb for the 3.89 ratio you have in the drawer as this looks to be the best compromise between cruising speed and acceleration.

All the above calcs are based on a 19" wheel with a 3.50 tyre.

Dave
johnfireball
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Re: British powered Dnepr

Post by johnfireball »

Hi Stormcoat,
How did I make the cover? Blue Peter style actually, I got some heavy cardboard 1.5mm thick (not corrugated) some masking tape and brass strip 25mm wide and 1mm thick. I cut the top panel and bent it round the frame taping it in place,I then cut a paper template for the side panels offered it up and trimmed to fit. I then cut 2 cardboard panels (one in reverse) off the paper template.Remove the center panel from the frame and tape the whole lot together at the seams back and front neat as you can. The card tank should now fit the bike but make the edges a bit longer for trimming afterwards. I used the brass strip on the underside bending it to fit right to left underneath the tank,I used 2 strips and glued them in they allow you to bend out the cardboard to shape the tank sides also they give useful reinforced mounting points. So now the tank fits its time to lay it up.Epoxy resin is the best as it soaks right into the cardboard making the whole structure really rigid. Start on the base of the tank and soak the card with epoxy you must use paper masking tape for the tank taping as it allows the epoxy through. While the epoxy is wet start adding the chopped strand: Tear it into pieces lay it on and wet it out( a resin roller is great for wetting out), I found 2 layers to be sufficient(dont worry about overlapping the edges as they be trimmed later).Leave to dry overnight.
Tank should be quite rigid now so turn over and sand down any epoxy spills on the tank top. Again soak the cardboard with epoxy and apply a sheet of woven glass over the complete tank top, a few cuts with sissors are required to get it to lay flat at the tank rear, again add resin and roll it in with a resin roller. I put 2 layers of woven glass on my tank top surface while still wet, when happy with the wetting out leave it to dry for a few days. Trim the edges with a jigsaw and add edging strip to finish. I cut the filler neck off my old tank and bonded it onto the new one to keep the filler cap look.
A bit of work I know but is that not part of the fun.
Regards John
stormcoat
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Re: British powered Dnepr

Post by stormcoat »

Dear all,
I would like to thank the two respondents, "johnnyfireball" and "dieseldave" for their help and their interest. I have not been able to log on, for some technical reason, so I have not been able to reply.

Since last time, I have successfully fired up the motor, albeit on a temporary fuel supply, so I know, at least, that I can make a bit more progress without having to take the heads off.

Regards, stormcoat.
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coachgeo
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Re: British powered Dnepr

Post by coachgeo »

welcome back and congratulations on your fire it up success
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