Thinking of putting a 1200 Evo motor in a Slimline frame

acotrel · May 27, 2015

The Parilla in the background of that photo looks interesting. I've often thought a 1000cc Godden motor would be good in a Mk3 Seeley frame. How do you get close ratio gearbox into a 1200cc Sportster motor ?

jimbo · May 28, 2015

acotrel said:
The Parilla in the background of that photo looks interesting. I've often thought a 1000cc Godden motor would be good in a Mk3 Seeley frame. How do you get close ratio gearbox into a 1200cc Sportster motor ?

IMHO you really don't need a CR box on the street , with a low RPM, high torque engine.

BTW that photo of the Godden was taken in the Barber Motorsport museum.

Rohan · May 28, 2015

jimbo said:
IMHO you really don't need a CR box on the street , with a low RPM, high torque engine.

And the Evo sportsters are all 5 speed already...

Andrews do make close ratio gears for them, if the competition bug bites.
Amongst others (?).

ashman · May 29, 2015

91 the Sportsters came out with the five speed box before that they had the four speed box, I brought a new 91 and had to order it, I could have brought a 90 model but it still had the 4 speed and chain drive rear, the 91 had the 5 speed and belt drive, so I do have experance with Evo sportsters.

Ashley

Fast Eddie · May 30, 2015

ashman said:
91 the Sportsters came out with the five speed box before that they had the four speed box, I brought a new 91 and had to order it, I could have brought a 90 model but it still had the 4 speed and chain drive rear, the 91 had the 5 speed and belt drive, so I do have experance with Evo sportsters.

Ashley

Does the 1200 Sporty need 5 cogs?

I notice the new big twins, 103ci torque monster have 6 gears! That just seems daft to me, I reckon it'd be a great selling point to only have 3 gears! Which should be plenty for a motor like that surely.

jimbo · May 31, 2015

buy one?

http://www.ebay.co.uk/itm/Harley-Davids ... 7675.l2557

HopperXL · Jun 6, 2015

I have a 1000 Ironhead motor in a Slimline frame and it is pretty tight for clearance around the rear rocker box area.
I know the Evo motors are an inch or two taller in the rear rocker box area, because they will not fit into a stock Ironhead frame without bending and welding the frame to fit the rear rocker box.

So I would say the Evo might be a VERY tight fit in a Slimline.
To get my Ironhead engine in, I had to lay the engine on its side on the floor, work the top rails of the frame down over the rocker boxes as far as I could, then jump on the frame to get it to pop over the oil pump and into position. Then stand the whole lot upright for the joy of making engine plates.

But if you have enough width in the frame to clear Evo rocker boxes, you can always just let the rocker boxes poke up under the tank and get the tank bottom modified to clear.

Another alternative is to cut and modify the frame under the oil pump to allow the motor to drop down an exta inch or so. You run into primary chaincase clearance issues then. But tubes could be flattened on that side too.

IIRC Dave Degens at Dresda is/was making Wideline frames specifically to fit the Evo motor to make "Hartons". His frames are/were an inch higher between the bottom and top frame rails to fit the Evo motor better. Can't remember where I read that though.

Good luck with the project. They are a fun bike. All that V-twin grunt in a package that handles!

dave M · Jun 6, 2015

HopperXl, Do you have any photos of your bike? I am building an identical machines to yours and have not yet mofified the frame to accomodate the oil pump, although I have managed to get the engine in position as you described. I would be very grateful if I could get some advice on chain run etc.

HopperXL · Jun 8, 2015

dave M said:
HopperXl, Do you have any photos of your bike? I am building an identical machines to yours and have not yet mofified the frame to accomodate the oil pump, although I have managed to get the engine in position as you described. I would be very grateful if I could get some advice on chain run etc.

I dont have much for pics as I built the bike in the 80s, then canibalized parts off it for another project and it currently sits languishing in my shed while I finish off my WLA engined Featherbed project. But here are a couple pics I can find:

Thinking of putting a 1200 Evo motor in a Slimline frame

I made a rear engine mount up out of 1" angle iron that bolted to the stock rear mount on the Sporty engine and to the original norton frame tabs. Front engine mounts were original Sporty plates cut and redrilled and spaced to fit the Norton frame, from memory. (And remember this was all done more than 25 years ago.)

I just set the motor in place as described before, set the motor up on wooden blocks to where I wanted it, lined up the Sporty output sprocket with the sprocket on the Triumph chronical hub wheel I used in the back and then made the plates and spacers to suit. Bit of fiddling about but not too much. Did it all with a 4" bench vice and a pistol drill as I was an impoverished student at the time.

I had a tab welded on the swingarm on the right hand side to anchor the Triumph brake and a chainguard. Had a little trouble with the chain rubbing on a frame cross member on full spring compression, but a smaller sprocket or dropping the engine would cure that. Or just putting a piece of Teflon etc on the frame like modern Jap bikes do. I just put up with the occasional rattle over bumps.

I never did get around to modding the frame to clear the oil pump but it would be easy enough done. Either do like a GoldStar and put a curved piece of tube in place of the straight bottom frame rail to clear the pump. Or flatten the bottom frame rail in a press like the 1977 and later Sportster frames were done in order to clear the later geroter pump and allow its removal without pulling the whole engine out of the frame. ( I have seen Sportsters riding around quite happily with six inches of the bottom frame rail missing where someone hacksawed it out to get to the oil pump! Only in America!)

dave M · Jun 8, 2015

Thank you HopperXL, this is very helpful. I also have a Triumph conical hub for the rear and a Norton hub with Triumph TLS backing plate for the front. I will probably modify the right frame rail (I notice this has been done on the Dresda bike on the internet) I will also see whether I can fit the oilump cover using countersunk Alen screws to gain a little more clearance.

The beginnings of my own project can be see on page 4 of the thread in this section titled 'My project and a few questions'.

Many thanks

Dave

jimbo · Jun 11, 2015

http://losangeles.craigslist.org/wst/mc ... 78315.html

jimbo · Jul 5, 2015

XR750 motor, brand new!

heres your motor!

http://www.ebay.com/itm/Harley-Davidson ... 1793362757

ashman · Jul 5, 2015