v twin engine for bike

[proto-techjorge]

hi all, new to this site. been a machinist as career for 35 yrs, self employed for 22. have a manual Bridgeport and engine lathe. want to build a early 1900s vintage motorbike. there are a few companies out there makin them, but they all have cheapo Chinese single cylinder 2 strokes. I would like to have a v twin 4 stroke. soo the question up for discussion is, looking at the plans available, the howell v twin and the britnell (sp) both look good , tho the howell looks like maybe less overall hand finishing. both are only 32cc , quite tiny for real use I think. I realize these are "model" engines so 1: could I scale up the design by simply 1.5 or 2.0 x the dimentions ? 2: are these motors capable of real work/use? 3: has anyone got any first hand experience of either scenario?4: is anyone aware of other choices of plans out there? thx, Jorge

 

[Jasonb]

There are some old books about with engine designs that you could make yourself, this one is a single but you could fairly easily alter the crankcase to make it a twin, there is a link to the boox on the first page

http://madmodder.net/index.php/topic,8107.0.html

Most of the model ones would not really be suitable if scaled up. Though an enlarged Hoglet with enclosed crancase would be a possibility, search here for "Hoglet"

 

[gbritnell]

When I designed my V-twin engine it was for exhibition, meaning that it would be run periodically for short periods of time, 4-5 shows a year running for 2-3 minute intervals 10-15 times per show. Using an engine for work involves certain changes for durability and longevity, good bearing material whether plain or ball type, good oil feed to critical points and the need for hardening on certain components, cams/lifters.
The crank pin on my engine is made from drill rod and left unhardened. It could be hardened and possibly ground to size. My crankshaft rides on sealed ball bearings. The sealed bearing could be exchanged for open bearings but a seal would need to be incorporated on the outboard side to retain oil. My cams are also made from drill rod which means they could also be hardened. My engine has room to increase the fin size on the cylinders which would help the cooling. I use a dual fire ignition which could be used for a larger engine or substituted for a unit from a motorcycle.
I have a set of drawings for the Howell engine and it fits into the same categories as mine, basically a show engine.
Both engines could be scaled up and the critical areas that I mentioned could be addressed but as for drawings for something that could be machined and used for the purpose of powering a bike I don't know of any that exist.
You might be better off to take a commercial engine and modify it for your needs. By that I mean using salvaged engine parts and only having to make a crankcase and some other parts.
As far as the cosmetics of my V-twin, they could be eliminated for the sake of a quicker build, (radiused corners, bolt bosses, fillets etc.) but these are what make the engine attractive.
gbritnell

 

[WOB]

When deciding on the engine layout, look here for some info on the shaking forces: http://sense.net//~blaine/twin/twin.html

RWO

 

[proto-techjorge]

thx for all the replies. plenty to think about. gbritnell your design surely wins me for the beauty and vintage look. it would be a lot of work to get there and since im a manual old school guy I know my hands would be sore from polishing!! never learned cnc but it would also give a wonderful billet look that is popular today, especially if clear anodized. I see on jerrys website where he used to run his for hrs at shows to generate electric only stopping to fuel up. and he does mention the v twin would be perfect on a bicycle. I haven't purchased the dwgs but I agree 100% that either one would need the standard practice in engine durability materials applied. hardening and grinding to finish is something I have done in the past but I do not have the capability in my shop. well I will look into this some more and thanks again for everyones replies. hard to believe with that big world full of people out there no one is making a small v twin? the motorized bike website has tons of posts looking for the same. even saw where someone in hungary if I remember right is trying to get enuf interest to have a small production run of the howell done. would be a good business opportunity for a kickstart fund!! a new vintage American motor bike.

 

[Jasonb]

If you want a vintage American bike then read through this build series of an Excelsior reproduction.

http://flashbackfab.com/excelsior-project-paul-brodie/

The main problem with a lot of teh model engines is they have a 90deg Vee which can be a bit wide to fit in a frame, thats why teh hoglet would be better with its steeper V, I did start drawing it up with an enclosed crankcase

View attachment Hogass2.pdf

 

[proto-techjorge]

wow thx for the linx!! some stunning work being done. the excelsior is amazing beyond words. and the madmodder tom whos build is a single and equally impressive for the simplicity and speed that it came together. wish I could weld. what I really would like to build is a smaller 50cc motor-bicycle with a v twin. I agree 90 degree is hard to fit in the frame. I didn't want to design from scratch for obvious reasons, ie;time /money/ ability. so the search continues. the hoglet may be an answer. is that your design? I may just build the howell to plan just for the experience and go from there. ive not built a ic motor so theres a lot to learn. nor do I weld or braze, tho I will need to learn to make a frame. :fan:

 

[cfellows]

This is Randall Cox, the fellow that designed and built the original V-Twin Hoglett, which is featured in the project of the month, although not built by Randall. In this video, Randall has a scaled up version of his Hoglett V-twin installed in an old Harley Hummer frame. Really neat video...

https://www.youtube.com/watch?v=-708khmH3vY&feature=related

Chuck

 

[Jasonb]

The open crank Hoglet plans were in Model Engine Builder mag, you can buy digital back issues from them. Issues 10 & 11, go to subscribe and it will eventually get you to the back issues

https://www.modelenginebuilder.com/default.htm

 

[Richard-Vanderpol]

这个怎么样

 

[Vietti]

I was a good friend of Randall Cox. When he made his large scale twin he used the bbls and heads from older Briggs engines that had a detachable bbl. Don't know the model but pretty early I think. He made the transmission with gears from a model t or a. The bike ran really well, he took it to a few shows, unfortunately many visitors thought it was some kind of a real Harley.

Richard V, I wonder if you could provide more details on the good looking twin you posted?

John

 

[Richard-Vanderpol]

yes.

 

[kadora]

hello prototech
I am building mini motorcycle powered by four cylinder inline 50 ccm engine .
Something like vintage Henderson .
But my intention is to run it only on the stand due to homemade engine.

 

[danallen]

这个怎么样

I love this engine. Can you share more like pictures or plans or even some specs?

 

[kadora]

for danallen

 

[Richard-Vanderpol]

for danallen
View attachment 128990View attachment 128991

wow. so beautiful

 

[Richard-Vanderpol]

I love this engine. Can you share more like pictures or plans or even some specs?

yes. here you are
.Cylinder: V-type two-cylinder;
.Stroke: Four-stroke
.Displacement: 9(4.5*2)cc
.Bore: 16.67mm
.Stroke: 21mm; Angle: 45°
.Speed: 2000-rpm
.Power: 0.8ps