1950? 500cc BSA project

harry76 said:
Ive had a decent search on the 23" Honda rim and i did find a complete wheel for sale, but then i tried to search for a tyre to fit and i couldnt find any (obviously there are tyres available), and i definitely didnt see any tyres i liked
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same story, you need to take the measurements as suggested by Mr.B and try to find a tire which fits. Haven't measured it yet but I am planning to build another bike with those wheels and some decent tyres.
 
I went to the motorcycle wreckers today to look for rims and hubs. I drove all the way there and it was shut. So ill need to find another wreckers.

Since im a novice to engine building (my only experience is rebuilding my old 2 stroke motorcross bikes) im waiting for my workshop and parts list manuals to have a quick read before i start pulling down the engine. I dont want to wreck anything.

So while awaiting the manuals i decided to draw up a frame. Im sure it needs a little tweaking to sort out rake and trail etc. And i may have to tweak the rear as im still waiting for my Albion gearbox from England to arrive.

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Bicycle rims probably wont hold the weight, good thing im not using them. That rim is a 21" motocross rim that i will have laced to a motorcycle hub.

I was going to attatch the engine to the frame via the four bolt holes, 2 front and 2 rear, and connect them via engine plates out of thick steel. The frame will most likely be cromoly and have solid engine mounts, i will tack weld with a mig welder but i will get a professional TIG welder to finish it (My brother makes roll cages for race cars but gets another fellow to TIG them).... are you saying this wont work?
 
I'll need to redo/modify the drawing as I didn't leave room for the seperate oil tank that will be behind the seat post, so I need to lengthen my chainstays which will also create a little more room for the Albion box to be mounted

My workshop manual showed up, so I'll do some reading and then start pulling down the engine..... And I will be sure to test the mag like Ibedayank recommended
 
curtisfox said:
I am suprized you don't want to see if it runs first,might be a good running engine the way it is..............Curt
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Thats what i had initially planned but Goldy from this site gave me a little advice over at Jockey Journal, he said he just finished rebuilding a MW20, and he went on to say "Whatever it is and wherever it was originally from I suggest you haul it apart before you even bother to try and start it... it probably will run as long as the mag has some life, but the main and crank pin bearings are probably pitted, spalled and fretted just from sitting for a dogs age...I have found this to be the case with almost every old brit I have overhauled."

And since i have little experience rebuilding engines im willing to take any advice offered to me. Especially from someone as knowlegable as Goldy, just hope i can get it back together after pulling it down

laff

Like i said i always used to rebuild my 2 stroke motorcross bikes years ago but 2 strokes are very easy to work on..... i actually used to be quite hestitant to try new things myself but since finding this hobby i WANT to try new things and techniques and so far its worked out well....... at least i know if im making a big mistake there are plenty of people to advise a better way....... ill thank all of you for your advice in advance..... as ill be needing it

dance1
 
I wouldn't worry about the mags conditon too much. Main thing is that you have one to work with. If it were missing, that would be a real problem.
There ain't too much in there that can't be fixed or replaced by magneto rebuilders or yourself. It also needs to be dismanteled anyway and have it's bearings greased.
Worse case, you could convert to battery igniton with an external coil wired to the mag's points.
 
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wayne z said:
I wouldn't worry about the mags conditon too much. Main thing is that you have one to work with. If it were missing, that would be a real problem.
There ain't too much in there that can't be fixed or replaced by magneto rebuilders or yourself. It also needs to be dismanteled anyway and have it's bearings greased.
Worse case, you could convert to battery igniton with an external coil wired to the mag's points.
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Thanks Wayne Z, i like any advice where i can save money and/or do the work myself. Like i said i got my workshopmanual so i have a little reading to do before i jump in.

I was actually just watching an old American Chopper where Paul Snr buys a couple of old Indians and the guy restoring them for the Teutels said he cleaned up the mag to get a spark again, he said it nearly dropped him when he got spark so ill be careful to avoid a shock LOL
 
harry76 said:
I'll need to redo/modify the drawing as I didn't leave room for the seperate oil tank that will be behind the seat post, so I need to lengthen my chainstays which will also create a little more room for the Albion box to be mounted

My workshop manual showed up, so I'll do some reading and then start pulling down the engine..... And I will be sure to test the mag like Ibedayank recommended
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I just realised it isnt necessary to mount an oiltank behind the seatpost (toolbox postion) but i can mount it in front of the seatpost lie this Indian

http://www.google.com.au/imgres?q=i...1&tbnw=200&start=0&ndsp=18&ved=1t:429,r:3,s:0
 
I gave the engine a little clean up ready for when i start pulling it down.

I think ill polish the lower cases like you see on some board trackers. Should look good.

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Harry, you have a good start here but I have a few things I would like to point out.

1. The bike seems very short. When I was a the motorcycle museum a few weeks ago I measured a lot of bikes and the shortest I found was 82". That was a 1923 hd flat track racer. every thing looks fine on yours but I think the middle of the bike could be a tad bit longer. I think mine is around 32"

2. The top tube angle looks a bit awkward, I have found on most bike the angle of the sloping part of the top tube is about 20 deg. Some have more but 20 seems to be the minimum. I find that the lesser the angle the more options you will have when you go to mount the seat.

Please don't take this criticism the wrong way. I want to see this build become one of the best on the site, and I am only trying to help you see the potential of the idea you already have.

We have a saying in the art world "don't be afraid to kill your babies."
sometimes you have a good idea but the one you have after it is always better. Keep up the good work.

p.s. I think you should try and fire that engine up. If it spins freely what have you got to loose?
 
Im always willing to take advice and start again, especially off you as i know you have an eye for these things....but maybe i should have been more clear..... this isnt my final design but a rough draft to get an idea, i was a little bored last night and decided to do a sketch. Its close to the Cyclone board track racer measurements that are on the web, i was just getting an idea of what it looked like and if id need to change much. As i said it was never meant to be my final frame design. Like you said the middle portion needs to be slightly larger to have room for the engine and engine mounts/plates.

If the dimensions on the drawing are correct i have the same 55" wheelsbase as in the drawing and the tank/toptubes are very close.

Lurker, where are you measuring your 82" wheelbase? Are you measuring from outside of tyre to outside of tyre? If so that would equal about a 52" wheelbase, 3" shorter then this.

http://www.google.com.au/imgres?q=c...tart=0&ndsp=18&ved=1t:429,r:2,s:0&tx=48&ty=61
 
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I had a thought and wondered if anyone knew the answer...... since this engine was most likely used as a stationary engine, and is actually an air cooled motorcycle engine, do you guys think any damage would have been done from running this engine while stationary? How would they have kept it cool? There are no fins on the flywheel like a normal stationry engine?

Would they have hooked up a fan off the pulley or something?

Im wondering the same thing with Birds Harley engine seeing as it was also used as a stationary engine.
 
I am confident in speculating that the extra pulley was used for powering a cooling fan.
If the engine was indeed used as a stationary engine and it has lasted this long, the person who did the conversion took into account a means for cooling it.
If there were any damage done due to overheating it would have gone catastrophic early on after the stationary conversion. I doubt that the engine would even be around anymore if that happened.
 
harry76 said:
I had a thought and wondered if anyone knew the answer...... since this engine was most likely used as a stationary engine, and is actually an air cooled motorcycle engine, do you guys think any damage would have been done from running this engine while stationary? How would they have kept it cool? There are no fins on the flywheel like a normal stationry engine?

Would they have hooked up a fan off the pulley or something?

Im wondering the same thing with Birds Harley engine seeing as it was also used as a stationary engine.
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In Bird's first pics, I could see what looked like homemade sheetmetal shrouding over the cylinder. I'm sure those old timers figured out early that they needed to address cooling
 
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