Demonstrated Speeds With Original Drive Train

[David Stinson]

My 1958 Simplex has a speedometer that worked when I first started riding although it bounced around a lot.  On a recent road test it quit altogether.

Today I strapped my GPS on the handlebar and went for a ride.  On an uphill grade I got about 12 to 14 mph depending on the grade.  On relatively level ground I got up as high as 31 or 32 mph.  On a downhill grade I got as fast as 42 mph.

Based on a spreadsheet that I put together with the pitch diameters of the pulleys as best I could measure I would be turning about 1800 rpm’s at 32 mph.

Does anyone have any information regarding the running rpm’s of the 150 cc original engine or have any measured data to share?

[relic]

My 57 did about the same and it had the 125 cc engine. My 54 Simplex 1/4 ton truck i have had up to 29 mph so far.

[David Stinson]

Regarding my earlier statement, "Based on a spreadsheet that I put together with the pitch diameters of the pulleys as best I could measure I would be turning about 1800 rpm’s at 32 mph.", I have been tweaking my spreadsheet to correct my pulley diameters and also corrected an error that I built into my speed calculations.

I think that at 32 mph my engine rpm is 2600.

I don't have a convenient way to physically check rpm so I connected a DC motor to the crank and measured its output when idling and determined that my idle rpm is 950.  I intend to try and use the DC motor to either directly supplement my poor lighting or as a battery charging system if I can work out the regulator part of the system.  In either case I should be able to determine the engine rpm by the motor's output once permanently mounted.

[Ricks]

David, did you ever get anywhere further with this?

[David Stinson]

I haven't done anything further on this.

[pd]

For 10 - 15 bucks you can get a digital tach on ebay . No wires to hook up , but for wrapping the pickup wire around the high tension plug wire .

[Ricks]

For 10 - 15 bucks you can get a digital tach on ebay . No wires to hook up , but for wrapping the pickup wire around the high tension plug wire .

Pete, have you tried one of those?

[pd]

I have not , Rick .
According to the number of units sold , I'd think they would do the job . They are a simple pulse and time counter .
I'll likely pick one up before Portland . If for no other reason than curiosity .

Pete .

[oil-lamp]

Well the one I have been looking at on ebay is a non contact one. # 161270564314 it has a stick on reflector spot that it reads with a beam. I was going to order one this weekend. 

[Ricks]

Well the one I have been looking at on ebay is a non contact one. # 161270564314 it has a stick on reflector spot that it reads with a beam. I was going to order one this weekend. 

I see a couple of issues with that Reese.  First, on what will you stick the reflector?  I would put it on the flywheel, but this meads you have to remove the cover. Second, this would work at idle, but how would you ride and aim it at the flywheel?

I think the one Pete has in mind would solve both issues.

These are all over eBay:   http://www.ebay.com/itm/Tachometer-Hour-meter-2-4-Stroke-Small-Engine-Spark-utv-atv-outboard-motor-pwc-/400368946443

[kartjockey]

I have one of the tachs on the way.     

[pd]

Tom ,

We'll be watching for a review .

Pete .

[Bruce]

A lot of automotive multimeter's have a tach on them...with a connection that clips right on the plug wire like a timing light. 

[pd]

Bruce ,

Those generally cost a bit more than $13.70 delivered to your door .

Pete .

[Bruce]

Yes....oops