Old Yamaha Revived with Electric Motor but...

BR650
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Muskegon, MI US
BR650
Edited Date/Time 3/23/2020 5:52pm
... I need help replacing the chain.

I was given the bike below for my Electrical Engineering Senior Design Project. All I know is that it is a Yamaha and it is old.



My brother is a tool maker and welder and with his help, we successfully mounted the electric motor, the Prius battery (Lithium Ion batteries were not in the budget), and the controller. I wired everything up and we were ready to ride (on asphalt as we have not built a water/dust tight enclosure yet). Problem is, the chain that came in a bag with this bike is 8 inches too short. I need some help knowing where to buy a chain for a bike this old. The chain that came with it is either the wrong chain or someone cut it down because the sprocket on the electric motor is almost in the same place the gas engine was.



Does anybody know what model and year this bike is?
Who sells chains for old bikes like this?
What dimensions need to be measured in order to buy a replacement chain?

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Paw Paw 271
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Paw Paw 271 3/23/2020 6:18am
3/23/2020 6:18am
If you have a "Bearing Services" store in your area, take the complete unit to them for a proper chain fitting.

Paw Paw
1
Dirty Points 3/23/2020 6:35am
3/23/2020 6:35am Edited Date/Time 3/23/2020 1:47pm
It's a Pre-reed valve (68-74) Yamaha Dt1 250. Any motorcycle chain supplier should be able to get you one, just buy a longer length chain in whatever width with a master link and cut to fit.

That sprocket looks like the wrong width/pitch to me to match the rear sprocket, but you can deal with that however you choose.
1
ledger
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ledger 3/23/2020 7:10am
3/23/2020 7:10am
I think that bike came with a 420 chain, but I could be wrong...?
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BR650
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BR650 3/23/2020 7:43am
3/23/2020 7:43am
newmann wrote:
Engineering? Here are some good chain and sprocket references for you. Also, Sprocket Specialties may be a good source for some sprockets for that old bike...
Engineering? Here are some good chain and sprocket references for you. Also, Sprocket Specialties may be a good source for some sprockets for that old bike. Dealer can verify the VIN, betting someone here can as well.

https://www.rbracing-rsr.com/chainlength.html

https://www.rbracing-rsr.com/calcsprocketdiam.html

Thanks everyone for the references. This is a capstone project for an electrical engineering degree, all that work was done with choosing/sourcing the motor, controller (parameter selection), and conductor sizing. The best way to familiarize with something (in this case chains) is to ask someone who knows. Everybody who has worked in manufacturing knows the engineer who thinks he knows it all, I do not want to be that engineer.
2
SEEMEFIRST
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SEEMEFIRST 3/23/2020 5:44pm
3/23/2020 5:44pm
newmann wrote:
Engineering? Here are some good chain and sprocket references for you. Also, Sprocket Specialties may be a good source for some sprockets for that old bike...
Engineering? Here are some good chain and sprocket references for you. Also, Sprocket Specialties may be a good source for some sprockets for that old bike. Dealer can verify the VIN, betting someone here can as well.

https://www.rbracing-rsr.com/chainlength.html

https://www.rbracing-rsr.com/calcsprocketdiam.html

BR650 wrote:
Thanks everyone for the references. This is a capstone project for an electrical engineering degree, all that work was done with choosing/sourcing the motor, controller (parameter...
Thanks everyone for the references. This is a capstone project for an electrical engineering degree, all that work was done with choosing/sourcing the motor, controller (parameter selection), and conductor sizing. The best way to familiarize with something (in this case chains) is to ask someone who knows. Everybody who has worked in manufacturing knows the engineer who thinks he knows it all, I do not want to be that engineer.
Yep, just see if the chain you have fits both sprockets correctly. Pitch (length between lowest points, and width (fitment between chain plates).

I
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SEEMEFIRST
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SEEMEFIRST 3/23/2020 5:52pm
3/23/2020 5:52pm
If it's a DT250. The chain is a 520.
Here's what I found.

1
cwtoyota
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cwtoyota 3/23/2020 7:07pm
3/23/2020 7:07pm
newmann wrote:
Engineering? Here are some good chain and sprocket references for you. Also, Sprocket Specialties may be a good source for some sprockets for that old bike...
Engineering? Here are some good chain and sprocket references for you. Also, Sprocket Specialties may be a good source for some sprockets for that old bike. Dealer can verify the VIN, betting someone here can as well.

https://www.rbracing-rsr.com/chainlength.html

https://www.rbracing-rsr.com/calcsprocketdiam.html

BR650 wrote:
Thanks everyone for the references. This is a capstone project for an electrical engineering degree, all that work was done with choosing/sourcing the motor, controller (parameter...
Thanks everyone for the references. This is a capstone project for an electrical engineering degree, all that work was done with choosing/sourcing the motor, controller (parameter selection), and conductor sizing. The best way to familiarize with something (in this case chains) is to ask someone who knows. Everybody who has worked in manufacturing knows the engineer who thinks he knows it all, I do not want to be that engineer.
Let me add something to that. Go research and read up on whatever related information you can prior to asking if the question is complex.

Often times your own research can help you know the right questions to ask.
Also, it helps you build research skills and experience so you can avoid being the guy who makes a career asking someone else to make every design decision for you.

MxKyle (MD)
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MxKyle (MD) 3/25/2020 7:08pm
3/25/2020 7:08pm
newmann wrote:
Our local university has some cool mechanical engineering projects and competitions.

https://www.lamar.edu/engineering/enginuity/mechanical-baja.html
For my mechanical engineering design project I had to design and build a scaled down tractor pull sled to be used at the collegiate BAJA competitions. As far as I know they are still using it.

1
Racer142
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Byhalia, MS US
Racer142 3/25/2020 7:41pm
3/25/2020 7:41pm
It's around a 78 dt 100. I think it's a 420 chain but not sure
Dirty Points 3/25/2020 7:46pm
3/25/2020 7:46pm
Racer142 wrote:
It's around a 78 dt 100. I think it's a 420 chain but not sure
Not a 100. And it's a first gen Dt model.
1

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