Moses searching the desert for how to restore his FS1

[davidfindling]

Hello Members:

I own what is probably a rare 1977 red FS1-C purchased in Canada. My great-grandparents moved from Morocco to Montreal. On a summer trip to visit them, my awesome father bought me my FS1. I rode it everywhere and would regularly get pulled over by the police. They thought I was riding a motorcycle without a helmet. I had to keep a copy of the Michigan statute in the side cover to explain the law.

Fast forward to today. My FS1 needs to be restored but I am struggling with the choices. My 15 year old son, Noah loves the bike and I want it to go faster than 40 kph. I have too many questions which are unanswered. I need the assistance of the forum to decide how to proceed:

1. How loyal should I be to NOS parts? I do not intend on displaying my FS1 at the Concours D'Elegance.

2. What should I choose for the piston and cylinder? Overbore, Athena etc.?

3. What about the wheels? I always felt the wheels and tires were a bit spindly. What is the largest wheel/tire combination?

4. What should I choose for the exhaust? I would love a better tune.

5. I never loved the look of the OEM shocks. Any suggestions for a nicer look? I would even consider a pair with colored springs.

6. Should I change the gearing through the sprocket? What should I consider?

7. Are there changes to the ignition from points to electronic? Is it worth the effort?

8. What about the carb? Is there a recommended carb or just the jet?

That is a good start. I am excited to learn from the responses. Thank you in advance for your assistance.

David
P.S. You can see pre-restoration photos here: https://photos.app.goo.gl/uZM8Getkcw42VoaN9" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

[kittop]

Hoi David,


Those are a lot of questions, but the answers to these questions you first have to look at your goal.
Here on the forum there are some guys who pushed their FS1 up to 100 km / h.
However, this has to do with costs and how responsible it is for your 15 year old boy.
An FS1 is fairly easy to get to 65 km / h, making it easier to keep up with local traffic.
Is this what you mean?

[davidfindling]

Hi:

It has been a long time since I logged in to this forum. I just saw your response and I apologize for my delay in responding. I do not want to build a fire breathing FS1 monster. I would like to rebuild it as close to new as possible. I was always disappointed that I could never break 40kph. I would like to improve the performance through a cylinder change, jetting or whatever else is appropriate.

It is hard to choose one vendor to purchase parts. Prices are all over the place. I would appreciate if any of the forum members have a recommendation as to where I should purchase my parts. In the event I go over on piston size, what would you recommend? Should I purchase an 60cc Athena head? Any suggestions that are in keeping with the original design will be greatly appreciated.

David

[kittop]

a Few pictures would help to give some advice. But also the numbers on the exhaust, cylinder and engine block are essential to get started.
Most who visit this site are Belgians and Dutch, but we also often look at local internet stores.
Our/my favorites are:
https://www.fs1shop.nl/onderdelen-c-76.html
https://fs1parts.nl/shop/index.php?cPat ... 45275742a1
https://www.jmpbonderdelen.nl/yamaha-on ... rd-dt.html
a Global provider that is reasonably complete is CSMNL, but also quite pricey

To mount a cylinder head from a 60cc Athena is not really recommended, provided you also mount the cylinder from Athena. These are in combination with the right carburetor ( and setting) and right exhaust pretty fast.
Personally I would wait with that for a while and first see what the bike is assembled with.

[Tombo]

The JMPB webshop is also available in English! This webshop is one of my favorites regarding parts for my FS1
https://www.jmpbparts.com/yamaha.html

[NIX]

Some of your questions affact each other as you need to match your setup. Most imitation or aftermarket is just fine, especially parts that need to be replaced often. But some are better avoided.

2.75 Front and 3.00 rear are the most massive combination, but 2.50 and 2,75 will fit better and will not rub anything. My choice would be the 17" 2.50/2.75 combo, just because it works and looks nice. The centrestand is long and wide enough for a 2.75, a 3.00 gets tight and unstable.

About the setup, a mild tuned version has a fast imitation standard looking exhaust. yours is the slow original one. Avoid the FS1 cilinder. It has no mid-power and shifting from 3 to 4 is always troublesome. My choice would be to overbore a standard cilinder on a preferably original oversize piston. Make sure the machine shop bores on 0,05mm play. Your 10mm carb needs an original mikuni 130 main jet. Maybe the compression needs te be raised, but if the cilinder is not tuned, it might be already ok. Sprocket combination should be 13/44 or if the guy is really skinny even 14/44 will work. This will bring the top speed at 60km/h. It will have plenty of mid-range power and is still lean and reliable. If you want to go quicker, a 16mm carb with 150 jet can be used, but in case of an original cilinder, I would raise the exhaustport 2-3mm. The head needs to shaved a bit then as well. It will do about 70kmh, then.

No need for electronic ignition. Just avoid imitation points and condensator. Set the points on opening at 1.8mm before tdc and use an NGK B8HS plug. Avoid the blue lettered resistor plugs like the BR8HS. They die really quick.

[davidfindling]

It has been awhile since I was on this site. I am back to working on my FS1-C. The frame has been painted and I am starting to check the chrome pieces. I polished out the headlight ring and the front flashers. I will attach photos to my post. I am very grateful for the advice on this site.

I always hated riding my bike at night. The incandescent bulb would get brighter and dimmer based on RPM's, However, it was weak and dim. Has anyone replaced their bulb for an LED? Based on the difference in watts to lumens, it would make sense for the FS1. What bulb did forum members choose?

David

<img src="Myfiles/downloads/fs1.jpg"