restoring vintage 76 Yamaha YZ250

AK rider
Posts
7
Joined
5/19/2021
Location
Eagle River, AK, USA
Edited Date/Time 8/27/2021 6:58pm
good afternoon folks,
I am restoring a 1976 Yamaha YZ 250 to show room condition I hope.
what I need is anyone with the specs to ohm out the stator, I am not sure what I should have for ohm, the videos on you tube all say to refer to the repair manual, which doesn't have the spec in it or the test in it.
I am also looking for someone other then myself that remembers these bikes, the parts and the appearance.
It seems to have bin mixed matched with parts, which is okay if that works, but i doubt that it will work on everything
so the first step, is to get it running and work the bugs out before I take it apart

if you have part if you have manuals, or knowledge on theses bike contact me
1
|
RDnutz
Posts
720
Joined
2/13/2021
Location
Dolores, CO, USA
5/23/2021 9:21am
Yeah I remember the bikes. Still have a bunch of 1st generation MXB & YZC bikes and currently working on a couple. The little yellow & black owners manual does include Ohm specs for the coils in the Specifications section near the front. I can check it for you later and post or email to you. 1st, make sure it is the stock stator & rotor. These used Mitsubishi model M100-19 and should be stamped in plain view on both stator and rotor. If not that model, write down what is stamped there and reply here and we go from there.
1
AK rider
Posts
7
Joined
5/19/2021
Location
Eagle River, AK, USA
5/24/2021 4:43pm
could you send me what you can
Mike
RDnutz
Posts
720
Joined
2/13/2021
Location
Dolores, CO, USA
5/25/2021 5:55am
There are probably ~10 different Yamaha OEM ignitions that will "work" on there, as well as a couple aftermarket. I don't know of a master catalogue that would cover specs and test procedures for all those possibilities. You said you think things are mis-matched on the bike- so it will probably take some detective work to determine correct resistance measurements for the 1 on your bike. This stuff is ancient and mostly NLA from Yamaha. From my experience, the quickest way we can get you going in the right direction is to identify what is on there already, then see if it is a viable system or not. Starting with, is it a complete system we can work with: Rotor, stator, CDI brain box, ignition coil?

If you can copy the stamped/printed info on each 1 of those parts and post here (a picture of each component would really help) that is our best starting point. Otherwise I'll have no clue what you are dealing with and probably won't be able to be much help...

Paul
AK rider
Posts
7
Joined
5/19/2021
Location
Eagle River, AK, USA
5/25/2021 8:20am


So yesterday I ordered a powerdynamo VAPE ignition system.
they say it is a drop in complete system for this bike. this will take the mix-match system away.

I have done an awful lot of research on the ignition, and the original Yamaha system was only made 76 to 78 and was a 250 bike only. the last owner put on a 79 125 system and it just wont work, it keeps shutting the coil off.
since nobody has the original system on line I am choosing to go aftermarket
Don't worry I have a ton of more questions. I spend a lot of time looking at pictures trying to pick out stuff for the finished product.

do you know from the factory, was the rear swing arm black or silver? I seem to think they were a duel chrome type of finish but most of the current pictures show black.
I am shooting for very close to factory restoration. it's going to depend of factory look a like parts.
mike

The Shop

RDnutz
Posts
720
Joined
2/13/2021
Location
Dolores, CO, USA
5/25/2021 8:34am Edited Date/Time 5/25/2021 1:00pm
AK rider wrote:
[img]https://p.vitalmx.com/photos/forums/2021/05/25/494804/s1200_vape_system.jpg[/img] So yesterday I ordered a powerdynamo VAPE ignition system. they say it is a drop in complete system for this bike. this will take the...


So yesterday I ordered a powerdynamo VAPE ignition system.
they say it is a drop in complete system for this bike. this will take the mix-match system away.

I have done an awful lot of research on the ignition, and the original Yamaha system was only made 76 to 78 and was a 250 bike only. the last owner put on a 79 125 system and it just wont work, it keeps shutting the coil off.
since nobody has the original system on line I am choosing to go aftermarket
Don't worry I have a ton of more questions. I spend a lot of time looking at pictures trying to pick out stuff for the finished product.

do you know from the factory, was the rear swing arm black or silver? I seem to think they were a duel chrome type of finish but most of the current pictures show black.
I am shooting for very close to factory restoration. it's going to depend of factory look a like parts.
mike
good solution Wink that should eliminate the uncertainty and be more reliable than rebuilding an OEM unit. Swingarms were Black from the factory. 1978 was start of Silver aluminum units on the redesigned chassis. FYI, 1976 YZ250C, YZ400C, and IT400C are virtually identical rolling Chassis, but IT400C did not have the air cannister forks. I've swapped 250C & 400C motors back and forth between chassis many times.

In case you don't already know about it, Yamaha North America website is a great resource for parts lists and diagrams and can be found here: https://www.shopyamaha.com/parts-catalog/lines

willbilly
Posts
408
Joined
6/28/2016
Location
Corpus Christi, TX, USA
6/4/2021 5:51pm
Installed Powerdynamo in 75 Pursang. Starts first kick every time.
8/27/2021 6:58pm
Hey guys I have a 1979 yamaha yz250 that needs a flywheel and key.
8/27/2021 6:58pm
Just wondering if there's any leads on where to get one or a different option
RDnutz
Posts
720
Joined
2/13/2021
Location
Dolores, CO, USA
8/27/2021 7:28pm
Just wondering if there's any leads on where to get one or a different option
eBay
AK rider
Posts
7
Joined
5/19/2021
Location
Eagle River, AK, USA
8/29/2021 9:51pm
so as I said earlier, the answer is to install the after market kit, it comes with the flywheel and stator you need.
it is very hard to come by a fly wheel,
mine. I had to weld a tool to it and then pull it, the threads were already gone. Which might be your problem as well.
AK Rider

Post a reply to: restoring vintage 76 Yamaha YZ250

The Latest