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My 76 YZ125 Restoration

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My 76 YZ125 Restoration was created by Grussell

This restoration is special to me as I raced a new 76 back in the day when I worked at Fuqua Yamaha in Bossier City. I bought a package deal. Two 125c rolling chassis with tanks, engines, exhaust, plastics and 1 seat. One 125x rolling chassis and a 100c rolling chassis with an engine missing top end. So I am building a X with C motor for the first resto. Surprised how easy it has been to find nos parts. Here are some pictures of my progress. I spent an hour on each fork boot removing Blue paint.

1978 DT400
1975 DT250
1976 YZ125C (in progress)
1976 YZ125X (in progress)
2018 YZ250FX (my race bike)
2010 Triumph America (my cruiser)
The following user(s) Liked this Post: MarkT, RT325, AirborneSilva, Schu
Last edit: 25 Jan 2021 17:34 by Grussell.
25 Jan 2021 17:32 #1

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Replied by Grussell on topic My 76 YZ125 Restoration

I recieved the new clutch plates (4 steel & 5 fiber) and installed the clutch only to find the pressure plate is hitting the push rod before seating in the basket. The push lever is installed correctly with long push rod and 3/16 ball, but looks like it sticks out too much. I double checked the washer inside and behind the basket and I am left scratching my head. Here is a short video of the clutch. Does anyone see anything I am missing? The primary gear lines up with the clutch basket gear

1978 DT400
1975 DT250
1976 YZ125C (in progress)
1976 YZ125X (in progress)
2018 YZ250FX (my race bike)
2010 Triumph America (my cruiser)
01 Feb 2021 21:15 #2

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Replied by MarkT on topic My 76 YZ125 Restoration

Something looks wrong with the pushrods or actuator lever. 

Wrong parts? 

What do the ends of the pushrods look like? (especially the internal one) Yamaha used rounded ends on some models and deleted the ball.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
01 Feb 2021 21:30 #3

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Replied by MarkT on topic My 76 YZ125 Restoration

Yamaha also used a 6 friction plate - 5 steel plate clutch after engine number 009465. 

Basket looks like it might be sticking up a little high but the pushrod is what looks the most "off" to me...  it's sticking out pretty far.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
01 Feb 2021 21:46 #4

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Replied by MarkT on topic My 76 YZ125 Restoration

Here's info on the clutch...  not likely "this" problem but could be important.  has dimensions to ID the updated parts.

 

 



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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
01 Feb 2021 22:05 #5

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Replied by Grussell on topic My 76 YZ125 Restoration

MarkT wrote: Something looks wrong with the pushrods or actuator lever. 

Wrong parts? 

What do the ends of the pushrods look like? (especially the internal one) Yamaha used rounded ends on some models and deleted the ball.

Both ends of the push rod are rounded.
 

1978 DT400
1975 DT250
1976 YZ125C (in progress)
1976 YZ125X (in progress)
2018 YZ250FX (my race bike)
2010 Triumph America (my cruiser)
02 Feb 2021 06:24 #6

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Replied by Grussell on topic My 76 YZ125 Restoration

MarkT wrote: Here's info on the clutch...  not likely "this" problem but could be important.  has dimensions to ID the updated parts.

 

 

I will measure the components today and see how they compare. I used a parts diagram from RMATVMC that show a ball between the pushrods. Now that I think about it I couldnt find the ball when I reassemble so I thought it was missing. Maybe it didn't have one! I had 2 C engines disassembled and the other engine serial number is before this parts list applies. The engines had been disassembled for a few months. The serial number of this engine would definitely fall within the parts list you posted. I used the best parts from both engines so I will also inspect the other clutch components and see if I mexed them up.

Thanks Mark, I will let you know my findings



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1978 DT400
1975 DT250
1976 YZ125C (in progress)
1976 YZ125X (in progress)
2018 YZ250FX (my race bike)
2010 Triumph America (my cruiser)
02 Feb 2021 06:31 #7

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Replied by MarkT on topic My 76 YZ125 Restoration

I can't find the documentation but I think there was a different long pushrod that did not require the ball?  It had rounded ends where I believe the other type of pushrod with the ball had a flat square end.

In some of the parts lists I can find different pushrod options and "see notes"...  but no notes.  Look close at the YZ125c list and you'll see a pushrod listed as "0" above and then another different one below...  then the ball is listed twice and even the push lever has a note.  There definitely are some different pushrod options.

I've seen models of the 125/175 starting around 1976 come either with or without a ball.  I will see if I can find any documentation.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
02 Feb 2021 07:24 #8

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Replied by Grussell on topic My 76 YZ125 Restoration

Your information was spot on. I pulled out the other clutch assembly and immediately noticed it had 6 friction plates. I measured the components and they matched the diagrams you posted. So I did install the older clutch assembly on this newer engine. I wil clean this correct one and install and see how the pushrod fitment is. I had ordered 5 steel plates for some reason, so just need to order another friction plate.

Thanks again for sharing your in depth knowledge. Did you work in dealerships?
1978 DT400
1975 DT250
1976 YZ125C (in progress)
1976 YZ125X (in progress)
2018 YZ250FX (my race bike)
2010 Triumph America (my cruiser)
02 Feb 2021 08:03 #9

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Replied by Grussell on topic My 76 YZ125 Restoration

I just looked at the 125X parts diagram on the Yamaha site and it shows the same clutch components and part numbers as the old 125C engine and not the updated ones.  Parts diagrams may not always be updated. 

1978 DT400
1975 DT250
1976 YZ125C (in progress)
1976 YZ125X (in progress)
2018 YZ250FX (my race bike)
2010 Triumph America (my cruiser)
02 Feb 2021 08:14 #10

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