Rebuilding 650cc / early 750cc cylinder heads

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petermertos
Hero of the Soviet Union - 2020
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Rebuilding 650cc / early 750cc cylinder heads

Post by petermertos » Tue May 11, 2021 12:40 am

Hey guys, wanted to share my experience of rebuilding valves, changing valve guides, springs etc.
The idea is not new - there are Ural mechanics in Europe/Russia who have already done something similar using aftermarket valves and bronze valve guides. I haven't found related info on this forum yet.
So I am planning to make separate videos about each component. Here is the first one about the aftermarket valves:



Please your comments, suggestions.
Thanks,
Petermertos
2013 GU
2012 Solo
1999 BC

Portland, OR

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VWK75S
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Re: Rebuilding 650cc / early 750cc cylinder heads

Post by VWK75S » Tue May 11, 2021 4:55 am

:lurker: John
The Ural's made Maine a much bigger state.

2009 GearUp 155,000kms
2007 Retro 25,000kms
1991 VWK75S 110,000miles

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Tomcatfixer
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Re: Rebuilding 650cc / early 750cc cylinder heads

Post by Tomcatfixer » Tue May 11, 2021 9:07 am

:lurker:
- Chad

Gordonsville, Virginia, USA

Current rides:
2015 Ural cT "Mobile Chernobyl", 2001 Ural Patrol "Little Red Bear", 1999 Ural Tourist "The RPOC", Mid-Nineties Ural Tourist "The Heap", 1994 Honda VFR750F, 2007 BMW K1200GT

Previous rides:
2007 Honda VTR1000 FireStorm (Super Hawk in U.S.)
2001 Buell Blast! - - - - - - - 2005 Yamaha FJR1300
1993 Honda CBR600F2 - -1984 Yamaha FJ1100
Two different 1986 Yamaha FZX700S Fazers

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petermertos
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Re: Rebuilding 650cc / early 750cc cylinder heads

Post by petermertos » Sat May 15, 2021 1:54 pm

Valve guides overview.
2013 GU
2012 Solo
1999 BC

Portland, OR

Scott E
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Re: Rebuilding 650cc / early 750cc cylinder heads

Post by Scott E » Sun May 16, 2021 10:16 pm

I'd love to install valves, guides, and seats in my Dnepr heads that would allow me to run unleaded gasoline. I just need to know what valves to use. I have a metal lathe and mill so I can do the necessary work but I have no idea where and which valves to buy. In one video a watched a Youtuber with a Dnepr MT-16 talked about having his heads modified using valves for two different makes of automobile heads. One from a Mazda head but he forgot what the other valve was from and he didn't give any other information. Just that he could use unleaded fuel without damaging his valves and seats. Adding a lead substitute is not expensive or difficult but it sure would be nice to just pull up to the pump and fill Ivan's tank without adding a viscus oil to the tank before pumping gas and putting the bottle back in it's holder in the trunk. Just pump and go.

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petermertos
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Re: Rebuilding 650cc / early 750cc cylinder heads

Post by petermertos » Mon May 17, 2021 11:25 pm

Scott E wrote:
Sun May 16, 2021 10:16 pm
I'd love to install valves, guides, and seats in my Dnepr heads that would allow me to run unleaded gasoline. I just need to know what valves to use. I have a metal lathe and mill so I can do the necessary work but I have no idea where and which valves to buy. In one video a watched a Youtuber with a Dnepr MT-16 talked about having his heads modified using valves for two different makes of automobile heads. One from a Mazda head but he forgot what the other valve was from and he didn't give any other information. Just that he could use unleaded fuel without damaging his valves and seats. Adding a lead substitute is not expensive or difficult but it sure would be nice to just pull up to the pump and fill Ivan's tank without adding a viscus oil to the tank before pumping gas and putting the bottle back in it's holder in the trunk. Just pump and go.
I don't know much about Dneprs... Do you have an MT-16?
There is a guy in Russia who sells repair kits (guides/seats/valves/springs etc) for 650cc Urals/Dneprs. I bought some stuff from him.
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2013 GU
2012 Solo
1999 BC

Portland, OR

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petermertos
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Re: Rebuilding 650cc / early 750cc cylinder heads

Post by petermertos » Mon May 17, 2021 11:27 pm

Springs.
2013 GU
2012 Solo
1999 BC

Portland, OR

Scott E
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Re: Rebuilding 650cc / early 750cc cylinder heads

Post by Scott E » Wed May 19, 2021 3:20 pm

petermertos wrote:
Mon May 17, 2021 11:25 pm
Scott E wrote:
Sun May 16, 2021 10:16 pm
I'd love to install valves, guides, and seats in my Dnepr heads that would allow me to run unleaded gasoline. I just need to know what valves to use. I have a metal lathe and mill so I can do the necessary work but I have no idea where and which valves to buy. In one video a watched a Youtuber with a Dnepr MT-16 talked about having his heads modified using valves for two different makes of automobile heads. One from a Mazda head but he forgot what the other valve was from and he didn't give any other information. Just that he could use unleaded fuel without damaging his valves and seats. Adding a lead substitute is not expensive or difficult but it sure would be nice to just pull up to the pump and fill Ivan's tank without adding a viscus oil to the tank before pumping gas and putting the bottle back in it's holder in the trunk. Just pump and go.
I don't know much about Dneprs... Do you have an MT-16?
There is a guy in Russia who sells repair kits (guides/seats/valves/springs etc) for 650cc Urals/Dneprs. I bought some stuff from him.
The picture shows brass valve seats, not hardened steel. All those parts are what came in the heads originally. My heads are fine as long as I use a lead substitute. The valve guides are shinny brass. The valve guides needed for unleaded gasoline would be a porous dark bronze color. Oil seeps into the porous bronze valve guides to lubricate them. The Brass valve guides that come with older Ural and Dnepr 650 engines do not have seals so oil can pass from under the push rod tubes and get sucked into the space between the valve and guide for lubrication. That's the reason Ural and Dnepr 650 engines use more oil than modern engines. They are designed that way. I have a single wheel drive Dnepr MT-11, not the full time 2WD MT-16. I'm too old for off road riding and my MT-11 is faster than the MT-16. If the Dnepr I found in that barn had been an MT-16 it would still be sitting there. If a came across a Ural CT at a good price I'd jump on it but if it were a 2WD gear up I would not want it. There are much better off road vehicles that cost a lot less than a Ural Gear up and if I were into off road riding it would not be a Ural.

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