Individual / single heads from another Yamaha

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Stinke
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Re: Individual / single heads from another Yamaha

#31 Post by Stinke » Mon Dec 25, 2017 6:51 pm

Here are a few pics both of the heads installed and the cooling mod. The heads was really "bolt on" so I´m not afraid to recomend them. Merry Christmas - God Jul (in Swedish) Thanks NS86 for the tip on posting pics

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2 x rd 500 -84
Rd 350 ypvs -84
Rd 250 -74
Kh400, t20

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Vinpg
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Re: Individual / single heads from another Yamaha

#32 Post by Vinpg » Mon Dec 25, 2017 7:02 pm

Thanks Stinke, the reason I did this was mainly for big bore cylinders, I'm finishing my new motor and it's a 64 bore, so it make's it easy to swap. Also to all that have these heads custom domes are totally available, change squish clearances or compression whatever you may need.

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tacky1
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Re: Individual / single heads from another Yamaha

#33 Post by tacky1 » Mon Dec 25, 2017 8:01 pm

Stinke wrote:Here are a few pics both of the heads installed and the cooling mod. The heads was really "bolt on" so I´m not afraid to recomend them. Merry Christmas - God Jul (in Swedish) Thanks NS86 for the tip on posting pics
Many thanks for posting this Stinke. Its nice to see pics of the mod,
Question for you, I see you running a different Fan switch up by the stat, Do you have a part number for this, The OEM switch does not work on Both my bikes. I would like one top open at 85 DEG with an RG250 stat, That way both are roughly 85 deg with the stat opening and the fan kicking in, I have both mine on a switch.

Thanks.
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1989 VFR750R RC30
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Stinke
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Location: Sweden, Borgeby

Re: Individual / single heads from another Yamaha

#34 Post by Stinke » Mon Dec 25, 2017 8:58 pm

Well Tacky1, Thats not a fan switch, its for my Koso instrument to measure temp. I actually removed my fan. As you can se I use the temp switch Threads for the return flow from the rear cylinders. We rarely get over 30 degrees Celsius in the summer in Sweden and I rarely drive in town so the fan is useless. The engine has about 95rwhp but stays at around 70 degrees Celius when I drive it in the summer 18-30 degrees in the south where I live (a lot of WOT). The specs of the bike is: Keihin 28´s, heavy cleanup on barrels, heads by Gus, flowed reeds with carbon fiber, zeeltronic ignition (51GE curve +5 advance) and different pv opening, Jolly Moto GP Pipes. It runs fantastic.

Please ask more questions if I'm not making any sense, english not my first langauge. I would like to help as this forum has hop me ALOT.

/ Stinke
2 x rd 500 -84
Rd 350 ypvs -84
Rd 250 -74
Kh400, t20

The best of swedish metal: https://youtu.be/gkBt7yLXyDk" onclick="window.open(this.href);return false;

Ron57
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Re: Individual / single heads from another Yamaha

#35 Post by Ron57 » Tue Dec 26, 2017 6:13 am

Hi Gus, your heads look a bit taller than standard, would there be any clearance issues using different front ends I'm keen in ordering a set off you. I've also used two sets of your cranks with no problems.
Cheers Ron.

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tacky1
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Re: Individual / single heads from another Yamaha

#36 Post by tacky1 » Tue Dec 26, 2017 3:21 pm

Thanks Stinke. I have to pull the top end off mine and I'll do the mod for sure. What size brass inserts did you use on the cylinders
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1989 VFR750R RC30
1984 GPZ750 Turbo

Vinpg
Posts: 73
Joined: Wed Sep 13, 2017 7:35 pm

Re: Individual / single heads from another Yamaha

#37 Post by Vinpg » Tue Dec 26, 2017 6:33 pm

I'm trying to post pictures of the machining process and am having a hard time but will figure it out. Lol

Vinpg
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Re: Individual / single heads from another Yamaha

#38 Post by Vinpg » Tue Dec 26, 2017 8:30 pm

Ron, I'm sure they are taller but use the stock studs so I'm sure they don't cause any issues

Vinpg
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Re: Individual / single heads from another Yamaha

#39 Post by Vinpg » Tue Dec 26, 2017 8:42 pm

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Vinpg
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Re: Individual / single heads from another Yamaha

#40 Post by Vinpg » Tue Dec 26, 2017 8:46 pm

sorry for the huge size but you can see the casting does not go to the top stopping the water flow, the water enters the head and instead of being forced down the barrel it goes around both sides of the combustion chamber and out the exit, to me this is why the rear cylinders run excessively hot.

Vinpg
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Re: Individual / single heads from another Yamaha

#41 Post by Vinpg » Tue Dec 26, 2017 8:49 pm

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Vinpg
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Re: Individual / single heads from another Yamaha

#42 Post by Vinpg » Tue Dec 26, 2017 8:53 pm

again sorry, ok the casted cylinder head has a coat hanger shoved through the water passage to show the path water may be taking, on my head the wall forces the water down the back of the barrel and allows a large exit out around the exhaust, the square lug is turned in the next operation, but you can see what I'm referring to.

Ron57
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Re: Individual / single heads from another Yamaha

#43 Post by Ron57 » Tue Dec 26, 2017 10:50 pm

Hi Gus, thanks for the reply and yes you can see how your heads will definitely flow coolant better than stock.
Cheers Ron.

Vinpg
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Re: Individual / single heads from another Yamaha

#44 Post by Vinpg » Tue Dec 26, 2017 11:17 pm

I believe the flow on the rear heads is not a good design, if you run a stock head something needs to be done to fix that straight in and out problem in my opinion.

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Rick Lance
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Re: Individual / single heads from another Yamaha

#45 Post by Rick Lance » Wed Dec 27, 2017 11:32 am

Gus, you may want to review what differences there are with the stock head gasket (front vs rear) with regards to regulating water flow. Not negating any improvement with your design but Yamaha made an attempt to address this issue with the gasket portals.
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