ID this head please.

[YZ250H]

Came on the YZ250C, but doesn't look like it gets along with the exhaust very well.  The only stamp on it is "118"
I suspect a ring-in.  Can anyone confirm or deny ??

[Iain Cameron]

need to see a front on photo but from what you have shown looks  right ,they had only a poofteenth of a gap for clearance
Iain

[YZ250H]

You might have to wait until next week-end now Iain 
So what was the reason for the 2 plugs ?

i think Vandy has a 2 plug head on hit RT1.

This head has the right amount of studs, but it looked to be really close to the pipe 

[motomaniac]

The 2 plugs came on the IT heads

[cyclegod]

Looks like a 75 MX250B head to me

[YZ250H]

MX 250 B the same as YZ250 C ??

[Iain Cameron]

Yes the mx 250 b is the same head , twin plugs where the go till the 77D model if one got fouled switch to the other
regards   Iain . ps Ill check my yz 250 c head tomorrow

[mudguard]

My 250C has only 1 spark plug. Thats correct  as per the parts manual. There is enough clearence to fit my fingers between the head and exhaust. Pretty sure mx250b has same head as 250c, the exhaust is identical for both bikes.  Could be mx250a.

[Nathan S]

MX-A has fins cut out for exhaust clearance.

DT250 mono shock?

[the stig]

[quote author=iainyz
Yes the mx 250 b is the same head , twin plugs where the go till the 77D model if one got fouled switch to the other
regards   Iain . ps Ill check my yz 250 c head tomorrow
[/quote]

                 The Idea of the Twin plug Head was to start your Motor on an 8 plug
                 then Switch Over to a 10 or Race plug once you warmed the motor
                 up..To save Having to Change Plugs..on the Start line..
                 
                    The Stig..

       

[YZ250H]

That is actually a brilliant idea.  I wnder why they didn't continue it on ?
A blessing for all of those that have had to change a plug .... on the start line 

[Nathan S]

Was the head originally a twin-plug head, or a single plug head that's modified?

[Iain Cameron]

Page 57 of the mxb75 250 manual show the head with the blank in place . best photos in the yzc250 manual is page 73  on page 40 you can see the cut away through the fin in front of the dail guage
Iain

[bruiser]

I had a worked YZ250C many years a go with a dual plug head and 2 coils to run both plugs at the same time.
The bike went very fast and no problems with detonation or pre ignition.

[Iain Cameron]