Weird head I found on a blasty. Anyone know what it actually fits?

[Austin Chapman]

Alright new guy here got a buddy into riding and decided his first quad to be a blasty. I also own one. Well the Chinese carb he ordered and didn't jet fried his top end. Which is what led me to this... Does any one know what kind of bike this came off of? I've searched the web and can't find a clue. The bike was running great with it on there though. (With my genuine carb jetted to the bike)

 

[Larry's Shee]

Does the gasket fit head and cylinder properly?

The off center combustion chamber is weird.

My best guess would be a DT 175, mid to late 70s, because of the cutout at right rear, which would be for pipe clearance

https://www.ebay.com/itm/YAMAHA-DT1...404675?hash=item3d976b6c03:g:6I8AAOSw5LRdza5C
Late 70s
Early heads had two plugs

 

[Austin Chapman]

Yes. Everything fit perfectly. Ran the bike for awhile with it on there. Ran the same as a normal blaster head. And that's what I was thinking too. The cooling fins are taller than a blaster head. Maybe could have some increase in cooling.

 

[79 bronco]

I seen heads like that when I was trying to hunt down what bike this head was from.
https://www.blasterforum.com/threads/different-heads-that-fit-the-blaster-cylinder.73193/

 

[79 bronco]

There are a lot of heads that will fit. It looks like you got a old yz head?

 

[Larry's Shee]

There are a lot of heads that will fit. It looks like you got a old yz head?

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What’s your theory on offset combustion chamber?

 

[Slydog]

What’s your theory on offset combustion chamber?

Cleaner burn?

 

[Austin Chapman]

Thought it could be an old yz head but as larry pointed out it has the offsets combustion chamber. Now I'm curious as to if there is or could be any benefit gained from this head.

 

[Slydog]

Look at the pics bronco put up.one of combustion chamber is offset.

 

[79 bronco]

What’s your theory on offset combustion chamber?

I dont know anything about the offset. Never looked into it.

 

[79 bronco]

If it is a yz250 head then its cut for a 70mm piston, when a blaster is 66mm.
Is the chamber in the yz head shallower then the blaster head?

 

[79 bronco]

Could be a it250 head. Some of them have 2 plug holes.

 

[Austin Chapman]

Sorry for the delay... Been working and digging on this head. You guys helped alot. Still unsure what it actually is but we are close. It matches up perfect anyways I put it on my blaster for sh*ts and giggles, immediately had to drop the main from a 290 to a 260 with the needle raised one clip for a matching plug chop. After that it really ran the same, not a noticeable difference at all besides maybe a different power curve right on the pipe. Also noticed (this could be jetting) that there was more smoke out of the exhaust right off of idle, After that it's normal. Idk guys I'm stumped. I've measured this thing every way possible and it all matches up. I'm now curious to find the jug this belongs too and see what it has to offer. BTW my blaster is a 99 ported and Polished the jug myself per Ken's vids and a little extra I did my self, I'm running 1987 trx 250 ex shocks, weisco crank, and a namura Piston.

 

[Slydog]

Or have ken rechamber. A stock head.makes a difference