250-500cc Is WR300 racing head a good choice?

The part number of hi comp head is 8000H0944

To be honest I didn't and you really should. The combustion chamber visually looks smaller than std although again I didn't check the volume against std. I really did bolt it on and ride.

don't feel bad, I did that exact same thing

IMO, the race head is the only way to go. Even if you're going to have it machined for a full race motor, it's a better starting point than the stocker.

Is there a factory race head for the 250 or did you have yours machined?

No there isn't a race head for the 250, but I had one on my bike when it was a 300.

Doug the squish on my 250 was .095 thousandths with the thinnest base gasket.I'm gonna bring it down to .080. I'll let you know how it works.

You know reducing the base gasket thickness will also effect your port timing so won't be the same as a race head. The squish sounds a lot at .095". what is the CR reading?

I bought the bike used so i just replace the base gasket that came on it.I'll probably end up going to the next size thicker base gasket as i noticed the ports are not fully opened at BDC. Don't know what the compression is at the moment.

i was told by a dealer that the bike pings with the high comp head even with high octane fuel - comments?

High compression with poor fuel is one of the most common problems that cause pinging but not the only one. It can ping because it's lean, overheating, or too much spark advance, carbon deposits on the piston can get hot and cause preignition which is going to sound like pinging as well.

The race head isn't that radical as to cause ping on good pump gas here in the states. The stock head is a very low compression tub head that should be able to run on the worst gas.

That is not an issue. 90% of the flow through the port takes place in the first half of the port opening. Ten or twenty thou. on the bottom isn't going to make any difference as long as the open time is long enough to fill and scavange the cylinder.

Well, I bought piston, powervalves and hi comp head to transform my 250 to WR300. More or less 30 days do arrive here in Brazil. I will make a DY transform 250-300 and post in cafehusky.
I am thinking, what I will tell to my wife I guess, this a global problem ....

I didn't have any pinging on my 300 with the racehead, and i used 95 octane fuel on the icetracks on a lot of wot. No problems at all.

Wow Johnny 64 ft. lbs of TQ that must be FUN!! I think I'm going to pick up a 300 TM MX for my tq. fix.

HRC630 that pic looks familiar

Here's my 300 head I modded.
http://www.cafehusky.com/attachments/wr300head-006-jpg.1398/

Just a FYI: if you look at the stock squish angle you will see it "looks" like it was designed for a domed piston.
If I had to do it all over again, I would have picked up a domed piston and modded the head to match.
If it even needed it!

Motorsportz in Washington State sells them for around $120. Talk to Kelly, good guy, he'll set you up.

Hi
I installed the racing head '0944 ' with these settings:

Cylinder gasket 0,7 mm
jet needle (6 gay) on 3rd clip
pilot jet 45
main jet 440
2 , 3/4 turns out on the air screw
exaust similar fmf gnarly
silencer leovince X3

The bike has significantly increased power at all engine speeds while still providing a very straightforward,
power at low engine rpm like 4 stroke and high engine rpm never ceases to power like a 125 2t,
very very nice to drive, very good product.

Does anyone have one of this products? Is this high compression head or standard(replacement)? And reinforced power vave springs, what effect do the have?

http://www.htmracing.it/cms/index.php?option=com_content&task=view&id=187&Itemid=178