250-500cc racing cilinderhead wr250 wr300

Hallo,

Does anyone use a racing head on the wr250?
What will be the difference to te Stock head?
I looked by HTM racing Italy.
Thee Sell heads

Greets marco

I'm not sure what year wr 250 you are asking about but I know on my 09 a racing head won't get you much since the factory stock head gets you about 205 psi cranking compression. The WR300 is another story and there is a gain to be had from the race head.

Hallo ich have also the 2009 wr250. I have the fmf gnarly on it.
The carb is the stock mikuni.
I would do some mods to get it run smoother of idle
I changed all ready the needle and main jet.
Also a little more power would be nice
Is it better to run with stock ignition timing with the gnarly or can I go a little earlier or later.
The racing head will not help to increase the power?
The form off the head looks also better with the nice squesch erea.

My perfect settings for my Mikuni on my 09 wr250 with Gnarly pipe.

32.5 pilot jet
GAY needle in middle clip
420 main
air screw 1 turn out

If you can afford it then get a 38mm Lectron carb. It will run better everywhere and use a lot less fuel. I wish I had bought a Lectron before I spent money on jets and needles to tune my Mikuni which has been sitting on the shelf for the last 3 years.

Oke thanks for the answer.

I run 430 main with 40 pilot and needle from the power kit husqvarna. Needle clip on third.
I think main would be a little less 410 or 420 and pilot 35 37.5
But at the moment it is almost ok for me wenn it will get a little better of idle is ok for me

I'm from Holland the adjustment would be here a litte different to us i think.

Your bike will probably idle better with a smaller pilot. My settings are for 1,500 ft above seal level (about 500 meters), usually around 2,000 ft (about 700 meters) air density altitude. I think the Husqvarna power kit comes with the GAY needle, it will be stamped on the needle near the clip grooves. Your 230 main should be good assuming your air density altitude is less than at my location.

I will try it ordered the jd needle kit as well to try.
I heard the mikuni carb from 2009-2013 wich I have would be better than the older tmx.
The jd comes with two needles wich one do you think will be the best for Holland.

I don't have any experience running a JD needle. The GAY needle should work fine, it worked for me in the middle groove from 1,500 ft in Missouri to 9,000 ft in Colorado with only a tweak on the air screw. If your bike is running fine except for the idle you should not change anything but the pilot and maybe try playing with the air screw and idle screw, then once you have the idle sorted then decide if the needle or the main need adjusting.

I think with the JD Kit the important part is the nozzle (or needle jet). The JD Kit will come with recommendations on which needle to use for based on your riding altitude and temperature.

Oke I didn't now that also the needle jet was included. Are normally also pilot jets included?
I ordered the kit in Germany and it comes with three days to holland :-)
Also now I will have more variations to test.
Off throttle it's blubbering but at half throttle it's to lean I can't wait to test.
The htm racing company also sell spacers for between inlet and cilinder, does anyone has a Idee what will be the difference with those spacers.

I have the jd kit on my 09 wr250.
It comes with 4 main jets 380,400,410,420
32.5 pilot
s-9 nozzle
and two needles, red and white.

There are comprehensive instructions included but I have ended up quite a bit leaner (except main) than where I started.

After two years riding and several different combinations I have found the best setting for my bike and conditions is:

s9 nozzle
white #4
30.0 pj
420 mj

Standard pipe
40:1
sea level to 100m
20 dg celsius

It absolutely rips from idle to max rpm, starts easy, will idle all day, plug light tan. I put a new piston in at 90 hrs but could have easily done rings only. Over half the bikes total hours(about 130 now) have been racing and a lot of that in sand.

Oke nice to hear thanks a lot.
I have now pilot 40 32.5 looks very little but we will see.
What do you change in summer to winter only the main 10 bigger or even more?

Installed today the jd kit and it works just fine.
I used the red needle third spot
Pilot jet 35
Main jet 430 (winter and below sealevel)
Runs great what an improvement
I had the J8-6DEY15-74 needle in it whit 440 main and R-8 needle pipe.

I bought the kit from htm. Cylinder, graphite piston, black race head and the spacers. My wr has now become a 450 destroyer. What a weapon. I also run the kiehin pwk and red jd jetting needle. Jetting can be fun. I now run 35 pilot and 162 main. If you are looking to jet your bike it will usually be different from one bike to the next so just trial and error. Pipe seems to affect jetting also. Love this thing. What a ball tearer!!!

Never hear if htm racing before. Got heaps of gear!!! Can't get prices tho on website n in Italian?

Hello,

They speak english no problem at all.
The racinghead and spacers are a real improfement.
I use the FMF exhaust and one inlet spacers

I just had my engine rebuild and have now the 6 gearbox from the WR360
front 15teeth and 47 rear

new piston and rod etc.
Now had to make a little changes to the jetting

JD JETTING WITH MIKUNI TMXX

iddle 27.5
Main 440 (spark plug nice brown :-) )
needle clip second position
jetting is perfect everywere

the bike is realy strong and the 6 gear is ment to be a overdrive but i can ride in de sand standing on de bike easely about 130km/h

remember to jet for temperature and altitude