2006 bike 2003 head possibly complete motor?

[823bonestockracing]

Im a former 2 stroke guy. I have only had 1 4 stroke which was a 04 yz250f so i have little knowledge with the 4 strokes.... so i bought a 06 crf450 has clean title (matches vin on bike) get to guys house and the bike looks ok not pristine but not a pile... bike was cold to the touch when i got there, checked fluids all looked good, he fired it up it ran strong no pops or anything rip down the road all was good even at slow speed. Checked the coolant after the test ride looked good. Bring it home... today tried to fire it up and no luck. Decided to check a few things- pulled the valve cover to check auto decompression and i find milky oil.... bike has a blown head gasket or base gasket ( hope there isnt a cracked case or something) anyway then just for shits im looking at my bike next to my buddys 06 and sure enough the head is different mine has a 02-03 head on it. Got f#@ked in the a@% with a sand paper condom with this thing. Anyway looks likeim spending some $$$$ to get it right. So my question is.... are there any differences in a 02-03 crankcase and assembly?? Good/bad? One better? I have no clue how to tell if it is a 02-3 crankcase or a 06. The heads for sure a 02-3 so that being said other than the valve issues i have read for those years is that head ok or do i spend the $$$$ and try to find a 06 head? Thanks im pretty much lost

[Diggla117]

First I'd call a dealer with the vin and try to figure out what year motor you have.

[823bonestockracing]

i checked out the number stamped on the case today and ist a 2006 crankcase. The head is for sure a 02-03though it has the two bolts just below for the valve cover which i believe was for decompression cable or something this one has a sight glass/plate bolted there.  do i junk the head and get a 06 or is the 02-03 head ok as long as it has a valve upgrade????? any help would be appreciated!

[Diggla117]

i checked out the number stamped on the case today and ist a 2006 crankcase. The head is for sure a 02-03though it has the two bolts just below for the valve cover which i believe was for decompression cable or something this one has a sight glass/plate bolted there. do i junk the head and get a 06 or is the 02-03 head ok as long as it has a valve upgrade????? any help would be appreciated!

If you do buy another cylinder head get a 08! Better flow due to the valve sizes. If there isn't anything wrong with that head then I say run it

[bushman45]

the 08 head does not flow as good as an 06. and if you are porting it, go with the 06 because of the bigger exhaust valves. i'm having an 08 head done now and the bigger exhaust valves are going in. it does't cost any more to cut the seats for the 06 valves. i'm building an 08 now for dirt track and using the 06 decomp (it's better) and exhaust components. now my flattracker framer has a big valve 06 head and it's a beast.

[Diggla117]

the 08 head does not flow as good as an 06. and if you are porting it, go with the 06 because of the bigger exhaust valves. i'm having an 08 head done now and the bigger exhaust valves are going in. it does't cost any more to cut the seats for the 06 valves. i'm building an 08 now for dirt track and using the 06 decomp (it's better) and exhaust components. now my flattracker framer has a big valve 06 head and it's a beast.

I always heard the 08 head made more ponies because of the smaller exhaust valves.. also if the 08 was the bike honda just threw everything at(speaking of upgrades) then why would they go backwards and put a head on that dosnt flow as well as previous years hmmm Edited April 20, 2014 by Diggla117

[823bonestockracing]

the 08 head does not flow as good as an 06. and if you are porting it, go with the 06 because of the bigger exhaust valves. i'm having an 08 head done now and the bigger exhaust valves are going in. it does't cost any more to cut the seats for the 06 valves. i'm building an 08 now for dirt track and using the 06 decomp (it's better) and exhaust components. now my flattracker framer has a big valve 06 head and it's a beast.

^--- good info! i read that the 06 head is better and is what i would like (not sure why they stuck a 02-03 head on this bike) ... but my question really is if the 02-03 head that is on the 06 crankcase etc worth keeping and putting stainless valves in (if it hasnt been done already) is there a difference in the porting etc between them 02-03 vs 06 or is it just the valve issue in the earlier heads that make the 06 more desirable! by the way i have a good friend that owns a extremely well known head shop that does big dollar heads on race cars etc..  he could do my head work... but $$ into 02-03 head or not????

[bushman45]

honda updated the head and changed cam profiles over the years, thus the differences. these tuners have created packages that produce different type of power.and buying from them is not off the shelf. cam design is very important and these tuners have them ground to their specs. these heads are not like your automotive design so experience working on them is important. runner profiles have been changed along with rod lengths which changes how cam timing and lifts are determined. if you go to some of camshaft web sites they give you the information on how timing works and how to check it. i have been told that the honda design is the best and easiest to get horsepower. i look for a good power curve with torque numbers, not just peak hp.  

[Diggla117]

I'm pretty sure your trying to explain to me how a cam/timing works

Edited April 20, 2014 by Diggla117

[bushman45]

believe me i'm no engine genius. my notes and cam cards are at the shop, but one i have here is webcam grind #493/1081. this is a good all around cam short track, tt, and half mile. the one i'm using in my dtx build is a little milder. i also have run the 07 and hrc atv cam. the one in my framer is real big with a lot of exhaust duration because i have a stroker crank in it. installing the cam in the right place is the key, so get yourself a degree wheel and a dial indicator and have at it. and oh be sure to check clearances!

[823bonestockracing]

I understand that they did all the updates over the years, im not a track rider/race guy. Im a woods rider so a stock 450 does just fine with me! But is the 02-03 head ok to run if i check to see if it has stainless valves and if not put some in it or do i just spend the $550 and get a 06 head that is already done.... bigborethumper.....

[bushman45]

I understand that they did all the updates over the years, im not a track rider/race guy. Im a woods rider so a stock 450 does just fine with me! But is the 02-03 head ok to run if i check to see if it has stainless valves and if not put some in it or do i just spend the $550 and get a 06 head that is already done.... bigborethumper.....

yea see what you have first, don't go spending money if you don't have to. i ride an 08 in the woods and it's stock with trail friendly mods and it's a bit much. probably should get a something smaller and lighter but it's my baby.

[Shawn_Mc]

Honda is kind of famous for the introductory engine being a beast and then detuning it for ridability until its almost useless.

 

The 02-03 head was fine after the valve/seat issue was corrected. The later model heads were to make the engine more "rideable" not more powerful. The smaller valves on the 08 head were to add some bottom punch without making it violent in the middle. Honda did all sorts of stuff to make the engine easier to ride. The selector switch on the shift drum to back the timing off in first and second etc.

The 02 had the wildest cam they ever made from OEM.

 

If it was me, and I was just going to have play bike, Id leave the 02-03 head on it. Just fix it and enjoy it.

[823bonestockracing]

Shawn- thankyou thats what i was after simple "fix valve issue" and the head is good! Ill be sure it has been upgraded persay and ride and have fun! Thanks again