crankcase heights

can someone fill me in a bit about the difference in crankcases?

anyone actually got the specs or measured it all up?

while i stripped the engine of my 400 last year i quicky nabbed the new woessner that i have waiting on the shelf ready to go in. i slipped the gudgeon pin of the new piston through and into the eye of the existing 400 and checked the crowns. I COULD CRY!!!!!

the piston crown as i recall; was about 2-3mm higher than the stock piston. i need taller crankcases! i even seem to think the taller spigot didn't want to fit but that's vague...

i believe the 400 is small, the 450/501/550 are mediuma nd the 650 is tallest?

have i got that right?

regards

Taffy

well we're getting closer!

regards

Taffy

bump

for those interested in measuring i suggest from under the ID hole of the main bearing up to the cylinder head surface and then add half the crank journal - or we'll add it here!

anyway, got my old owner's book out and also took the measurement of the con rods into account from the doc (engine tuning).

as the 550 and 501 share the same stroke i trust they have the same rod and case? they have a stroke of 70.7mm compared to the 400/470's 60.1mm and the 'throw' is therefore 5.3mm longer. the 400 rod was 120mm and the con rod on the earlier 550/501 was 123/124mm so add the extra throw and the rod length together and you have 5.3 plus 3/4mm which equals 8 - 9.3mm. i expect that give or take a mm to get from the GP to the piston crown that this will be the figure.

the 650 (644cc) has a stroke of 82mm and a rod length of 130mm. the throw difference to the 400 is 11mm, add 7mm for the rod difference and you get 11 + 7 = 18mm.

so within reason we can say that the 501/550 case was 8-9.3mm higher than the 400 and the 650 case was 18mm higher than the 400 case (also about 9mm more than the 501/550).

sorry i didn't add the newer 630 and the 450 in here but as FSF says - the 450 has the same cases as the 400/470 and the 630 will share the same cases as the 644.

anyway! maybe that explains some of those handling traits!

regards

Taffy

oh! dear this has opened a hornets nest hasn't it!

thanks hribman for the offer. if your 450's throw is 1.5mm shorter than the 400 then the con rod would need to be 121.5mm long to use exactly the same cases. so if we can find out what the deck height is of a 450 piston compared to a 400 or 470 - well that would start to tell us something! i'm using the 400 as a starting point and bouncing everything off that.

i forgot to mention here, that the BV heads have another 1.8mm of metal on the cylinder head face. and nearly every other model than the 400 has the BV head. given that it's possible for the 450 to run a 123mm rod and have the piston clear the block slightly i would have thought that the rod would have been 123mm long and not 120 long hribman?

we then start to explain why the 470 has the tallest 100mm crown because it has to reach up over the 400 cases and through into the BV head. case solved and now closed!!!!

i don't even know the difference in the 470's the 550's the 650's and the 450's: 100mm piston. there's one for simon and Dr C!

as for the 650's rod length: well i was given that info and i'm as susceptible to mistakes as anyone as i don't double check things.

was there ever a 130mm rod on the 650? once we get all this confirmed i will change the doc but if the good doctor is right with:

"The conrod length on the 01-02 650cc was 134 mm, which changed with the 03 to 135 mm, if I'm correct"

then we have just raised the 644 cases another 4mm to 22mm more than the 400. the 630 has 1mm less throw but gains it back with the 135mm piston. if i was a tuner of the 650 i would get the longer stroke 644 crank but keep the 135mm rod. if the piston comes out at say .060" (1.5mm) squish and you want just .040" (1mm) then you only need skim and feather in .5mm of the piston and you'll have lovely compresssion and all that goes with it (after you've done the necassary checks).

would like to know why the 550 got a longer rod later as well. i think if we did a parts number check we'd learn a lot more - anyone fancy that?

so if i take into account the BV head this time i make the difference as follows.

400 and 470 case
501 and 550 case around 8mm higher probably than the 400.
650 case is around 21mm higher than the 400.

also remember that it's ok to measure from the top edge of the GP/WP hole but that the 400 has a smaller little end and should be taken into account. when we have these figures we may know even more.

regards

Taffy

hribman i would like to find out what the 450 rod length is?

regards

Taffy

Fourstrokeforce said:

The 450 has a lower crankcase than 501/550 and a shorter timing chain(64L)just as the 400.

Click to expand...

and this by hribman:
I measured some con rod lengths, I´m not 100% sure, but I think that the 450 has got only 117mm and the 400 120mm

hribman, is there anyway you can check that please?

also i can't imagine the rod being smaller with a shorter stroke crank as well? if it is a shorter rod it is a shorter case as well and then based on FSF's comment at the top we would be doomed to a slack camchain wouldn't we?

regards

Taffy

well alex from DCR has made my day and reported back with the 450 rod length. it's 117mm!!!

this means that my long stroke 450 can start to come together now.

one thig i would like to ask here though is: does anyone in europe have a set of 501/550 or maybe even 650 cases?

regards

Taffy

then PM me a price simon. my first spare £50 must go to ady and after that i'll turn my pockets out if it's a great fabo price!!!

regards

Taffy

hribman has just asked me about the possibility of the 400 crank being put in the 450 to send it out to 470. he has told us that the modern pistons are 3mm taller than the older model ones (all 100mm) so surely todays piston is a good bit heavier?

my maths make it as follows
450 throw 1.5 shorter + con rod also shorter by 3mm = 4.5mm shorter. but if you keep the 450 rod all you have is the 1.5mm difference in the throw of the crank. now it all depends on what the squish was like on the 450 beforehand doesn't it?

if you use an old style (i.e shorter) piston though you must be getting close. i'm afraid i couldn't say unless i knew the 450's squish before we started.

regards

Taffy

i'm changing the doc to indicate that the rod lengths went from 134mm in 2002 to 135mm in 2003 and not as the doc indicates: 130mm for the 650 and 131mm for the 630. HAVE I GOT THIS RIGHT?

also, if you get the chance, go into popups gallery and look at the pair of pistons he has that don't even make the top of the crankcase for chrissakes!!!!!. 3mm below for standard and only 2mm below for a H/C woessner!

so when did the taller piston start? was it '04 plus?

regards

Taffy