644 vs 628

popup · May 29, 2010

[quote="bushmechanicMig sounds nice, the pin welds are not as effective as I first though so ive probably been over doing things a little with the preheat oven and TIG, sounds good though

[/quote]
why do you say that bushy?
i like your idea of over trueing it slightly then welding it.
..weed..

bushmechanic · May 29, 2010

I thought the welds would stop crank spread or at least reduce it to an insignificant amount but they don't

unwelded my crank came out spread 0.08mm runout between centres, the flywheel runout was 0.03mm when i got the bike

welded and trued came out spread 0.05mm but i added crankweights so its got more loads on it. i tested in the press, to get the same runout from trued the crank needs to be flexing so the gap between the webs opposite the pin grows by 4mm. the spread was dead opposite the pin so that tells us the biggest flexing loads are due to the crank flywheel weight and not from the power stroke or the rod/piston inertia on the exhaust stroke. the power stroke adds some to the cranks flexing loads and some guys reckon the mains last longer with lower compression / slower burn.

overtrued by 0.05mm and then welded ... i'll find out later, only just managed to empty the shed of broken rhondas and bucking suzukis :lol:

the welds do make it impossible to twist the crank if thats a problem

what i'd like to try one day if i can get another set of cases or if the 700 explodes is getting an 80mm or one of those weird no oles 82mm cranks down to under 4kgs total, 270gms or less lightened elko or wossner and a Ti pin,

popup · May 30, 2010

all good info bushy!
if the crank with the 35mm pin is spreading 4mm,i don't even wana think what the 644 crank with 32mm pin & 90%bf counterweights is spreading! 8O
sounds like a worry doesn't it? but i'm over it. i have flogged it & flogged it & i have confidence in it 8) .i have not held back at all.it has copped whatever i have delt out.
in saying that, i do see your point.the 644 crank weighing in @ over 5kg swinging off a 32mm pin,is a recipe for crank flex.has to be!
when i pull it down, i'm thinking i should be see some evidence of crank flex on the ends of rollers of the mains & main bearing inners,after all thats where they break the inners.
tell ya what! :idea:
if we find a 04 644 crank,i will pay for it & your time to do your bushmechanics on it,then i will glady test it for the good of all "husaberg mans" sake.

i'm not joking.......well only slightly :mrgreen:see what comes up.
i must be getting lazy or old,dunno? but i have enough grey hairs.
i am seeing what the theory says, 04 644 crank lightened,composite rod, ti pin,std wossner piston for minimal crank flex. i think you would have to have a flywheel weight because it would just be too "cracky",everytime you crack the throttle it would throw you & the bike into the scrub.it is touchy enough now!
as they say....add $ & stirr.....
..weed..

Taffy · May 30, 2010

bushmechanic said:
welded and trued came out spread 0.05mm but i added crankweights so its got more loads on it. i tested in the press, to get the same runout from trued the crank needs to be flexing so the gap between the webs opposite the pin grows by 4mm. the spread was dead opposite the pin so that tells us the biggest flexing loads are due to the crank flywheel weight and not from the power stroke or the rod/piston inertia on the exhaust stroke. the power stroke adds some to the cranks flexing loads and some guys reckon the mains last longer with lower compression / slower burn.

so surely we're talking about an unbalanced crank here? too much weight opposite the pin?

regards

Taffy

bushmechanic · May 30, 2010

yes absolutely but there is less weight opposite the pin than a stock 644 ?, if the total weight was around 3.5 kgs including rod and pin I don't think it would spread much

FWIW the overtrued and welded crank has gone to 0.06mm spread between centres, but each time i do more to reduce the spread I've also increased the loads on the crank. in each case though its ended up about the same

so is the crank spread limited by reducing the spreading loads and stiffening the crank or do the mains just limit the spread?

would like to know how much Weed or DrCs cranks spread.

lots to think over but like you said Weed they cop a flogging Dr-Cs and your 32 and my 35 get the bejesus squeezed out of em, none of us have mains issues... i think ? .... i never have and you guys have fixed it by now so I say nothing to worry about... more power capitan :twisted:

bushmechanic · Jun 1, 2010

tell ya what!
if we find a 04 644 crank,i will pay for it & your time to do your bushmechanics on it,then i will glady test it for the good of all "husaberg mans" sake. i'm not joking.......well only slightly see what comes up.
i must be getting lazy or old,dunno? but i have enough grey hairs.
i am seeing what the theory says, 04 644 crank lightened,composite rod, ti pin,std wossner piston for minimal crank flex. i think you would have to have a flywheel weight because it would just be too "cracky",everytime you crack the throttle it would throw you & the bike into the scrub.it is touchy enough now!
as they say....add $ & stirr.....
..weed..

hey no worries you find it ill cut it down and you can try and break it. too touchy? you need to move over here, ive got some spare paddle tyres :twisted:

644 vs 628 ... :idea: if the 28ccs is only worth 2.65 HP what about the 600?

ProCro · Jun 11, 2012

one stupid question :mrgreen:

is it possible to fit 35mm rod on 644 ('04) engine with some minor modification? Or do i need that bell type crankshaft? I see that cylinder liner and pistons are the same

ProCro · Jun 15, 2012

anyone?

i see that engine cases are diferent part number

2004 820.30.000.044
2005 820.30.000.144

Peej · Jun 15, 2012

Cases will be different, the change of crank happened at the same time as switching over to the Kokusan ignition, same as KTM RFS. It requires a pickup so the cases are altered to accomodate this.

Ghost · Jun 15, 2012

Peej said:
Cases will be different, the change of crank happened at the same time as switching over to the Kokusan ignition, same as KTM RFS. It requires a pickup so the cases are altered to accomodate this.

Change of crank happened after the change to Kokusan. -04 has Kokusan ignition and 644cc, -05 and later has Kokusan ignition and 628cc. -04 is also the first year using a Keihin carb.

regards

Nick

ProCro · Jun 15, 2012

that's right, I have kokusan and 644. So it is, or it's not compatible?

644 vs 628

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