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so how come? (big end chat!)

Taffy

Taffy

Joined Nov 2001
17K Posts | 774+
Ely, England
how come this husky 577 i'm working on gets away with a 30mm big end? the crank is a solid piece of kit with huge main bearings. surely if what we know about the husabergs are true - the 30mm big end should be way too small?

i saw it written once that it was critical that the pin was as narrow as possible compared to it's diameter and i see that it's still wide due to the 22mm rod when the early huseys ran 18mm wide and from 2001+ they ran 20mm wide?

what gives there? we were always assured that the 32mm crank flexes too much?

regards

Taffy
 
if the mains can handle it maybe flex is OK

orrite more info please taffy

how much does the crank weigh? what is the stroke? full circle or pork chop? how big are the mains? how thick are the flywheels where the pin goes through them?
 
Yes, I wear a flat cap, send sms without any abbreviations and welcome rain as it will do the lawn good. Simply an old fart who repeats himself:

No need for a space for the counter balancer => less distance between the mains => less flex
Larger distance with press fit on the crank pin compared to its diameter => more firm fit => less flex

Just to mention a few parameters.
 
well the husky 577 from 2001 has;

98mm bore x 76.5mm stroke
6306 mains (8-ball) 30-72-19.
the flywheels are circular, 24mm thick, 62mm across the shoulders.
crank c/w rod weighs 5625 gms or 5510gms if i hold up the little end.
30mm journals.
30mm little end.
it's 61mm across the big end pin.

i also have a kawazaki KLR650 in bits here;
100 x 82mm 644cc
40mm journals
40mm big end
24mm little end, 22mm wide.
27mm flywheels, 68mm across the flywheels.
roller mains

just thought i'd mention it....

i can't get over that 30mm big end? it makes you think that the balancer putting the shoulder of support further away makes the situation worse than the fact that the old 644 had a 32mm big end? maybe a 32mm big end was otherwise good enough and the balancer just wrecks it!

if that is the case, a 400 single row balancer, narrowed right down to the width of the single row bearing could be fitted in all engines with a 20mm wide main.

regards

Taffy
 
Is it possible to remove the balancer and fit a wider bearing? (i already have the balancer removed)
 
there is a 20mm wide main that jason (weed) and JBS have used. i think the code is 62226 or similar. maybe you didn't understand me but i make your point in the post above.

regards

Taffy
 
Taffy said:
there is a 20mm wide main that jason (weed) and JBS have used. i think the code is 62226 or similar. maybe you didn't understand me but i make your point in the post above.

regards

Taffy
Click to expand...

Sorry Taffy mis-read your post. Interesting, if I need to split my engine for my missing 6th gear I will try that 20mm bearing :)
 
I run no CB 75% bal factor and rollway Nj2206 C4 (20mm wide) on drive side.

there are some with concerns over the bearing being unsupported in (or not in) the cases for 4mm.

the rollers themselves are not 20mm wide so when installed the bearing outer has support from the cases over the area where the rollers run.

I found the engine to be a lot smoother going from 16 - 20mm wide but i also rebuilt the crank with a new pin/rod and had less runout than before too so not sure if its one or the other. 0.08 runout then rebuilt to 0.02

the counterbalancers location is rediculous.

interesting find taffy, the husky crank is a heavy SOB, whats the BGP crank weigh?
 
Re: RE: so how come? (big end chat!)

Taffy said:
well the husky 577 from 2001 has;

98mm bore x 76.5mm stroke
6306 mains (8-ball) 30-72-19.
the flywheels are circular, 24mm thick, 62mm across the shoulders.
crank c/w rod weighs 5625 gms or 5510gms if i hold up the little end.
30mm journals.
30mm little end.
it's 61mm across the big end pin.

i also have a kawazaki KLR650 in bits here;
100 x 82mm 644cc
40mm journals
40mm big end
24mm little end, 22mm wide.
27mm flywheels, 68mm across the flywheels.
roller mains

just thought i'd mention it....

i can't get over that 30mm big end? it makes you think that the balancer putting the shoulder of support further away makes the situation worse than the fact that the old 644 had a 32mm big end? maybe a 32mm big end was otherwise good enough and the balancer just wrecks it!
if that is the case, a 400 single row balancer, narrowed right down to the width of the single row bearing could be fitted in all engines with a 20mm wide main.

regards

Taffy
Click to expand...

I think you will find JBS adressed this issue with their early(full circle?) cranks by tapering the outer OD down to be adjacent to the main instead of allowing room for the CB to try and stiffen them up??
 
hey taffy before the site crash you weighed the 644cc BBP crank at 7kg plus?

the single row balancer with the 20mm wide main bearing sounds good would like to see a pic of a single row balancer, enginehardware has one in his gallery I think.
 
so what do you need to know about the 644 crank bushie? not following you?

i don't have an intricate one of the 400 balancer available right now. but i will take one.

regards

taffy
 
just wanted to stick the data back in after the crash

7kg+ for the Big Black Pig crank, like you said its no cat
 
so how come the husaberg runs a really narrow rod at 18mm and the husky 22mm?

how come the FC/FE600 has an 84mm stroke yet only a 30mm big end pin with no oil feed and had no trouble? or did it?

so how come hey?

regards

Taffy
 
sort of depends on what you are getting at taffy.
there never has been a problem with the big end in any std husaberg motor,whether it would be 30mm/32mm/35mm.
hey... have a look @ the honda cr500 crank it runs a 26mm crank pin with a 414g piston hanging off it,where my old fe650 has 32mm pin with a 280g piston hanging off it.my berg looks much stonger than the cr doesn't it.
the problem with the smaller pin dia (30mm/32mm) is that it can cause the crank to flex under full steam.the 35mm pin holds the crank webs more rigid.the more the flex ,the more it has a detrimental effect it has on the mains especially the roller type main.so now we just done a full circle back to main bearings.........
ok you say,don't use the roller mains,use the 9 ball instead.well yeah maybe.....they last ok,& don't have a problem with crank flex like the roller mains,but they are too undersized to last the same mileage of a yamaha or honda.
remember the yamaha & honda have the same ball as you just described as "huge" (6306).
so it really can't be just a big end chat without getting the mains involved
..weed..
 
well the husaberg piston is lighter by 35%
the husaberg rod looks a lot lighter as well.
if the big end pins are the same width at 61mm but the rods are 4mm different: well that means the husky flywheel is 2mm wider on each cheek. so surely, if the husaberg big end bends what the friggin hell happens to the husky big end 4mm further between the flywheels!

something doesn't add up. are we predisposed to thinking it's the big end being weak all because of the tests that ben ballard had carried out?

regards

Taffy
 
weed

i don't think the crank flexes at all. I think that there are a lot machines that have been put together wrongly at some point. you're right, big ends haven't gone so it's all in the mains.

we've had poor axial tolerances, poor quality, bad manufacture, we've had tight cases, tight journals, we've had the 'bull ring' system of dragging everything to the left but when all is said and done; the idea of the crank being in a different resonance on the left from that of the right that the right suffers from a lack of oil - these are the two things that run through this.

but i'm saying weed that a 30mm big end was good enough in the FC600 and it's been good enough in the huskies so i think that all this 32mm being too weak is bollocks. the japs run far smaller big ends. the only big ends i know to have gone are those that didn't have oil or the mains went first.

there are a lot of bad engine builders out there. Enginehardwear has and still does use 32mm big end cranks and i know that DCR prefers them as well.

I therefore declare not only the 32mm big end to be adequete but make a case for the 30mm big end being good as well.

here's to good mechanics!

regards

Taffy
 
i did notice the 32mm pin 550 crank moves very easily on the pin

about half the force to move it compared to the 35mm pin with the same interference fit

i did a 250 2t crank yesterday, interference fit was huge took about 15 ton to move a tiny pin

perhaps the 30mm husky pin has a tighter fit than the 550 berg. flex or not if the crank moves on the pin your endfloat is out and the crank alignment is gone.

every crank Ive seen is spread opposite the pin, to get a welded trued 628 crank to spread as far as it does in use I have to flex it 3-4mm in the press. so I say the flex in my engine (35mm pin) at the flywheels is around 3-4mm

the 550 crank was spread so bad it was out 0.2mm between centres and in the press it took about 4-5mm deflection to get it to move that far from trued

with the CB location forcing the LH main out further than the husky you have to agree whatever deflection a crank has in the husky will be more in the berg, beam deflection varies with the cube of the beam length, more deflection means more chance the crank can move on the pin.

I don't know what really happens :oops:

like you said its probably everything all at once, if you get most of it right there is a far better chance its all going to work.
 
so are you saying your 35mm crank does spread or that it would have to spread 3-4mm to make 0.2mm difference opposite?

i don't believe for a second that the pin moves in the flywheels but i'm prepared to hear that it flexes if you say so. however, that doesn't explain all the reasons why huskies don't and husabergs do have problems and why others have smaller pins. there has to be another answer methinks. wish i could mount a camera!

why do we put a ball on the left and a roller on the right? is that coz the left flexes and the right runs short of oil?

regards

taffy
 

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