400->470 failed, need help

does anybody know!!!!!

i always like that one and i know what you really mean!

your squish is .75mm and wants to be safely about 1.2mm so i would take .5mm off around the circumference so that at no point is it less.

470 plus 34 is 504 divided by 34 = 14.7 to 1

the bit you take off will bring that down to about 14 to 1.

you really must get the ignition timing right, the jetting, the valve timing, exhaust system THE LOT right.

as i say, i would consider a 450 rod kit and an elko piston NOW. sorry but thats £400 right there. E500.

regards

Taffy

Ok engine builders,The marks on the top of that piston look to me to have come
from metal pieces not detination!! If it had that type of detination going on it
would have not lasted 30hr. & ran well at all!

your rocker arms won't transfer. you want a head complete with valves and a rocker cover OR you can use your rocker cover but with BVH arms.

i tend to think these bikes are always getting soome detritus in from somewhere. but i don't think it's anything more serious than that boss.

regards

Taffy

Here is a 400 head on Oz eBay that seems cheap at the moment if you need a spare.

its a 400 bundy so its a small valve head. the only SV head is on the 400 (35/27) and all '04> bikes (35/30).

regards

Taffy

be warned. i have had a 470 in recently that had the '04 head on it. the head has no oil feed to the head, the valves are 35/30 and the compression is probably high. what's killing it is the two squish areas behind the pairs of valves.

this area must be 8mm wide maximum and i think that this is the reason that husaberg have a 3mm high squish. that's because at 3mm - it isn't a squish!!!!!!! for a squish to be effective the gases must be forced out of the gap as the flame path arrives. if it can't escape it is forced to sit there and be compressed to enormous levels. this is detonation time.

boss and artus i think are right i reckon, these craters are from detonation. but to take it further....

the detonation causes a hammer blow on the piston and it appears the big end really can't take it on the 400 and 470 which must be down to the con rod angle and revs i guess.

i've had 4 rods from 400/470s where the inside face of the big end has pitted up under where the rest of the rod sits above it. this spawling is particular to the 470 especially and my tuned 400 racer was the 4th.

so i think that the factory all these years wasn't afraid of high compression but that they couldn't have it and have a 20mm+ wide squish area. IMPOSSIBLE. SO THEY WENT FOR THE 3MM SQUISH ON ALL THE 37/30 HEADS ON THE BIGGER BIKES to save this problem.

YET WENT FOR THE FULL HIGH_COMP DOMED PISTON ON THE 470.

anyway, i've had this trouble with this modern 35/30 head on an old 470 and have been forced to remove 0.4mm/0.0016" from within the combustion chamber.

with the big end going and the little end spreading, the detonation has been disguised in some cases by the contacting of the head and piston - as seen in one of artus' photos. this i believe can have the effect of smacking the detonation craters flat. that doesn't explain all engines but if a piston rosks for and aft it will contact the head right in the two areas that artus is concerned about. so the worn bearings allow the piston to smack flat the pre-ignition.

Boss, i was originally told a reason, by someone more knowledgeable than me that there can be a great deal of dust and debris in the frame tube sitting on an oilly film, that gets there via poor filtering and on occasion, having broken through the filter it will enter the chamber and bounce around getting crushed in the squish. But one particular bike i have had, started this detonation and the alloy got onto the thrust face of the piston and started chewing itself up. massive costly damage to the linar and piston entailed from this.

also BOSS, i have done an article in 'electrical' about strobing the ignitions and every single one is different. you never know what the SEMs are going to do next! have a read and add to it if you could please? BTW, no special lean jetting from me. just standard!

i'm also sure that the SEM ignition is sparking all over the show and thats why all husaberg owners should be running the best plug they can afford. this helps to stop rogue sparks. rtus, this may mean a 9 or even a 10 from NGK. DCPR9IEX or a 10 if they do it.

two of the bikes with this trouble have been on MX gearing but on the road so we know that they have sustained high revs but light loads....

there's a lot going on in these engines we just can't see.....

regards

Taffy

It is possible that detonation issues may be the root cause for the crank bearing failures/counter balancer issues.As the model years progressed they seemed to diminish...what was dramaticaly different in the later engines?
When asked,a few years ago,if lowering the compression ratio may be benificial for engine life to the average club racer Lineaweaver seemed to know just how much material to remove from the head and where...obviously been there and done that!!
Husaberg do spec(from the 2002 owners manual) fuel of(minimun) RON 98 octane which is a quality that is not available on a reliable basis in may places.Normal supreme in most places is now RON97 or MON 91,both slightly below recommended spec.

i need to see more photos of detonation and what it looks like. not 2T but 4T detonation. perhaps there is a site somewhere?

remember, proper, full time detonation destroys the engine in minutes which is what happened i think to one i've had here. yet this seems to slow happening, on the slo burner! the one i had, had a good plug and the ignition timing was advanced to the correct place.

maybe husaberg have known these things all along and aren't stupid after all!

regards

Taffy