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Engine rattle..

M

mackan123

Joined Apr 2019
13 Posts | 0+
Sweden
I recently aquired a Husaberg fe450e 2006, which had stood still for a few years. Upon start up i heard some rattle, so i did some research and came to the conclusion that it was the CCT. I took it out and checked it, didnt seem to be faulty in any way, so i reset it and put it back in. Then when i went on to turn the engine over using the kickstarter, i heard a somewhat loud pop. Scared and confused, i went on to check on my valves if they were running like they should, which they seem to be doing just fine. I took out the spark plug and checked as well, but nothing seems to be NOT working. I turned the engine over in 6th gear over TDC a few times, did not hear any weird noise, nor does it seem to run improperly.
Now, what could that pop possibly be? What should i do from here? I dare not start it in case i broke something..
 
depends what the loud 'pop' was/

exhaust backfiring?
carb backfiring?

what type of nosie was it?

Taffy
 
That's what im wondering.. Come to think of it, it did sound a bit like a small firecracker, but it came from the front. It made me think i snapped the timing chain, but im not sure thats even possible AND the valves were running fine. I did smell a weird smell afterwards also.. Can the carb backfire if you slowly turn the engine around with fuel line on?
 
Right, yes.. Still got this rattle issue. Any idea what i should do to fix it? As mentioned, it does sound like the timing chain
 
i doubt it is the timing chain. it just sounds like it but the TC gets the blame for a lot of things. get a video done and put it up somewhere.

Taffy
 
none the wiser really?

you could try taking off the rocker inspection caps...both and then starting the engine and as long as it doesn't spew oil you could try and hear more but I'm just not sure what that is.
 
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you never said how many clicks were left on the cct.
it sounds like the timing chain be cause it goes away off idle.
 
Seems to me it's 5 clicks left, the timing chain should definitely be tensioned, right? Is there any minor nut or anything in particular that may have come loose behind the left cover?
 
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If the cam chain is O.K. you may want to look at the autodecompression device "spring". As the bike ages the spring can lose tension or become unseated so that there is no tension whatsoever. At low RPM's the decomp will flop around hitting the stop making a sort of metal on metal ting ting ting sound. As RPM's increase the decomp stays seated against the stop and the noise subsides.

Taffmeisters - Husaberg, KTM, Husqvarna, Gas Gas, dirt bikes - servicing, tuning, rebuilds, parts

Use a mechanics stethoscope or take a large screwdriver and put the handle part up to your ear to help determine the location of the noise.
 
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Yes, it does sound like its coming from the top of the engine, not the bottom as i first thought. Now, if its the decomp spring making the noise, is it safe to drive with or should i replace it before any driving? What can happen if it fails? Also, do i need to buy new gaskets etc. when replacing the spring?
 
grabe the flywheel with your hands and try and shake the crank. then turn the crank into a new position and try again. there are two turns to a cycle so have several goes.

just take the rocker cover off and check but i don't think that that is top end either.

balncer rattling? mains?

not sure

Taffy
 
The decomp spring, is it supposed to be under tension? It was pretty loose indeed, i could jiggle it very easy.
When i shook the crank, i could feel a small "gap" like it was loose, but only every other turn. So one turn it was completely solid, next it was a small play in there.
Hope you can make sense out of this :cry:
 
one time around there is a compression, the next time there isn't. the compression stops you "bouncing" the crankshaft. if you pull the plug out it may do it all the time.

any hint, no matter how small = mains have gone and that will be the noise.

cheers

Taffy
 
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flick back a seal and see if it is a ball or a roller bearing.

if ball you should have 0.2mm of float with a good whallop of the crank.

if roller, you should have 0.5mm of float. left right left 0.5mm.

this is where it goes wrong. that and cheap bearings.

Taffy
 

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