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engine rattle
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TOPIC: engine rattle

engine rattle 8 years, 1 month ago #283

Hi Guys,

my bike has an engine rattle under hard acceleration. It is most noticable when you are in top gear at about 60km/h and wind the throttle up to 100%.

Does anybody elses bike do this?

Cheers,

Re:engine rattle 8 years, 1 month ago #284

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Cam chain?

Maybe supply us a bit more info eg how many km's

Re:engine rattle 8 years, 1 month ago #286

Bike only has about 800km on it.

I have been nursing it a bit as a run in and now that i am hitting the gas hard it makes a noise about 50% of the time. A mate with the same bike has the same noise with his, and it wouldn't make the noise when the mechanic took it for a run (or so he reckons). I guessed cam chain and another mate reckon that the auto cam chain adjuster is between clicks. but i just dont know.

Re:engine rattle 8 years, 1 month ago #287

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Are you running premium? It could be pinging as well. The 'E' model has a high comp head compared to the 'S' and 'SM'

The cam chain will slap at idle too if loose, be will be louder at a higher rpm.

Re:engine rattle 8 years, 1 month ago #288

First check Cam Chain

Re:engine rattle 8 years ago #394

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I would also suggest cam chain. I just purchased a second hand '07 with just over 3000 km's, he made a point about having run it in gently. Advised that for much of its life had a top end tap, had Suzuki check top end under warranty and declare all well, they gave him a spare ACCT just in case (which I got). Bike went like stink so I accepted the noise (my research showed not an uncommon DRZ trait) and purchased.

Well, after one ride noise drove me crazy (bike still went like stink), had my local shop check cam chain (appeared tight), valve clearances (perfect) primary and counterbalance nut (not loose but removed and loctited anyway) and remove auto decompressor (pin loose) - :angry: result - no change to top end tap. Decided to try new cam chain, and fit new ACCT that came with bike.

Well, I'm away o'seas at the minute but called the shop and they've told me motor is all good now, nice and quiet. Well, as quiet as a DRZ ever gets, anyway... :whistle: (chain was stretched compared to new)

Couple of thoughts... Low rpm's offer highest stress on valve train/cam components (no momentum to offset pressure on cam lobes) - maybe mollycoddle run in combined with new ACCT spring tension prematurely stretches the cam chain??? Anyone?? With that possibility in mind I have a MCCT on the way, will fit ASAP b4 this one goes the same way... (and ride it hard!)

Also, I couldn't for the life of me figure how a loose chain only produced a solitary tap from top end at lower freq than engine speed until saw a youtube video (not a DRZ but similar) that might explain it. Will try to explain:

Cam chain rotates same direction as engine so pulls intake cam from exhaust cam. As intake cam rotates past high point on lobe, intake valves spring pressure pushes the cam around, possibly quicker than the chain wants to pull it at lower rpm's. If ACCT not so firm anymore, or maybe just too much length in the chain, this slight overrun may produce a bit of slack in the chain between the two cam sprockets. Once the intake valve is mostly off the cam lobe, the chain movement takes up the slack, causing it to tighten quickly between the cams and "tap" the metal guide that runs between the two cam sprockets. Just my thoughts but that certainly seemed like the area the noise was coming from. (I could almost feel it with my fingertips)

FYI, to add to the multitude of other threads on this topic in forums all over the net!

chrs
In some societies, what I do would be considered normal...

Re:engine rattle 8 years ago #396

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Updating above post, have ridden the bike and it doesn't seem like the same engine, very quiet mechanically and goes really well.

Had a look at the old chain, main issue seemed to be slight movement between every link ie pins were not firm in the links, so I guess I can see how even under tension from the ACCT between crankshaft and intake cam you can still get some movement between the cams, which I think caused the classic tapping/slapping in the top end.

Interestingly labour costs were only $80, my local shops fixes this by threading the new chain thru attached to the old one, then re-staking it when it's back on the engine. (they do this repair often with no issues reported from other clients)

MCCT still on the way, will be fitted JIC...

chrs jc
In some societies, what I do would be considered normal...
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