yamaha DT400 engine noise w/corrected link

[79yamdt]

I recently put a engine with a new top end in my 77 DT400. This engine had a new top end put in a few years ago and wasn't used until now. It makes this rattling type sound at idle and low tons. Above 3000 or so rpms it goes away. The engine that was replaced also made this noise. Is it normal? Or is something wrong. Here is a link to what it sounds like. This is not my bike but it is the same sound.

I have a DT250 also and it does not make a noise like this. I also see comments on other videos stating that this is normal. I've never had a big single cylinder 2 stroke so I don't know if this is normal or not.

Edited October 10, 2011 by 79yamdt
bad link

[Motosprtman]

I have been told that wiseco pistons rattle and the OEM ones do not....

[Horri]

Your video doesn't lead anywhere,,ie,,it's broken..Having owned a DT360 years ago I can say it always made a loud sort of rattle at idle or thereabouts..I say normal..

[79yamdt]

Sorry about that. I posted it from my phone it was the mobile website. I have the correct link now. I know two strokes do rattle and and make some noise but this seems very loud.

[79yamdt]

here is another video of the sound. The 75 and up dt's have the same top end as my bike

[Horri]

Going on my DT360 experience your 400 sounds absolutely normal..All the bigger yammys of around then made that noise,,well certainly in the DT/IT range..Wait for others opinion but I say "Go with throttle up Gene"..

[79yamdt]

Thanks for your opinion. I've never been around any other bikes with engines this big just it & dt 250s and smaller so I have nothing to compare it to.

[ctune80]

How much clearance did your shop give you on that piston? Is it a cast factory piston or a forged Wiseco?

As was mentioned before, the Wiseco will make more noise, since it runs more clearance. If you are sure

the numbers are good, Run it. Did you check the rod bearing play when it was apart?

[79yamdt]

Well it was an ebay engine so that information is unavailible to me. I did inspect the piston and bore. It's cast piston from what I can tell, 2nd over. I am thinking about tearing apart to find if there is excess play in the rod bearing. I'd rather be safe than ruin an engine.

[BRS]

My 76 IT 400 sounds exactly the same and it is all fresh.

[Wildweasel]

Normal.

[79yamdt]

Thanks for the input everyone.