Rattle at high temp

[Cyprus Joe]

Hi guys,

I have a 99m750 with 35k miles.  Previous owner abused it terribly, riding it on a dirt track and not caring for it.  I am very slowly fixing it up.

I was at a stoplight on o hot day and a rattle started.  I revved it a little, but the rattle didn't change.  I drove a short distance and shut the bike down.  I checked it over a bit and the crankcase breather had come apart.  I ordered a new one and also changed the belts. 

Two questions:

1). Any ideas on the rattle?
2). Now the bike won't start.  I thought maybe I had the timing wrong, but triple checked it, and the three dots on the pulleys line up with the marks exactly.  Any ideas?

Out of desperation, I took off the carbs and cleaned them, but they were surpeingly clean inside and I don't think were the problem.

Thanks in advance for any help

[the_Journeyman]

How hot?  Was it a valve rattle?  My 280Z got too hot one day and I started getting some valve clatter.

JM

[Cyprus Joe]

I don't think it was the valves b/c it didnt change with the revs.

My brother works on restoring 280z's.  He'just finishing one that was complete frame off interior, engine.

[Dellikose]

What do you mean by doesn't start?

Lights don't turn on? Just keeps spinning the starter but no firing up? Nothing at all?

Any more info in the rattle or how the bike was performing before the rattle?

It could be a lot of things, need to starting narrowing it down.

[Cyprus Joe]

I checked the spark by removing the plug and taping it to the side of the engine.  It was pretty good.  When I turn it on, I get light and the starter turns over, just no fire at all.  Not even a cough.  The bikr did sit for about 6 months while saving up for belts and breather.

[Cyprus Joe]

Before the rattle, the bike was running really well.  Immediate starts and smooth running with appropriate power for the bike.  The rectifier went bad, but I replaced it and checked everything associated with the charging system.  The rattle just happened the one time, but I haven't run the bike since then.

[Langanobob]

I don't think it was the valves b/c it didnt change with the revs...

Interesting.  If the rattle was coming from the engine it's gonna change with the revs.  One of the first things I'd do is check the compression.  It it's good you've at least eliminated one possible problem.

[ducpainter]

If the bike sat for 6 months with unstabilized fuel you may have some phase separation of the ethanol.

I'd drain the carbs and tank and add fresh fuel.

[Dellikose]

I'd also add some Seafoam to the fresh gas...couldn't hurt. It would be a good idea to change the fuel filter while you are at it for some cheap insurance.