jmpy motor no noises.

[gixxer750king]

what can cause the jumpy motor inside the block with out making noises. i know it can be the rod bearings or the crank bearings so if there is anything else it could possibly be i would really like to know thank you

[The_AirHawk]

You still haven't had the bike's EFI-system checked out yet, have you?

When was the last time you had the valve-lash checked on it? (how many thousand miles ago)

If you answer with "valve-lash..........?" I'll reach through this computer and thump you on the helmet.

If there's a bearing out, or something along those lines - you'll bloody know it, as the engine will cease to function in short order. Any bottom-end problem will have a horrible knock - typically rods will knock harder if you rev the engine, main-bearings will knock on decel. Doesn't matter either way, typical Japanese moto-engine will cost about 15-times as much to rebuild the engine as it will to just buy another used one from a breaker.

[gixxer750king]

i had the efi checked i had the whole bike looked over buy a dealer and a computer hooked to it. no readings of anything on the electrical systems i am told the problem is internal. so i am trying to find out the possibilaties

[The_AirHawk]

Originally Posted by gixxer750king

i had the efi checked i had the whole bike looked over buy a dealer and a computer hooked to it. no readings of anything on the electrical systems i am told the problem is internal. so i am trying to find out the possibilaties

The Dealer couldn't figure it out with a quick diagnosis? I certainly hope you didn't give them any money, and will shy all your friends away from a shop that has a machine IN THEIR HANDS and can't figure-out what's wrong with it.

I've got to tell you king, mechanical problems are far, far easier to diagnose than electrical. It either clanks, clunks, or knocks - and something as simple as draining the oil and looking for metallic bits can be performed by even the most inept of mechanics (generally).

[gixxer750king]

the thing is it rattals really bad like something is vibrated loose but there is no noise at all. it idles just fine nothing is wrong with the idle just when it gets up to about 4k rpms it starts to shake really badly. checked all motor mounts everything is correct all tightened right. i just dont see what the problem could be the only other thing i can think of is there is a counter balance weight off but i wouldnt know were to start looking for that at any ideas

[The_AirHawk]

Ah-HA! Now we're getting somewhere!

Engine vibrates badly, and makes a racket when you rev it under load, correct? Or makes no odd noises, just vibrates badly?

If the latter, as you suggested: the counterbalancer has "jumped time" and gone out of phase with the rest of the reciprocating assembly. Being out of phase, in and of itself will not harm the engine (although the vibrations will make the bike unrideable). What would concern me, is exactly why they've gone out of phase. That is the $6.39 question.

If they're chain-driven, (and the chain is independant of the cam-timing chain) it may be as simple as pull the sidecover off, correct the phasing, install a new chain, new idler/tensioner (if applicable), and button it back up.

If the thing is gear-driven, you're probably screwed. Something broke, and it's only a matter of time before the broken bits grind-up the crank and bearings. I might pull it apart to confirm, but essentially the engine is junk. Find a decent used motor on ebay, or a bike-breaker.

[gixxer750king]

ok the bike makes no noise at all. just vibrats very badly when reved doesnt have to be in gear can be in nuetral. so thats why i think its a counter balance. is there any way to check that besides ripping the top of the block off

[Kenneth_Moore]

Originally Posted by gixxer750king

is there any way to check that besides ripping the top of the block off

Yes. First, insert the motorcycle in a giant X-Ray machine.

[pushrod]

Just out of curiosity, would a dead hole (non-firing plug) cause the engine to shake? As it's not a Vee, I'd think not, and I'd guess the 'computer' would have seen it.

[sarnali2]

If it's just really jumpy without noise then it's probably just nerves..........Try talking to it in a soothing voice, be reassuring but firm. Before you go for a ride perhaps tell it where you plan on going..what to expect along the way and just generally reassure the bike that yes, there will be traffic and cars but you'll do your best to avoid them, remind the bike it's a team effort and you must both work as a team so that you can both return home safely.....after the ride instead of just turning the bike off and leaving it in a darkened garage let it idle for a few minutes, perhaps go over the highlights of the trip and try to reinforce the positive aspects of the ride.....help the motorcycle to build confidence in it's self as a machine and in you as the pilot.........