Ex500 - Sat for 2 years, has random "Slap" while trying to start

chris_y2k_r1 · 05-20-2009, 07:39 AM

I recently picked up an EX500 in very good shape for next to nothing. It has been sitting for quite some time (A year or two). When I tried to start it up, while the bike was cranking - just on the starter, it would not catch, every couple of rotations I was getting a nasty and very audible "Slap". It can be felt on the cylinder. I put my hand on the bottom end and on the cylinder and it is definitely top end. I'm a bit curious (and nervous) about this. Everything on the bike is stiff from sitting so I am assuming that the wrist pin is just stiff and causing the skirt to hit the bottom of the cylinder.

It's completely random but does it more when initially trying to start the bike. It becomes less and less frequent but is more frequent w/ the throttle at WOT.

I'm an experienced mechanic for sure but I wanted to see if anyone else had experience with this specific symptom. I"m not looking for theories... I got plenty of those - I'm hoping someone else has experienced this exact issue - at start up. The EX is a 90, but I"m sure that any EX including the 250 is likely to have the same problem under similar circumstances.

Thanks in advance for any experience you can share.

ChR1s

was92v · 05-20-2009, 08:47 AM

Yes. But only theories as to why.
It will always do that, sometimes, sitting for a long time or not. Ignore it and ride. It's an EX thing, just to keep you nervous and attentive.

Digifox · 05-20-2009, 11:56 AM

Was92V is right

My 250 DID it.....
And i think its just the cam chain slapping around in the head.
(Tightens up the slack then pops and slaps something in there?)

BobTheBiker · 05-20-2009, 03:45 PM

What you're experiencing is the primary chain connecting the crank and clutch missing a tooth on it's sprocket. that chain doesnt have a tensioner, and a 90 is likely to have a good bit of wear, which makes the feeling more apparent.

you dont want to know how much I know about the EX500 motors, or the bike itself.

chris_y2k_r1 · 05-20-2009, 11:24 PM

Crap,I just had the clutch cover off and I have a spare motor - I could have replaced the gear. A missing tooth explains that.

I also noticed that this motor vibrates like crazy in the handle bars. Is that normal? I've seen alot of 250s but nothing like this. There's no engine noise to go with the vibrations so it's not bearings of wrist pins or crank etc... I'm just wondering if that's normal? I suspect it is but wow. I couldn't ride this thing.

Thanks for the answers so far... very .. umm... consoling... except for the tooth thing. LOL

was92v · 05-20-2009, 11:36 PM

I don't remember the EX500 I raced vibrating badly when the motor mounts were tight, but I was racing British twins and triples at that time too, so it might be that I just didn't notice.
My SO's EX250 doesn't vibrate too bad for a parallel twin. It does have some thumps at low RPMs, but it is a twin.

BobTheBiker · 05-20-2009, 11:43 PM

Quote:

Originally Posted by chris_y2k_r1

Crap,I just had the clutch cover off and I have a spare motor - I could have replaced the gear. A missing tooth explains that.

No, you misunderstand. its because the chain is untensioned it jumps a tooth and makes that sound you hear. from the sound of it the bike you're working on needs a lot of work, and some new motor mounts. if it has frame sliders they have to be removed as they dont help anything at all on that bike.

05-20-2009, 07:39 AM	#1
chris_y2k_r1 Squid Join Date: May 2009 Posts: 4	Ex500 - Sat for 2 years, has random "Slap" while trying to start I recently picked up an EX500 in very good shape for next to nothing. It has been sitting for quite some time (A year or two). When I tried to start it up, while the bike was cranking - just on the starter, it would not catch, every couple of rotations I was getting a nasty and very audible "Slap". It can be felt on the cylinder. I put my hand on the bottom end and on the cylinder and it is definitely top end. I'm a bit curious (and nervous) about this. Everything on the bike is stiff from sitting so I am assuming that the wrist pin is just stiff and causing the skirt to hit the bottom of the cylinder. It's completely random but does it more when initially trying to start the bike. It becomes less and less frequent but is more frequent w/ the throttle at WOT. I'm an experienced mechanic for sure but I wanted to see if anyone else had experience with this specific symptom. I"m not looking for theories... I got plenty of those - I'm hoping someone else has experienced this exact issue - at start up. The EX is a 90, but I"m sure that any EX including the 250 is likely to have the same problem under similar circumstances. Thanks in advance for any experience you can share. ChR1s

05-20-2009, 11:56 AM	#3
Digifox Cl4p-Trap Join Date: Nov 2008 Location: Columbus, Ohio Moto: Your mom. Posts: 734	Was92V is right My 250 DID it..... And i think its just the cam chain slapping around in the head. (Tightens up the slack then pops and slaps something in there?) __________________ Firm as cherries.

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05-20-2009, 08:47 AM	#2
was92v Nowhere Man Join Date: Nov 2008 Posts: 558	Yes. But only theories as to why. It will always do that, sometimes, sitting for a long time or not. Ignore it and ride. It's an EX thing, just to keep you nervous and attentive.

05-20-2009, 03:45 PM	#4
BobTheBiker too much time on my hands Join Date: Jul 2008 Location: the northern district of god damn Moto: 01 ZX6R, looking for more now. Posts: 1,802	What you're experiencing is the primary chain connecting the crank and clutch missing a tooth on it's sprocket. that chain doesnt have a tensioner, and a 90 is likely to have a good bit of wear, which makes the feeling more apparent. you dont want to know how much I know about the EX500 motors, or the bike itself.

05-20-2009, 11:24 PM	#5
chris_y2k_r1 Squid Join Date: May 2009 Posts: 4	Crap,I just had the clutch cover off and I have a spare motor - I could have replaced the gear. A missing tooth explains that. I also noticed that this motor vibrates like crazy in the handle bars. Is that normal? I've seen alot of 250s but nothing like this. There's no engine noise to go with the vibrations so it's not bearings of wrist pins or crank etc... I'm just wondering if that's normal? I suspect it is but wow. I couldn't ride this thing. Thanks for the answers so far... very .. umm... consoling... except for the tooth thing. LOL

05-20-2009, 11:36 PM	#6
was92v Nowhere Man Join Date: Nov 2008 Posts: 558	I don't remember the EX500 I raced vibrating badly when the motor mounts were tight, but I was racing British twins and triples at that time too, so it might be that I just didn't notice. My SO's EX250 doesn't vibrate too bad for a parallel twin. It does have some thumps at low RPMs, but it is a twin.