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

[chris_y2k_r1]

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]

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]

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]

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]

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]

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]

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.

[chris_y2k_r1]

Originally Posted by BobTheBiker

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.

OK - I thought, wow - this guy really knows this bike. I've never seen a bike that had actual adjustable mounts like this one. Te bike is actually in good shape it was garaged and has low miles. It sat because it hit a mailbox.

[BobTheBiker]

being a 90, you need to get a 2nd gen flywheel, gen 1 flywheels have no metal plate to hold the magnets in place, and they usually come off, which destroys at LEAST a stator, if not in some cases whole engines.

you should hang out on ex-500.com, theres more knowledge over there about that bike than you'd EVER want to know. when a man known as FOG speaks, heed his wisdom, dont ask, just do as he says.

[chris_y2k_r1]

Originally Posted by BobTheBiker

being a 90, you need to get a 2nd gen flywheel, gen 1 flywheels have no metal plate to hold the magnets in place, and they usually come off, which destroys at LEAST a stator, if not in some cases whole engines.

you should hang out on ex-500.com, theres more knowledge over there about that bike than you'd EVER want to know. when a man known as FOG speaks, heed his wisdom, dont ask, just do as he says.

Let me clarify, I have no intentions of keeping this bike. My days of inline twins and lower than 600cc bikes are over. I got spoiled by my first liter bike (y2k_r1 thus) and I'll never got back, at least for street. I own a buisness that reconditions sportbikes. It's my fulltime job, I find good rebuildables online, I fix them and sell them. Our goal is dealer quality bikes at less than individual sale retail. So far, so good. This is our second year and this year we have taken off. I also do fairing repair/welding with a completely unique technique that does not employ a standard plastic welder and works and looks as good as factory even if we combine two completely seperate pieces of plastic. We also do motor work for a few customers who only trust us. We are working very very hard on a reputation that stands miles about others when it comes to honesty, transparency and most important price. Lastly we also purchase old pieces of plastic that are bound for the trash since we can fix any plastic damage and replace voids.

Wooo, I didn't mean to go off there. I just really enjoy what we are doing. I have some customers driving 3 plus hours to get to us because they took advantage of our Fall special. $550 gets you a full fairing and tank repair job and includes a single color (two stage high quality paint - Sherwin Williams or House of Kolor) along with wet sand and polish. We do it every Fall and it keeps us going until Spring of the next year. Many guys collect up their buddy's damaged body work and bring it to us, then we re do it at the $550 price (As long as what they bring amounts to roughly 1 bike worth of bodywork) and they make a few dollars for their efforts.. but people who have had us do work are always very happy. Every panel we do is completely wet sanded until it's flat - perfectly flat and then polished to produce a super high gloss mirror finish. Even with the excellent modern robot paint jobs that are coming out of the factory these days, our finish is still better with less orange peel and overall less paint anomalies. I"ll post a quick "before & after" of one of our cheaper rebuilds.. The name is MS Re~Cycle and we located in Essington PA.

Out of curiosity, what would you expect to pay for an EX500 (Black/Grey/Red) that is in phenomenal condition. Just about every fastener on the bike is still virgin (No one has touched this bike but me), there is absolutely NO rust on it and the motor only sports 3,400 miles. It's 100% stock without a scratch and everything works 100%. New tires, clutch, brakes and a battery. What would you expect to pay for a person to person sale? I'm just curious because NADA and KBB are out of whack on early model EXs. Acutally they are out of whack on alot of early model bikes period. For example, here is what NADA states about the Ninja 600R retail for excellent condition for the years: 1993 $1200, 1994 $2500, 1995 $1200. WTF!? I guess the 94 is... 'special' even though they are the exact same bike for all 3 years. Anyway for the earlier stuff, they are way, way below what I see them selling for, even in crap condition people are getting better than the NADA numbers especially for the EX 250s/500s.

Sorry for the long winded advertisement. It wasn't meant to be a "sale", like I said I'm just jazzed about what were dong and our level of success. After writing code for 8 hours or more a day for just shy of 20 years.. working with my hands and being able to see a product at the end of the day is a welcome alternate reality.

Thanks again for you help, Bob and friends And I'm curious what you would have to say about that EX 500 price.

P.S. I'll have to add pictures later, I forgot that I sold the processor in my media server where the pictures live. The new processor is due today - a nice AMD quad core (3.2 GHZ Black edition - should be able to hit 4GHZ without a hitch) and another 2 GB of DDR3 1800. I needed to upgrade this because it is also the businesses web server. I just started developing the website, it's down until the processor is installed later today: www.msrecycle.com

Won't be available for about another 6 hours.

Thanks again folks! All of you for responding.

If you made it this far you deserve a cookie!