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Discussion Starter #1
Greetings to all. I have a low knock on the engine on the right, where the clutch basket is. Well heard at low 700-900 RPM. When riding a motorcycle at 4000-5000 RPM, I feel a strong vibration from engine. Now I completely disassembled the engine, in the service they say that my primary chain has a weak stretch, and if I change it my knocking problem will be solved. I measured the chain according to the manual, it is within normal limits, but if you hold it horizontally with pins up and down, then it sags 3-4 cm (1.575 in). Is this normal? Please tell me if anyone ever changed the primary chain and whether the engine could knock because of it. I can’t upload videos and photos as I don’t have 10 posts yet. :(

P.S. Sorry for my english :)
 

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The idle speed is not supposed to be so low. The specifications mark that it must be between 1250 and 1500 RPM.

If the idle is very low, the knock you hear is caused by compression of the engine fighting against the inertia of the flywheel that keeps the engine running.

As for the vibration, I have no way of giving you accurate information. Maybe if you give us more information about the model year and mileage of your motorcycle, some of the most experienced members can help you.

Greetings from Mexico!
 

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Discussion Starter #3
The idle speed is not supposed to be so low. The specifications mark that it must be between 1250 and 1500 RPM.

If the idle is very low, the knock you hear is caused by compression of the engine fighting against the inertia of the flywheel that keeps the engine running.
At 1200 rpm, there is also a knock. At 700 - 900 rpm it is more powerful. I listened same engine on Kawasaki ER-5 (1996 year, mileage 48000 km) at 700 rpm and its worked very smoothly.

As for the vibration, I have no way of giving you accurate information. Maybe if you give us more information about the model year and mileage of your motorcycle, some of the most experienced members can help you.
My Kawasaki EX500D (GPZ500S) 1995, mileage 53000 km.
 

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If the issue persists in neutral then I doubt it could be the chain. Although if there is a lot of front/back flex, it will only be a matter of time before the chain is done, so I would suggest replacing it.

But I doubt its the issue as you mention it happens at idle.

When you say you "completely disassembled the engine" what does that mean? Did you take the engine out and strip it down to the bone? just the head off? or just valve service? how far did this go.

What year/mileage is the bike?

Since you said clutch basket, I saw this video not too long ago. Does it sound like this? maybe could put you in the right direction:
 

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At 1200 rpm, there is also a knock. At 700 - 900 rpm it is more powerful. I listened same engine on Kawasaki ER-5 (1996 year, mileage 48000 km) at 700 rpm and its worked very smoothly.


My Kawasaki EX500D (GPZ500S) 1995, mileage 53000 km.
The engine, due to the extreme rotation (540º or 1.5 rotations) between firing impulses, should never be run below about 1000 RPM - especially under any type of load. The crankshaft is speeding up and slowing down rather radically at that excessively low RPM. It was not engineered to run so low. That can cause the crank speed changes to cause backlash in chains as well as gears.



A knock at higher RPM does indicate a potential problem, and it may not be the primary chain - in your case it does not appear to be. Does the knock change at all when clutch lever is in versus out? That would point you toward clutch and not chain. Does the knock change while accelerating, running at neutral throttle and on the overrun? That again is something which must be considered.



The behavior of the knock can tell you as much, if not more than the location, type or loudness of the knock.
 

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hi guys. just an observation from someone who has a high mileage. GPX/EX a lot of enquiries on this forum are from new members, who may not always understand how these bikes work. if you come to the [EX] from a previous bike that wasn't a EX they can be extremely frightening in there antics. note these bikes. are noisy. lumpy. vibrate a lot. and emit strange noises. that convince you the engine is either going to explode or shake it's self to bits. but not to worry too much it won't once set up properly.

for starters as it has been said the engine rotation is odd being a 180 degree crank but having opposed pistons. so it fires in quick succession in 180 degrees then has to revolve 540 degrees before it fires again. this makes it lumpy, vibrate and quite noisy as the crank struggles to keep turning only being able to do so by the weight of the flywheel and the balancer weights in front of the crank. once revolving everything smooths out somewhat but still has a tendency to vibrate. this is made worse the more mileage it has under it's belt.

unlike some bikes that are more precise it lacks the refinement of any form of vibration dampening such things as primary chain are not adjustable and require a complete engine strip to replace so they get left, also many of the bushes in the engine are phosphor bronze and these wear out over time. adding play to any that is there already [as in the video above] timing chains rattle a either a little or a lot depends on how far the chain slack is before the front adjuster goes another click.

everything on the engine rattles a little. the more mileage the more noise. there are steps one can make to ease the situation never slug out the bike at low revs in high gear. keep the tick over above 1100 rpm do regular maintenance valve adjustments cable adjustments and such like. done well these bikes will last a long time you have to understand what noises are normal and what are not this takes time its no Honda and will never sound or feel like one.

I am not trying to say there isn't something wrong just that on average it's not knowing what is wrong. the old adage for these bikes when running well is they sound like a sewing machine well if you have heard a sewing machine you will know they are neither quite or smooth.
 

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All the above is true,
I fear you have created more work that you wished for/ I hope you did not remove the head. if so you must do a recap of the head and cylinders.
Read my piece in the how too section for details

FOG
 

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Not sure where you are getting you're information, but its incorrect. All models of the ex500 have a 180 crank. The ex500 was designed in the mid 80's, but 270 cranks didn't start to appear until the mid to late 90's. According to Wikipedia, the Yamaha TRX850 (1996) was the first production bike to feature a 270 crank.
 

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well I have only one comment to make on this. if the EX500 gen 1 [like mine] does not have a 180 crank why are the triggers for the ignition 180 degrees apart and not off set to either 270 or 90 degrees.
plus the cam sprockets are clearly marked IN and EX on both sprockets either side when I piston is at [or near] the top of the stroke the marks show the inlet mark to the rear and EX to the front. turn the engine until the other piston is at the top [or near] the marks line up perfectly only reversed. this suggest to me 180 degrees of crank angle is correct. perhaps FOG could enlighten us.
 

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Just pull the plugs an turn the crank you will shortly see it’s a180 craNk

Fog
 

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Discussion Starter #12
Hi everyone, thanks for the answers, I have not visited the forum for a long time and have not seen that there are so many useful tips and answers in my topic.
I fear you have created more work that you wished for/ I hope you did not remove the head. if so you must do a recap of the head and cylinders.
Yes, I completely disassembled the engine, now I am assembling it. I bought a new camchain, generator chain, primary chain, a set of all gaskets, valve seals, connecting rod bushings, output transmission shaft oil seal. All valves are lapped, the surfaces of the cylinder head are polished, the connecting rods are replaced, the main chain is replaced (I hope because of it there is a knock of the engine, although I already doubt it).

P.S. Now I can already add a link to the video engine knock #1 engine knock #2
 

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polished? there is no polish in lapping. Flat is what you want. if you haven't lapped them with free abrasive against a flat surface. you haven't done anything.

Fog
 

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Discussion Starter #14 (Edited)
Hurrah! Finally, after ten months I rebuild and successfully started my engine, now it works smoothly and without knocking, and there’s no vibration while riding. As I understand it, the problem was a weakened primary chain.
What has been done and replaced:
1. Primary chain (used, but much better than mine :) )
2. Genuine valves oil seals
3. Valves lapped
4. Resurfaced head and cylinder block
5. Engine gasket set Vesrah VG 4018 M
6. Pump cover gasket (genuine)
7. Pump housing gasket (genuine)
8. Shaft transmission output oil seal (genuine)

Thank you all for your advice and help.

polished? there is no polish in lapping.
Sorry, I don’t know the correct English technical words, I use Google translator :) . Probably it will be correct not polish, maybe resurfaced?
 
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