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Royal Enfield Motorcycles => Bullet with the UCE engine => Topic started by: 2bikebill on July 06, 2010, 08:35:56 am

Title: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 06, 2010, 08:35:56 am
After 4000 happy and troublefree miles my G5 has recently begun a strange and disconcerting behavior when starting. It's not every time, but occasionally, instead of starting on the button, it'll turn over in an irregular sort of way with a loud metal to metal CLACK instead of firing up. It feels and sounds like something in there has just got stuck in the wrong position. Switching off and trying again generally cures it and away she goes. Sometimes I kick it over slowly first.
This is definitely a bike not suffering from neglect or thrashing and is ridden pretty much every day. Regular servicing, oil changes etc.
This symptom kind of rings a bell from an earlier post which I can't find, so any clues welcome.
Thanks.
Will
Title: Re: What's that CLACK when she turns over but wont start?
Post by: clubman on July 06, 2010, 08:57:23 am
I don't have an answer Will but, incredibly enough, at 3,700 mine started doing exactly the same. Just the last few times it's been starting first time again. The CLACK seems to be from the starter motor area but realistically could be anywhere. For sure it's from the engine area and is a mechanical CLACK, and not a starter motor relay click. Naturally when I mentioned it to my dealer it behaved perfectly.  ::)
Title: Re: What's that CLACK when she turns over but wont start?
Post by: r80rt on July 06, 2010, 01:08:38 pm
Could it be the decompressor flyweight?
Title: Re: What's that CLACK when she turns over but wont start?
Post by: ace.cafe on July 06, 2010, 01:16:39 pm
Could it be the decompressor flyweight?

That was my first thought too.
Auto-decompressor noise.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: ES-335 on July 06, 2010, 02:01:32 pm
I am afraid it might be the decompressor if clacking on the right side of  the motor. I have had that part replaced twice, first time the flyweight "hinge" was broken, managed to drive home that time. Taken to service. The second time the cam lifter pin of the decompressor got loose and fortunately ended at the bottom of the engine (that´s what the mechanic explained to me). This incident misfired the engine at speed of 90 km/h and blasted the airfilter box lid open, also lid lock broken. Had to push the RE closer to home, though engine a bit later started again and ran for some 10 kilometers. Then the engine stopped when revs close to idling at traffic lights, started no more. Another 1,5 km push to home. In total 2 trips on a tow truck to nearest RE service (50 kms away). Now there is no auto decompressor installed at all.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 06, 2010, 03:59:03 pm
Well that all sounds more than a bit alarming. And since it's happened three times more today I think perhaps I'll get on the phone to the dealership.
And Clubman, it's spookier than you think. I should've said almost 4000 miles - I'm actually at 3900, but this first started a couple of hundred miles ago (cue Twilight Zone theme tune.... :o )
So if the bike runs without the auto decompressor fitted - what's it for..?  ???
Title: Re: What's that CLACK when she turns over but wont start?
Post by: Ragmas on July 06, 2010, 04:12:08 pm
It is for starting the bike.  A big 500cc trying to turn over in full compression  might be a bit difficult on the foot, if using kicker.  I don't know how this hurts the starter motor if at all. 

I would imagine that this is why the non-efi bikes have a decompressor lever, for starting.

Sam
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 06, 2010, 04:37:44 pm
Thanks Sam. Assuming it has no effect on the electric starter, might as well ditch it then, if it comes to that.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: SSR on July 06, 2010, 04:57:44 pm
In my case it was the sprag which unfortunately I had to change it three times by now.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: ES-335 on July 06, 2010, 05:19:30 pm
My C5 had these decompressor failures at around 4700 and 5300 kms (2900 and 3300 miles). The RE importer in Finland explained me that the autodecompressor was aimed exactly to Indian C5 (and other) models that have both estart and kickstart. In order to ease kickstarting. It was also told that RE UK informed the Finnish importer that the auto decompressor could be left out regarding RE models without kickstart. That was the recommendation after that 2nd case. So far I have not sensed that full cylinder pressure would be a burden for that electric start. Now my RE has thumped about 1000 kms (620 miles) without decompressor.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: Ice on July 06, 2010, 05:27:33 pm
In my case it was the sprag which unfortunately I had to change it three times by now.

Is yours a UCE powered machine or one of the older models ?
Title: Re: What's that CLACK when she turns over but wont start?
Post by: SSR on July 06, 2010, 05:36:12 pm
Is yours a UCE powered machine or one of the older models ?

Its UCE C5.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: r80rt on July 06, 2010, 05:42:29 pm
Thanks Sam. Assuming it has no effect on the electric starter, might as well ditch it then, if it comes to that.
It lifts the exhaust valve momentarily, and makes life easier on the starter and sprag.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 11, 2010, 01:11:58 pm
So is this  wheeze - CLACK, wheeze - CLACK  more likely to be the auto decompressor or the sprag? (a word I have heard but don't fully understand)

It's happening more and more, and embarrassed the hell out of me yesterday when I tried to get off the Dartmouth ferry!  I thought it wasn't going to start at all, but persistence paid off in the end.

 I'd like a theory in place before I take it in to the dealer because I know they're new to Royal Enfields, and probably haven't come across this   -  yet.

4200 miles otherwise trouble-free.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: ace.cafe on July 11, 2010, 01:37:36 pm
So is this  wheeze - CLACK, wheeze - CLACK  more likely to be the auto decompressor or the sprag? (a word I have heard but don't fully understand)

It's happening more and more, and embarrassed the hell out of me yesterday when I tried to get off the Dartmouth ferry!  I thought it wasn't going to start at all, but persistence paid off in the end.

 I'd like a theory in place before I take it in to the dealer because I know they're new to Royal Enfields, and probably haven't come across this   -  yet.

4200 miles otherwise trouble-free.

Yes, more likely to be the auto-decompressor. That's a sound that a decompressor would make.

The sprag is simply one of the gears in the electric starter system, which is a one-way gear like a ratchet, which the starter turns when starting.
It has parts inside the sprag gear, called a sprag clutch, and this is what makes it work in one direction only.
If something happens to make the bike kick back, it can break the sprag clutch mechanism, which was a common occurrence on the older models which had electric starters.

It is my view that the auto-decompressor also helps to protect the sprag clutch from breakage, by letting the engine begin to spin-up and get some forward momentum, before the auto-decompressor releases at the specified rpm point, and then the engine starts.
By removing the auto-decompressor, you do raise the risk of damage to the sprag clutch by a kickback. It's simply a matter of solving one problem, but leaving yourself open to another problem occurring later.

The ideal circumstance would be to fix the auto-decompressor so that it works properly, and the system will function as intended, and the sprag clutch will be more protected from damage.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 11, 2010, 01:47:38 pm
Thanks Ace. Fixing rather than removal is my plan - it's there for a reason after all. Hopefully I can reproduce the symptom when I take it in - although sod's law generally predicts otherwise.... ::)
Title: Re: What's that CLACK when she turns over but wont start?
Post by: Ragmas on July 11, 2010, 02:39:42 pm
Pure novice here but, Perhaps your battery is low and the starter is not quite spinning things fast enough to disengage the Auto-decomp.  I say maybe.   My bike did this once or twice when I first got it but has not done it in over a thousand miles now.  I wish you luck.  I prefer not to take things out of an engine that were put there for a reason.

Good luck friend.


Sam
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 11, 2010, 02:52:34 pm
Thanks Sam. No the battery's fine. It spins like a good'n. I do a lot of miles so it's well charged. This is definitely a fault, albeit intermittent, but getting more frequent. I shant be taking anything out - just getting it fixed. It's a warranty issue.

Just to be 100% certain, I'll put it on charge and see how we go....
Title: Re: What's that CLACK when she turns over but wont start?
Post by: gashousegorilla on July 11, 2010, 02:58:20 pm
Pure novice here but, Perhaps your battery is low and the starter is not quite spinning things fast enough to disengage the Auto-decomp.  I say maybe.   My bike did this once or twice when I first got it but has not done it in over a thousand miles now.  I wish you luck.  I prefer not to take things out of an engine that were put there for a reason.

Good luck friend.


Sam
 
 Thats good common sence.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 11, 2010, 03:17:11 pm
Battery is showing as fully charged on my tester.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: Ragmas on July 11, 2010, 03:26:53 pm
Next stop, the dealership!!! 
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 11, 2010, 03:38:18 pm
Alas yes -  hopefully during a rainy week.... ;)
Title: Re: What's that CLACK when she turns over but wont start?
Post by: SSR on July 11, 2010, 06:53:24 pm
I think its the sprag clutch on its way out but get the decomp sorted first as thats the reason why the sprag is getting strained due to backfire.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: clubman on July 11, 2010, 09:08:25 pm
Battery is showing as fully charged on my tester.

Just a thought but have you made sure all the connections from battery to starter motor are good and tight?
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 11, 2010, 09:25:29 pm
Yes I checked everything over today when I tested the battery, it's all good and tight. I've been out a couple of times today, and started the bike a few tiimes with no problems. I'll give it a day or two before booking it in for diagnosis/repair.
How's your's behaving Clubman? Also, how much engine noise do you have? I sometimes think my bike is a sight noisier now than when it was new. (I do mean the engine and not the pipe!)
Title: Re: What's that CLACK when she turns over but wont start?
Post by: clubman on July 11, 2010, 09:53:45 pm
Starting on mine's been fine for the last couple of weeks. I took it in for a service on Friday gone and went through all this with the dealer. He confirmed it's definitely the auto decompressor. Of course we only get the clack if it fails to catch and all things being equal they should fire up first time. So the real question is why isn't that happening? Have you tried changing the plug? The dealer also questioned battery health but like you my Optimate indicated the condition to be excellent. However that was all a few weeks back and the problem has gone for now. I'm still not confident it's gone for good though, especially hearing of your experience.

Engine noise. It varies. Do you wear ear plugs? I do and it changes a lot depending on how deep I plug them. Nice and deep is best cos you only hear the boom and all the rattles go. So on another day I'm convinced it's falling apart until I open it up and once it goes as fast as it ever does I relax. Chain tension also makes a difference. There are so many variables I can't really answer your question except to say it's definitely no quieter. I know received wisdom is the tappet noise goes as the adjusters bed in but that's not the case with mine so far.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 11, 2010, 11:00:43 pm
Haven't changed the plug but I've had it out and cleaned it up a couple of times. Perhaps I'll change it and see how it goes. As you say, if it fires up straight away, and it usually does, there's no problem. The ferry incident was disconcerting however, and I'm wary of switching off now when I'm out and about.
As to engine noise, it does vary but I'd say it's noisier when warmed up. I usually put it down to how much I'm focussing on it, but I generally notice it because I notice it, not because I was listening for it. I'm also aware that for the first weeks I was fully focused on staying on the bike and noise wasn't registering much. But as you say, it runs fine so it's probably ok. I'm thinking earplugs are a very good idea. First long trip with the new pipe the other day I stopped on the way to buy some in fact. The helmet helps of course, but I suspect the noise level is above what's desirable.
So is your dealer going to replace the auto decompressor - or is it wait and see ?
Title: Re: What's that CLACK when she turns over but wont start?
Post by: siddharthmenon on July 12, 2010, 08:46:34 am
Hi,

I am from India and I have exactly same problem with my C500 when it reached 4000km. Its the gear crunching sound which is so loud that you rather try kick start. It almost stopped my heart !! Phew :P

Anyways for me it started when monsoon began, and once the engine warms up its difficult to replicate the problem. Lucky I live very close a RE service station, one day I called one of the guy and he tried to start it, and wohla he heard that too.

According to him its something to do with bearing, which may be the cause of gear slippage or something, I am waiting for new set of bearing and will get it replaced and give you guys the feedback.

Also not sure if my other problem is related but I also have little problem with engine start, both started around same time. Engine may start in one Kick but sometimes it shuts down and if it does then its difficult to start again. I use to start my engine in 1 kick or 1button self start before with no shutdowns ever. The RE guy was saying its all related as the bearing make it difficult or something. May be he is clueless, i am yet to find out :)

Hopefully I ll ask them to hook the ECU to laptop and check.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 12, 2010, 09:56:28 am
He surely can't mean THE bearing can he - I think we'd surely be hearing it more than just on start-up it it were that!   ???
Sorry to hear you're having problems too. In my bike's case I'm convinced it's the auto decompressor - plenty of evidence and expertise in this thread points that way.
Let us know how things turn out at your end.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: siddharthmenon on July 13, 2010, 06:56:08 am
He surely can't mean THE bearing can he - I think we'd surely be hearing it more than just on start-up it it were that!   ???

Exactly even I feel so, the sound doesn't even come close to bearing noise. Its really loud gear slip or something. Well good I found about this thread, I will try to convince him.

BTW if its auto decomp what should I ask him to look for ?
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 13, 2010, 08:35:50 am
I don't know what it looks like, but presumably he does - he's the mechanic, so let's hope so... :-\
Title: Re: What's that CLACK when she turns over but wont start?
Post by: clubman on July 13, 2010, 08:59:14 am
So is your dealer going to replace the auto decompressor - or is it wait and see ?

It's wait and see. Which I'm quite OK with as it's not done it for a while now.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: qgolden on July 13, 2010, 04:47:47 pm
You know I was re-reading this post for the second or third time and I see you (for good reasons) have been focused on the decompressor.  In your first message or so you indicate it seemed to be coming from the starter area.

What if the Bendix drive in the starter is not fully engaging?  That would allow the teeth to mesh, perhaps enough to begin to turn the motor, then when the motor begins to turn the alignment betwixt the starter drive gears and the clutch basket gears lines up and then drive gear sets in the rest of the way.  Under load it would be quite a THWACK when it sets.  Conversely what if the starter drive has a chipped tooth, so when it just happens that the starter drive is lined up with the teeth on the clutch basket  in that particular tooth, it slips to the next tooth causing a loud and unpleasant noise.

The starter is pretty easy to remove and check.  I would think  if that were the problem then the damage is on the starter side rather than the flywheel side because of the frequency of the issue.  The starter has maybe 8 or 10 teeth on it and the flywheel a 70 or so.  So statistically the problem would present itself once every 8 starts if it were on the starter side and once every 70 or so starts if it were on the clutch side.  It seems to me from reading the post that the frequency of the issue might average once every 8 or so starts?

Just a thought, my .02 your mileage may vary!   ;)
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 13, 2010, 05:48:18 pm
Well, it's another theory, and thanks for your input. I didn't actually say it was coming from the starter area, but just when starting. It's not ocurred for the last few days, and I've started up repeatedly quite a bit to see if I can repeat the fault, so naturally I'm hoping the happy bike fairy has made the problem go away ;)
It is quite a disconcerting THWACK, as you say, or wheeze-thwack, wheeze-thwack more like, as the thing turns over, but seems from deeper in the bowels than the starter itself. But yes, since the starter is pretty easy to get off I'll check it out. I am more inclined to the auto decompressor theory though because of others' reports of such a fault, and because it just sounds like something more out of kilter than a broken tooth. I'll let you know..... :-\
Title: Re: What's that CLACK when she turns over but wont start?
Post by: qgolden on July 13, 2010, 07:34:08 pm
Maybe you can try to get into a habit of laying you hand on the side of the Clutch Side Cover or the Starter Gear Cover on top of the Clutch Side Cover when you start it for a bit,  If is is in there and it occurs, I think you will feel it.   'Course it will also be entertaining for the neighbors if you are using a kick start!  ;D 

That might help you figure out if it is in the front side or back side of the motor.  There are not too many options to cause the issue in each end....you just havta' figger' out which end...
Title: Re: What's that CLACK when she turns over but wont start?
Post by: clubman on July 13, 2010, 09:07:35 pm
To be fair I did say I first thought it seemed to be from the starter area. Your theory is certainly interesting and logical but I think unlikely in my case since it's not been so much a case of every eight starts as every start for a while only to have completely gone away. That the same thing seems to have happened with Will at the same time is spooky indeed, though from the sound of it his case was worse and longer. 
Title: Re: What's that CLACK when she turns over but wont start?
Post by: mbevo1 on July 13, 2010, 09:09:29 pm
What if the Bendix drive in the starter is not fully engaging? 

I'm just throwing this out, 'cause I've got an '07 iron-lung  - which has undergone a sucessfull starterectomy...  ;)

I've heard the UCE starting system is similar to the "old" e-start - which doesn't use a Bendix.  It uses the sprague clutch to engage the starting gears... until it attempts to turn backwards a couple of times.  Then it becomes metal bits in the primary case...

Mike and Stumpy in Michigan
Title: Re: What's that CLACK when she turns over but wont start?
Post by: qgolden on July 13, 2010, 10:25:00 pm
mbevo1
I believe you are right regarding the Sprag unit. I think I read that somewhere as well.  My Bad.

Still viable for the same problem though of a nicked gear. But, as clubman pointed out it went away for a while completely so maybe not the starter gear, But why would the decompressor give the issue every once in a while?  Of course I have never seen a bike with an automatic decompressor until now, so I know nothing more than what I have read here.

I think I would still pull the starter to eliminate it.  It is an easy job.  Could possibly start a bunch of times without happening to hit the bad tooth, then hit it three or four times in a row.  Murphy's law you know, it will only happen at the worst possible times. Of course I am pretty Anal Retentive and when I get in idea into my head and usually have to prove myself wrong before I can move on ... ::)
Title: Re: What's that CLACK when she turns over but wont start?
Post by: SSR on July 14, 2010, 09:33:31 am
IT happens when the autodecomp does not de-compresses and engine backfires resulting in all the torque getting on to the sprag bearing which isn't designed to rotate clockwise.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: siddharthmenon on July 14, 2010, 05:11:47 pm
Even for me this problem has not repeated since long time. If it was teeth or bearing it should have continued right ? I am banking more on the auto decomp theory, may be it decomp parts has settle down properly.
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 14, 2010, 06:21:19 pm
I'm pretty sure it's NOT teeth, judging by the intermittent nature of the problem, and by the sound - which just aint teeth.... :-\  
And I'm CERTAIN it's not the bearing  ???
Good luck. Hope it stays quiet. So far so good with mine...... :)
Title: Re: What's that CLACK when she turns over but wont start?
Post by: qgolden on July 14, 2010, 11:48:34 pm
Well, if you solve the problem what are we gonna' have to talk about?       ;D
Title: Re: What's that CLACK when she turns over but wont start?
Post by: 2bikebill on July 15, 2010, 12:40:49 am
Oh there'll be something - there always is, isn't there.....? ;)