Unofficial Royal Enfield Community Forum
Royal Enfield Motorcycles => Bullet with the UCE engine => Topic started by: 2bikebill on July 22, 2010, 09:52:50 pm
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A bit of backfiring this evening so thought I'd have a quick check for leaks at the top of the exhaust. Does this look right to you? Should the flange (?) be up flush up against the cylinder - or is that sodding great gap how it's meant to look? To my untrained eye it looks like a bodge, particularly as the nuts are two different sizes. I'm guessing the top of the pipe is rounded over to make a press seal against the outlet, but my instinct tells me that flange should be much closer in.
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Can't see the top stud, but the bottom one looks like there's a spacer in there?!
>WTF?<
Unless this engine is employing new ideas, the flange should be against the cylinder. I can't remember if there's a gasket in there, or not.
Is this a new bike? If used- maybe the PO put a different heder on there and tried to make it fit. Careful you don't strip any threads.
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Thanks Uncle Ernie. It's a new bike which has had warranty work done on the exhaust. When the heatshield came off they had to fit a new front pipe because the clip for the front of the heatshield had snapped off. I did have a suspicion at the time that they'd put on a pipe that wasn't new because it was a bit discoloured at the top already.
If this has been bodged on then I'm going to be very pissed off about it.
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Can't see the top stud, but the bottom one looks like there's a spacer in there?!
>WTF?<
Unless this engine is employing new ideas, the flange should be against the cylinder. I can't remember if there's a gasket in there, or not.
Is this a new bike? If used- maybe the PO put a different heder on there and tried to make it fit. Careful you don't strip any threads.
NOT!! - Still your turn ..... I'm more familiar with THIS crap than I EVER wanted to be ..... The two-bolt flange presses against a ring that is welded onto the pipe out a ways from where the actual face of the pipe seals in the cylinder. The flanges bend quite easily when torqued too much, trying to get the exhaust leaks to BE QUIET! The good and proper fix for most of those is to remove the silencer and then remove the pipe. Straighten the flange (a big adjustable wrench works WONDERS here .... ), replace the studs (I'll bet you they are splayed out, bent) and then use two gaskets when putting it all back together after assuring the sealing face of the pipe is smooth and squared off. DO NOT tighten the flange until the whole system is loosely hung - then tighten the nuts until they are barely tight - but equal - there are usually about two threads showing at this point. Tighten the silencer mounts next and start the engine - then gently tighten each nut on the flange until the exhaust quits leaking. Turn the bike off now and finish tightening the rest of the clamp bolts on the silencer. Check one more time for leaks - tighten ONLY as much as is needed and equally on both sides of the flange for the complete cure. Tedious, yes - difficult, no ..... There you GO!
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Thanks Bob, but I'm now still not sure whether that gap between the flange and the cylinder is meant to be there.
I don't think there's an exhaust leak.
But look at the size of that gap - and what's that spacer doing in there? And I just KNOW those nuts shouldn't be two different sizes.
So you're saying the end of the pipe seals against the cylinder, but the flange doesn't fit flush against it's matching outlet on the cylinder?
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I have an AVL, so I'll shut up and sit down now.
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A bit of backfiring this evening so thought I'd have a quick check for leaks at the top of the exhaust. Does this look right to you? Should the flange (?) be up flush up against the cylinder - or is that sodding great gap how it's meant to look?
Will:
Here are three pictures of my G5 exhaust taken from three different angles - from below, from top, and one from left side. Looks similar to yours !
singhg5
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It does look similar doesn't it. Thanks Singh, that's reassuring.
It just looks wrong to this tidy mind I suppose.
I think I'm going to take it all off and re-seal with fire gum - something's causing the old girl to backfire from time to time - moreso than usual this evening.
This bike's making a worrier out of me..... :-\
Stupid really - when I'm on it I just enjoy the ride. It's all this thinkin is the trouble....... :(
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It does look similar doesn't it. Thanks Singh, that's reassuring.
It just looks wrong to this tidy mind I suppose.
I think I'm going to take it all off and re-seal with fire gum - something's causing the old girl to backfire from time to time - moreso than usual this evening.
This bike's making a worrier out of me..... :-\
Stupid really - when I'm on it I just enjoy the ride. It's all this thinkin is the trouble....... :(
There could be other reasons for backfiring ! Did you check the spark plug ? Here is a good general description and causes of it - including too lean, too rich, timing of spark, removing catalytic converter, spark plug condition, air leak etc. etc. ???
http://en.wikipedia.org/wiki/Back-fire
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Yes the plug's good, in fact I cleaned it today just to try out my new plug cleaning brush!
Re our previous plug conversation - I've just ordered the NKG Iridium plug - BPR6EIX. It meets all the criteria of the Bosch code, and less than six quid delivered from Amazon so I didn't think it extravagant. It'll leave me the Bosch to carry as a spare.
Thanks for the backfiring link. I have changed the exhaust of course, and expected a bit of backfiring, but it's odd that sometime's it does it a lot and other times hardly at all.
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It does look similar doesn't it. Thanks Singh, that's reassuring.
It just looks wrong to this tidy mind I suppose.
I think I'm going to take it all off and re-seal with fire gum - something's causing the old girl to backfire from time to time - moreso than usual this evening.
This bike's making a worrier out of me..... :-\
Stupid really - when I'm on it I just enjoy the ride. It's all this thinkin is the trouble....... :(
Will - Do NOT put "sealer shit" around the exhaust!! It will ruin the rather expensive "Oh-Two" sensor! If it doesn't leak - leave it be! I'm betting (hoping) you can't see it when you are riding the bike anyway ..... Save the redo for when it isn't riding weather - and do it exactly like I outlined for you and it'll be just fine. Singhg - the G5 is very much the same - but without the stylish "heat clump" on the end of the pipe. The G5 just has a flange - and it is the same dimension as the AVL - BUT - it crams the pipe into the hole in the head, rather than bolting flush to a flat opening.
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".... it crams the pipe into the hole in the head, rather than bolting flush to a flat opening...."
Seems to be the case. If that's how they've done it then that's how they've done it I guess. Good job I'm not manufacturing motorbikes - they'd never get out the factory. Me? Obsessive? :-\
Point taken about adding sealer gunge above the O2 sensor. And I'll leave well alone until winter and see how I feel about it then. I don't think it's leaking at the top, if it is then it's very slight. Can't get my hand close enough to feel for leaks when its hot so I'll have a go when cold. I sealed it pretty well where the silencer joins the front pipe, but I don't know whether a slight leak that far along would cause the backfiring?
Thanks again for your input. Scuse my confusion after your earlier response - couple of bottles of that good Czech lager wasn't helping ny comprehension....... ;)
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".... it crams the pipe into the hole in the head, rather than bolting flush to a flat opening...."
Seems to be the case. If that's how they've done it then that's how they've done it I guess. Good job I'm not manufacturing motorbikes - they'd never get out the factory. Me? Obsessive? :-\
Point taken about adding sealer gunge above the O2 sensor. And I'll leave well alone until winter and see how I feel about it then. I don't think it's leaking at the top, if it is then it's very slight. Can't get my hand close enough to feel for leaks when its hot so I'll have a go when cold. I sealed it pretty well where the silencer joins the front pipe, but I don't know whether a slight leak that far along would cause the backfiring?
Thanks again for your input. Scuse my confusion after your earlier response - couple of bottles of that good Czech lager wasn't helping ny comprehension....... ;)
As long as it isn't leaking in front of the "Oh-Two" sensor - you are fine .... after it just makes racket! That lager should tune a fellow up to think better .... it seems to work that way for ME, anyway! hahahaha! ;)
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"....That lager should tune a fellow up to think better......"
Nice theory....hic....if only it were so...... :P
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"....That lager should tune a fellow up to think better......"
Nice theory....hic....if only it were so...... :P
I'm guessing that you'll need to exercise that liver a bit more - my would be the equivalent of the World Weight Lifting Champion I think ..... Hahahaha! ::) Once you get it RIGHT - it just gets better and better. My HERO, Henry Yunick invented the counter-rotating Offenhauser engine for an Indy racer while partaking in quantities of V.O. Canadian Whiskey ....... so it CAN be an inspiration!
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I think I'm going to take it all off and re-seal with fire gum - something's causing the old girl to backfire from time to time - moreso than usual this evening.
Mine is the same Will, taking it all apart won't solve the problem. The reason your bike is backfiring is because you've put on an aftermarket sports exhaust, mine did the same. I've now re-fitted the stock exhaust and all's well again.
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Yeah I expected a bit of backfiring, the original exhaust does it but it's way more subdued. It's nothing I can't live with, but I'm puzzled by the wholly random nature of it. Sometimes it don't, and sometimes it do.
Doh! I guess that must be the nature of it..... :D
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Yeah I expected a bit of backfiring, the original exhaust does it but it's way more subdued. It's nothing I can't live with, but I'm puzzled by the wholly random nature of it. Sometimes it don't, and sometimes it do.
Doh! I guess that must be the nature of it..... :D
Though I believe that your bike is doing what Rusty's did and if you replace the stock exhaust back on it, the back firing will disappear to the way it was before.
Just out of curiosity, do this test and see if you notice any difference in backfire -
1. Start the bike and let it warm up for 60 seconds by watch in neutral just standing still. Then put in first gear and gradually build up speed into higher gear.
2. Start the bike and just go, without waiting to warm up.
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I will conduct this interesting experiment at the first opportunity. :)
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hi will,if the joint was leaking wouldn't it have a sooty mark.just for the record mine on the standard exhaust doe's a little backfire now and again.
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I don't really think there's any leak Billy. There are no signs.
Singh, I tried the slow warm up before a good long ride today - in all truth I generally do leave it ticking over while I don helmet & gloves. Also I have 300 yards of very narrow lane with high sides and curves to negotiate before I turn onto a not quite so narrow lane for 600 yards before I reach proper road, so the bike is really barely above idle all that time. I also try to stay focused and mindful - zen and the art of and all that... So I'm not thrashing about like a boy racer.
So today, 70 mile round trip on mixed roads. The odd little pop on the overrun, a couple of good'ns, but random, as usual. Slowing onto the slip road after five miles or so at 75mph on the dual carriageway - not a pop. Yet just chugging along in traffic on rural road - a good bang as the throttle closed.
It's the nature of the thing, and not a nuisance.
On a side note, I realised today I just can't get on with earplugs while riding. Makes me feel somehow disconnected. I had to stop and take them out. The helmet provides some level of ear protection of course. It'll have to do.
Ride on my brothers. Joyful heart, quiet mind.