Honda XRV Forum banner

1 - 20 of 29 Posts

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #1 ·
Ok got your attention or not perhaps.

I am on route to the Austrian Alps and my exhaust has been popping and banging on the over run since leaving Wales.

Ok I know all the things to do - I am pretty handy with all that stuff but want to check out a couple of things - now no disrespect but only chip in if you really really know about this stuff.

Ok I have a Motad Venom with baffle in - it's Bern on a year with no problems - then I did an bike check over and stuff for the trip and now it's popping - so here is what I have changed.

Balanced the carbs - bike running smooth and like silk all the way through the rev range

Fitted K&N filter - not too happy with fit it seemed a tad tight and I had to remove the mesh over the inlet to the carbs in the airbox to get it to seat correctly - I also ad a precaution gaffs taped the complete join of the k&n to the air box

I took the exhaust apart and removed the spark arrestor as it was loose and rattling then I used a good exhaust sealer to rebuild the system as well as 2 stainless clamps at the lower joint NOTE I have stripped this here in France and used serious exhaust sealer to put it back thinking that it was sucking in there.

I am about to remove the tank and see if I have disturbed the rubber inlet pipes but I would have thought it would have run badly if these were loose etc

So the backfiring only happens when you shut off completely and the bike gets down to about 35mph in top. If I keep some throttle open it doesn't backfire neither does it if I drop a gear or two - above 3000 rpm all ok below not so good

Now I wouldn't mind but I know from experience that the Alps need a lot of shut off throttle on the long descents.

Any advise gladly revieved especially diagnostic stuff

Cheers guys
 

·
Hill Rider
Joined
·
3,105 Posts
Mine started that recently - it was a loose header pipe.

Give the nuts a nip up and see if they're loose.

Steve T

:cool:
 

·
Ride the Sumo!
Joined
·
1,089 Posts
Mine started that recently - it was a loose header pipe.

Give the nuts a nip up and see if they're loose.

Steve T

:cool:

Yeah that - happened to mine not too long ago - turned out one of the front stud nuts was loose - 5 mins with a long socket extension and sorted.
 

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #4 ·
Ok that's a possibility as I have never tightened them - everything else I'd so well sealed perhaps it's sucking in there

Although I did the hand over the exhaust at tick over thing and it will choke and stop.

Now the laughable bit - I hummed and hah over how many tools as it's been so reliable over the past 30k miles I ended ip only taking the standard kit plus a few others but no real socket set.

What size nuts are they? 10mm? 12mm?

Cheers
 

·
Hill Rider
Joined
·
3,105 Posts
The nuts are 12mm and you'll need a 1/4inch drive socket, cos anything bigger just doesn't get into where you need to get :thumbup:
Also useful to have a UJ adapter, as one of the front & one of the rear nuts needs an angled approach to get the socket onto it.

Hope this sorts your problem.

Steve T

:cool:
 

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #6 ·
The nuts are 12mm and you'll need a 1/4inch drive socket, cos anything bigger just doesn't get into where you need to get :thumbup:
Also useful to have a UJ adapter, as one of the front & one of the rear nuts needs an angled approach to get the socket onto it.

Hope this sorts your problem.

Steve T

:cool:
Cheers mate - I will buy a cheapy one on an Intermarche - the irony is I have a set of quarter drive sockets from 6mm to 13mm as part of a tool set to get you out of a fix but the drive part seems as though it was made of putty because it just broke apart. Mo extensions though. Before leaving I chose not to bring a small extension with t handle oh bother!!! Ha ha Anyhow this will now be a test of ingenuity.

Thanks again I will post in a couple of days on progress. If it fails I will be waking up the cows in the Alps!
 

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #7 ·
Hi just a quick update

Took tank off and checked manifold nuts on exhaust - they seemed tight enough - I am not going to force them in case the snap.

I did notice that one of the inlet rubbers from the airbox to the rear carb was quite loose so tightened that. Did a plug check - they are clean and correct.

Cannot see anything else. The only thing changed then apart from the airfilter is the removal of the spark arrestor - and that is only a mesh - single skin across the pipe before the silencer - can't see that making the difference .

Started it up and it seems better on reving it on the stand but I will see ad soon as soon as I start on the passes.

For info it's raining here in Landeck Austria - I didn't come here for the rain! It's supposed to get better in the week.
 

·
Wing Commander
Joined
·
14,437 Posts
When you find the solution, let me know. The Zebra does an almighty backfire if I suddenly shut off the throttle and pops constantly at low speed.
 

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #9 ·
That makes 4 of us, including my friend here in Athens. Replacing the seals didn't make much of a difference in popping and banging.

What made a difference was the air filter replacement I did today morning. The previous one was quite blocked ie there were spider webs built around it. It smoothened the banging but the popping is still there. It makes me think that the popping isn't caused by lean mixture but rich. To be honest I didn't bother to check the plugs last weekend while replacing the seals so I have no idea what the mixture quality is.

Personally I have a few more things to check like intake integrity, choke mechanism etc but I am going to take the tank out again next weekend.

I think we have already hijacked this one so from now on we should start a new thread titled "Popping & banging"...
There was a thread I started some time ago - it was called "a Popping we will go ..." I will reserect it with a copy of this post if I can find it.

OK HERE IT IS
 

·
Registered
Joined
·
32 Posts
Thank you Angelo!

I just remembered another culprit that causes that popping and banging. Worn air cutoff valve (part number 9 on the rd03 fiche couldn't find the rd07 one).



I faced this problem with my previous bike xtz750 and got over it by putting a drop of a 2 component epoxy glue on the hole.
Just another thing to be checked
 

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #11 ·
Thank you Angelo!

I just remembered another culprit that causes that popping and banging. Worn air cutoff valve (part number 9 on the rd03 fiche couldn't find the rd07 one).



I faced this problem with my previous bike xtz750 and got over it by putting a drop of a 2 component epoxy glue on the hole.
Just another thing to be checked
Thats interesting. My bike is in very good nick - well and corrcelty services cos I do it! and only 33k miles - I did take the carbs off a couple of years ago and open them up and they were in excellent condition BUT 2 years ago so perhaps there is something here.

I did put the standard can on and there is no popping - well not that I ca hear which made me think it was a weakening on shut off. What does this valve actually do?
 

·
Registered
Joined
·
32 Posts
It cuts off the air and enrichens the mixture when closing the throttle in order to avoid fuel starvation at overun with the known noisy results.

If the popping stopped when you put on the original can then you should stop looking. The aftermarket one, which I suppose is more free flow, probably lowers the back pressure in the headers letting unburned fuel reach the exhaust downpipes at valve overlap, which then explodes because of the heat producing those bursts.
 

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #13 · (Edited)
Ok mow we are getting somewhere. I am pretty confident the usual stuff is ok - the back pressure is a distinct possibilty because before I went to Austria this year I took the rear can off because of a rattle inside - the Db reducer cone had broken - the mesh baffle which sits across the pipe had cone away do I just took it out. This year in the Alps the popping was noticeably loud. When I got back I welded it back onto the cone so effectively introducing a mild restrictor and the popping is better - almost but not quite gone.

So how can I get some back pressure in there then? Restrict further? Maybe worth a try.
 

·
Registered
Joined
·
2,270 Posts
Mines a popping and a banging when i shut off and coast all started after fitting the motad venom exhaust refitted the standard can and it went. If i turn the tickover up it stops it also, so my bet is the idle mixture needs tweeking
once i've ballanced the carbs i will adjust them and report back:thumbup:
 

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #15 ·
Mines a popping and a banging when i shut off and coast all started after fitting the motad venom exhaust refitted the standard can and it went. If i turn the tickover up it stops it also so my bet is the idle mixture needs tweeking
once i've ballanced the carbs i will adjust them and report back:thumbup:
That was my thinking some time ago it's just such a hassle getting those screws to turn let alone getting to them. I even have one of those right angled screwdrivers.
 

·
Registered
Joined
·
52 Posts
Add me to the "Mine does this too" Club. Only just started though, right after I changed the fuel pump to the Facet one. I've got to the South of France, and as per usual, this is where I find the things that ain't right on this bike! Ah well, apart from it being annoying, is it much of a problem? I'm heading East in a couple of days, don't want to be doing any damage....
 

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #17 ·
I don't think it'd a problem but with constant backfiring damage will happen to the pipe eventually. More so is the unwanted attention I get descending the Alps.
 

·
Ride the Sumo!
Joined
·
1,089 Posts
You might want to check with some of the guys more experienced with fuel/exhaust setup.

I seem to recall from the days I spent fortunes at Dyno's that popping can mean a too lean mixture which can cause damage to valves/pistons etc.

Worth doing a plug chop (although with modern fuel this method can be suspect) and also checking the base settings, trying a larger jet but also to look at a free-er air filter to match the free-er exhaust gasses.
 

·
Registered
Joined
·
2,270 Posts
You might want to check with some of the guys more experienced with fuel/exhaust setup.

I seem to recall from the days I spent fortunes at Dyno's that popping can mean a too lean mixture which can cause damage to valves/pistons etc.

Worth doing a plug chop (although with modern fuel this method can be suspect) and also checking the base settings, trying a larger jet but also to look at a free-er air filter to match the free-er exhaust gasses.
I've done this and the plugs look fine that***8217;s why I***8217;m not too worried
It happens worst when cold just after choke is turned off, I live on a steep hill and usually ride down it when I go out, so allot of pops on zero throttle going down it. The popping almost disappears when hot, once the carbs are ballanced my next step is to stick it on a dyno i want the fuelling to be spot on.
 

·
Born to Slide
Joined
·
1,741 Posts
Discussion Starter · #20 · (Edited)
Let's keep this one going.

I have a K&N so a freer filter to match the freer exhaust. I am more inclined to think it is the mixture screw under carbs - if I am right these on act on tick over when throttle is shut and the bike only backfires when on the over run down hill with throttle shut - so I am thinking that if I richen it then it may just sort it? Any thoughts? It's a real fiddle getting something to the screws - anyone got any tips on this?
 
1 - 20 of 29 Posts
Top