XBR500 - BANG BANG POP POPOP BANG POP etc

[pigafetta]

Hiya All

I've a quick question if you don't mind. I'll try and be brief.
I'm getting a lot of banging and popping on the overrun on my XBR. It's been like that for ages but its starting to get on my nerves. I've recently fitted a new cam chain so I've checked valve clearances and all looks fine in the top end. I've redone all the joints on my exhaust with FireGum and fitted new gaskets but to no avail. To be honest I thought that would cure it but it hasn't. My Predator is fairly loud anyway so I tried fitting the dBkiller that I use for MOTs. Still banging and Farting.

So now I'm thinking carbs. I've been told that adjusting the pilot screw might help although I haven't tried that yet. Am I right in thinking that a lean mixture might cause the popping? I'm not great with carbs, does anybody have any suggestions as to what I might try next? I'd be grateful for any advice (and so would my neighbours  )

Thanks,
Dave B

[SteveC#222]

Hairline cracks in the carb inlet rubbers?

[pigafetta]

Well I tried some noodling with the pilot screw and a couple of test rides last night but still no joy. I had a quick look at the air cutoff valve, it all looks in good order. It's crossed my mind that the last time the carb was off, it wasn't done by me but one of the mechanics at work. That'll be a lesson learned, then 

I'll pop the carb off later and give it a good going over. Cheers SteveC, I'll give the rubbers a thorough examine.

Thanks,
Dave B

[Andy M]

Spray any intake rubbers with WD40 or grease them up. If the temporary seal does the trick you know which tree to bark up.

Andy

[pigafetta]

I pulled the carb off this afternoon. The rubbers seem to be in good order but the two o-rings on the carb insulator thingy look pretty well knackered. I've a feeling these may be the culprits. I've just priced them up, £15 for two bloody o-rings! And they'll take 5-7 days to get them to me.

I'll order them but I can't be bikeless for a week so I'm going to smear a bit of gasket goo on them and stick them back on for now.

Cheers,
Dave B

[Dick Scratcher]

If these rings are simple Neoprene things, try your local (if you've got one) bearing/seals stockist, probably end up spending 50p !.

[pigafetta]

I'd have to get them mail-order.

I can get nitrile ones that'll fit for a couple of quid but I'm not sure if they can handle the temperature. How hot does a cylinder head get?
I could get higher temp Viton ones but I can only find them in ruddy big bags in which'll cost as much as getting the Honda jobs from Dave Silvers.

Cheers,
Dave B

[Dick Scratcher]

Just lately I've heard of several cases of parts being available and cheaper from your local Honda dealer than fro David Silver.

[pigafetta]

I've ordered some nitrile ones for now. For the cost of a few quid I thought I might as well give them ago. If they don't work I'll shop around for the Honda jobbies. I agree David Silvers can be a bit pricey. I'll prbably get a better price from Fowlers.

Cheers,
Dave

[guest1155]

I have a predator on mine and it bangs like hell on the overrun. i quite like it but it does get quite tedious on a daily rider. I'l be very interested to see if this cures your problem.

[pigafetta]

The Predator was on when I got the bike about 5 or 6 years ago. It only started banging about 12 months after my pal fitted a new camchain guide. It doesn't bother me that much, it's just that it didn't bang and then it did and I preferred it when it didn't 

Anyway, the o-ring replacement could've gone better. Whatever that carb insulator piece is made of, it breaks surprisingly easily 

Serves me right for being a tight-arse and not buying the proper Honda o-rings. The ones I got were just a tiny bit thicker and I thought they'd probably be ok. Duh! So now I'm grounded for another few days until I get the new insulator.

It's been one of those days 

Cheers,
Dave B

[pigafetta]

Well, thanks to an insulator from Simmo and two of the most expensive o-rings in the world, I seem to have put right the results of my ineptitude and cured (or greatly reduced) my popping and banging. I'm happy with it. I'm going to stop fiddling now before I break something else 

Cheers

Dave B

[guest1155]

excellent. glad it's working better. i'll be checking for air leaks this weekend.