backfire valve timinig ???????????????????

[dave09]

hello all had my vtr couple weeks now first thing i did was change the can but when i fire the bike up it wil sit the on tick over fine but will back fire alot more like a popping sound it did it when i had standard cans but was alot quiter.

i done a full carb clean on it today but the noise is still there the bike rides fine i ride for about 30mins to work each day soon as i get there the noise is atill there.

now im left with the conclusion its either valve seats or possible timing issue.

[VTRDark]

What cans have you put on, and have they got baffles in? with some cans re-jetting is possibly required. But if you had the problem before a tune up is probably in order. Check that there are no leaks whatsoever in the exhaust around the seals and downpipes. This will cause popping especially on the overrun, though a little popping is normal V Twin sound. Backfires No.

Did you have the carbs off the bike. Also check that you put the vaccum hose back on the tank fuel tap in the right place. I suspect this is your problem.

[/quote]

Note the small vacuum hose does not connect on the bottom but behind the fuel hose. Right hand side of pic.

(:-})

[dave09]

cheers for the reply its not the tap i did this once before
it does it from cold just sitting on tick over soon as i start it in the morning popping out both cans the bloke who had it before me had some work done to it from a bloke on here tony.mon he had all the heads off done gaskets/clearance's/manual ccts.

ive put on 2 micron cans the baffles cant be removed tacked on by 3 welds thinking of removing these re drill them use a 6mm cap head so they can be removed but put back in for mot's.
but it did do it befor with the standard cans but was alot quiter

[VTRDark]

Well there's nothing wrong with the valves or timing if Tony's worked on it. That's better than Mr Honda himself

The first thing to check is that there are no leaks in your exhaust seals but I suspect a good tune up is in order. You could also set the TPS to 500 ohms, this may help. Search for TPS on here and have a read up. If you can't find anything I will explain it to you.

When you had the carbs off to clean did you strip them down? And did you make a note of what jets are installed. If you did strip them down, how far did you go, did you have the diaphragms and needles out. Also did all the breather pipes go back on the air box correctly and securely. Especially the front one which can be awkward.

(:-})

[tony.mon]

I've replied to your PM, but I think that the exhaust leaking might be the first port of call.

As has already been suggested, check exhaust port gaskets as well as the three graphite seals on the system joints.
You might not have all three on yours if you have aftermarket cans on now, though.

No, it's not valve timing, you can relax about that one- all went back together and was test ridden at handover, so no probs there.
But it did have the head gaskets renewed, and valve clearances set within spec at the same time, so those won't need attention just yet.

also check that the carbs are seated on their rubbers correctly, and that the vacuum pipes are attached.
if the front cylinder had a vac pipe take-off (can't remember) then make sure it's properly sealed, not leaking and has a blanking plug or similar in the end.
It's only used to balance the carbs, and a short length of rubber tubing is usually attached and left blanked off.
If the stopper has come out of the end or the rubber tube has come off the brass stub behind the front cylinder head, then it will cause misfires and uneven running.

[VTRDark]

Yes the front vacuum, I forgot about that. Heres a pic so you now where to look. Sorry it's a bit blurry.

This is from the right hand side on the front cylinder. You can see it through the V in the frame by rad.

On mine there is a brass nipple, I have a hose attached to this for carb sync purposes. Yours will either have been adapted and has a hose attached as well, so check the end of the hose and make sure it's blocked off. Or yours will be capped off where I have the brass nipple in pic.

(:-})

[dave09]

just been to check mine and it has a cap head in its place

[dave09]

do you get one on the rear carb ill get a video of it today and show you

[VTRDark]

There are two vacuums. The front is capped off as standard, but it's a good idea to run a tube from it to make carb syncs easy. http://www.vtr1000.org/phpBB3/viewtopic ... 31&t=18430 and then the rear is the one that leads to the petcock/fuel tap.

(:-})

[dave09]

hope the link work this is a video of my bike when i got home

[tony.mon]

Possibly an airleak in the exhaust system connections and running a little rich?

Check the plug caps are good and tight on the plugs.

[VTRDark]

Carb cough that is. Check for leaks in exhaust. Also when you cleaned the carbs I presume you removed them off the bike. Check these are seated back on the carb rubbers securely. Did you do a carb sync when they where put back on. Sounds to me like the bike needs a good tuning.

(:-})

[dave09]

cheers for the reply thats one thing i need to get done is balance the carbs im gonna change the carb manifolds i noticed one of them was slighty perished also when i got to work me and a mate covered both cans and we found a slight blow out the front exhaust manifold

[dave09]

gonna try re doing the exhaust's found i got a slight blow of the front gasket

[Wicky]

David Silvers have the round copper crush gaskets, make sure you get the old ones out first with a pick. And plus ensure there is a good seal at the header/link pipe connection.

http://www.ronayers.com/Fiche/TypeID/26 ... up/MUFFLER

http://www.davidsilverspares.co.uk/part ... mber_6498/