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Re: 1993 XV535 UK Backfiring.

Have a question about fixing something on a Yamaha Virago XV250? Post it here!

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TommyTurbo
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Re: 1993 XV535 UK Backfiring.

Post by TommyTurbo » Mon Apr 15, 2019 3:15 pm

Hi chaps.

Took my bike out yesterday and noticed it seems to be backfiring quite a lot on deceleration with the throttle closed. I’ve only had the bike a couple of weeks and covered 40 miles, it’s probably been doing this the whole time.

I’m waiting for a set of feeler gauges to arrive in the post to check the valve clearances first off.

Are there any other things I could try that don’t involve me diving too deep for now?

The bike runs and idles fine, I can’t feel any hesitation/miss firing whilst riding and the idle is fine also. Everything I’ve searched upto now points at carbs but that would suggest I’d get faults with misfiring and rough idling which I am not.

I’d be great full for any tips if any owners have had this before.

Cheers
Tom.

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ViragoJoe
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Re: 1993 XV535 UK Backfiring.

Post by ViragoJoe » Mon Apr 15, 2019 4:24 pm

TommyTurbo wrote:Hi chaps.

Took my bike out yesterday and noticed it seems to be backfiring quite a lot on deceleration with the throttle closed. I’ve only had the bike a couple of weeks and covered 40 miles, it’s probably been doing this the whole time.

I’m waiting for a set of feeler gauges to arrive in the post to check the valve clearances first off.

Are there any other things I could try that don’t involve me diving too deep for now?

The bike runs and idles fine, I can’t feel any hesitation/miss firing whilst riding and the idle is fine also. Everything I’ve searched upto now points at carbs but that would suggest I’d get faults with misfiring and rough idling which I am not.

I’d be great full for any tips if any owners have had this before.

Cheers
Tom.
Tom,
Virago's are somewhat plagued with deceleration backfiring.
My XV1100 use to backfire more than it should. My fix was adjusting the valves and Synchronizing the Carburetors and Spark Plug gap. Now, backfiring is few and far between to the point of nonexistence. Now, when and if she backfires, I'm really surprised. And I just say: "I thought you forgot how to do that!!!" :lol:

Similar to Mac (Dr. Piston) I too am at a disadvantage when it comes to XV535's.

Virago XV535:
https://www.viragohelp.com/virago-xv-535/

Deceleration Backfiring with some fixes:
https://www.viragohelp.com/virago-owner ... ackfiring/

Hope something above will help you out. Possibly others with 535's can share what they have done, if they too experience backfiring.

I think adjusting the valves as you say is a good start.

Valve adjustment Video XV535:
https://www.youtube.com/watch?v=kznhLvc ... dex=8&t=0s

Joe
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1996 XV1100SH Virago Special
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Re: 1993 XV535 UK Backfiring.

Post by TommyTurbo » Tue Apr 16, 2019 4:59 am

Thanks once again Joe. I’ll have a read through those and see where I get to.

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Re: 1993 XV535 UK Backfiring.

Post by TommyTurbo » Fri Apr 26, 2019 11:50 am

So today I set the valve clearances and fitted a new exhaust I bought on eBay. Tried to fire the bike up and.... nothing.

It cranks over and I have fuel as the spark plugs were wet.
I tried cranking with the plugs out of the cylinders against the frame and I’ve got no spark on either cylinder :(

Abit of Googling points towards the Cdi unit but I’ve got tests to do that the Haynes manual recommends doing before buying one as they’re expensive.

Would a faulty cdi possibly cause my backfiring issue though? If it’s not sparking and exhausting petrol? Do the normally gradually fail or just give up completely?

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Re: 1993 XV535 UK Backfiring.

Post by ViragoJoe » Fri Apr 26, 2019 1:20 pm

TommyTurbo wrote:So today I set the valve clearances and fitted a new exhaust I bought on eBay. Tried to fire the bike up and.... nothing.

It cranks over and I have fuel as the spark plugs were wet.
I tried cranking with the plugs out of the cylinders against the frame and I’ve got no spark on either cylinder :(

A bit of Googling points towards the Cdi unit but I’ve got tests to do that the Haynes manual recommends doing before buying one as they’re expensive.

Would a faulty cdi possibly cause my backfiring issue though? If it’s not sparking and exhausting petrol? Do the normally gradually fail or just give up completely?
Tom,
Really sorry to hear you are having problems. This makes no sense. Your bike was running fine outside of an occasionally back firing. Adjusting the valves has nothing to do with your electrical system. You are now not getting Spark?

What or who's adjustment procedure was used for the valve adjustment. What did you set the intake valves to and what setting for the exhaust valves

Did you do anything else besides the valve adjustment and fitting a new exhaust. Is it the same type of exhaust system you originally had or totally different?

Were the spark plugs against a painted frame? Ground them to the heads and see if they indeed spark.

When you are experiencing a problem. Work on that problem alone. When you start adding more things to the mix muddies the water and places you were you are right now with a no run condition.
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Re: 1993 XV535 UK Backfiring.

Post by TommyTurbo » Fri Apr 26, 2019 1:29 pm

Hey Joe,

Yeah it’s got me scratching my head. Last time I started it a week ago it did struggle to start. Once it kicked in it was fine and I forgot all about it.

A week later (Today) I did the valve clearances and exhaust. I followed Haynes procedure and have watched a few tutorials on YouTube for the XV535. I’m confident I’ve done them correctly, I only moved them a fraction to mid spec as they were bottom of the spec.

I can’t think why i suddenly have no spark. I’m going to go back and have a look at the bike and make sure I haven’t disturbed anything... but I don’t think I have. I’m hoping it’s something simple I’ve missed as it doesn’t really make any sense like you say, the systems I’ve worked on are separate from each other.

The exhaust is a second hand Jardine system. It says the carbs won’t need re jetting with this exhaust.

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Re: 1993 XV535 UK Backfiring.

Post by ViragoJoe » Fri Apr 26, 2019 1:44 pm

TommyTurbo wrote:Hey Joe,

Yeah it’s got me scratching my head. Last time I started it a week ago it did struggle to start. Once it kicked in it was fine and I forgot all about it.

A week later (Today) I did the valve clearances and exhaust. I followed Haynes procedure and have watched a few tutorials on YouTube for the XV535. I’m confident I’ve done them correctly, I only moved them a fraction to mid spec as they were bottom of the spec.

I can’t think why i suddenly have no spark. I’m going to go back and have a look at the bike and make sure I haven’t disturbed anything... but I don’t think I have. I’m hoping it’s something simple I’ve missed as it doesn’t really make any sense like you say, the systems I’ve worked on are separate from each other.

The exhaust is a second hand Jardine system. It says the carbs won’t need re jetting with this exhaust.
Was your previous exhaust system the standard Virago exhaust. By changing exhaust systems changes exhaust back pressures that affects how the engine will run. You should have left the old system in place until you corrected the back firing issue.

Provide pictures of the two different exhaust systems. Who said the Jardine system doesn't need rejetting, Jardine or the person you bought them from?


"A week later (Today) I did the valve clearances and exhaust. I followed Haynes procedure and have watched a few tutorials on YouTube for the XV535. I’m confident I’ve done them correctly, I only moved them a fraction to mid spec as they were bottom of the spec."


Sorry the above statement means nothing. What are the feeler gauge values you set the valves to. That is what tells you if they were set correctly or not!!

Lets work on one thing at a time. Starting first with the valves. Then we will take the next one until we get back to a running bike.

What year is your XV535?
ViragoJoe
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Re: 1993 XV535 UK Backfiring.

Post by TommyTurbo » Fri Apr 26, 2019 2:34 pm

Jardine advertise the system on their website as an exhaust that doesn’t need re jetting. ( https://www.customcruisers.com/contents ... haust.html ) The exhaust prior was a standard system. Yes your right I shouldn’t really have messed with the exhaust before fixing the original fault.

I’ve been back to the bike, dried the plugs out and checked all the connections I could have possibly disturbed. The battery was starting to struggle so I decided to do one last crank and check battery voltage while cranking and it burst into life!?

Valve clearances were set to;

Intake - 0.10mm (Haynes says spec is between 0.07 - 0.12)
Exhaust - 0.16mm (Haynes spec 0.12 - 0.17)

Now I’ve had the bike running it still has the backfire. Albeit with more volume :shock:

Bike is a 1993 XV535 UK model.

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Re: 1993 XV535 UK Backfiring.

Post by ViragoJoe » Fri Apr 26, 2019 3:49 pm

Quick spec page: Specifications XV535 1981-1994 Yamaha Virago:
https://www.viragohelp.com/specificatio ... ha-virago/

We'll assume the valves are on the mark for now. If the next test does not provide any answers we'll have to double check the valves to confirm accuracy.

If your spark plugs are old replace with a new set. Check gap for accuracy.

Take a can of starting fluid with the engine running. Spray the starting fluid on all hoses including the carburetor mounting boots. If the idle changes up or down in any area recheck the area where it changes. If there is an rpm change you have a vacuum leak in that area. Check for cracks and loose hose connections if idle changes. For this can cause backfiring.

Take precautionary steps for starting fluid is flammable. Have a fire extinguisher near by or method to quench out any flame. Do this out doors for obvious reasons. There shouldn't be an issue. But safety first!!

1. Have these carburetors ever been off the bike for any reason. Cleaning, float adjustments, etc.?

2. Was the bike in good running condition prior to you buying it? Without any back firing.

3. Had it been stored for a long period prior to you buying it?

4. Are you using fresh gasoline?

5. Has the fuel filter been checked?

6. What is your oil level?

I don't know the history of this bike and there is a lot I don't know about it. Reason for all the questions.

YEP, your back firing will be louder now that you have on Jardine exhaust pipes. Did you use brand new exhaust gaskets? Hope so! If they leak you can get back firing as well!! Make sure they are on correctly and tightened adequitely. Not to tight. For those studs have been under a lot of heat stress and will loose tensile strength. You don't want to snap them for then the real fun starts.
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"Never ride faster than your Guardian Angel can fly!!"
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Re: 1993 XV535 UK Backfiring.

Post by TommyTurbo » Fri Apr 26, 2019 4:05 pm

1. Have these carburetors ever been off the bike for any reason. Cleaning, float adjustments, etc.?

Answer - I couldn’t tell you. Although I’ve noticed the screws holding the diaphragm covers and float bowls are a different types to those I’ve seen in videos, so it’d suggest they have been ‘touched’ in the past.

2. Was the bike in good running condition prior to you buying it? Without any back firing.

Answer - Its running the same now as it has done in my ownership. The back fire was probably always there, it’s my first bike and the excitement of riding the bike probably distracted me from taking any notice of the backfire, although I’m pretty sure it’s always been there. (I’ve only covered 65 miles) It has always started and run fine though and I’ve never noticed any problems in the general running.

3. Had it been stored for a long period prior to you buying it?

Answer - Yes. It’s only covered around 500 miles in the last 8 years.

4. Are you using fresh gasoline?

Answer - Yes it’s a brand new fuel.

5. Has the fuel filter been checked?

Answer - The fuel filter is brand new. I changed the Air filter, spark plugs (gaps are correct), oil and oil filter when I bought the bike as I didn’t know it’s history.

6. What is your oil level?

Answer - Oil level is between max and min marks. It is fresh oil.

Sorry I’m not sure what you mean by Starting fluid, but I think I’ve seen carburettor cleaner used for something similar whilst googling, I take it that’ll show the same results?

Thanks for taking the time to reply. It’s my first bike and my first time working on bikes so I have more questions than answers at this point. I have an engineering background do not a total idiot, just not familiar with bikes... yet! :lol:

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