Author Topic: Backfiring and smell of fuel from exhaust  (Read 1989 times)

Online Shiney

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Re: Backfiring and smell of fuel from exhaust
« Reply #50 on: May 30, 2018, 12:19:34 AM »
When you say backfiring do you mean popping back through the air cleaner or popping crackling out the exhaust?
The pipe at the back of the air box that you blocked is the air injection, witchI believe feeds fresh air into the exhaust ports thru a pair of reed valves in the head and is controlled by the large valve just behind the airbox.
The crankcase breather goes to the front right corner of the airbox.
If too much air is being bled into the exhaust it will mess with the O2 sensors cursing a over rich situation.
Also check for leaks in the exhaust system.
 :blu13   


Hi mate,
The popping and crackling is coming out of the exhaust not through the air cleaner and is joined by the smell of fuel.
I am working on the valve clearances at the moment but when I am done (if the issue remains) I will start looking at the air injection, reed valves and inspect the entire exhaust system again.


Makes sense to me
Since fitting Staintune mufflers I get a little crackle from exhaust but a lot of bikes and cars with aftermarket exhausts does it
But not actual backfire
But I don't get a fuel smell
Sometimes sounds good  ++


I put the aftermarket exhaust cans on the bike shortly after getting it and have always had a bit of a burble but this is nothing like that, it will backfire (pop) even when changing gears while riding |-i
But when it is working properly it really sounds good :rockon
My Ride: 2015 (Model) ST1300  :wht13
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Online Shiney

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Re: Backfiring and smell of fuel from exhaust
« Reply #51 on: November 02, 2019, 02:13:10 AM »
I have just realised that I completely forgot to update this topic with the outcome, so here it is...


After trying everything that was suggested and still having no luck I took the bike in to the Honda dealer that deals with Police ST1300s (Brisbane Motorcycles at Windsor).

They were able to fix the issue of excessive fuel usage, the smell of fuel from the exhaust and the backfiring by balancing the throttle bodies and blocking off the PAIR system.
Once this was done the bike ran perfectly :runyay

Hopefully this will help anyone that has similar issues in the future.

Cheers
Shiney
My Ride: 2015 (Model) ST1300  :wht13
OzSTOC #104   STOC# 8512   IBA # 59142
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Online HunterTodd

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Re: Backfiring and smell of fuel from exhaust
« Reply #52 on: November 02, 2019, 07:47:22 AM »
hi shiney
That pipe at the rear of the airbox goes to the pair valve which ultimately is connected to two reed valves on the top of each rocker cover.
The reeds recirculate engine fumes and can get gummed up. Easy job to do and since you noticed some effect when you bkocked the pipe might be worth a try. I am chasing a fuelling problem myself and it is on my to do list tomorrow.
The tip apparently is not to pull the actual reed assemblies apart. Just clean them with carby cleaner.
Cheers
 
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Online Shiney

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Re: Backfiring and smell of fuel from exhaust
« Reply #53 on: November 02, 2019, 05:40:15 PM »
hi shiney
That pipe at the rear of the airbox goes to the pair valve which ultimately is connected to two reed valves on the top of each rocker cover.
The reeds recirculate engine fumes and can get gummed up. Easy job to do and since you noticed some effect when you bkocked the pipe might be worth a try. I am chasing a fuelling problem myself and it is on my to do list tomorrow.
The tip apparently is not to pull the actual reed assemblies apart. Just clean them with carby cleaner.
Cheers

G'day HunterTodd,

Before I took the bike to the Honda shop I did do the cleaning of the reeds but it made no difference :'(
The Honda mechanics blocking off the PAIR system did fix the issue though :thumbsup

However it is a good thing for anyone having similar issues in the future to check :thumbs

Cheers
Shiney
My Ride: 2015 (Model) ST1300  :wht13
OzSTOC #104   STOC# 8512   IBA # 59142
Find me in The Who's Who of OzSTOC!

I like shiney things :grin
One of the Dave, Dave, Dave and Duncan crew 8)
 
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Online HunterTodd

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Re: Backfiring and smell of fuel from exhaust
« Reply #54 on: November 02, 2019, 09:20:10 PM »
Hi Shiney

Attached is a photo of a fitting I made to measure fuel pressure on the ST.

I turned it out of an M20 bolt from Bunnings and it replaces the M12 cap on the end of the left hand fuel rail. (the one which hold the fuel supply line)

I coupled my fleabay fuel pressure gauge to it and it worked a treat with the pressure proving to be right on spec.

If my examination of the o2 sensors proves fruitless my next step with be to purchase a needle valve of ebay and meter the fuel under pressure to a measuring cylinder to determine if the flow is sufficient.

My bike is leaning out and fuel supply is one of the usual culprits. I have examined the entire fuel delivery  system from the steel wool  inlet strainer to the fuel injectors and my gut feeling is that the issue is not fuel supply but I really am at a loss now.

Will post the results of the O2 sensor investigation. Fingers crossed.

Cheers
 

Online Shiney

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Re: Backfiring and smell of fuel from exhaust
« Reply #55 on: November 02, 2019, 09:40:07 PM »
Good luck mate, hopefully the O2 sensor investigation reveals the issue, I look forward to the results :popcorn
My Ride: 2015 (Model) ST1300  :wht13
OzSTOC #104   STOC# 8512   IBA # 59142
Find me in The Who's Who of OzSTOC!

I like shiney things :grin
One of the Dave, Dave, Dave and Duncan crew 8)