Pop fart crackle

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bingo808
Posts: 83
Joined: Sun Jul 04, 2021 12:01 am

Pop fart crackle

Post by bingo808 »

Hi
I set myself a task today - change engine oil and filter.

So started up the bike to warm it up a bit. Idles ok but sometimes has a hiccup. What could be causing this? Was also idling a bit high - around 1800rpm.
Should I take it down a notch? And how?

Once it warmed up I cracked the side bolt to let out oil. Really black, so it's been doing it's job.

Now I can't get the front filter off. Have bought a $8 chain filter wrench. Will pickup tomorrow.

I know you can drive a small flathead screwdriver into the guts of the filter then turn to release it, but too messy. You're going to scrap the old filter anyhow. I have used this method before on cars.
Someone put it together, so I should be able to pull it apart.
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bingo808
Posts: 83
Joined: Sun Jul 04, 2021 12:01 am

Re: Pop fart crackle

Post by bingo808 »

All good. I busted the side of the old filter with a screwdriver and hammer and got it off.

Filled her up with some 15W-40 oil. Will drain again after a few kms and refill. According to registration statistics my bike was last registered in 2015!!!
Someone put it together, so I should be able to pull it apart.
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MacV2
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Location: Grain

Re: Pop fart crackle

Post by MacV2 »

Set idle to 1300 ish give or take 1000 rpm.

Front carb R/H side black plastic thumb screw...
IMG_000202IMG_0002.jpg
Do it when bike is up to temp, turn eith way it will be apparent which way is up or down.

Give it a blip between adjustments.

https://www.ebay.co.uk/itm/313665179449 ... SwBMJhN3iX
Making up since 2007, sometimes it's true...Honest...
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bingo808
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Joined: Sun Jul 04, 2021 12:01 am

Re: Pop fart crackle

Post by bingo808 »

Thanks. Bike idles around 1300-1400rpm when hot.

Bike still pops a bit sometimes at idle. Seems to rev ok. Does it need the carbies sychronised? What is involved in that process?

Mind you I've yet to take it for a ride. I'm sure more surprises will come up!

Under tank:
Image
Last edited by bingo808 on Wed Sep 22, 2021 10:32 am, edited 1 time in total.
Someone put it together, so I should be able to pull it apart.
Mototrick
Posts: 22
Joined: Mon Jul 02, 2018 3:37 pm

Re: Pop fart crackle

Post by Mototrick »

Of all the mods I've done to my VTR, balancing the carbs has produced the most satisfying results. No more pops & farts at idle, and now a choke that actually works!
As per MacV2s picture above, in the red circle, you need to remove the blanking screw from the front carb, and add a brass vacuum adaptor. Then hack in to the existing rear carb vacuum line with a t-piece. Then get hold of a suitable balancing tool, i bought an electronic one. Balance adjuster is on the rear carb, which can be reached without taking the tank off with a long thin screwdriver with an angled/swivel adaptor on the end.
The front adaptor and rear t-piece can be left in place and blanked off when you're done, ready for any future balancing.

There's a detailed thread about it somewhere here in the workshop section.
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bingo808
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Re: Pop fart crackle

Post by bingo808 »

Thanks Mototrick. I've decided to take it to a professional to do the carbies for me once it's legally on the road.

On 2nd thoughts I'll have a go myself.

Is this the carby sync thread? viewtopic.php?f=31&t=18430

NOTE: Link to PDF of carby sync document no longer valid.

What size vacuum hose? And what are the dimensions of the brass adaptor? What size t-piece?

Is this kit okay? https://www.ebay.com.au/itm/124186918683
Someone put it together, so I should be able to pull it apart.
Mototrick
Posts: 22
Joined: Mon Jul 02, 2018 3:37 pm

Re: Pop fart crackle

Post by Mototrick »

I'll answer what i can!

Yes, that is the carb sync thread i mentioned.

The original Honda Vacuum adaptor is known as a JOINT BOOST, Part number 16214MB0000. I think it's a 5mm thread, but maybe get a 2nd opinion on that. If you get one, (maybe buy 2?) be very careful when you tighten it. It's brass and fragile, i broke my first one and nearly ended up with the threaded part stuck in the cylinder head. There's a washer associated with it, part number WASHER, SEALING, 5MM 90452323000. I used some thread lock to seal it as well.

3.5mm ID vacuum hose will work, i bought a 4mm t-piece.

All of the above is pretty cheap and you can get to the stage where you can balance the carbs in less than an hour. The actual balancing gauge is the expensive part. I bought a 2nd hand Twinmax electronic gauge for £45, expensive but very nice to use.
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