Popping & Banging on the Overrun

[dandywarhol]

Check item number 46, diaphragm, isn't perished with ethanol/age. It's an anti popping valve

https://www.motorcyclespareparts.eu/yam ... 43944.aspx

[DAVID THOMPSON]

posted this in case link goes dead

click to make it bigger

[starfield181]

I wound the pilot adjuster screw out. Probably about 4 turns in total now and the popping & banging was much reduced. The tickover also speeded up a bit so. I will try another 1/2 turn out to see if it continues to improve.

Interesting concept of an anti popping valve. Wonder how its supposed to work. Looks as though you have to buy the whole assembly rather than just the diaphragm. Think I will continue with adjustments for the moment. Bike is certainly much better now.

PeterF

[billr]

EDFManiac wrote: "The Mikuni VM28/486 #40 pilot jet works. It doesn't look like the stock jet but it functions just fine and is available at almost any place that carries Mikuni jets."
I took that advice and changed mine out. No more popping and I'm at 3 turns out.
BillR

[breakwellmz]

I see the biggest size these (UK) suppliers keep is a 37.5, what size is the standard jet?

http://www.ebay.co.uk/itm/142044406653? ... EBIDX%3AIT

[Nabsteel]

Have a look at my thread 'Does this spark plug look ok?'

I bought a Baghira a while back and it was backfiring on the over run badly. I turned the mixer screw out as much as i dare, which helped but didn't completely solve the problem. It was running lean, but wasn't completely sure, so put it on the rolling road and paid £80 in total to get it re jetted correctly and now it runs great and pulls better to boot!

viewtopic.php?f=3&t=8340

[edfmaniac]

I see the biggest size these (UK) suppliers keep is a 37.5, what size is the standard jet?

http://www.ebay.co.uk/itm/142044406653? ... EBIDX%3AIT

There's no way of telling what the stock Mikuni equivalent would be because they flow differently than a Tekei jet. But my bike was just slightly rich with the #40. A #37.5 might be right on the money.

[edfmaniac]

https://www.catalyst-findit.co.uk/index ... pid=27-406

[breakwellmz]

I see the biggest size these (UK) suppliers keep is a 37.5, what size is the standard jet?

http://www.ebay.co.uk/itm/142044406653? ... EBIDX%3AIT

There's no way of telling what the stock Mikuni equivalent would be because they flow differently than a Tekei jet. But my bike was just slightly rich with the #40. A #37.5 might be right on the money.

I got one from these people it turned up today, you can`t go wrong at that price but it`s gone up already!

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... _500wt_969

[Henry74]

Hi, you are mentioning nbr 37.5 and nbr 40 Mikuni Pilot jets. But what do these numbers stand for ? the jet hole measurements maybe eg .40 mm ?

[dandywarhol]

Hi, you are mentioning nbr 37.5 and nbr 40 Mikuni Pilot jets. But what do these numbers stand for ? the jet hole measurements maybe eg .40 mm ?

Mikuni numbers indicate flow rate in cc/minute