Bs34 query advice needed!!

Hi guys so this is my first post on here and I need a lil advice.

So picked a modified 1981 xs650 with some pods and 2-1 exhaust, bike was running ok but needed jetting.
This is the first bike I've ever taken the carbs off. I've read through some of the carb guide and watched quite a few videos. So I took the carbs off, gave em a light clean and removed the floats bowls and there seems to be a little plug on the pilot jet hole and it doesn't look as if it's meant to be there?
On all the videos ive watched no one else has this plug on their pilot jet hole?
Any advice would be gladly appreciated.
Cheers

BAYSA said:

Hi guys so this is my first post on here and I need a lil advice.

So picked a modified 1981 xs650 with some pods and 2-1 exhaust, bike was running ok but needed jetting.
This is the first bike I've ever taken the carbs off. I've read through some of the carb guide and watched quite a few videos. So I took the carbs off, gave em a light clean and removed the floats bowls and there seems to be a little plug on the pilot jet hole and it doesn't look as if it's meant to be there?
On all the videos ive watched no one else has this plug on their pilot jet hole?
Any advice would be gladly appreciated.
Cheers

Click to expand...

BAYSA said:

Hi guys so this is my first post on here and I need a lil advice.

So picked a modified 1981 xs650 with some pods and 2-1 exhaust, bike was running ok but needed jetting.
This is the first bike I've ever taken the carbs off. I've read through some of the carb guide and watched quite a few videos. So I took the carbs off, gave em a light clean and removed the floats bowls and there seems to be a little plug on the pilot jet hole and it doesn't look as if it's meant to be there?
On all the videos ive watched no one else has this plug on their pilot jet hole?
Any advice would be gladly appreciated.
Cheers

Click to expand...

Can't tell you what these plugs do but my '81 special (bs34s) has them. They don't seem to fit too securely . Wondered what happens if these drop out while on the road. I guess they have held on this long. Good luck. I'll be following.

Yeah seems like a strange, I mean how will the fuel get past it to get to the pilot jet? Bike idling fine before I took them off so I guess it's not an issue.
Looking at the main jets and they say 110 on them and I'm sure they are meant to be 130 as standard?
Always fun diving into a modified bike...

Plugs GOTTA be there.
Completes pilot fuel circuit.
All xs650 with bs34 use them, other bikes are set up different and don't use them

Ah brill!
Thought I'd opened a major can of worms but il leave them there. My new jets should hopefully be arriving tomorrow. Is it standard to have the 110 mains on these carbs?

Cheap pods block ports in bell mouth, known issue. 132.5 stock mains youll be up from there a bit prolly 45 pilots also.

Yeah the bike originally came with nasty dirt cheap pods but I've replaced them with some uni 4200st, I also got a fresh seat is 6229st for after I've jetted the carbs, the 4200st pods were a lil too tight.

Il give the ports a blast with some carb cleaner too, cheers for the heads up!

I can get you in the ball park with your jetting for your set up, because the 2-1 will be hard to tune the flat spot out at 4500 rpm. Here is what worked for me when I had only pods and a two into one with my bs34s. You need the Heiden needle and kit can’t remember if I was on the third or fourth clip from the top, but I believe I stayed with third from the top then. It is my honest opinion this needle is needed to factor where the cv slide will be at a certain rpm. I did drill out the slide with the supplied drill bit. I used the supplied 45 pilot jet that came with the kit. After experimenting with a range of main jets a 140 main pulled the hardest. I also ran a size smaller on the air jet at 132.5 (Yamaha OEM Part 3G2-14231-77-00).That is the little one under the air filter. One more thing if you use the stock air mix screws I had to turn them out about 3 1/4 - 3 1/2 turns out. With the mikesXS mix screws I turned them about 1 turn out. A color tune really helps with the idle air fuel mix screw adjustment unless you have a keen ear for the change in rpm. My plugs also liked to be run at .032” gap. It’s very important you have the carbs synced too. So if you don’t have one buy a dual vacuum gauge or make one.

I highly recommend niche cycles on eBay for parts. You can buy the needle kit and jets from them and they combine shipping and I believe give a multiple item discount. https://www.ebay.com/itm/152032118180

Mikexs fuel mixture screw
https://www.mikesxs.net/yamaha-xs650-carb-mixture-screw-kit-80-84-bs-34-oem-12r-14105-00.html

Also follow this guide http://www.factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,lower_rpm_engines.html

BAYSA said:

Hi guys so this is my first post on here and I need a lil advice.

So picked a modified 1981 xs650 with some pods and 2-1 exhaust, bike was running ok but needed jetting.
This is the first bike I've ever taken the carbs off. I've read through some of the carb guide and watched quite a few videos. So I took the carbs off, gave em a light clean and removed the floats bowls and there seems to be a little plug on the pilot jet hole and it doesn't look as if it's meant to be there?
On all the videos ive watched no one else has this plug on their pilot jet hole?
Any advice would be gladly appreciated.
Cheers

Click to expand...

Hi BAYSA,
that plug gotta be there so the bike runs right.
It bungs up the hole the slow running jet inserts through and there's a cast nubbin in the float bowl to hold the plug in place.
There's a hole cross-drilled between the two passages to let the fuel flow through.
& check that the EPA-mandated idle adjustment needles' security plugs have been removed, eh?
Because if they ain't your carbs have NEVER been properly cleaned.

Well good news news carbs are all back together and bike is running great!
Got a sigma 6 kit, main 147.5 and put two spaces on the needle. Might try a another spacer making 3 in total but thanks for all the great info guys, really helped a lot!

Does the sigma 6 kit come with needles or are you shimming up the stock needle? It might work for you but I bet the 147.5 main will run on the rich side. If you can crack your throttle wide open and above 4500 rpm feel no hesitation or stumbles then it is probably the correct size. Also did you stick with the stock pilot jet or does the kit come with a new one?

The kit came with upped pilots, two 147.5 mains, two 150 mains and the kit came with little spacers for the stock needle. Doesn't seem to be any hesitation above 4500 however the previous owner plugged the tacho drive. Took the plug off today to realise that shaft which connects to the oil pump is not there so I don't have a tach reading to go off.
I now need to hunt down the parts to have an actual tachometer.