Jawa 210 carb set up

So I have a 1988 210 sport.

Compression is at 135✔️

Spark✔️

No nests or cloggs at intake or exhaust ✔️

Cleaned carb and new gaskets✔️

Peddles around the yard and checked the plug. It was bone dry. After that I checked the bowl. Fuel✔️

Fuck this Jawa carb ✔️✔️✔️

I’ve gotten feed back about using a 12mm bing or I can also use a dellorto.

Which am I going to use AND with what jet

Re: Jawa 210 carb set up

Re: Jawa 210 carb set up

Luke Martin /

Ya, i read that. 🙏

Re: Jawa 210 carb set up

Well, going from a 12mm Jikov to a 12mm Bing isn't much of an upgrade. If I were you, I'd do the work to use a 15 SHA or a 14 PHVA if you want a carb with a needle.

With a 15 SHA, I'd expect the jetting to be around 60.

Re: Jawa 210 carb set up

Luke Martin /

I have a new 16mm sha. Too much?

Re: Jawa 210 carb set up

Nah, a 16mm SHA will be fine.

Re: Jawa 210 carb set up

Luke Martin /

Thanks dude🤘🏽✊🏽

Re: Jawa 210 carb set up

No problem, good luck!

Re: Jawa 210 carb set up

I think the stock intake is a whopping 9mm ID. You really think slamming all that air from a carb over 12mm is going to be tunable,...with everything stock including the pipe? I'll follow this to see how well it turns out. Cool if it does, but doesn't make sense to me

Re: Jawa 210 carb set up

The stock intake on my Jawas are 12mm.

But you're gonna need to make an intake to use a 15 SHA anyway.

Re: Jawa 210 carb set up

Eric Davenport /

Re: Jawa 210 carb set up

Got out my calipers and glad to admit I had it wrong. These intakes look super tiny and I recall reading somewhere that the manifold necks down around 9mm, but the port is 12mm l, so that's what matters. The SHA adaptor works sweet and so I may swap the 12mm Bing for a SHA 14.12. It's all about tunability.

Re: Jawa 210 carb set up

Yeah, I suppose if you want to stick to a 12mm carb for some reason, you can use that...

Re: Jawa 210 carb set up

Re: Jawa 210 carb set up

yea of course going over 12mm you wanna get a bigger intake and match it to the cylinder but it can help a lot especailly if you're doing other porting. all else stock but a matched 15 carb and intake, I wouldn't expect very noticeable gains

still anything to ditch the jikov is pretty worthwhile.

Re: Jawa 210 carb set up

kim jensen /

Yeah you will likely need to make a custom intake to fit a better carb. With the effort though.

A welder is your best friend here.

Re: Jawa 210 carb set up

Eric Davenport /

Just use a puch sha square port intake

Re: Jawa 210 carb set up

Luke Martin /

So I needed up using a 12mm bing. There’s an adaptor plate on treats for the stock intake.

I got it running last month finally on a cold 15 degree day. It was awesome. A solid top speed of 33mph-ish. I had to use the smallest jet I had, a 48. Now that the weather is warming up I can only get it to idle. The 48 is way to fat.

I can’t find any jets smaller than 48 either. I tried every needle position I could. Today I’m going to try to use a a different needle. I also think I should f with the atomizer. Not sure what’s in there.

Any thoughts on how to get this 12mm bing to stop puking fuel into the chamber would be helpful.

image.jpg

Re: Jawa 210 carb set up

Luke Martin /

What’s the deal with bing atomizers? The bigger the number the bigger the particles?

I want that shit misty af.

Re: Jawa 210 carb set up

Luke Martin /

Cancel that. I just learned about the importance of slide selection. For others that may be searching for similar questions in life:

The cut in the slide determines the mix in the mid range. The depth of the the cut determines the mix for the mid range.

So in my situation I was paying no mind to the slide. I was idling perfect but at mid and top end it was shit. Every time I inspected the plug it was soaked. Due to my ignorance I tried to control that by going with a smaller main jet. Silly me. at full throttle I’d have not enough fuel and the same richness in the mid range. I was doing nothing but messing up two ranges of operation.

I could have had seized by doing this I suppose. And that is bad.

Re: Jawa 210 carb set up

Luke Martin /

Never mind. Everything I think I know I don’t. Jawa is impossible and only runs in 15 degree weather

Re: Jawa 210 carb set up

You can also adjust the midrange mix on a bing by changing moving the needle clip to a different position.

https://www.mopedarmy.com/wiki/Needle (edited)

Re: Jawa 210 carb set up

Luke Martin /

Yea I messed with the needle. No matter what I’m getting rich conditions.

I removed the pipe last night, disassembled, and inspected. It’s clean. According to my readings a clogged pipe creates rich conditions on two stroke.

While I didn’t have a clogged pipe I did in fact find something interesting. I pointed the camera into the exhaust port and spun the crank manually. The at the bottom of the stroke the top of the piston is about 1.5mm into the port. So I’m thinking the piston itself is the “clog”

Being that it’s a Jawa, there isn’t many options out there to modify this thing. But I have an idea. PLEASE, any input is appreciated.

So the stock pipe is pretty restricted AND the piston is in the exhaust port at the bottom of the stroke. If I were to drill some additional holes in the exhaust components it could lean out conditions. Im thinking I’ll drill out a everything(baffle and plates) with a couple small holes. Then I sequentially make holes bigger until I get some good response at the throttle.

OR I find/make a base gasket that’s thick as fuck so the piston can actually clear the exhaust port.

Thoughts?

Re: Jawa 210 carb set up

Luke Martin /

Sorry, im deep in this hole.

Going with a thicker base gasket would be silly, no? Pretty sure I’d lose compression. BUT if I were to open the exhaust port at the top maybe that would help control the issue.

Again, any thoughts appreciated

Re: Jawa 210 carb set up

Why not relieve the piston crown at the ports ?

Take the crown down about half the way from the piston edge to the top of the upper landing and bevel upward toward the center of the crown .

I did that on my FA50 with excellent results . Sure , you lose a bit of compression , but , that may just be a good thing . ;)

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