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Ninja EX500 carbs on an XS650?
- Thread starter Highside
- Start date
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- Tags
- cafe carburetors custom engine
I dont know much about carburetors
Are we talking the Motorcycle Kawasaki GPZ carburetors when the thread is about EX500 carbs.
But if the GPZ is a sport bike .Is there not a risk for problems
The XS 650 cruises at 3-5 k rpm Perhaps not GPZ
I dont believe heard of GPZ carbs used
OK Got it please report how it goes . Not time to read all at this point in time .
Depending on year the carb rubbers on the XS will be either the correct diameter or too loose. If loose like mine I had to buy new(aftermarket) rubbers. Also the spacing between the carbs is 3mm wider on the Kwaka carbs. New soft rubbers will deal with that tho. Stock airbox will be a tad short and also the Kwaka carbs have a bigger inlet throat diameter so most use cone filters(eg k and n types). Throtlle cable needs modding/making new and a choke mech needs adding/fabricating. Kwaka carbs have 1 inlet for fuel and twin tap XS's need a T piece to feed that. Not quite the bolt on fit some say.
They're certainly working just fine for me
Popshot
XS650 Member
I have just fitted a set of gpz500 carbs to mine with the suggested jetting and it's a big improvement on the previous ones. However I am getting both carbs leaking from the rear hole suggesting the float valves aren't cutting off the fuel. I set the floats to 17mm as per the Kawasaki. Am I in error or am I unlucky enough to have two knackered float valve seats? I put new floats and valves in and have cleaned the carbs in an ultrasonic bath. Despite looking a fairly clean set the bath took off a load of filth.
Mine are set exactly the same and there's no issue with overflow or leaking. The float valve seats are not replaceable on CVK34 carbs. Best you can do is clean them thoroughly with a cotton wool bud making sure you leave no bits behind off the bud. Are you 100% certain that the floats aren't taking in fuel internally? I see that you fitted new floats, but worth a check. The float valves you fitted, are they genuine Keihin? There's a lot of rubbish around in the market. I used Keyster parts, they're working well.
Popshot
XS650 Member
Best Chinesium valves. The floats are not holed. The seats are press fit so will likely come out with a tap. Some press fit seats use an o ring to seal to the body to keep fuel from going down the sides and I'm wondering if the carbs have them and if they've died. The valves offer resistance and appear to seal when upside down and the weight of the floats closing them to me blowing through the fuel line.
Then I suggest you have an issue with Chinesium needle valves.
I think you're going to find that the needle valve seats are cast into the carburettor body. I really don't think they're serviceable. But good luck anyway.
I see you're in Yorkshire, not a zillion miles from NRP CARBS in Manchester. Their Keyster parts are Japanese manufacture, I personally have never had a problem using them in place of Keihin or Mikuni parts.
I think you're going to find that the needle valve seats are cast into the carburettor body. I really don't think they're serviceable. But good luck anyway.
I see you're in Yorkshire, not a zillion miles from NRP CARBS in Manchester. Their Keyster parts are Japanese manufacture, I personally have never had a problem using them in place of Keihin or Mikuni parts.
rickthefix
XS650 Enthusiast
i have had the exact same issues, eventually bought OEM needles. Set to 19mm instead of 17 to see if lowering fuel level would work. Then I used a ss ball & peened it in the seats to maybe take out any ovalness to it. I'm leaning toward some sort of seal between the seats and carb bodies leaking.
Popshot
XS650 Member
Made of brass and a press fit. Look like the type that typically comes out via running a tap down until it bottoms then twist and pull till out and often have an o ring sealing them to the body
The fuel exits the rear of the carbs down the holes from the float valves so fuel is either bypassing the float valve / seat or is escaping past the valve seat to carb body join.
Will get some Japanese valves before I destroy the seats getting them out.
Attachments
Popshot
XS650 Member
I managed to get a macro picture down each float valve seat...
No wonder they leak. Will have to get one out to see what they look like. There's quite a few variations on seats. Here's a pic of the 9l worth of fluid from the sonic bath. Remember these carbs looked like clean secondhand units. Clear unused fluid for comparison.The bath removed a lot.
No wonder they leak. Will have to get one out to see what they look like. There's quite a few variations on seats. Here's a pic of the 9l worth of fluid from the sonic bath. Remember these carbs looked like clean secondhand units. Clear unused fluid for comparison.The bath removed a lot.
Popshot
XS650 Member
Got them out. Doesn't look like a leak past them so likely the seats. Not any of the common seat types available though.
The Bing cabs used on old BMW Airheads use press-in float needle seats. They're 7mm in dia., not sure what size you need ......
https://www.ebay.com/itm/3735737901...fEI2jvGKX27Ioq5aex_73XMb_PL14zDYlKRS7D1whI9oQ
https://www.ebay.com/itm/3735737901...fEI2jvGKX27Ioq5aex_73XMb_PL14zDYlKRS7D1whI9oQ
According to the EX500 forum, those valves aren't available.
https://www.ex-500.com/threads/press-in-float-valve-seat.43290/
https://www.ex-500.com/threads/press-in-float-valve-seat.43290/
rickthefix
XS650 Enthusiast
How did you get them out? I was thinking either freezer or oven
Popshot
XS650 Member
Ran a tap up them M6. When the tap bottoms it then twists the seat. Twist and pull and they shift easily. It does unfortunately ruin them in the process. These are 9.8mm in diameter.
