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· Registered
1991 Honda CBR250RR MC22
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4 Posts
Discussion Starter · #1 ·
Ok so this is the story so far…
Bought a mc22 1991 and it was running just bit hard to get it started up. So I started with the carbs and had them cleaned and did a basic bench sync. Got a new battery and have a jumper pack, have an auxiliary fuel system on it rn (fuel line and a funnel lol) but I can’t get it to consistently start. Last I got it started it was running fine but idle was at 4k rpm.
i had the dyno sync tool attached to it so I thought it was causing an air leak so Itook em off and I haven’t had any luck getting the bike to idle. Is there any advice cuz I feel like I’ve hit a dead end🥲
 

· Super Moderator
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221 Posts
Did you split carbs?
Disassemble to every last nut, bolt and individual component?
Scrub everything with PEA-based fuel-system cleaner?
Including secret hidden secret passages in carb body?
Poke out all bleed holes in jets, emulsion tubes and carb venturi?
Soak everything in ultrasonic cleaner?
Micro soda-blast?
Replace all rubbers when assembling: float valves, float bowl seals, fuel-rail O-rings, pilot-screw O-rings?

That's a lot of work and requires lots of equipment. Easiest to send to customcarbservices.com, Professional motorcycle carb cleaning . Expert workmanship, reasonable fees and fast turnaround.
 

· Registered
1991 Honda CBR250RR MC22
Joined
·
4 Posts
Discussion Starter · #3 ·
Did you split carbs?
Disassemble to every last nut, bolt and individual component?
Scrub everything with PEA-based fuel-system cleaner?
Including secret hidden secret passages in carb body?
Poke out all bleed holes in jets, emulsion tubes and carb venturi?
Soak everything in ultrasonic cleaner?
Micro soda-blast?
Replace all rubbers when assembling: float valves, float bowl seals, fuel-rail O-rings, pilot-screw O-rings?

That's a lot of work and requires lots of equipment. Easiest to send to customcarbservices.com, Professional motorcycle carb cleaning . Expert workmanship, reasonable fees and fast turnaround.
Yea I definitely wasn’t that extensive with it. I think I’ll get a professional to clean em incase I messed some part up. I’ll do that after I get the sparks changed.
 

· Registered
1991 Honda CBR250RR MC22
Joined
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4 Posts
Discussion Starter · #7 ·
Ok so update so far. Got it to start and idle for a tad bit, then she dies. I was able to ride for around 5 mins before dying on me. From the exhaust some black smoke was coming out when opening throttle. I’m thinking it’s smth to do with the air fuel mixture and still a possible air leak.
I’ll also check valve clearances since I also need to fix a small oil leak
Any other suggestions pls let me know
 

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390 Posts
Black smoke is too much petrol. Verify:

  • float height
  • all stock jet sizes
  • all stock needles
  • all stock slide springs
Bench test the float valve as well! Can't tell you the number of issues I've caught by hooking carbs up to a fuel source off the bike, only to discover shortly later they are pissing fuel. If the float needle(s) are suspect, replace them. IIRC The float seats are not replaceable, but can be cleaned up with a LIGHT polishing (i.e. q-tip and aluminum/mag polish) If they are removeable you'll need new o-rings before reinstall and they will be a lot easier to clean (ultrasonic, FTW!)
 
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