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Discussion Starter · #1 ·
I have a 1991 MC22. I bought it as a project and have most of the mechanical work done but I can't get it to fire. It has never started in my possession.
I replaced plugs, air filter, changed oil, replaced the battery (Li-ion), and fuel tap. The engine sputters and I can hear ignition while cranking but it won't fire and continue running. It'll run a couple seconds if I spray starter fluid.
I tried pouring gas into the fuel line without the tank and fuel starts to flow out of the overflow ports on the carb so I don't want to try that again. Strangely the engine sometimes stalls the starter. I can turn the engine over if I attempt a bump start but still no continuous ignition.
What am I missing? I reviewed the "Bike Won't Start" thread and verified the run switch and fuel are turned on.
The only electrical peculiarity I can find is the neutral light is always on. If the sensor is grounding out, can this be my issue? Send me what you have, I'll try anything!
 

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Discussion Starter · #2 ·
I replaced the fuel tap and cleaned the carbs as best as I can a second time. Some of the screws securing the bowls are stuck and won't come loose. I tried a spare carb but still nothing. (Spare carb leaked)

I know it's getting gas because fuel pours out of the carbs when I remove them.

Is it possible I have the wrong spark plugs? I think it's getting spark because it runs for a few seconds on starter fluid. It ran strong for a brief moment when I poured too much starting fluid in.

Also, I'm running 91 octane gas (US). This is a long shot, but would I be better off with 87?
 

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I have a 1991 MC22. I bought it as a project and have most of the mechanical work done but I can't get it to fire. It has never started in my possession.
I replaced plugs, air filter, changed oil, replaced the battery (Li-ion), and fuel tap. The engine sputters and I can hear ignition while cranking but it won't fire and continue running. It'll run a couple seconds if I spray starter fluid.
I tried pouring gas into the fuel line without the tank and fuel starts to flow out of the overflow ports on the carb so I don't want to try that again. Strangely the engine sometimes stalls the starter. I can turn the engine over if I attempt a bump start but still no continuous ignition.
What am I missing? I reviewed the "Bike Won't Start" thread and verified the run switch and fuel are turned on.
The only electrical peculiarity I can find is the neutral light is always on. If the sensor is grounding out, can this be my issue? Send me what you have, I'll try anything!
I also had a mc19 that was difficult to start
I disassembled carbscleaned every jet readjusted-float bowl. Heights etc
With no success
I have finally found a way
The mc19 doesn’t have a choke which adds fuel it has an air enrichment circuit
So the CHOKE cannot ever get blocked by old fuel
So how could it not work !
So I put some grease on the 4 plungers located on the top of carbs
In the workshop manual it’s called the bi starter system
So previously whenI pulled the CHOKE nob all I was doing was bending the plastic pivot on the carb s
The actual air plunger /jet didn’t move and so the bike wouldn’t start
When I serviced the carbs and checked the bi stater mechanism everything worked
So with greasing of the plunger everything worked 😂
It took me two years to work this one out !!!!!
 

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If it runs on starter fluid, but not on it's own, carbs have not been disassembled far enough and thoroughly cleaned. Petrol is not flowing from float-bowls to carb venturi. Needs:

1. complete disassembly to very last individual components. All secret and hidden petrol circuits scrubbed from end-to-end with brushes

2. all bleed holes in jets and emulsion tubes poked out with matching gauge copper wire. Will push out dried petrol plugs like little grains of sand.

3. everything soaked in ultrasonic cleaner for days

4. micro soda-blast entire flow-path of petrol through carbs

5. replace all rubber parts with new OEM: fuel-rail O-rings, float-bowl seals, float valves, maybe even slide diaphragms.


Bike ran perfectly fine with factory-fresh clean carbs right off showroom floor. It will again when carbs have been restored to factory fresh clean. Fact that it doesn't run like that means carbs aren't factory fresh clean.

Expert mechanics who can rebuild engines with their teeth having hands tied behind their backs, have had to remove carbs 4-5 times for ever deeper cleaning and restoration. I recommend you save yourself tonnes of time and do full restoration 1st time around. Or 2nd now.
 

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BTW, don't use starter fluid! It's extremely toxic to slide diaphragms and will dissolve holes in them! Use squirt bottle and spray little spritz of petrol into carbs instead. Much safer for rubber parts.
 

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Discussion Starter · #7 ·
Got it. I could only open one of the fuel bowls because at least one of the 3 screws on each one is stuck and won't break loose. I tried penetrating oil for several days to get them to pop loose. I'll give it another go today and get it cleaned up.

What gauge copper wire should I be using? I'll need to get some
 

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Float bowl removal is first 1-2% of job. Be sure to use JIS screwdriver, screws are not philips! Impact screwdriver helps free corroded stuck screws without stripping. Also You'll want to disassemble to every last piece for restoration:

uc?export=download&id=1Q3pmKZ-h5Zz8q8XDK

Different carb, but all Keihin CV carbs are similar. Remove jets and scrub hidden secret fuel-circuits clean from end-to-end. I like using 50/50 mix of acetone/ATF, much better than "carb cleaner" sprays that no longer work due to removal of chlorinated compounds. Or undiluted PEA-based fuel-system cleaner also works. Amazon - Carb Cleaning Brushes.

uc?export=download&id=1mZZztQzOfdjZ1qUJk

uc?export=download&id=1HuYvS5DG7ZpaWJfvv

uc?export=download&id=1q48pjdTx1hPR_KcOT

uc?export=download&id=1DdrgfX-WZ9CoVj5j7

uc?export=download&id=1Ka__m6n4sPIlNg4Nk

Poke out all bleed holes in jets and emulsion tubes with matching gauge copper wire. Start with 26ga and feel if it wiggles, if so, go next size up. It'll push out little dried-petrol plugs like grains of sand. Be extremely careful not to gouge holes and change their diameter. Heck, there was recent case where choke-jets had to be drilled with micro bit because dried-petrol was so tough!

uc?export=download&id=1xdo6P9_is97acag0f

Then soak everything (except diaphrams) in ultrasonic cleaner for 6-12 hrs. Rinse, dry, then micro soda-blast to clear out remaining chunks chipped off from scrubbing and poking.

Reassemble with all new rubbers: float-valves, fuel-rail O-rings, float-bowl seals, and slide diaphragms if needed.

I actually do this on my race-bike carbs every winter during off-season to maintain maximum performance.
 

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Discussion Starter · #9 ·
Wow, thanks for that! I ordered some brushes this morning. I have JIS screwdrivers but I don't have a JIS bit for my impact screwdriver. I'll get one on order today.

For reassembling the jets, do they just go back together or is there a whole tuning process upon reassembly?
 

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If you get frustrated with slow progress on carbs, I recommend sending them to Gordon @ https://customcarbservices.com . He's got decades of experience with cleaning and tuning thousands of carbs. Has all the tools and equipment. Extremely reasonable prices and fast turnaround.

I send him carbs from my race Ninja 250 every winter because it takes me over 30-hrs to do full refurb/restoration and it's just so much easier to send it to Gordon and get back brand-new carbs in a week.
 

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Discussion Starter · #12 ·
I'm going to give them a shot this week. I sorta started last week but had a whole bunch of crap come up that stopped me from getting into the garage. Topping it off, the engine in my Tuono let go this past Friday at Buttonwillow. I'll address that later this summer.

If I still don't get anywhere, I'll give this guy a shout. I just wish he was on my side of the country!
 

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Yeah, being on other coast is pain. But with USPS Priority Mail shipping, I usually get carbs back in less than 2-weeks from day I sent it.
 

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Discussion Starter · #15 ·
I didn't do anything because he needed a rebuild kit before he could start any work. I set out to clean the jets that were in there just to see what would happen because the rebuild kit wasn't supposed to arrive until August. However it showed up Friday so I thought I'd give it a shot myself.

Install was easy and I found a good video online of what to remove and replace. So I swapped out both jets, cleaned the tunnels through the carb with carb cleaner, and figured I'd be good. Nope, still won't start.

I'm out of ideas and I'm beginning to think it's something other than just the carb. Will the bike run the starter if one of the safety switches is triggered, like the kickstand switch? Because it cranks, it just doesn't want to fire.
 

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no, you only did 5% of carb restoration. Look at photos I posted earlier. Need to scrub entire flow-path of petrol through carbs. After jets, there long passageway before bleed-hole to carb throat. Need to scrub that passage from jets all way to other end. Also to poke out bleed-hole in carb throat back towards jets. Did you separate carbs and replace fuel-rail O-rings? Did you replace float-valves and adjust float height? Verified float-height with wet-test?

Also need to soak everything in ultrasonic cleaner for at least 8-hrs. Then micro soda-blast everything.

You've only just started. You're not first one to have this problem. I've seen this easily 100 times! Myself included, I pulled and re-cleaned carbs at least 10x and it got better each time. But after while, improvements stopped. I spent over 50-hrs re-cleaning carbs. I didn't have ultrasonic cleaner or micro soda-blaster to do deeper cleaning needed.

Solution was to send it to Gordon and carbs came back brand-new! Bike ran like brand-new bike off showroom floor!
 

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Discussion Starter · #17 ·
I'll try him because I'm out of ideas. I sprayed carb cleaner through the ports and they're flowing. Cleaner in the jet inlets exits through the carb throat. Choke flows too.
 

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Discussion Starter · #18 ·
The bike runs! I took it out for a few laps around the neighborhood this afternoon. I'm going to send the carbs out tomorrow to Gordon anyway, at this point it can't hurt.
 

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woohoo!!! yeah, bike will run even better, like brand new!
BTW, where did you get rebuild kit? I need to send him spare set of MC19 carbs for restoration. thx
 

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Discussion Starter · #20 ·
I got the rebuild kit off ebay but the jets were 4 sizes smaller than what came with the bike. Gordon cleaned the stock jets and it works perfectly. I'm registered for a trackday in a week! Can't wait.

Do you have your bike registered in CA? If so, did you have to go through any crazy hoops to get a title?
 
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