Here's some equipment needed to really do thorough job of carb cleaning. Note that spray carb-cleaners in cans no longer work due to removal of chlorinated compounds (carbon-tetrachloride, tri-chloroethylene, etc.). Real fuel-system cleaners with healthy dose of PEA (mix 50/50 with acetone): - Red Line SI-1 - Techron Concentrate Plus - Gumout All-in-One - 3M Max Strength Fuel System Cleaner #08814 - Royal Purple Max Atomizer 18000 Amazon - nylon scrub brushes Amazon - 4L Ultrasonic cleaner TCPglobal - mini soda blaster I just bought an MC19 and MC22 in boxes, so will be going through this myself. I'll post where I found replacement rubber carb parts. May be more difficult in U.S. than over there.
Can you get Threebond Super Engine Conditioner (petrol engine's) over there ? Subaru dealer's usually sell it for doing upper engine clean's, remove's basked on carbon, fuel deposit's etc etc and work's really well. Doesn't take long at all to disolve dried up gum etc @maelstrom from Litetek Thailand sell's Viton carby kit's MC19 https://litetek.co/Carb_Kit_Honda_CBR250R_MC19.html MC22 https://litetek.co/Carb_Kit_Honda_CBR250RR_MC22.html
California's really strict on VOC-volatile oraganic compounds, so lots of good stuff is prohibited. I'll order from other areas and have shipped to Las Vegas and drive over to pick it up myself. While we don't have Threebond Super Engine Conditioner which appears to be primarily naphtha, alcohol and water, we do have similar product called Seafoam which has similar cleaning effects. Thanks for links to carb seal kits! I may need to split carbs first as I don't think entire rack will fit into my ultrasonic cleaner. BTW, DO NOT use Simple Green for cleaning any metals, especially in ultrasonic cleaner! Decades ago, cycling-forums discovered it dissolved metals! Chains soaked in stuff came out corroded and crumbling! U.S. military also put out maintenance-bulletin forbidding its use.
Welcome to the forum. You can get OEM parts from Impex in Japan https://en.impex-jp.com/catalogs/moto/honda.html and Megazip, also in Japan. @kiffsta on the forum has a bike wrecking business in Aus and the online auction sites in Japan have almost everything. For those I recommend use Jauce for searching and Zenmarket for buying. We ship to the US at no extra cost using a hybrid service that takes about 5-12 days. Cheers Blair
Bike won't run at all - none of the cylinders are firing. Probably just going to sell it. Thanks for the help, everyone.
Don’t give up, you’re so close! You’ve done 90-95% of work needed. Probably something simple, a tiny adjustment here and there. When you say “none of cylinders are firing” do you mean you’re not getting combustion? We just need to back-track to when 3 out of 4 were running. What changed since then? Do you have access to oscilloscope?
Step back and take a breather from it, it's at times when it's difficult and dis-spiriting that you'll come to spot the mistake if you take a break - that's also where the lessons are learned
Put some fuel in a plastic squirt bottle. Take the tank and airbox off and squirt some fuel into the carbs whilst cranking. If it doesn't fire you know it is electrical.
Convinced someone to lend me a set of carbs off a running bike. Will keep you updated. Thanks for the kind words.
Got another 250 I-4 back on the road. This is a '96 GSF250. Gave this one a bit of a carb clean / sync and she runs beautifully. If only my CBR would be so easy! Still waiting on those carbs to come in the mail.
Got new carbs on the MC22. Nothing. One or two small pops. There is strong spark on all 4. I left plugs out and cranked it to make sure cylinders weren't flooded. Tried without choke first, then with choke, then with a tiny bit of ether. Nothing. The workshop manual makes the timing a bit confusing. When 1,4 TDC line up the IN mark on intake camshaft flush with the housing on the intake side, line up EX line on exhaust camshaft with the housing on the exhaust side? I don't think the timing is wrong but because of the wasted spark system it could still run if 180 degrees of out whack, right? Any thoughts are appreciated.
Cams spin at half engine speed so you mean it will still run if 360 degrees out. Yes, because of the wasted spark and crank mounted ignition trigger there is no real 'lines up only Cyl 1', it lines up cyl 1 or 4 at TDC compression each crank revolution.
So: The high tension leads have all been re-threaded. The coils' resistances are in spec. got 12V going into primary on both coils. Spark on all 4 plugs. New spark plugs. 'new' carburetors off a running bike, new carb boots. Compression is above 100psi for all cylinders. Valve timing is correct. Ignition pickup resistance is 40 ohms out of spec, is this something to worry about? The bike doesn't even make pops anymore - choke doesn't make a difference and neither does ether. What am i missing?
Have you tried to push start it? If you cannot push start it (first gear please) then I would be looking at ignition timing. There are only 3 things for an engine to run 1/ Spark 2/ Compression 3/ Fuel If the working carbs have fuel in them then that only leaves spark. So it either does not have enough or it is firing at the wrong time. You said it has strong spark on all 4. I assume you mean a clear blue spark. Cranking, with the plugs in, draws a lot of amps. Hence voltage drops and the spark is a lot weaker. My friend had an MC19 and it would catch as soon as I took my finger off the start button because as soon as that happens you get full voltage to the coil. This happens on a lot of bikes with electric starters. Especially high strung engines with small batteries. Engines that have their carbs perfectly synched and mixture screws set perfectly, and I do not mean 'n' turns out as stated in a service manual, will start a lot easier than those that are not. You are not in that position yet, so this exacerbates the problem. To sum up: The 250 4's have to catch straight away. You can't keep cranking them because the batteries are way too small for that.
Haha, I'm using a boat battery with jumpers attached. It has more CCA than the starter motor could ever dream of pulling! The battery drops by less than 0.1V when cranking, i checked. I'll try push starting it tomorrow. I live on a pretty steep hill. I'll get new plugs for it. The ones i have in are pretty fouled. Yeah, clear blue spark. I jumps about 3cm when i hold it away from the frame. Should i get CR9EH again as the manual recommends? The bike had CR8's in when i first got it... Thanks for the replies.
Spark appears strong, it jumps 3cm!!! Have you confirmed coil-trigger wiring between igniter and coils? I got them mixed up one time and 1+4 coils were firing from 2+3 trigger and 2+3 coils were firing by 1+4.
Put new CR9EH plugs in it. The point that @DannoXYZ makes is important. An easy mistake to make. How far the spark jumps is good but you need to verify that the spark is actually jumping effectively across the spark plug gaps. If the spark jumps across the insulator your plugs are in need of attention. Even then there is no guarantee that they will fire effectively under cylinder pressure.