| Author | Message | ||
     Mhlunsford |
I bought a carb but it had the air fuel screw plugged all my tools are in CA some 2500 miles away. M2 pops when reving but much smoother with choke on. I am thinking I need to get the air fuel screw checked. I bought another drill so will try adjusting the air fuel and see what happens. It is jetted at I believe 48/200. Any other recommendations ? | ||
| Steveford |
Check intake and exhaust seals for good measure. | ||
| Mhlunsford |
Yep done that a few times | ||
| Hootowl |
Is it a new carb? Could it have a semi clogged fuel passage? | ||
| Ratbuell |
+1 on plugged passages. Stock M2? That seems awfully rich...even with the race kit on my M2 (or on about any other Buell I've had), a 45/190 or 45/195 with 2.5 turns out does the trick. Anything else just soots the plugs. The 190/195 debate is settled during hot-engine decel - popping? Needs 195. No pop? Leave the 190. | ||
| Mhlunsford |
Is the passage on the jet or somewhere else? | ||
| Mhlunsford |
Best way to clear the passages ? | ||
| Steveford |
Strip, Gunk HydroSeal soak, rinse, blow out with compressed air, finish up with contact cleaner squirted through everything. | ||
| Upthemaiden |
If you go with compressed air, make sure you try to blow through the passages in reverse. If something was in the float bowl and got sucked into a passage and got stuck, you could just wedge it in further if you blow air in through that end. Does it just idle better with the choke on, or does it ride better with the choke on as well? If it's only sitting at idle that makes a difference, you could check the idle mix screw that's behind that plug, but otherwise that screw has no affect on what the bike's doing while you're actually riding it. Is there certain times it does it? If it's when you're just putting along easy on the throttle, it could be the pilot jet, if it's when you have the throttle wide open, it'd be the main jet. The majority of the throttle range in the middle is based off of the needle. Might help you narrow it down if you can try to pin point when it's giving you trouble. For reference I have a 48 pilot and 195 main with a V&H exhaust and Forcewinder intake, at about 700-800ft. That's how my bike came, so I've never tried a 45 or 190, but it seems to run well as is. | ||
| Mhlunsford |
so it will idle but not as smooth as it should, it will like sputter every few cycles. It is really noticeable when the holding the throttle at say 3K RPM, sputter and then add the choke and it gets a lot better but not perfect. It is a what looks like remanufactured carb from ebay. "high performance" but does not have the Harley name on it. Still has the air/fuel plug closed. I was going to drill it and see where it is. Adjust it say 2.75 turn out. Clean the jets with some spray carb cleaner. | ||
| Upthemaiden |
If you're holding the throttle steady when you're at 3k rpm, that's the needles job. Do you have the stock airbox and exhaust, or aftermarket? Are there any shims on your needle? I think it's common for people throw in new jets with an exhaust and air filter and not do anything with the needle. The rest of my bike was running well, but always had a sputter right at 3k rpm when I was either holding my speed steady, or just accelerating gently(would get uncomfortable in corners). I eventually put 2 washers on the needle, around .06" thick combined I believe, and it smoothed it right out and rode great. Don't think I've had a sputter since. if I remember right, the washers were size #4, you can get some thin brass ones at lowes, a little package of 4-5 washers for $1. The sputter at idle... what is your idle turned up to? Make sure it's turned up to right around 1k rpm, and if it's still rough it might benefit from having the mix screw adjusted, or it might have a clogged pilot jet. I'd start with pulling the carb apart, and check the needle for washers, clean out the jets and passageways while you have it apart. Hopefully the washers would help the 3k rpm stumble, and if you're lucky you'll have cleaned out whatever was causing the rough idle. If not try the idle mix screw(starting at 2.5 turns out) and see if that helps. | ||
| Mhlunsford |
yes - DIY exhaust and aftermarket air filter. Any pictures of the needle with washer mod ? | ||
| Robertl |
Here's a video on the needle shimming: https://www.youtube.com/watch?v=TcIuewAIi-k Same steps on any CV carb. | ||
| 89rs1200 |
Recommend replacing the intake rubber seals at the heads before going further. These rubber rings get hard from the heat. Twice I diagnosed carburetor problems to air leaks past these intake seals. It they leak you will never be able to correctly tune the carburetor. Also put a little silicone grease on the rubber seals to help them last longer. Agree a 200 main jet is way too rich and points to an air leak around an intake seal. | ||
| Mhlunsford |
Thanks for the video. I replaced the intake seals - even has some silicone. I will try adjusting the air/fuel and maybe adding the shim. clean the jets (or just buy new). thanks!! I want another 55K miles from it. | ||
| Upthemaiden |
 | ||
| Mhlunsford |
Nice picture. I have also noticed my emulsion tube has a slight bend. I am thinking the coller is not in all the way. Maybe this is moving the needle way that obstructs fuel from the primary jet ? Should the emulsion tube be perfectly straight ? (Message edited by mhlunsford on July 07, 2017) | ||
| Imadog |
The emulsion tube is threaded into the carb body and should be straight. I assume that you have the correct Keihin CV 40 mm carb for your M2. My bike came stock with a #42 idle and a #200 main jet. If this is a used carb a complete cleaning and rebuild kit should be performed. I increased the idle jet to #45. Rebuild kit from Amazon: https://www.amazon.com/gp/product/B000MU8JCY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 All passages and jets need to be cleaned out with carb cleaner and compressed air. New intake gaskets replaced and the Accelerator pump diaphragm replaced. You should see a squirt of extra fuel come out of the accelerator pump when you blip the throttle. This will smooth out the transition when revving the engine. Inspect the rubber on the vacuum slide diaphragm and replace as needed. Amazon: https://www.amazon.com/gp/product/B007KPSQWM/ref=oh_aui_search_detailpage?ie=UTF8&psc=1  There are many good youtube videos and websites going over the cleaning, operation, tuning and rebuild. Hope this helps. | ||
| Williamscottrobertson |
The CVP kit comes highly recommended by several people. Better mileage than the Yost power tube and better power than the dynojet kit. They have rebuild kits too. https://cv-performance.com/cvp-harley-carb-deluxe- tuners-kit | ||
| Harleyelf |
I have one of those Chinese carburetors from Ebay on my Softtail. It wouldn't pull properly through mid-range until I noticed that there is a different pattern of tiny holes in the emulsion tube that the needle drops into. I swapped out the needle and emulsion tube from my old leaky Harley carburetor and performance smoothed out. | ||
| Mhlunsford |
What I bought was https://www.ebay.com/itm/192241936443 No HD logo no drain plug other that looks the same. | ||
| Harleyelf |
Looks exactly like mine, I could tell from the picture of the needle without grooves. Go to the dealer and buy an emulsion tube and needle with clip, they'll slip right in and improve things immensely. | ||
| Mhlunsford |
So I got a used HD carb put my original voes back on and pulling the front tire off ground again - finally  Stay away from Chinese replica cv carbs! | ||
| Imadog |
That's great to hear. Too many blogs never have the original poster come back and say what fixed the problem. What size jets do you have now? | ||
| Mhlunsford |
45/190 this is a X1 motor in a m2. It pops a little on quick deceleration - might just be my exhaust. I will run for a while and see what the plugs look like (Message edited by mhlunsford on July 10, 2017) | ||
| Natexlh1000 |
Chinese replica CV40? I guess it was only a matter of time. They rip everything off eventually. | ||
| Mhlunsford |
Yes sold by wincycles in Florida. Chinese replica CV40 "Harley Davidsion" but no company name on the carb. | ||
| Upthemaiden |
Popping on decel probably means you need to go up a little on the main jet/needle shims. Typically when you put a new exhaust on a stock bike it'll pop like that when you let off the gas. My XB9 always did that because I never loaded the race map on. | ||
| Jim2 |
I think the later M2's came with a stock 200 main jet. Earlier M2's came with 190. | ||
| Mhlunsford |
Reading on jet vs needle interesting read http://forums.cycleworld.com/showthread.php?t=3478 4 |
