| Author | Message | ||
     Modrummer |
Hey guys! Just got a 2000 Buell Blast for cheap. The bike starts up with starter fluid (I know this is bad for the engine so I only did it the first time to make sure it ran) and once I hold the throttle partially open for a minute or so to warm it up, it idles just fine. I can ride it around, but it definitely isn't getting full throttle (it's slow to rev, even in neutral). If I try to start the bike without starter fluid, it just cranks endlessly and won't start. Any ideas? I'm not particularly familiar with these carbs, but I was planning on removing the jets and cleaning them out. But it idles so smoothly it's hard to imagine that a clogged jet is what's causing it to not start on it's own. I just ordered a replacement carb boot even though the current one looks fine. Let me know what you think. Thanks. | ||
| Gearheaderiko |
DO NOT "take the carb apart and give it a good cleaning". Please. Does it start on its iwn once warm? Good idle means the slow jet should be fine (which is usually the problem). However, stock they are super lean and should be replaced with a #45. It will make starting easier. The main, if still stock, has a 165 and should be changed to a 170. Also drill out the idle mixture screw cap and turn the screw to 2 1/2 turns out. Running good probably means the auto enrichener is stuck or not working. The about carb adjustment might alleviate the problem, but they are worth doing regardless. (Since your Blast apparently runs fine, just doesn't start). How many miles on it? Any mods? If the spark plug is original or has 10,000 miles on it, it needs to be replaced. | ||
| Gearheaderiko |
Replacing the boot was a good idea-so I won't address that. Also, there is one vacuum nipple on the carb that is capped. Check it. The rubber cap is probably dry and cracked, replace it. It will also cause a lean condition. Jets:$6-$10 Plug: $7 Vacuum cap: $2-$5 (if you buy a variety pack). Welcome! And good luck! | ||
| Modrummer |
Ordered a new plug and new jets just now. (is this the correct low jet? It's the only #45 jet I could find that seemed right http://www.ebay.com/itm/KEIHIN-CARBURETOR-PILOT-SLOW-JET-45-HARLEY-BIG-TWIN-40MM-CARB-/122158306639?hash=item1c7133d54f:g:GhwAAOSwVFlT6Bzt&vxp=mtr). I'll be sure to adjust the idle mixture. How do I go about adjusting/fixing the auto-enricher? Thanks for the help. (Message edited by modrummer on October 18, 2016) | ||
| Gearheaderiko |
That looks like the correct jet. After you do all of the above your start problem may go away. There are things to check and do, but let's just wait and see if they are truly necessary. | ||
| Modrummer |
One other thought. The bike seems low on power, and the previous owner (who was very honest and upfront with me about the issues) said he noticed he seemed to only get the bike to rev like it should when he reached down and manually opened the slide on the carb. That sounds like a throttle cable out of adjustment to me, but I checked and it seems like the throttle fully actuates when I twist it. Any thoughts? | ||
| Gearheaderiko |
If he was reaching down to move the slide in the carb, that begs the question: what modifications have been done to this blast? | ||
| Modrummer |
None as far as I can see. Stock air box, stock exhaust. The guy restores old Honda CBs. He did say he took the carb off, cleaned it out, and changed the gaskets. Which has me worried after reading here that that is NOT recommended... Once my super carb boot and jets show up I'll install them and see if that does the trick. If not, I have the feeling I'm going to have to check the float level and needle height in the carb as well. | ||
| Gearheaderiko |
The reality is they are very simple carbs and when someone does or says: "take the carb off and give it a good cleaning" or "rebuild it", it literally translates to "I have no idea what's wrong, but I hope this fixes it". Often it leads to more problems. Now knowing that the carb was completely disassembled, it complicates the diagnostic process as you don't know if the carb was reassembled correctly. It remains hugely in suspect. Just fix what you know is wrong first, then tackle it problem by problem. My saying to change the jets and adjust the mixture does go against my own advice, but it's something that should (or must) be done anyway. If you were having serious problems, I would say to fix those problems first before changing jets and mixture. | ||
| Modrummer |
Good advice. I should have alot more answers later this morning, heading over to the garage to change the jets, inspect the carb, change the boot, and replace the plug. The more I think about it, the more I suspect the autoenricher. If the bike only starts with starting fluid, and won't idle until warm, sure sounds like a choke issue to me. | ||
| Gearheaderiko |
Concur! But I would just make sure the other stuff is up to snuff first before messing with the AE. If its a 2000 model, it's super lean to start with and a bad plug and boot will just kill it. It can be converted to manual choke and if the carb ain't put back together right, then who knows. Good luck today! | ||
| Modrummer |
UPDATE: Bike now starts, runs, and idles by itself. However, it is majorly down on power. It struggles to break 55mph. One weird thing, it almost seems to bog at wide open throttle, as in it actually accelerates a little bit faster at half throttle than at full throttle. Going back to what the previous owner said to me about how he had to manually lift up the slide to get full power... what would cause that? | ||
| Gearheaderiko |
Did you change the main jet? Do we know if it had the problem BEFORE he "rebuilt" the carb? Could be a torn diaphragm. Incorrect piston spring or incorrectly installed spring. Improperly adjusted throttle cables. | ||
| Gearheaderiko |
So it had more power before you did the work? Are you the second or third owner? Wide open throttle and no acceleration means too lean. It could also mean the piston isn't sliding up. If the throttle plate is loose and jamming, then it won't accelerate. | ||
| Modrummer |
I didn't change the main jet, the one I ordered had a different thread size and didn't fit (i'll order another) so it's still running a 165. Diaphragm is in good shape, no tears. The spring just goes under the lid on top of the diaphragm correct? It didn't have more power before I did work. The previous owner told me that when he had it running it was low on power, but he could get full power by manually pushing the piston (slide) up. So for some reason the piston isn't sliding up far enough under wide open throttle. What would cause that? It moves freely by hand. | ||
| Gearheaderiko |
http://www.badweatherbikers.com/buell/messages/201 64/6812.html?1462159418 If the main jet had the wrong threads, it may have had a "jet kit" installed. Someone may have also drilled out the hole in the piston slide (probably not if the idle mixture screw was still capped). But put all the wrong parts together and it won't work right. As you suspect I'm sure, the issue probably lies in the slide(piston)/diaphragm/spring. Check the above link for carb diagrams. If the slide/piston isn't moving up, then it's either diaphragm, piston or spring related. If the throttle isn't opening all the way because the plate is loose or the cables need adjustment, that would cause this issue. Does the throttle plate open all the way at full throttle? This is the crap you go through when someone "takes the carb apart to give it a good cleaning". Everything is suspect as lots of things can be wrong that aren't part of normal wear or malfunction. | ||
| Modrummer |
Well the main jet still had 165 in it (which should be stock size) so I'm assuming no jet kit was installed? I may have just bought the wrong jet. This is the one I bought (http://www.ebay.com/itm/151136998036?_trksid=p2057 872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT) The throttle plate opens all the way and is operating smoothly, no issues there. I can push the slide/piston up easily by hand and it works smoothly. But when the engine is running, it doesn't go up on it's own. Diaphragm appears to be in good shape, no apparent tears. And I"m fairly sure the spring is installed correctly. Thanks for your help so far! | ||
| Gearheaderiko |
That looks like the right jet. A Dynojet can have the same number, but it's a different jet and isn't interchangeable. That may also mean the needle has been changed. The best description I can give is a stock CV needle is shaped like the Washington monument with the corners rounded off and gray in colour. A Dynojet needle (if I remember correctly) looks more like a sewing needle, shiny and coming to more of a point. If they drilled the wrong hole or wrong hole in the slide, that will affect the vacuum. The Blast carb spring has much less tension than a twin carb (big twin, Sportster) spring. That could cause the piston/slide to be slow to open, but wouldn't cause it not to open all the way. Unless you had a mal-modified slide, bad diaphragm or if they used a completely different spring. | ||
| Modrummer |
Ok took the carb off again. This is the needle in my carb, does it look correct to you?  Also, I've read a few times that it's a pain in the butt to put the diahpragm back in correctly, but it seems incredibly easy. It just falls into place in it's groove when I put it in. Am I missing something? just seems too easy with how many different tips I've read on how to put it in... Also, in my airbox, the port circled in blue doesn't attach to anything, and the port circled in red just goes over top of one of the allen bolts that attached the airbox to the carb which seems weird. Why would it end there? Is that correct?  | ||
| Gearheaderiko |
That's a stock type needle. The airbox is normal. The open port used to have a hose that pointed directly into the carb and that causes excessive oil consumption. Is your bike a California model? I wonder if you have a dynojet main with a stock needle. I'm not sure if that's even possible, but if it was, it certainly wouldn't run right!! Diaphragm install isn't that hard. But like I say, people keep screwing up such a simple carb by taking it apart. A few pics of your carb and reassembly steps might help, if that's possible. | ||
| Modrummer |
I don't think my bike is a California model. What's the easiest way to tell? Also, would this kit ( http://www.ebay.com/itm/331833478034?_trksid=p2057 872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT ) work on my carb (I think it does)? It comes with the main jet holder and main jets so I could put a 170 jet in that would definitely fit the holder. Also it has the shims for the needle. I'll take the carb apart again tonight and take a bunch of pictures for you. | ||
| Modrummer |
Ok I think I Figured something out. I was spraying some carb cleaner around the carb boot to check for leaks (no leaks there!) but when I sprayed some carb cleaner closer to the head, the engine bogged and tried to die. I removed the metal flange thing that connects the carb to the head http://thumbs.ebaystatic.com/images/g/-MAAAOSwTA9X 83R2/s-l225.jpg to check the gasket. The gasket looks OK, maybe a little too crushed to seal? What is this gasket called? I want to order a new one but it's hard to lookup without a name. | ||
| Gearheaderiko |
It's the intake manifold O ring and if remember correctly they can be hard to come by. Also, if you tighten it too tight, you can warp it and it will never seal again. Why they used that set up I can't figure out. I doubt that jet kit is stock CV parts. A big twin with pipes is going to use a 195 main and that kit only goes from 150-190, which indicates it's probably not stock CV parts. * Bike Bandit carries OEM parts cheap. Just use HD 2005 FXST OR 2005 XL to find carb parts, if they require it. It used to be you could just use part numbers. I don't think Buell or Blast is even listed in their parts scheme anymore. *your bike is why I always recommend using stock parts. Non stock parts become hard to find and even harder to diagnose. Maybe your bikes carb is stock, maybe not. But you can see the trouble it causes. | ||
| Gearheaderiko |
California bikes have a soda can sized black canister mounted under the seat above the wheel. It has 3 hoses going to it. It also says California on the VIN and swingarm. | ||
| Gearheaderiko |
27444-00Y Manifold O ring | ||
| Gearheaderiko |
http://www.boardtrackerharleyonline.com/harley-dav idson/o-ring-27444-00y That's just one place that turned up when I searched the part number online. Bike Bandit doesn't do Harley OEM parts anymore (from what I can see on their website). | ||
| Modrummer |
Ok cool, I'll pick up a new o ring. Hopefully my intake manifold isn't warped! Where would you recommend I get a 170 main jet from? If you have a link to the correct one, that would be great. I'm worried I"ll get the wrong one. Thanks for the help! I'm fairly confident that this intake manifold seal is the problem. Definitely explains why the piston doesn't go up under throttle, all the vacuum is escaping (similar to if I had a cracked carb boot). | ||
| Jetlee |
Have you checked the static ignition timing? https://www.youtube.com/watch?v=vCBtfz0toRw | ||
| Jetlee |
Also, here's some videos I made a while back about some common issues with the carb: https://www.youtube.com/playlist?list=PL7xSpUu4-mE 3db8CZz4K1JbF6ICqCfkxD | ||
| Modrummer |
Thanks for the link Jetlee. Still trying to find a good place to get a 170 jet that will fit a Buell blast. Reccomendations (preferably a link)? Also, I tried sealing the leak between the intake manifold and head with some high-heat silicon gasket maker, let it cure for 24 hours, and no luck. Still a leak there. So I'm guessing my intake manifold is actually warped. |
