| Author | Message | ||
     Shawn3d |
I bought my first street bike last year, a 2001 Blast. Since then I did the air box mod with K&N filter, Jardine exhause, 48/175 jets, .050 needle shim, idle screw at 2.75 turns out, new Das Boot. When I start the bike it idles high for a minute or two and then slowly tapers down until it dies. I try to ride off before it dies, sometimes I don't get my s#!t on in time. I understand the high idle and slow taper are normal and suggests the auto-enrichener is at least doing something. When it idles down I take off and baby the throttle for a little while to keep it from dying. From what I've read here so far this sounds normal. After a 5 mintues of riding the crank case and jug are all warmed up and riding fine. Power is quick and responsive, everything feels normal. A few more minutes of riding and it starts idling higher. Regardless if I'm taking it easy on the highway or ripping through gears, the longer I ride the higher it idles. If I shut it off for 5 minutes or so it idles fine when I start it back up, but is then idling high again after a few minutes. My first thought was I'm running lean and it was over heating, or the boot wasn't sealed and it was sucking too much air. After a new Boot, and it's tight, and 48/175 jets I'm confident it's neither of these. I'm really wondering what my next move should be. I'm leaning towards replacing the autochoke, but, could it be the ignition coil? I've read other threads about bad ignitions modules causing the motor to bog down when it warms up, could a bad module cause it to rev up instead? Any insight somebody could give me is greatly appreciated. Thank you in advance. | ||
| Vicenzajay |
Shawn, I'm not going to "have the answer", but I can say that 48 is a pretty rich slow jet for your setup (air box mod/K&N). The main and needle sound great, but a 48 jet and almost 3 turns out with that air flow is richer than optimum. I would put a 46 slow jet in there, put the air screw at 2 2/3 turns out, and then go for a ride until the bike was nice and warmed up. Then adjust the idle to 1300'ish rpms. That would be where I would start. You've got a new boot, so that should be good (it would be the other thing to check here). Just for reference - I'm running Thumpe's superboot/intake mod setup (even more flow than your configuration right now), and I'm using 46/175 jetting. (Message edited by vicenzajay on April 06, 2015) | ||
| Shawn3d |
I was running a 45/175 and was having a lot of popping when I backed off the gas or down shifted, even back fired in the carb and died a few times. After reading one of EZ's posts on jetting various setups I switched to 48 and haven't had any problems with that since. I'll try 47 and 46 and see how they work, but, 45 seems to be too lean. | ||
| Ezblast |
A 46 will do it - make sure air screw is 2 3/4 turns out, and shim needle with two #4 washers. EZ | ||
| Gearheaderiko |
Sounds like you have an intake leak. You have all the classic signs. When did this start? If after the mods, then you've made a mistake and something is messed up. Richening the mixture as you've done only masks a problem. I'm not sure if Iowa is warmer than Montana, but a five minute warmup in California isnt enough! 10 minutes riding in Montana, isnt enough! And it must be a ridden warm up. Idling for 5 minutes isnt warmed up-you're overheating some engine parts and leaving others cold. Check the vacuum plug, they get old and crack. Make sure your needle washers fit-they must be a good fit on the needle and fit inside the plastic "spider" piece. Make sure the boot has "locked" into place and it is a stock boot (no substitutes!). Double check fitment by close inspection. Check the plastic spacer between the filter box and carb for cracks along with the gasket (if you undid them). Check that you didnt lose or damage the O-ring on the idle mixture screw. A bad ignition module could cause a high idle, in theory. A bad TPS could too. Also a loose timing cup or loose module. All are not common, but if you messed with the timing or TPS,its possible. If you havent messed with it, then something loose is an unlikely cause. Was the bike stock when you got it? Again: when did this start? Try to avoid checking everything willy nilly. Check the stuff you messed with first (we ALL make mistakes)! (Message edited by Gearheaderiko on April 07, 2015) | ||
| Ezblast |
Check the vacuum line plug cap they do tear and crack in time - lol EZ | ||
| Shawn3d |
It's done this from day one. I agree everything points to a vacuum leak. The bike was pretty much stock when I got it. I did find the needle was shimmed to .035" and a bowl screw was missing. I haven't touched the TPS or timing. I'm going to the Harley dealership for 46 jet today. I'll check the boot again, the diaphragm, and idle screw o-ring while I have the carb open. We have bad weather forecast tonight so I gotta ride right? | ||
| Gearheaderiko |
If the needle was shimmed, the bike is not stock and has been tampered with. You're going to have to check things carefully to figure out what the problem is. It's more than diagnosing a regular problem as this may have been caused by improper modifications. And please do not take the carb apart to "give it a good cleaning". You'll likely do more harm than good. I'll be riding tonight   } | ||
| Shawn3d |
The HD shop didn't have 46 jets in stock, get back to you guys on that Saturday. I pulled the carb off and checked the diaphragm, mixture screw o-ring, boot, air box carb gasket and plastic spacer. All appear to be in good working order with no obvious tears, cracks, or dry rot. I'm not sure what the vacuum plug you're referring to is, I don't see it on any cv diagrams. Is it just below the TPS? | ||
| Gearheaderiko |
There is only one vacuum port on the carb. It should have a rubber (or now it would feel like hard plastic) cap. It may be gone, because they crack and eventually fall off with age. If thats the case is will look like a small tube, appx 1/8" with a hole in it. In a rare case it might not even be there. Only the California Blasts actually use this port and I have seen a few CV carbs with this port not even drilled. But it would be rare, but not impossible. If it was a California bike it would definitely have it. It would cause a problem and a lean issue. | ||
| Ezblast |
It's on the left side of the carb facing the front of the bike/sitting on the bike. That plug/cap was messing with me, but it is easy to replace and I zip tie it with a very small zip tie as well. The caps are just rubber, and you can get new ones at any auto parts store. EZ | ||
| Shawn3d |
While I've been waiting for the HD dealership to receive the 46 pilot jet I pulled the carb off and checked all the gaskets and o-rings. I replaced the vent tube cap and sinched it tight with zip tie (Thanks EZ). The other cap was rather stiff. I also put the autochoke back to stock position. I had messed with it late last season because when I first start the bike it idled high for a moment then the rpms drop and eventually dies. I don't mind babying the throttle when I'm riding, but it pisses me off babying the throttle while putting my glove and helmet on. So I did both of those things, put it back together, and now it's idling fine when it's warmed up. I rode around the neighborhood for a while, then went all balls out on the interstate. Before it would idle at 4k rpms after that kind of ride, now she purrs like a proper little b!^(#. Big thanks to you guys for pointing me in a more logical direction. Whether it was the autochoke, which I doubt because if it's working correctly it shouldn't matter once the bike is warmed up, or the vacuum tube, either way I'm glad the longer I ride the smoother it idles. Also, I've noticed that a lot of people get rid of the stock foot peg mount and go with something else. (EZ.. thumpe.. ratblastard... I've seen different versions) Do any of you guys have a 3d model or drawing of these custom parts? SolidWorks preferably but parasolid, step, iges, or any neutral format would be great too. Pro-shitE if you must. (Message edited by shawn-3d on April 14, 2015) | ||
| Gearheaderiko |
The AE and TPS will alter idle speed. As far as rearsets, if you like that riding position, are fairly simple to make. You can use the front pulley cover as a template for the holes, then cut a mount plate to the shape you like. Then mount the brake arm, carefully bending the brake line. You can use cardboard for a 3 hole template on the primary side or use the primary cover as a template if you have it off. The only tools needed are an electric drill and a jig saw. Bolts and spacers are available at Ace Hardeware. 3/8" aluminum plate at a metal supply shop. The shifter can be handmade, but it far easier just to get a shifter assembly from an XB. Bolts right on! (After drilling a hole in the primary cover, for which a boss is already there. | ||
| Ezblast |
http://www.badweatherbikers.com/buell/messages/201 64/15647.html?1342335323 EZ | ||
| Gearheaderiko |
Thanks EZ  |
