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Post by shally on Oct 19, 2013 19:18:47 GMT -6
Trike was running great until the air box broke and stranded me. Got it home, repaired the air-box, and it ran good but not great for about a week. Then the problem started. It started acting up when climbing a hill. The motor would loose power and it sounded like it was firing only on every other cycle. It would make a "BRAAAT" sound. I found that by backing off a quarter turn, the motor would settle in and if I advanced the throttle slowly, it would accelerate to around 45mph at around 68000rpm. Problem would get worse the longer I went. I figured messing with the air-box may have changed the carb settings. Found the stock carb had the setting screw capped and unadjustable. Replaced carb with one Alley sent me and proceeded to adjust it per a new Trail Tech tach. Take it on the road and found no improvement. No matter where I set it, results were the same. Installed a gravity-feed tank and bypassed the tank, filter, and pump; no improvement. Drilled out plug on OEM carb and reinstalled it; no improvement. Replaced CDI, and plug. Readjusted valves( found exhaust rocker had nearly no play); no improvement. Although the idle is a bit unstable, it is reliable and the trike only acts up when under load. Has anyone had this problem? Any ideas?
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Post by Alleyoop on Oct 19, 2013 19:24:45 GMT -6
Just so you know if the idle is bouncing it is LEAN you probably have an air leak. Lets take a look at your air box take a pic. Alleyoop
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Post by shally on Oct 19, 2013 21:21:53 GMT -6
I have removed the air box, carb, and intake manifold and went over them with a magnifier and couldn't find any leaks. I believe "unstable" was somewhat inaccurate, I get about a 200 to 400 rpm drift and I'm not sure if that is normal or not.
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Post by tvnacman on Oct 20, 2013 0:42:12 GMT -6
do you have emmisions on the engine ?
I bet a new Keihin with a pod and a new manifold will make quick work of this .
John
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Post by stevespidel on Oct 20, 2013 3:48:42 GMT -6
I had an on-going battle with those symptoms also. Mine had an intermitent vacuum leak at the diaphram input to the carb. Replacing that line cured that problem for me.
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Post by shally on Oct 20, 2013 9:48:05 GMT -6
Thanks for the help but I don't know what a "new Keihin with a pod and a new manifold" is but it sounds expensive and my budget is already shot. As far as the diaphragm, I swapped carbs. I have swapped or bypassed everything in the fuel system with no change. I couldn't find any visible air leaks, swapped the CDI, and readjusted the valve rockers. I had to take it on the road to duplicate the problem and each time it acted up I would adjust the carb 1/4 turn rich until it would start acting up in other ways. I then repeated the process adjusting lean. Nothing helped. Shally
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Post by stevespidel on Oct 20, 2013 10:12:15 GMT -6
Know what you mean about the budget. And I can't vote to raise my debt ceiling.
I was refering to the vacuum line that runs to the carb, not the to diaphram itself. That line lifts or lowers the diaphram. Mine had a tiny crack that kept opening up.
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Post by tvnacman on Oct 20, 2013 10:17:18 GMT -6
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Post by shally on Oct 20, 2013 20:35:38 GMT -6
I tried raising my debt limit but my wife spent it before I could use it. I went ahead and checked the vacuum lines and could not find any problems. I am using the stock muffler, how could that cause my problem? Shally
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Post by Alleyoop on Oct 20, 2013 21:15:47 GMT -6
Shally, Everything you have on there is fine. Right now your are running LEAN probably due to the cracked air box and it is getting to much air from someplace I guarantee.
To find an air leak unless of course you can see cracks someplace get a Spray Water of WATER and spray individual areas. Spray by the intake where connects to the motor many times since the air box came loose and cracked the carb was bouncing around and the rubber part of the INTAKE MANIFOLE may have cracked due to the bouncing. Also around the Vacuum line connectors and by the Air Filter side. When you spray around listen if the IDLE CHANGES if it does you found a leak.
The BRAATT sound is JUST ONE of the sounds the motor will make when it is running to LEAN. That carb I gave you is just fine all this was caused by the air box breaking and not sealing everything up and or some other part created a leak due to the carb bouncing around. So check for LEAKS and if you messed with the CARB richen it up if the motor makes the BRAAT sound.
Different sounds a motor makes tells you what it needs, so listen for any sounds the motor makes.
1. Popping while accelerating is a RICH condition. 2. Popping while de-celerating is a LEAN condition. 3. Burp/Brat Sounds accelerating is a LEAN condition 4. Backfires are a Lean condition.
Possible causes for above and fixes: 1. Here the problem is it is running OVERLEY rich and the main jet is to big. 2. Here couple things: a. You can richen up the Fuel Ratio Mixture b. Idling to low Bring up the idle a little 3. You can richen up the Fuel Ratio Mixture 4. Usually caused by it Leaking where the Pipe Connects to the motor. Bad air leaks cause the backfiring many think it is because it is to RICH but it is the OPPOSITE sucking in air causing very Lean condition and this can damage your exhaust valve.
If it just BOGS on you or starts dropping rpms or bucks but makes no distinguishing sounds then the good old Trick of the Trade will tell you what the motor needs:
TRICK OF THE TRADE: Lets find out which situation(LEAN OR RICH) is causing the problem. Run the sucker like you do when it STARTS TO ACT UP Back off the THROTTLE about 1/4 OF AN INCH and HOLD IT THERE: A. If the scoot Speeds up it is running LEAN. B. If the scoot Sputters or whatever BUT settles down it is running RICH.
This way you will know what it needs(more or less juice). Alleyoop
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Post by FrankenMech on Oct 20, 2013 21:32:57 GMT -6
Really nice writeup Alley!
Another trick is to use propane to track down leaks. An unlit propane torch with just a little gas flowing will show leaks. I find it easier and more accurate to use than water or other liquids like carb spray, WD, ATF, etc.
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Post by Alleyoop on Oct 20, 2013 21:38:32 GMT -6
Yes, I know but for safety sakes I always tell people to use water, if the motor is really hot it can ignite. Alleyoop
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Post by FrankenMech on Oct 20, 2013 21:40:11 GMT -6
Yeah, that is why I use very little gas, and if you pull the torch away, -flame gone.
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Post by Alleyoop on Oct 20, 2013 21:55:23 GMT -6
Don't forget Frank, many are not mechanically inclined and a lot do not even own any tools maybe a screwdriver and a pair of pliers let alone a propane torch. Alleyoop
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Post by tvnacman on Oct 21, 2013 3:19:55 GMT -6
torch , I thought that was a spark plug ? !!!!
John
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