Mightymouse
Well-Known Member
- Joined
- Mar 28, 2019
- Messages
- 45
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Hey all,
I'm really stumped about my bikes lack of acceleration.
It's a 97' v-max with about 66,000 miles on it. It's a California model. I had the carbs cleaned and synced 10 months ago. OEM pilot jets and main jets were replaced (I think it was only the ones for fuel. I don't think they replaced the air jets.)
When I got the bike back it could be cold started without the choke on. It seemed very lively to me after I got it back. I stored it for the winter with seafoam fuel stabilizer, brought it out of storage and rode it around this past summer but not as frequently as I would have liked. There were stretches of time that it would sit in the garage for 2 weeks with no fuel stabilizer. Since it was kind of far away from where I currently live, when I had time, I would take it out and run it for ~20-30 minutes. I think I've put about 2,000 miles on it this season. It can still be cold started without the choke but now the bike is not as lively anymore and struggles to get up to speed.
And It seemed to have happened very suddenly. The bike seemed fine one day and then the next day it wasn't. It couldn't accelerate like it used to.
I rolled on the throttle and the bike seemed really sluggish to accelerate. I suspect something is going on with the carbs but I don't know exactly what's causing the problem.
I replaced the fuel filter (hadn't changed it in about 8,000 miles). That didn't do anything. Sluggish acceleration is still there.
I searched these forums and did a few of the tests that were recommended. Here is what I found:
Test 1: Pilot mixture test: engine should complain if RPMs are held @ 1800 for 1-2 min or when the temp needle touches the first mark (should run lean when cold) After 2 min or needle is 1/2 way between mark and cold mark should not complain from 1500-2000 or popping back through carbs.
I just did this one tonight. Video here. No choke needed at startup. I only gently blipped the throttle to get it going. I think I heard some popping through a carb/carbs around the 14 second mark. It starts around 800-900RPMS. A few seconds after starting it, I roll on the throttle gently to raise the RPMs to 1,800 but it's hard to control. The rpms rev up real fast even if I keep the throttle steady. It takes several minor adjustments to maintain 1800 rpm. This takes about 30 seconds to achieve. After 2 minutes the temp needle hits the cold mark and idles around 1000. Because I could hold the engine at 1800 while cold then this seems to indicate the pilot mixture is too rich. I should either clean or enlarge PAJ2.
Here's another video. The only difference is the engine is warmer. I slowly increase rpms and hold it at 1800 and also rev it a few times towards the end. It was a lot easier to gradually increase rpms from 1000 to 1800 with a warmer engine. I noticed while holding 1800 the rpms increase by ~100-200 while my hand is real steady on the throttle. Is this normal? It'll increase for a few seconds and then drop back to 1800. I moved the camera closer to the needle to showcase this. The engine does not seem to complain when the engine is warm so it can't be a lean condition BUT I do routinely hear popping noises coming from the airbox when accelerating with a warm engine in 1st or 2nd gear. Seems like carb/carbs have symptoms of running too rich and too lean?
Test 2: pilot mixture cruise test: engine should run steady at 5k. If stumbles but ok everywhere else then not enough pilot.
I didn't take a video of this but the bike seems to run steady at 5k in 5th gear and ok everywhere else BUT...
I hear popping noises from the exhaust above 4500 RPM in 1st gear (and 2nd gear too but harder to hear (could be the wind). Seems to pop more in this gear when rolling off the throttle slowly). What could this mean?
Test 3: Slide jump test: cruise @ 4K in 5th gear. Pin it fast. There should be NO hesitation. If there is. Too rich. Needle is too rich
Didn't take a video. There IS hesitation. The needle seems to be too rich.
Test 4: hard WOT pull in 2nd or 3rd gear <3k. Should be smooth pull all the way. If it seems to lag in 4-5k range, too much needle. If sputters then not enough needle. {tests needle richness or leanness}
Didn't take a video. NOT smooth all the way through. Seems to quickly speed up and slow down irregularly through the 4-5k range. Not sure if this is a lag symptom or a sputter symptom.
Final videos: I pulled the spark plugs after the bike had been sitting for about 2 hours and inspected them. I took a video of each one. What do you guys think? Do they look normal or can you see something that might explain the symptoms above?
Here's the video for the spark plug from carb #1.
Here's the video for the spark plug from carb #2.
Here's the video for the spark plug from carb #3.
Here's the video for the spark plug from carb #4.
Many thanks for any insight y'all can lend! I've really been scratching my head on this one. I tried to document as many of the symptoms as I could to help all of you with your thoughts.
If y'all want any additional video or pictures or anything, I'll gladly upload them for you if you think it will help.
Best,
Eli
Oh, and just out of curiosity, I took a video of one of these popping events that I can hear in the air box. I uploaded it here. Is this what you mean when you say "popping back through the carbs"?
I'm really stumped about my bikes lack of acceleration.
It's a 97' v-max with about 66,000 miles on it. It's a California model. I had the carbs cleaned and synced 10 months ago. OEM pilot jets and main jets were replaced (I think it was only the ones for fuel. I don't think they replaced the air jets.)
When I got the bike back it could be cold started without the choke on. It seemed very lively to me after I got it back. I stored it for the winter with seafoam fuel stabilizer, brought it out of storage and rode it around this past summer but not as frequently as I would have liked. There were stretches of time that it would sit in the garage for 2 weeks with no fuel stabilizer. Since it was kind of far away from where I currently live, when I had time, I would take it out and run it for ~20-30 minutes. I think I've put about 2,000 miles on it this season. It can still be cold started without the choke but now the bike is not as lively anymore and struggles to get up to speed.
And It seemed to have happened very suddenly. The bike seemed fine one day and then the next day it wasn't. It couldn't accelerate like it used to.
I rolled on the throttle and the bike seemed really sluggish to accelerate. I suspect something is going on with the carbs but I don't know exactly what's causing the problem.
I replaced the fuel filter (hadn't changed it in about 8,000 miles). That didn't do anything. Sluggish acceleration is still there.
I searched these forums and did a few of the tests that were recommended. Here is what I found:
Test 1: Pilot mixture test: engine should complain if RPMs are held @ 1800 for 1-2 min or when the temp needle touches the first mark (should run lean when cold) After 2 min or needle is 1/2 way between mark and cold mark should not complain from 1500-2000 or popping back through carbs.
I just did this one tonight. Video here. No choke needed at startup. I only gently blipped the throttle to get it going. I think I heard some popping through a carb/carbs around the 14 second mark. It starts around 800-900RPMS. A few seconds after starting it, I roll on the throttle gently to raise the RPMs to 1,800 but it's hard to control. The rpms rev up real fast even if I keep the throttle steady. It takes several minor adjustments to maintain 1800 rpm. This takes about 30 seconds to achieve. After 2 minutes the temp needle hits the cold mark and idles around 1000. Because I could hold the engine at 1800 while cold then this seems to indicate the pilot mixture is too rich. I should either clean or enlarge PAJ2.
Here's another video. The only difference is the engine is warmer. I slowly increase rpms and hold it at 1800 and also rev it a few times towards the end. It was a lot easier to gradually increase rpms from 1000 to 1800 with a warmer engine. I noticed while holding 1800 the rpms increase by ~100-200 while my hand is real steady on the throttle. Is this normal? It'll increase for a few seconds and then drop back to 1800. I moved the camera closer to the needle to showcase this. The engine does not seem to complain when the engine is warm so it can't be a lean condition BUT I do routinely hear popping noises coming from the airbox when accelerating with a warm engine in 1st or 2nd gear. Seems like carb/carbs have symptoms of running too rich and too lean?
Test 2: pilot mixture cruise test: engine should run steady at 5k. If stumbles but ok everywhere else then not enough pilot.
I didn't take a video of this but the bike seems to run steady at 5k in 5th gear and ok everywhere else BUT...
I hear popping noises from the exhaust above 4500 RPM in 1st gear (and 2nd gear too but harder to hear (could be the wind). Seems to pop more in this gear when rolling off the throttle slowly). What could this mean?
Test 3: Slide jump test: cruise @ 4K in 5th gear. Pin it fast. There should be NO hesitation. If there is. Too rich. Needle is too rich
Didn't take a video. There IS hesitation. The needle seems to be too rich.
Test 4: hard WOT pull in 2nd or 3rd gear <3k. Should be smooth pull all the way. If it seems to lag in 4-5k range, too much needle. If sputters then not enough needle. {tests needle richness or leanness}
Didn't take a video. NOT smooth all the way through. Seems to quickly speed up and slow down irregularly through the 4-5k range. Not sure if this is a lag symptom or a sputter symptom.
Final videos: I pulled the spark plugs after the bike had been sitting for about 2 hours and inspected them. I took a video of each one. What do you guys think? Do they look normal or can you see something that might explain the symptoms above?
Here's the video for the spark plug from carb #1.
Here's the video for the spark plug from carb #2.
Here's the video for the spark plug from carb #3.
Here's the video for the spark plug from carb #4.
Many thanks for any insight y'all can lend! I've really been scratching my head on this one. I tried to document as many of the symptoms as I could to help all of you with your thoughts.
If y'all want any additional video or pictures or anything, I'll gladly upload them for you if you think it will help.
Best,
Eli
Oh, and just out of curiosity, I took a video of one of these popping events that I can hear in the air box. I uploaded it here. Is this what you mean when you say "popping back through the carbs"?
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