Hello everyone, I have searched far and wide for an answer to my issue with no avail, so now I am turning to you.
1986 Magna VF700
Sat for about 1 1/2 years outside in someones backyard
I cleaned the carbs out 3 times now and synced then each time, and changed the plugs as well.
The bike will idle smooth @ 1000k and will accelerate normal to 2.5k sometime 3k rpm and then after that you can hear the engine bog and it will barley keep accelerating till about 55mph. i can rev the bike just about all the way to red line,just does not make any power.
I keep pulling the carbs out to check that i put everything together right and cleaned every hole, and I am rather certain I have
-The larger jets are on the rear cylinders and i cleaned the air jets on the side and the screwed them out 2 turns. I can see through all the holes in all the jets. I really think the carbs are fine. I also did a rough measure of the floats and they are all resting at the same height; around 7mm.
-I replace the fuel filter and all plugs
-I did notice the new front plugs got darker while the rear ones stayed white.
Any one in the DFW is welcome to come out here and look, I would definitively have a cash reward if you can tell me what I have done wrong.
I am not familiar with the setup of this bike.
A few things come to mind,
1. This is not a pilot jet issue, your Main jets would have to be clogged.
2. Are all your cylinders running - are all of your header pipes equally hot.
3. Could be a bad coil
4. Are all of your diaphragms in good shape and workings as they should
5. Could be part of your electronic ignition/ignitor/pickup coil is not working properly.
6. Are the valves seating properly.
7. Compression of each cylinder.
8. Are your exhaust pipes free flowing, ie: no nest inside.
9. I don't know what your float level should be but I work on vintage bikes, last night I set mine at 27mm from where the bowl sits to the top of the float, maybe you are measuring to the bottom of the float. If your float level is wrong you are not getting enough fuel in the bowl.
Lot's to check, process of elimination or test the best way you can depending on the available tools.
Like Terry I'm not familiar with your bike either but another thing to check would be your air filter setup. I know on the 3rd gen. if you remove any restrictions (like the air box snorkel for example), you'll have issues getting her to rev as things get way too lean.
Thank you For the resposes guys! Reallly can't tell you how much I appreciate the help.
I've written responses inside of the quote below.
Quote from: TLRam1 on June 14, 2012, 11:41:16 AM
I am not familiar with the setup of this bike.
A few things come to mind,
1. This is not a pilot jet issue, your Main jets would have to be clogged.
Agreed, And every time I have removed the carbs ive re-checked the main jets. all clear
2. Are all your cylinders running - are all of your header pipes equally hot.
Yepp, All cylinders are firing.
3. Could be a bad coil
This is kind of what im suspecting, however I called a shop and mention this was my suspision, and he told me he doubted it, and mentioned he had only ever ran into a bad coil once in his experince.
4. Are all of your diaphragms in good shape and workings as they should
Yes, when i cleaned the jet needles I checked the condition of the diaphragms. all good there, and the travle up and down smoothly
5. Could be part of your electronic ignition/ignitor/pickup coil is not working properly.
Any ideas on how to test this?
6. Are the valves seating properly.
You mean like the bike needs a valve lash adjustment?
7. Compression of each cylinder.
Testing the compression when I get a compression tester that fitts the bike. however the bike is not burning oil and their is no oil mixing with the coolant.
8. Are your exhaust pipes free flowing, ie: no nest inside.
No sure, But the bike was sitting for a long time out side, may be alot of dirt in there. ill trry taking the pipes off and running her like that.
9. I don't know what your float level should be but I work on vintage bikes, last night I set mine at 27mm from where the bowl sits to the top of the float, maybe you are measuring to the bottom of the float. If your float level is wrong you are not getting enough fuel in the bowl.
The bike manual says 7mm
Lot's to check, process of elimination or test the best way you can depending on the available tools.
Quote from: TLRam1 on June 14, 2012, 11:41:16 AM
9. I don't know what your float level should be
I have the factory manual and it says the float level should be 7.5mm .
Okay, Ill adjust them to 7.5mm, they defiantly are not that open. however can them being .5mm off cause this amount of loss of power. I understand that the way that they work is by floating to the top and shutting off the gas flow. is my bikes carbs shutting off the flow too early? Ill pull the carbs out again and adjust them again.
Quote from: LIMagna on June 14, 2012, 11:56:29 AM
Like Terry I'm not familiar with your bike either but another thing to check would be your air filter setup. I know on the 3rd gen. if you remove any restrictions (like the air box snorkel for example), you'll have issues getting her to rev as things get way too lean.
I did check the air filter and tried a few set ups. ie: driving without it in, and re oiling the filter. nothing seemed to alter the issue though. thanks for the suggestion!
Quote from: HohltMagna700 on June 14, 2012, 04:14:51 PM
I did check the air filter and tried a few set ups. ie: driving without it in, and re oiling the filter. nothing seemed to alter the issue though. thanks for the suggestion!
That may not be a good sign or a sign that the intake isn't the problem because there probably should have been a noticeable difference with no air filter installed. I apologize for not being more familiar with your ride but are there any missing parts from the intake system/airbox? Are there any missing gaskets or anything else that might be letting in more air than than should be flowing through the system? Are there any other intake leaks for that matter (like around the carb boots)?
Quote from: HohltMagna700 on June 14, 2012, 04:12:38 PM
Okay, Ill adjust them to 7.5mm, they defiantly are not that open. however can them being .5mm off cause this amount of loss of power. I understand that the way that they work is by floating to the top and shutting off the gas flow. is my bikes carbs shutting off the flow too early? Ill pull the carbs out again and adjust them again.
Sorry, I was responding to Terry. I hadn't noticed that you said you set it to 7mm. My eyes probably can't even see 1/2 a mill. One thing I was going to add though was that when I got mine it was pretty much like your situation. It had sat for five years. After I got the carbs cleaned up and repaired it still didn't want to rev and would sputter around 2500 or 3 grand. When I got the manual I realized that one of the vacuum lines was actually a vent and they had it plugged. I unplugged it and that straightened it out. Just can't remember exactly where it was but you might want to check those just for the heck of it.
I scanned the post but did not see clutch plates
What did I miss why this is not clutch plates.
You are at red line and but not getting faster.
Quote from: filstoy on June 14, 2012, 06:17:34 PM
Quote from: HohltMagna700 on June 14, 2012, 04:12:38 PM
Okay, Ill adjust them to 7.5mm, they defiantly are not that open. however can them being .5mm off cause this amount of loss of power. I understand that the way that they work is by floating to the top and shutting off the gas flow. is my bikes carbs shutting off the flow too early? Ill pull the carbs out again and adjust them again.
Sorry, I was responding to Terry. I hadn't noticed that you said you set it to 7mm. My eyes probably can't even see 1/2 a mill. One thing I was going to add though was that when I got mine it was pretty much like your situation. It had sat for five years. After I got the carbs cleaned up and repaired it still didn't want to rev and would sputter around 2500 or 3 grand. When I got the manual I realized that one of the vacuum lines was actually a vent and they had it plugged. I unplugged it and that straightened it out. Just can't remember exactly where it was but you might want to check those just for the heck of it.
Now this sounds more like what I am seeing happen with my bike. Did yours ever climb over 3k? mine sputters @ 2500 rpm BUT it will continue to accelerate, Just reallllly slowly. I am really hoping its something simple like a vacuum hose in the wrong place. Any one have a manual for a 1986 VF700/
Quote from: HohltMagna700 on June 14, 2012, 11:35:28 PM
Quote from: filstoy on June 14, 2012, 06:17:34 PM
Quote from: HohltMagna700 on June 14, 2012, 04:12:38 PM
Okay, Ill adjust them to 7.5mm, they defiantly are not that open. however can them being .5mm off cause this amount of loss of power. I understand that the way that they work is by floating to the top and shutting off the gas flow. is my bikes carbs shutting off the flow too early? Ill pull the carbs out again and adjust them again.
Sorry, I was responding to Terry. I hadn't noticed that you said you set it to 7mm. My eyes probably can't even see 1/2 a mill. One thing I was going to add though was that when I got mine it was pretty much like your situation. It had sat for five years. After I got the carbs cleaned up and repaired it still didn't want to rev and would sputter around 2500 or 3 grand. When I got the manual I realized that one of the vacuum lines was actually a vent and they had it plugged. I unplugged it and that straightened it out. Just can't remember exactly where it was but you might want to check those just for the heck of it.
Now this sounds more like what I am seeing happen with my bike. Did yours ever climb over 3k? mine sputters @ 2500 rpm BUT it will continue to accelerate, Just reallllly slowly. I am really hoping its something simple like a vacuum hose in the wrong place. Any one have a manual for a 1986 VF700/
Just sent you an e-mail with some info.
HohltMagna,
You say:
"The bike will idle smooth @ 1000k and will accelerate normal to 2.5k sometime 3k rpm and then after that you can hear the engine bog and it will barley keep accelerating till about 55mph. i can rev the bike just about all the way to red line,just does not make any power."
How are you driving the bike? At what RPM are you shifting gears. Tell me what you do when you do the acceleration test. What happens after 55 mph and what gear are you in?
Orv.
fuel screen in the tank or the petcock????
We are all at Koyote Ranch and the internet is not the best......just to let you know responses will be slow until next week when everyone gets back.
The best signal that I found was at the cabins in the hill and you had to stand on a table to.
I wanted to let everyone know that the cause of the problem was in fact the coil controlling the front cylinders. As you would rev the bike, the spark would then die. just idling the spark would be weak, but anything above that. the spark would die off.
Special thank to those of you how help out and gave suggestions, and a special thanks to Phillip for sending me manual.
Glad you were able to fix it. Thanks also for posting what the problem was. It helps others who might run into a similar situation.
Quote from: filstoy on June 18, 2012, 03:53:11 PM
Glad you were able to fix it. Thanks also for posting what the problem was. It helps others who might run into a similar situation.
Yes that does help.
So do you have a new coil and it works as it should or are you in search for one.
I started reading this post, thinking gotta be ignition related. Continued reading all the great suggestions, and then got to end happy you found the problem. Were you able to locate a replacement coil easily?
I am glad you know what the problem is. One more thing to be watching
Quote from: tedkraus on June 18, 2012, 09:59:09 PM
I started reading this post, thinking gotta be ignition related. Continued reading all the great suggestions, and then got to end happy you found the problem. Were you able to locate a replacement coil easily?
Yep, no problem, however I replaced it, and it didnt change anything. Turns out it is the CDI box actually. I checked the resistance from the pulse generators and they were within spec.