Engine problems, please help... getting desperate
Stellar HDF Member
Joined: May 2009
Posts: 2,856
Likes: 127
From: Middle of Kansas
You did say that it would die with the adjustment screwed all the way in. So it is working to a degree. I have a 45 pilot jet in mine with a 180 main, and my EVO is stock except for drag pipes and K&N A/C, so you should be good on jets. How did it run on points? Or did you run it? When I installed points in my old Sportster, I had to take a hammer to the cam to tap it and center it up. That is what the book said to do. Anyway, I think your jets should be OK unless you want to go bigger and try that. Does you new ignition use the VOES? Might want to check the hose for that, and if it does not use it, make sure the vacuum port is plugged in the intake manifold.
Just a few things to consider.
Just a few things to consider.
Thread Starter
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Cruiser
Joined: Feb 2012
Posts: 160
Likes: 2
From: North Florida
Thanks for the info folks!
No VOES, using a VT-i, which is a hall effect type ignition, two lobes on the advance cam, equal height and width, trigger the sensor. One wire to each side of the coil, that's it. It's as close to points as it can be without being points.
It DID run on points, though the fact the rear was misfiring and the wide lobe was gapped really wide made me think that replacing it would resolve the issue. Apparently, it didn't, though it was a change I wanted to do initially. Points were because I couldn't afford anything else initially.
Vacuum is plugged, using a Pingel hi-flo petcock, so without a vacuum on that, and no VOES, I capped it securely.
Seems a divide on the cylinders running the same. I'm going to try the following, probably Wednesday, I work late the next two days:
1. Switch out the plug wires front for rear. Being a dual-fire, it shouldn't make a difference which is which, see if maybe the new coil is bad (wouldn't be the first time I've had that happen)
2. Compression test
3. check again for intake leaks
4. check for exhaust leaks
5. possibly step down to a smaller slow jet
No VOES, using a VT-i, which is a hall effect type ignition, two lobes on the advance cam, equal height and width, trigger the sensor. One wire to each side of the coil, that's it. It's as close to points as it can be without being points.
It DID run on points, though the fact the rear was misfiring and the wide lobe was gapped really wide made me think that replacing it would resolve the issue. Apparently, it didn't, though it was a change I wanted to do initially. Points were because I couldn't afford anything else initially.
Vacuum is plugged, using a Pingel hi-flo petcock, so without a vacuum on that, and no VOES, I capped it securely.
Seems a divide on the cylinders running the same. I'm going to try the following, probably Wednesday, I work late the next two days:
1. Switch out the plug wires front for rear. Being a dual-fire, it shouldn't make a difference which is which, see if maybe the new coil is bad (wouldn't be the first time I've had that happen)
2. Compression test
3. check again for intake leaks
4. check for exhaust leaks
5. possibly step down to a smaller slow jet
Seasoned HDF Member
Joined: Oct 2007
Posts: 8,852
Likes: 2,493
From: Decatur, Alabama
None of this is going to fix your immediate problem. Just food for thought:
When checking for intake leaks you can use water instead of WD-40. Obviously, if it dies, then there's a leak.
You didn't say anything about the coil you are using. Does it match the new ignition system?
Did you make a bracket to help hold the carb up? If it hangs on only the intake manifold, it will eventually cause a leak from all that vibration and weight.
When checking for intake leaks you can use water instead of WD-40. Obviously, if it dies, then there's a leak.
You didn't say anything about the coil you are using. Does it match the new ignition system?
Did you make a bracket to help hold the carb up? If it hangs on only the intake manifold, it will eventually cause a leak from all that vibration and weight.
Thread Starter
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Cruiser
Joined: Feb 2012
Posts: 160
Likes: 2
From: North Florida
Called Daytona TwinTec this morning, nice folks. I wouldn't have thought it, but the fact that the advance/cam was slightly eccentric CAN cause a problem with the trigger rotor they use.
The rear plug was sooty and near fouled, the front was clean and new looking, suggesting to me (dual fire) it was firing on the front combustion/rear exhaust, but not the rear combustion. rear cyl exhaust smelled gassy, front maybe just a touch rich.
I swapped the plug wires, front to rear on the plugs but not the coil, and nothing changed = coil good.
Sprayed the hell out of the manifold with cleaner, no RPM change = no intake leak anymore
So since the points gap was off, and the rotor looked to wobble, I tapped it with a hammer and got it near dead center.
It still runs a bit rough, but the wicked misfire is gone! Front and rear have a slightly different rhythm, each smooth in it's own pattern, I believe it is the normal difference between front and rear cylinders.
With the misfire gone, I can now turn my attention to the carb, will go out this week and try to get it tuned up, I'm not convinced the idle circuit is bad, though I can now see if the mix screw will affect change. I'm not sure a #42 is right, since the straight pipes and small foam air cleaner let it breathe like a screen door, but if the screw all the way in barely causes it to die, a 45 might be too much. a few tuner sites suggested a #44 from Drag Spec?
Thanks for all the suggestions, I'll report back later in the week with the next set of results.
The rear plug was sooty and near fouled, the front was clean and new looking, suggesting to me (dual fire) it was firing on the front combustion/rear exhaust, but not the rear combustion. rear cyl exhaust smelled gassy, front maybe just a touch rich.
I swapped the plug wires, front to rear on the plugs but not the coil, and nothing changed = coil good.
Sprayed the hell out of the manifold with cleaner, no RPM change = no intake leak anymore
So since the points gap was off, and the rotor looked to wobble, I tapped it with a hammer and got it near dead center.
It still runs a bit rough, but the wicked misfire is gone! Front and rear have a slightly different rhythm, each smooth in it's own pattern, I believe it is the normal difference between front and rear cylinders.
With the misfire gone, I can now turn my attention to the carb, will go out this week and try to get it tuned up, I'm not convinced the idle circuit is bad, though I can now see if the mix screw will affect change. I'm not sure a #42 is right, since the straight pipes and small foam air cleaner let it breathe like a screen door, but if the screw all the way in barely causes it to die, a 45 might be too much. a few tuner sites suggested a #44 from Drag Spec?
Thanks for all the suggestions, I'll report back later in the week with the next set of results.
Road Warrior
Joined: Dec 2007
Posts: 1,437
Likes: 0
From:
Use a small jet of propane near each intake port: if engine noise changes there's an intake leak.
Stellar HDF Member
Joined: Oct 2010
Posts: 2,594
Likes: 178
From: east texas
dont forget "a new plug may be a bad new plug"
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