Can Anyone Help with This???

[tomm]

Continued from Quick Question installing Chuckster's Dual Plate Intake. Figure it's best to start a new thread for the current problem.

2008 Nomad.

Problem started after doing the intake and adding cam chain extenders.

Current problem is a clacking noise as I rev the engine past about 2500 RPM and no power. The noise sounds almost like a continuous stream of high energy sparks in time with the engine speed, very loud and very sharp. Gets louder as RPM's continue to increase. If I back off the throttle, everything goes back to normal.

Bike starts fine, idles fine, and runs fine at low RPM (under 2000). I drove it up and down the driveway a few times with the intake open, and I smell gas when the clacking starts. Pressure at the exhaust pipes seems fine when idling. No smoke or anything else odd.

Thoughts are:
Vacuum leak, but don't think so since it starts and idles fine. But maybe it is a vacuum leak that is tied to higher RPM, whatever that could be. Possible, but doesn't seem to match the symptoms and I don't see how it would account for the noise.
Electrical (maybe a spark is shorting out at higher RPM, but can't figure out what might cause that to happen. What I'm hearing is the spark arching to the frame. Not likely.
Something happened to the ECU that is tied to higher RPM. Would think the FI light would come on though, which it doesn't.
A cam chain slipped a tooth while I was doing the extenders. Only thing I can think of is the front extender had to be pushed in pretty hard to get it to seat, which I understand can be normal if the valves are keeping the slack on the front side of the chain. But as I pushed in the extender, it suddenly released, like the slack moved to the back of the chain. If the chain slipped, then maybe the problem occurs as the advance kicks in on the ignition, and what I'm hearing is ignition through an open valve.

If anyone has any other ideas, please let me know. Although it seems the most improbable, I'm thinking the cam chain slip is the most likely given the symptoms.

My next step is to pull the intake off, look around and put it back together again. Hopefully, I'll find something. If not, I see no other alternative but to pull the engine and take the rocker cases off to check the valve timing, unless there is another way to check the timing. If they're off, then I guess I would have to pull the head as well to check for valve damage. Ugh!!!

Please - someone come up with another explanation.

Thanks,
Tom

[cactusjack]

What did you do with the 4 wires that went to your idle air solenoids? Are those ends properly insulated so they can't short to anything? I seriously doubt you skipped a tooth on the cam chain. The air intake is a pretty simple and straightforward modification, it would be hard to screw something up there.

[tomm]

Originally Posted by cactusjack

What did you do with the 4 wires that went to your idle air solenoids? Are those ends properly insulated so they can't short to anything? I seriously doubt you skipped a tooth on the cam chain. The air intake is a pretty simple and straightforward modification, it would be hard to screw something up there.

Well, if there's a way to screw something up, I can be pretty creative at finding it.

Since I cut out the crossover tube, I taped each wire up individually, then bundled them in a strip of that flexible plastic split tubing, wrapped the whole thing in electrical tape, and then used tie wraps to hold them against the spark plug wire holder that crosses over the top of the intake.

Wonder if I'm getting an arc across the spark plug wire to the ISC wires, since they are running parallel right next to each other for about 6 inches? Seems unlikely, but maybe worthwhile to move them somewhere else.

[ringadingh]

I doubt the cam chain "jumped a tooth" it would be almost impossible to do on a stationary motor. Unless you turned the motor over for some reason while the cam chain tensioner was out.
And you did remove the cold idle solenoids I take it. They make a clacking noise when they are operating.

[tomm]

Originally Posted by ringadingh

I doubt the cam chain "jumped a tooth" it would be almost impossible to do on a stationary motor. Unless you turned the motor over for some reason while the cam chain tensioner was out.
And you did remove the cold idle solenoids I take it. They make a clacking noise when they are operating.

No, I didn't turn over the engine or rotate the crankshaft. The back tensioner went in easily, with the only resistance being the guide having fallen back from gravity. The front tensioner had a lot of resistance, and the guide was very close to the opening for the tensioner. I had to push pretty hard to get the tensioner to seat. While I was pushing, the tension suddenly released. I'm thinking the engine stopped with a valve right at the top of a lobe. When I pushed, the camshaft rotated off the lobe and somehow jumped the chain. Does that even sound possible?

Yes, the ISC's are removed. This sound is much louder than the ISC's. Almost like the sound of straight pipes, but not that loud. I'll see if I can record it. Guess the first step is to get some opinions on exactly what the noise is.

[tomm]

Here is the sound.

Also, when I started it, it was running on only one cylinder, I think the back one, for about 30 seconds. Then the other one kicked in.

[ringadingh]

Its hard to tell from that sound clip, it almost sounds like an exhaust leak to me.
Also you may want to remove the tensioner on the front cylinder and check it carefully to see if you broke the spring when installing it.

[Monkeyman]

Maybe something's plugged up.

[VulcanE]

Originally Posted by ringadingh

Its hard to tell from that sound clip, it almost sounds like an exhaust leak to me.
Also you may want to remove the tensioner on the front cylinder and check it carefully to see if you broke the spring when installing it.

+1 on that, also check and make sure one of the extenders didn't fall off while you were installing them, and also, when you released the sear, did it make a zip sound?

[tomm]

Originally Posted by ringadingh

Its hard to tell from that sound clip, it almost sounds like an exhaust leak to me.
Also you may want to remove the tensioner on the front cylinder and check it carefully to see if you broke the spring when installing it.

Yup, I know, that sound clip really doesn't represent it very well. The quality isn't great, never mind the 97KB limit on the size of the file.

I'll pull that tensioner again though and check it thoroughly. Just in case. Will also pull the new intake off and check around there as well. After that, I am out of ideas on what to even take a look at.

[tomm]

OK. Just noticed something else. When I stick my fingers into the throttle body openings, I get puffs of air that are in sync with the clacking out of the front opening, but nothing out of the back opening. That can't be good.

[ringadingh]

Im not sure what would be causing that to happen, is the backing plate installed properly?

[tomm]

Originally Posted by ringadingh

Im not sure what would be causing that to happen, is the backing plate installed properly?

Pretty sure it is. But this is with the filter off, and sticking my fingers down the throttle bores almost to the butterflies. I didn't touch the throttle body at all doing the intake mod, except to remove that small bracket attached to the bottom of it that held the IACS tubes in place.

BTW - the puffs of air are cool, if that means anything.

[MAS Tequila]

I'll bet there is a vacuum leak. Are you sure you got all of the hoses plugged?

Take another look and see if you don't find a vacuum hose that is open.

Also, what did you do with the crank breather hose?

MT

[tomm]

Originally Posted by MAS Tequila

I'll bet there is a vacuum leak. Are you sure you got all of the hoses plugged?

Take another look and see if you don't find a vacuum hose that is open.

Also, what did you do with the crank breather hose?

MT

The breather hose is connected to the fitting on the new backplate. I did check to make sure that I could feel air pulsing from it. The drain that was on the old backplate is no longer needed. The two ISC tubes are capped and sealed. And the hose for the reed valves is plugged with the new plug that came with the kit. Those were the only hoses that needed to be touched. If I have a vacuum leak, it has to be something I dislodged by accident. I'll keep looking.

Another thought I had is that it is somehow related to the reed valves. Is anyone familiar enough with those to know if that would account for the symptoms I'm seeing?

I just can't come up with a lot of explanations for air puffing back out the intake on the front throttle bore other than something related to an intake valve.