Loss of power.

[ppgflyer]

On a bike ride with my son recently my bike started to give me problems. We were in stop and go traffic at the end of a freeway because the lights had failed. By the time I got through the lights the bike was having trouble idling, it was surging and I had to fully screw in the idle control to keep it happy. On acceleration sounds like it's bogging down and has a slight "leaky exhaust" sound. Top end pick up is poor but the bike will get to 80mph, just takes longer.

Details: 2001 VN1500 FI L2 with 42k. Vance & Hines Touring Duals with extended baffles and 4 x 1/2 tube baffles per extension, Wiseco fuel management system (Dobeck Gen3). Exhaust coasters installed.

Only diagnostics so far is compression test, 90 psi rear, 120 psi front. Didn't check for leak down but both seemed steady. I will do another pressure test with leak down this week. Will also be disconnecting the fuel processor.

Factory service manual states compression should be 50~85 psi @ 300 rpm with electric starter. Diagnosis for higher than usable compression, carbon build-up (unlikely as I recently had the engine apart and all carbon was removed), incorrect CH gasket thickness (new CH gaskets installed), KACR not operating correctly (they haven't disintegrated as far as I can tell).

It seems the front pot compression is high, so if anybody has experienced something similar please let me know what you found. I read a couple of posts from 2013 that had similar symptoms but neither of the OP's finished their thread with what they found was wrong, I assume they are still having problems!!!

[ringadingh]

If the bike is surging and you have to turn up the idle its usually a dirty throttle body, or a vacum leak. If you havn't scrubbed the throttle body with carb cleaner and an old toothbrush lately thats probably the culprit, and what I'd do first. Then if its still surging you can check for a vacum leak.

[cnc]

I don't know about the 1500's but I thought it was hard to do a proper compression test on the 1600 due to the automatic decompression system which holds the exhaust valve slightly open till the engine reaches a rpm faster than the starter can spin it.

[minst7877]

KACR system is also on the 1500's

DC

[ppgflyer]

Throttle body was cleaned during complete tear-down and rebuild.

Forgot to mention, air intake mod, K&N filters both sides.

If anybody else has done a compression test on their 1500 (with two KACR's) I would appreciate knowing what the results were.

I don't think the extra 30 psi on the front pot should be an issue, logically, if the front KACR is not releasing at the same rpm that the rear one is that is why it shows higher compression, the engine sounds like exhaust is leaking which would mean lower compression.

Maybe it is a vacuum leak that I hear, so I will probably pull the gas tank and take a good look.

One other thing, I installed 1/16" aluminum coasters between the exhaust air injection reeds, I'm wondering if it's possible one has a hole in it and some aluminum debris is holding the reed open? Not sure what the ultimate result would be of say a damaged or broken reed, I think it would probably cause excessive popping on deceleration (which I now have), would it cause loss of power or would it affect the vacuum system used to activate the air injection and so affect the running of the bike including loss of power! Has anybody experienced a broken exhaust reed and if so what were the symptoms?

[ppgflyer]

Pulled the air tubes from the exhaust reed valve assembly and detected no suck or blow there so coasters appear to still be in tact.

If one of the cam chains has jumped a tooth what would be the effect? Would the piston collide with the valves? Would it show as low compression in a test? How badly would the engine run?

[MAS Tequila]

Ring is probably right.

Look for a vacuum leak somewhere.

I had a vacuum cap come off one time, and it did similar to your description.

MT

[macmac]

The ft cly is supposed to be high. The rear is supposed to be low since there is a device to hold the exhaust vales open longer to reduce comp. You have a vac leak and i am certain of it.

Look at the tubings and rubber hoses from the ICS or any caps if you took them off first. Next look at the caps and or vac tubing to the pod that runs the reed valves under the tank unless you took that off too, and still check what ever was used to stop a vac leak. IF the engine popped at the light for sure you blew a capped off port off.

next it might be intake manifold O Rings. but I hope not. and or throttle plate shaft seals.

I have never heard of bad shaft seals yet on Nomads, but a few times the O rings had cracked on guys bikes here.

Most of the time a cap has been blown off or was old and cracked and fell off. ALL modded bikes where the ISC 's and the Vac pod to run the reed valves has been removed and capped should be replaced once a year.

[ppgflyer]

ICS valves are still in tact, I have coasters installed on the reed valves but the vac tubes and air valve are still installed, I checked that vac tube and it's still hooked up.

Next plan is to lift the tank and check the vac lines.

[macmac]

Originally Posted by ppgflyer

ICS valves are still in tact, I have coasters installed on the reed valves but the vac tubes and air valve are still installed, I checked that vac tube and it's still hooked up.

Next plan is to lift the tank and check the vac lines.

That's strange. You just allow that racket huh?

[ppgflyer]

Yes, that racket is somewhat annoying, especially as I replaced the closed dog bowl with a large K&N filter that lets even more noise to escape. I tried muffling them but that didn't work so the plan now is to put a switch in the circuit so that after warm up I can "mute" them.

[macmac]

Unplug the ISCs or remove them....... Mine are removed but the wires are taped up to make no possible contact. Just make sure the tubing behind are capped air tight. You can go to the intake manifold and cap them off there at the end of the line.Or you can cap tyhem off in a few other places, but be sure they are capped air tight forever, which means change the caps once a year.

[ppgflyer]

FOUND MY PROBLEM

Well, it seems I'm a victim of my own stupidity.

In an effort to quiet down those noisy ISC valves after I put my K&N filters on I placed a strip of foam inside the top of the filter not giving a second thought as to whether it would stay in place or not

Turns out it got sucked in to the rear venturi and was interfering with the butterfly valve, not to mention the air flow.
It was also partially blocking the front venturi. In hind site I should have placed a strip of perforated aluminum inside as a liner to keep the foam in place.

So out it came and I will be working on fabricating a small bracket with a push-on push-off switch connected to the ISC wires and mounted on the backing plate so that I can mute the ISC's after the bike has warmed up.

[plumber63]

Originally Posted by macmac

Unplug the ISCs or remove them....... Mine are removed but the wires are taped up to make no possible contact. Just make sure the tubing behind are capped air tight. You can go to the intake manifold and cap them off there at the end of the line.Or you can cap tyhem off in a few other places, but be sure they are capped air tight forever, which means change the caps once a year.

If you just unhook the wires but leave the ISCs in place do you need to cap any hoses off?

[macmac]

ISC's don't assist cold start they assist idle at any old time added air is called for. Mine are gone and the wires are just taped so they can never touch.

Good thing that foam didn't get deeper than it did.