Author Topic: Seeking Wisdom From An Odyssey "Guru"  (Read 1650 times)

snow3d

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Seeking Wisdom From An Odyssey "Guru"
« on: June 20, 2016, 06:12:55 AM »
Hello all, I want to state that this is my first post on this forum, but I have been stalking these boards for the last two years during my FL350 rebuild. And I have to give a big thanks to all of you who have helped my project along, even if you didn't know it! Unfortunately the time has come where reading posts will not solve my problem. I need some help from the big guns. I know that a few of you guys are in Michigan, (I'm in Ann Arbor) perhaps one of you can assist. I'm willing to put the machine on a trailer and drive it as far as I have to, and pay whatever it's worth to solve this issue. I have way too much invested in this machine to quit now.

So here goes, I'll try to keep this concise and get to the root. I had the engine rebuilt completely last summer. Every bearing, every seal, every gasket, and had the cylinder bored for an 80mm piston (it was still on it's original). I put it in the machine, set the idle, heat cycled it, then set out for the maiden voyage. Except that the voyage really didn't happen. Under load the engine bogged to literally 1/100th power. It smoked like a chimney, wouldn't rev over 3-3.5K, and couldn't event make it out of my driveway.

I tried running it without the airbox. Grounded the backup switch to defeat the rev limiter. Replaced the entire power side of the ignition circuit. And still no improvement. So I decided to check the compression, it was only at 90psi. (I had the kids at the local college do the rebuild, and apparently the cylinder head was over-torqued and made the cylinder into a hexagon) which wiped out the rings. I assumed that the super low compression was to blame. The engine didn't even have enough vacuum to pull fuel. So I tore it down again to have the cylinder re-bored. Time marches on.

I finally got the re-re-built engine back in the machine. Fired it up, set the idle, blah blah. Hop in for a spin and.... same exact behavior as before. No power, no revs, tons of smoke. Check compression, 125psi, which seems reasonable considering the rings haven't fully seated yet. Should be enough to make more power than it does anyhow. And even though the compression is a bit low, its within about 5% and should have at least made some improvement over the 90psi that the last one had. But alas it did not.

A few things I noticed this time around: Although it idles it doesn't sound quite right and it's not a smooth idle. I checked the spark and it seems a bit weak and erratic even though it has a new coil. Being a mechanic in the automotive field for more than a few years, I know that it's rare that modern ECU's and control modules fail, but this one isn't modern. And I always like to rule out everything else first. However, at this point all signs point to a bad CDI module. It's about the only thing that has not been replaced.

Ideally I would like to find someone with a running machine that I could swap CDI modules with to see if that is the culprit. Other than that, I'm completely at a loss.

Sorry if the post was long winded. Just want to give y'all the most info I can.

Thanks in advance for any help that you folks can offer!

JV


LiveWire

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Re: Seeking Wisdom From An Odyssey "Guru"
« Reply #1 on: June 21, 2016, 04:43:48 AM »
Are you checking spark using the electric starter? When they start to go bad, they suck power from the ignition. Generally the CDI works or doesn't.

I would check if there is anything in the pipe like a mouse nest.

snow3d

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Re: Seeking Wisdom From An Odyssey "Guru"
« Reply #2 on: June 30, 2016, 05:09:40 AM »
Thanks for the reply. I was tied up for a bit and couldn't back to my machine for the last week. I checked spark with and without the starter. Not much difference either way. I did manage to get my hands on a good CDI though hoping it would solve the issue. I installed it, but not much change in performance. Anything over 1/4 throttle and the thing still falls flat on it's face. I double checked the resistance on the pulse generator and alternator, and both are within spec. I grounded the change switch again, and still no dice. The exhaust seems to be free and clear. I just don't know what else to do. By all accounts this thing should run like a champ. I'm stumped.

The only thing I have not addressed are the reeds. But, could bad reeds really cause this problem? My machine came with a vforce3 reed cage and I have no idea of it's age. The reeds look physically ok, but I can see a ton of light around the edges of the petals. Is this normal with the vforce cages?


LiveWire

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Re: Seeking Wisdom From An Odyssey "Guru"
« Reply #3 on: July 01, 2016, 05:21:00 AM »
You should not be able to see light. You can flip the petals over to try, but they will probably break after a while from being flexed the other way. It would at least tell you if that is part of the problem.

125psi is still low. Was all the prep work done on the second rebuild: http://www.aftershockmotorsports.com/technical-articles/FL350-Rebuild-Tips

snow3d

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Re: Seeking Wisdom From An Odyssey "Guru"
« Reply #4 on: July 01, 2016, 06:22:29 AM »
I have some new reed petals on the way...hoping it makes some difference. I will at least be able to cross that off the list anyhow.

As far as the build on the engine is concerned, the second time around I had the work done by an old kart builder. I showed him that very article from your site. He drilled the oil holes, relieved the exhaust bridge, bored the cylinder to .005 tapering to .004 on the bottom. I trust his work. I realize that 125psi is a bit low. But I figured that since the engine has not been fully broken in, and the rings not fully seated, that the number should come up a bit. And if the reeds are not sealing completely would they not also have an effect on compression? Shouldn't the engine still make reasonable power only being down 10% on compression? Or are these engines that finicky?

I'm really starting to grasp at straws here. I'm also wondering if there isn't an electrical issue in the wiring going to the CDI. Any chance that high resistance on one of the wires going to the CDI could cause an issue like I'm having?


hoodlum

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Re: Seeking Wisdom From An Odyssey "Guru"
« Reply #5 on: July 05, 2016, 04:04:10 PM »
Have you checked your needle in the carb? What size jet you running? It really sounds like a jetting issue....

snow3d

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Re: Seeking Wisdom From An Odyssey "Guru"
« Reply #6 on: July 06, 2016, 05:37:53 PM »
I'm running stock jetting per Honda's specs with the clip at the 3rd notch on the needle. I also replaced the float assembly and set the level to 16mm, replaced the choke cable assembly as well as cleaned the bore for the choke to make sure it closes completely. New gasket, cap o-ring, even the rubber boot around the throttle cable where it screws into the cap. The air screw is set to 1 1/2 turns. The carburetor is completely rebuilt and clean as a whistle. Should be good to go.

In talking to a few other people about this, one guy told me he had similar issues on his bike once upon a time. Also thinking it was jetting, he went as far as dropping down 4 or 5 jet sizes and still had a pig rich condition. Turned out that he had bad reeds. Would you also concur with this analysis?

I'll be swapping out out the reed petals this weekend, provided they show in time. The reed valve is the only piece in the air/fuel circuit that I have not addressed. I will keep you posted.