Steve Saunders Goldwing Forums banner
Status
Not open for further replies.
1 - 20 of 25 Posts

·
Premium Member
Joined
·
19 Posts
Discussion Starter · #1 ·
imported post

I just purchased the bike and took it to the Honda dealership to have them look it over. They told me there is definitely a rod knocking in the engine. I'm toying with rebuilding it myself, but not sure if it will be very easy to come by the parts necessary to do this. Anyone have any thoughts on what I should do?
 

·
Premium Member
Joined
·
935 Posts
imported post

Before you try this route check the carb sync. The noise of un sync carbs sounds like a bad con rod fail.
 

·
Premium Member
Joined
·
19 Posts
Discussion Starter · #3 ·
imported post

I asked them about that, as they also said the carbs need to be rebuilt. they assured me it was definately a rod. Is there anyway to tell for sure? (maybe a compression test, or something?) The noise is only audible at idle, but when revved the bike sounds really smooth (i would guess it would get louder under acceleration)..Also would it be possible to just pull the heads, and feel if there is any play in the rods, rather than disassembling the entire engine?
 

·
Registered
Joined
·
10,509 Posts
imported post

Pull the plugs, if you can see the top of the piston at top dead center then you might get away with checking for the bad rod bearings by placing a pencil down the hole and have some one turn the engine over by hand while you pay attention to how the pencil moves on top of the piston. If there's a long lag of the piston moving back down after coming up to top dead center then that will be the one with the bad bearing most likely.

Also after this testing them turn the kill switch on, gas off, then spin the motor with the starter and listen closely to the piston in question, the slapping slap should be louder coming out of the spark plug hole.
 

·
Administrator
Joined
·
27,926 Posts
imported post

If you can only hear the noise at idle it is not a rod knocking. I would go the carb synch route, if it will idle there is not much wrong with them. The idle circuits are the first thing to plug up.
 

·
Premium Member
Joined
·
19 Posts
Discussion Starter · #6 ·
imported post

Dave, could you elaborate on the part about the idle? The bike does hold an idle, it's just loud. The other thing is that when the bike is cold, the noise is much louder than when it is warm. When cold I can hear that the carbs are out of adjustment because 1 side pops from the exhaust. Once everything warms up the sound is less noticeable, and the bike doesn't seem to miss. I will try with the pencil in the morning, but I suppose I will need to try all of them to see if 1 feels different. Would you suggest turning it over the alternator? And how much of a difference on lag should I feel ( very noticeable, or barely)?
Thanks everyone I'm starting to feel like the Honda dealer was wrong, and maybe I didn't buy a money pit!
 

·
Guru
Joined
·
3,074 Posts
imported post

You might have a valve just starting to touch a piston. Check your cam timing. If you get rid of this noise, replace your belts soon because if they fail your engine is destroyed. I think if you check valve clearance, cam position & do a carb sinc, you might have a keeper!!!

If not, look around for a replacement engine. its way cheaper than a re build job!
 

·
Premium Member
Joined
·
19 Posts
Discussion Starter · #8 ·
imported post

Actually I've looked at the engine replacement route, but haven't really found anything yet (there is only 1 on ebay, and it's questionable). Does anyone have some links to share for parts? The dealership told me I would probably need to replace the crankshaft, and the primary chain, both of which are unavailable from them. I have a LOT of VW engine experience, and honda trail experience but for some reason this bike scares me a little to complete disassemble. I'm going to try the pencil (I don't know if these old hands have the sensitive touch this may require to feel), and since the carbs need to be rebuilt will go that route first. Other than Randakk's site, does anyone have a good lead on carb rebuild kits that work?
 

·
Administrator
Joined
·
27,926 Posts
imported post

Paul McNeil wrote:
Dave, could you elaborate on the part about the idle? The bike does hold an idle, it's just loud. The other thing is that when the bike is cold, the noise is much louder than when it is warm. When cold I can hear that the carbs are out of adjustment because 1 side pops from the exhaust. Once everything warms up the sound is less noticeable, and the bike doesn't seem to miss.
What I mean is the first sign of needing a carb rebuild is the idle is real ragged or it won't idle at all. The idle circuits being very small they tend to get plugged up much easier than any of the other circuits. The popping is an indication of a lean mixture, probably is one of the idle circuits is partly clogged but a Seafoam treatment would probably clear it up.
The knocking being louder when cold is another clue that it is not a rod bearing, it would get worse as the oil gets thinner.
 

·
Premium Member
Joined
·
1,075 Posts
imported post

Oil pressure test might indicate a knocking rod or something like that. low oil pressure or a bad oil pump can cause knocking.
 

·
Premium Member
Joined
·
148 Posts
imported post

Bagmaster is right on the top dead center, pull all of the plugs and put one at a time on tdc place a screwdriver or pencil on the top of the piston at this time and brace it so that it does not move. using the gen. bolt rock the motor back and forth, if you can move the bolt what so ever without the piston moving you have a problem. Good luck, as for parts you can only pray and ebay, each of the bearings are set to the crank at the time of manufacture, if the crank is bad you might as well part it out.
 

·
Premium Member
Joined
·
771 Posts
imported post

Take the oil filter off cut it apart, if the bearings are bad there will be little pieces of metal in the filter.
 

·
Premium Member
Joined
·
1,136 Posts
imported post

If it is carb, then the rattling noise will be random. If it is con rod, then the sound will be more rythmic, like once or twice per revolution of the crankshaft.
 

·
Premium Member
Joined
·
148 Posts
imported post

Well I bought a 1977 with 7290 miles on it. Once I opened up the engine it had a spun bearing and the crankshaft was shot at that point. I bought the replacement crankshaft and all pistons and rods for 75 bucks off ebay.
I have experience with rebuilding engine so it was no problem for me.

The carbs just get a rebuild kit and rebuild them and sync them it's no big problem.
I say buy it
 

·
Premium Member
Joined
·
238 Posts
imported post

Paul, don't get too excited about the "at idle" noise, unless it continues to rpms above idle. Run a load of seafoam into the carbs and let it set over night or even for a day or two. After that check the sync on the carbs.

As was already stated, carbs out of sync makes the internal primary chain rattle. Carb sync takes most, but not all, of that rattle (or thrashing) out.

A bit of Seafoam in the crankcase (oil) will also help reduce any deposits in the engine. Even just a few minutes idling, with Seafoam in the oil, before oil change will help loosen engine deposites. Should you decide it necessary to splite the case, this will make the internals easier to deal with.

When you change the oil, check for metal flakes. If a rod is bad you will have lots of metal flakes in the drained oil. There will be lots of metal flakes in the filter, but there will still be some flakes in the oil/oil pan.
 

·
Premium Member
Joined
·
19 Posts
Discussion Starter · #17 ·
imported post

okay, latest update. I dropped the oil and the filter today. I didn't notice any metal flakes, and I went through it with a magnet. The oils was dark as dirt, and about the consistancy of water. It smelled like it was gull of gas, so I'm assuming I must have a stuck float. How much seafoam should I add to the new oil and how much should I add to the gallon on the gas? Also where in walmart would I fond this stuff? I'm thinking to pull the carbs and rebuild next, if I were to cover the intakes and turn it over without the carbs I should still hear the rod bearing.., right?
Sorry I'm on a mobile device...,
Thanks!
 

·
Premium Member
Joined
·
19 Posts
Discussion Starter · #18 ·
imported post

Just ordered the carb rebuild kits, and a new carb sync tool, so I guess I'm in limbo until they arrive. Does anyone have any idea why the oild would be filled with gas other than a bad float?
 

·
Premium Member
Joined
·
238 Posts
imported post

Paul,

Just cranking w/starter won't always cause a bad rod bearing to knock. Could you hear the rod knocking w/carbs in place while cranking?

I suspect once you get good oil (clean w/no gas) into the engine, you may find that the knock is gone. No metal flakes in the mixture from the crankcase is very good. I would not think you need to run Seafoam in the oil. Seafoam is to clean the internals of the engine. The gas thining the oil should have already dissolved the deposits.

As a temp fix some simply turn the petcock to the off position before turning the engine off. This way the leaking needle and seat can not keep allowing fuel to flow into the crankcase.

Were it me, I would run the bike with new oil/filter just to see IF the knock was present. You'll probably find that with clean oil to create the oil cushion, there is no rod knock. Remember to turn the petcock off before shutting down the engine you will have a mix if gas/oil in crankcase again.

To answer your question of where to find Seafoam, I found it at NAPA. I didn't even check Walmart. Simply follow the directions on the can.

There maybe a piece of crud between the needle and seat. Some remove fuel line from petcock and place it into the Seafoam can and fill carbs w/straight seafoam and let set a couple hours or overnight. If it is able to be dissolved Seafoam may do the trick.

Good luck and keep us informed. As you know each finding may change the possibility of what is wrong. I'll bet the PO heard the rod knock and decided to sell the bike rather than fix it. Changing the oil may have already "fixed" the knocking rod. Sorry for the long reply. Terry
 

·
Premium Member
Joined
·
19 Posts
Discussion Starter · #20 ·
imported post

Thanks Terry, I'm hoping this is all that's wrong. I decided I'd pull the air filter, plugs, and do a valve adjustment today. The valves were close and only needed some small adjustments. The plugs however are a different story. the plugs for 2 & 4 were wet, and smelled really strongly of gas (i also noticed that there was some wet gas on the bottom of one of the carb bowls. 1 & 3 were drier, but still had a faint odor. Air filter looked good, but I'll replace it anyways. I figure I'll leave the bike sit without oil in it until the carbs are rebuilt (I've ordered Randackk's kit and DVD). I guess next is to find out how to replace all of the brake fluid, rear shaft fluid, and coolant (i noticed the coolant reservoir was way below min). If all of this fixes the noise I am going to be pissed at the dealership for charging me 90.00 to tell me it had a rod knock, and needed new tires!
 
1 - 20 of 25 Posts
Status
Not open for further replies.
Top