Working on a Friend's Bike - Need Help - Honda Magna 700

[RedRider]

A buddy of mine is out of work and is exchanging some carpentry work for motorcycle repair. I hope he is a better carpenter than I am a mechanic. I am hoping someone knows something about this bike since I cannot seem to find a good forum for these.

 

My friend took his '84 Magna 700 out of storage yesterday and could not get it to run without the choke on. If the choke is released, it just dies. It ran fine when it was put away last fall.

We do not have a repair manual for the Magna.

So far, we changed the plugs, drained the bowls (gas looked good, no gunk), cleaned the air filter, and fixed a few unrelated wiring issues (stator connector was completely cooked).

Of the old plugs that were removed, 3 looked OK, one (front right) was wet.

I was not able to find mixture adjustment screws to see if they were out of whack.

Questions:

1) It appears there are sync adjustments on the linkage between the carbs. 2 between the front 2 carbs, and one between the rears. Is that what these screws are? I assume the rear right carb is the 'master' that the other 3 sync to - is this correct?

2) If these are the sync adjustments, where do I hook up the vacuum gage to measure the relative vacuum? I have a Morgan Carbtune that will read 4 carbs at once.

3) What would cause the bike to run while under choke, and die immediately when choke is removed? We ran it long enough to warm up.

4) How do you adjust the mixture in the carbs?

Thanks for your help. So far, I find the Magna to be an interesting bike with some very nice design features (love the hinged gas tank with the support rod).

 

RR

[Guest tx2sturgis]

Plugged jets, most likely.

[flb_78]

yep, I was going to mention plugged jets. With the choke pulled out, it'll run on the "fuel enrichment circuit". The choke on most motorcycles is not an actual choke.

[gscbertrand]

Try the famous sea foam in the tank make sure you take the beast out for a ride as the gas tank flows into a smaller tank before it gets to the carbs. There are small screws in the intake manifolds that you remove then put addapters in the holes for synching.

[tim44]

I used to have a Magna and a Sabre. The web site Sabmag.org has all kinds of info on these Hondas. The little I remember would only get me in trouble or you in trouble since you are working on it. Those bikes gum up pretty quickly and need carbs cleaned if they sit very long without a fuel additive. There are screws on the carbs you have to remove and screw in an adapter for your hoses for sync.

[juggler]

I have the same year and model Magna that's been in storage for years and does the same thing.

 

Seafoam won't help if it can't get to the problem. My guess is I'll have to remove the cards and clean the crap out of them.

[RedRider]

I have the same year and model Magna that's been in storage for years and does the same thing.

 

Seafoam won't help if it can't get to the problem. My guess is I'll have to remove the cards and clean the crap out of them.

 

Yup, that is what it is looking like now. Was hoping not to have to remove the carbs. However, I have a lot of work on the deck that needs done.

 

RR

[Condor]

Get ahold of Gone14S Kurt probably knows more about Magnas than anyone on here.

[Cerviperus]

My dad's Goldwing did the same thing. His ended up being a faulty petcock assembly. He tried a rebuild kit, but simply ended up removing the thing completely, and hasn't had a problem since.

[RedRider]

Get ahold of Gone14S Kurt probably knows more about Magnas than anyone on here.

 

I shot a PM to Kurt. We will see what he has to say. Thanks for the 'knowledge' lead.

 

RR

[Gone14S]

Hey Jack,

I did get his PM and we had a nice long talk on what to do to get her up and running. I think he will be riding soon.

 

Kurt

[RedRider]

Kurt,

 

Thank you for your time this afternoon going thru the procedure of removing and cleaning the carbs. With instructions like you provided, I have full confidence a shade tree hack mechanic like me can be successful. You were very generous with your time.

 

I will let you all know how it goes this weekend (first time I will have to work on it).

 

RR

[juggler]

Hey Jack,

I did get his PM and we had a nice long talk on what to do to get her up and running. I think he will be riding soon.

 

Kurt

 

Kurt,

 

Thank you for your time this afternoon going thru the procedure of removing and cleaning the carbs. With instructions like you provided, I have full confidence a shade tree hack mechanic like me can be successful. You were very generous with your time.

 

I will let you all know how it goes this weekend (first time I will have to work on it).

 

RR

 

Are those carb removal instructions in writing? I sure could use them as well. I've done a lot of mechanical work. I just hate carbs.

[RedRider]

No, it was all verbal. It seemed pretty straightforward. But then, it always does when an expert is explaining it to you.

 

I will try to take some pics when I take them apart this weekend.

 

RR

[Gone14S]

Are those carb removal instructions in writing? I sure could use them as well. I've done a lot of mechanical work. I just hate carbs.

 

If you want to give me a call I can walk you threw it. Just to much to type.

PM me and I'll give you my phone #

 

Kurt

[Condor]

If you want to give me a call I can walk you threw it. Just to much to type.

PM me and I'll give you my phone #

 

Kurt

 

[chabicheka]

here's a good article on how to do the carbs for the bike u working on. got it from site suggested by tim44.

 

http://users.rcn.com/kochc/moto/carb/carb.html

 

hope it helps. good luck.

[Gone14S]

Very good wright up on how to do the carb's.

There are ways to cut a few corners from this post but if you want to go all the way as this post says you will be fine.

 

Kurt

[GeorgeS]

Be sure to completly drain, the Fuel tank, and start with some fresh fuel.

[RedRider]

Success!!! 2 of the 4 low speed jets were completely clogged with gunk.

 

Started working on the Honda at about 10:30 and by 7:00, I took it for a ride. There were a few items that cost some extra time, I expect to do it again would only take 4 hours.

 

Wil, a couple of items I ran into that caused extra time and/or were not in the instructions.

 

1) There is a shield on the front of the aluminum airbox that holds some hoses. You will need to unmount (but not remove or disconnect any of the main hoses from) the radiator to get to the mounting screws. You don't need to remove the shield, just unscrew it from the airbox. It is helpful to disconnect the overflow tube and move it out of the way.

2) The airbox is the big aluminum box thing - not the plastic box that holds the filter (although you have to remove this too). There are 8 screws in there that will loosen easiest with a #3 phillips. You will need a couple of different screwdrivers to get these all out. A long standard #3 screwdriver is essential. For a couple of the screws I needed to used a 1/4" ratchet with about 2" of extension and a #3 phillips bit. Once you get the aluminum airbox off, the carbs come out easily.

3) There are a couple of small springs in the sync linkage that will likely come out when you remove the carbs. You will need to be patient reinstalling these spring after you reinstall the carbs. You can get to the locations to put them in place, it is just pretty tight. As a hint for the rear linkage spring - put a dab of grease on your right index finger to hold the spring while you lower it into place. You can then manauver the spring into place with your two index fingers and finally get it set in the proper final location with a small flat blad screwdriver.

4) Use a white marker to mark the orientation of the carb boots before you remove them. They are not straight and really only allow the carbs to be properly seated when they are in their proper orientation. (Advice from Kurt)

5) Wear safety glasses when you are shooting the carb cleaner thru the ports on the carbs. It comes out all over the place.

6) The orific in the slow speed jet is really small. To clean it out, I took apart a multistranded 16 gauge wire and used one of the strands. It probably would have better to use a multistranded 22 or 24 gauge wire, but I didn't have any of that handy.

7) Line the inside of the carb boots with a little oil and the carbs slide in much easier (great hint from Kurt)

 

Overall, it was pretty easy to do. It was a great feeling when the bike fired right up once I got it back together.

 

This is a sceaming little bike. When you hit 7000 or 7500 RPM, it hits a power band that really kicks. It is a little small for me, but a fun bike nonetheless.

 

Kurt, thanks again for your help. And you were right, once you see how the things comes off and goes back on, it is pretty easy to do. This bike is a very maintenance friendly machine.

 

Jeff