a few questions about my bike

I have a 1986 honda magna vf700c. It has about 38,000 miles on it. Im pretty sure it's time for a carb clean on it because once it starts up, i have to play with the throttle to get it to open up. if i just give it gas, it dies on me, but if i slowly give it gas, it'll cut out some then start to open up. My thiung is it has 4 carbs on it, and i'm afraid to mess it up. I have taken apart carbs on a 4 wheeler and dirt bike before, but they only had one carb. I just plan on taking them apart and cleaning them out, not putting in rebuild kits. Could this solve my problem? Also, as with its age, it has some pitting on the chrome. A friend suggested to me that i use 800 or higher sand paper and wet sand the chrome then finish it off with some mothers polish or something. Whats the best way to get a chrome finish on it?

I had an 85 Magna, and being a V-4 with the carbs in the center of the V, they are tough to get out of there. It's not impossible, and it can be done with the engine in the bike, but the utmost patience will be necessary. After cleaning them out, as with any multicarb engine, I would strongly suggest having them re-syncronized. While cleaning them, you will most likely mess their adjustment up. This can cause one or more cylinders to run too lean damaging your engine.

How do i re-syncronize them? Also, is replacing the fork seals hard to do at home, or should a mechanic do that?

The fork seals are easy if you have a factory or Clymer repair manual for your bike, the hardest part is measuring the proper amount of fork oil to put back in. I used a mechanics syringe marked in cc's. Also, are your forks air adjustable like my 85 was? It will have schrader valves under the caps at the tops of the forks if it does. If it does, make sure you put the proper air pressure back in so they don't dive too much.

um, i dont think it is air adjustable. I dont see anywhere on the bike where i can hook up an air hose. Where can i get one of those manuals at? The local honda shop wants like $50 for them. Thats too high.

I forgot to answer your carb question. You can buy a carburetor sync tool if you want to do it yourself, but a decent one is pretty pricey. It's basically 4 vacuum guages hooked together that you use to set the carbs so they are all pulling the same vacuum readings at a given RPM.

On the manual, here's one I found on e-bay, no bids $19.95 starting bid $3 s/h:

http://cgi.ebay.com/ebaymotors/Clymer-Honda-V-Four-Service-Manual-Magna-Sabre-700-1100_W0QQcmdZViewItemQQ_trkparmsZ66Q3a2Q7c65Q3a1Q7 c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a5 0QQ_trksidZp3286Q2ec0Q2em14QQhashZitem380119301891 QQitemZ380119301891QQptZMotorsQ5fManualsQ5fLiterat ure

ok, so now im stuck on what to do as far as cleaning the carbs. If i could find a way to re-sync them at home by myself, i would take them completly apart as the honda shop wants $500 to do the job. Thats rediculus and im not paying it. My thing is, the bike will start and run, i just cant jump on it and take off so i dont think they are that bad. I just have to open the throttle a little until it stops sputtering little by little until i open it almost all the way. Are my carbs really that bad then? If not, i saw a method on here where you could just get carb cleaner and disconect the tank from the fuel line then pour carb cleaner into the line itself and run it like that and they said it should clean it out. opinions please?

you could try running some good carb/fuel injection cleaner ( like Lucas or Chevron)through the tank and see if that cures your stumble. By your description, it sounds as if your carbs are just dirty and/or sticky due to lacquer deposits as my bike did the exact same thing. If it's lacquer deposits, you might even try putting some gas stabilizer (like you put in before storing a bike) and running that through. For a couple of bucks, it's worth a try before puling the carbs out.

Rich, are those vacuum slide type carbs on the Magna?

It sounds like how slide carbs act when the diaphragms are blown...

if something was blown, wouldnt it run rough all the time? I can kill it then start it back up 10 mins later and it'll run fine. It just is harder to crank once sitting overnight.

On vacuum slides when you open the throttle, pressure drops in the chamber above the slide, that vacuum lifts the slide and needle, metering more fuel and air.

When the slide diaphragms get holed, they are slow to react as vacuum is bleeding away and they don't wanna lift. The bike just blubbers and stumbles and falls on it's face the faster you try to open throttle. But they will idle fine, and run at speed once coaxed into the higher revs, but sometimes if leaking too much, they can't fully lift and won't give you all on top...

I was thinking the good news if that's the case is the the slides and diaphragms can be removed without removing the carbs...you simply take the top cover off, and pull the slide/diapragm/needle out, paying attention to compensating springs and how they go together, then replace if they are shot....

The bad news would be that they are pretty expensive usually....

if something was blown, wouldnt it run rough all the time? I can kill it then start it back up 10 mins later and it'll run fine. It just is harder to crank once sitting overnight.

Now you seem to be talking about a completely different problem.

If I were you I'd start by taking the tank off and making sure you don't just have an old fuel line gone soft and folding over and cutting flow on demand or something.

Had it happen on a couple of older bikes...

When the carbs on my 85 were mucked up, it would start hard as if the enrichener was messed up. Then it would idle fine, and cough/sputter on any throttle input. As the engine slowly built revs it would catch up, but it didn't like any abrupt throttle inputs whether under load or not. I took them out, cleaned them up, and a buddy of mine helped me resync them (he had a sync guage set). Bike ran like new after that.

Another suggestion would be to look at the condition of the plugs to see if they are wet/sooty like it's running rich, or white as if running lean.

Now you seem to be talking about a completely different problem.

If I were you I'd start by taking the tank off and making sure you don't just have an old fuel line gone soft and folding over and cutting flow on demand or something.

Had it happen on a couple of older bikes...


This is why i think it is a dirty carb problem, because when the other guy had it, i know it sat up some time without being started, and this past winter it sat up on me without being started. If i do take the diphram out, what do i need to look for? I mean, what does the dipharm look like? I'm not good with names. I just know how to take things apart and how to put them back together. And if i was to take all the carbs off, but were to leave them all connected and just took the float bowl off then cleaned everything inside, would if effect the sync of the carbs then?

When I did mine, I took the float bowls off, cleaned the insides of the bowls, the needle and seat, and sprayed the hell out of the throats and slides with carb cleaner. I reset all the idle mixture screws to factory baseline settings (which I don't remember what they were, sorry...) and then my buddy and I fine tuned them with the sync tool after they were re-installed. The bike ran like new when we were done, and I didn't have to rebuild any of them.

Did you check the air pressure in the tires??

well, im seeing all kinds of homemade re-sync tools and i think im going to try that out. http://faq.ninja250.org/wiki/How_do_I_synchronize_the_carburetors%3F there is the link to what i'm going to make, but i would need 2 sets since i have 4 carbs, right? Or could i hook it up to 2 of them, set them, then hook up the other 2 and set them?

Did you check the air pressure in the tires??


what does the air pressure have anything to do with my carbs?

what does the air pressure have anything to do with my carbs?

Nothing, taken care of.

This is why i think it is a dirty carb problem, because when the other guy had it, i know it sat up some time without being started, and this past winter it sat up on me without being started. If i do take the diphram out, what do i need to look for? I mean, what does the dipharm look like? I'm not good with names. I just know how to take things apart and how to put them back together. And if i was to take all the carbs off, but were to leave them all connected and just took the float bowl off then cleaned everything inside, would if effect the sync of the carbs then?

Wouldn't affect sync as long as the float drop wasn't changed. Assuming one or more carbs were not working right, it would improve sync, assuming they were properly synched before they degraded.

Here's a good overview of how MC carbs work...

http://www.bikerenews.com/Stories_Archives/Carburetors.html

Coupla things:

Go to another shop $500 is an outrage to synch carbs - even R & R & synch.

You need not only some type of synch gauge but there is a special screw driver (90 degree tip with locator) for adjusting V-4 carbs.

$50 is not too much for a service manual - see the price of carb synch you quoted.

As to "The fork seals are easy if you have a factory or Clymer repair manual for your bike" - I disagree. Reading the instructions is easy; actually doing the job, if everything goes easily can be easy enough - but how about if you can't get the bottom bolt to break from the piston by hand? How about if something is broken inside these 20 year old forks?

Based on your concerns and questions about your carbs, I do not think r&r fork seals is the job for you