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Honda V4 VF700F Interceptor Troubleshooting help needed...


ccriderXX

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Here is a message I posted to the SABMAG email list. I figured I would ask for help here to since several members have V4 histories:

I am desperate and need some help from the collective. Any advice would be greatly appreciated. My brother in law and I tried to get the Interceptor running better today. It still in not right.

The symptoms it has are: It doesn't accelerate like it should, down on power. The engine is not smooth over 3500 rpm, a tingly kind of vibration. Run it in taller gears at 3500 and below and it is smooth. Get back to the driveway after a test spin and a slight amount of dark brown/ black smoke or carbon comes out of the pipes. Eventually this fouls the plugs. We did notice today, that if you put turned the petcock off, as the bike leaned out the smoke would get worse as you rap it out. This makes me think it is a fuel flow issue? One other symptom, the idle isn't consistent. It will idle fine for awhile, then sometimes stay revved up. I used a Harbor Freight temperature tool and found all four cylinders were all around the same temp about 190F. I didn't notice pairs of cylinders stopping. But it does almost feel like at least one cylinder is not firing.

Some history on the bike. My brother in law rode the bike out from Minnesota to Seattle a few years back. It seemed to cruise OK on the Interstate, but would load up and foul plugs going slow in town. He got a little over 30mpg. When I got it I had the valves adjusted, cleaned the carbs a couple times, then later had BillyC really rebuild the carbs. The carbs have stock jetting, are in awesome condition but need to be synced. I also made sure I had a good ground to the coil pack. The bike has a K&N air filter, and Kerker slip ons. I also have the stock pipes.

Today we took a big swing at it to see if we could fix it. I had some coils and spark boxes from Matt Sherrill's known running VF700F. We through those on. One wire to a coil had a poor connection, the wire was just barely attached to the connector, but it was attached. I crimped a new fitting onto the end of the wire. Sprayed Deoxit contact cleaner on all connections. This step seemed to be a slight improvement. But I may go back to the stock parts someday, I don't think ignition is the problem.

After seeing lean smoke type conditions when running out of fuel we started thinking it is a fuel flow issue. We bypassed the fuel pump by running the fuel line directly from tank to the carbs for a gravity system. I wonder why Interceptor has a fuel pump, as the tank is above the carbs. Before connecting the lines I blew on the hose to the carbs. It seemed unrestricted, but not sure. This bypass seemed to make another very slight improvement. We were thinking a poorly performing pump might restrict fuel flow. It did seem to be pumping.

At this point we were thinking we had made some improvements, and the plugs had not fouled as soon as they usually do. But after the last couple test rides it started smoking again, and fouling the plugs.

What do you think it is? I plan to pull the fuel line to the carbs to make sure it is not restricted. I feel the bike is running lean. Maybe due to the slip-ons? I could put the stock pipes back on. Oh, the battery is fine takes and keeps a charge, started the bike fine all day.

I am pretty sure the issue is fuel related. I seems to me if it was too rich, I would notice some fuel smell out of the exhaust. I don't. I don't understand how it can be lean when running the stock jetting. Maybe stock pipes and a stock air filter will help this?

Oh and for some perspective. I remember what a good running V45 Sabre feels like. My Sabre would pull hard from 5K to 11K, I loved it. Also, I understand it is no Blackbird. My bird has more power and is incredibly smooth and fuel injected. My current map allows me to get 48mpg. It does have a lean area in the map that feels similar to how the VF700F is feeling.

At this point I am out of ideas. I hate to give up now and waste some money at a bike shop. Anyone have any suggestions? I would love to get this old gem back out on the road. Could a restricted fuel line cause a bike to lean out?

Thanks in advance,

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We did notice today, that if you put turned the petcock off, as the bike leaned out the smoke would get worse as you rap it out.

For Stan.

It is not the cans. I had slip ons on my VF1000 and it didn't hurt it a bit. After leaving it sit a long time it did gum up the carbs which a good cleaning fixed. Sorry for no help.

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We did notice today, that if you put turned the petcock off, as the bike leaned out the smoke would get worse as you rap it out.

For Stan.

It is not the cans. I had slip ons on my VF1000 and it didn't hurt it a bit. After leaving it sit a long time it did gum up the carbs which a good cleaning fixed. Sorry for no help.

Yes the SABMAG carbs do gum up easily. I have cleaned them a couple times, then had an expert ultrasonically clean them. He put new orings and restored them. I did drain the gas from the carbs and tank before the bike sat this last time.

The original owner had added a Dynojet needle and main jet kit when he put the slip ons on. Those were richer than stock. I may need to go that route. At this point I am just trying to get the bike to how it ran stock.

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Yeah, saw that, but could not figure out why it would do that. Unless the needles had hung open and dumped gas in the pan. You would have more oil and thin too.

Leaning will raise the exhaust temp and cook off the fuel in the pipes too. Fuel can get in the pipes at overlap when the motor is off and the petcock open and the needles are leaking.

Exhaust temps should be higher ,,,a lot , by the engine. 1000 deg. Unless wet.

still thinking. not getting much else.

If you wanta call and talk,,pm me.

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Yeah, saw that, but could not figure out why it would do that. Unless the needles had hung open and dumped gas in the pan. You would have more oil and thin too.

Leaning will raise the exhaust temp and cook off the fuel in the pipes too. Fuel can get in the pipes at overlap when the motor is off and the petcock open and the needles are leaking.

Exhaust temps should be higher ,,,a lot , by the engine. 1000 deg. Unless wet.

still thinking. not getting much else.

If you wanta call and talk,,pm me.

Thanks Stan.

I agree it sounds like a rich problem. The needles should be fine. The carbs were rebuilt well, I think. I did use a infrared temp tester and saw up to about 212 at the header pipes. The cylinders were more like 196 F.

I am going to tear into it again tomorrow. It is sounding more like a stuck choke. It runs OK, not good when cold, but when it is warmed up it is way too rich. I'll let you know what I find out.

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Yeah, saw that, but could not figure out why it would do that. Unless the needles had hung open and dumped gas in the pan. You would have more oil and thin too.

Leaning will raise the exhaust temp and cook off the fuel in the pipes too. Fuel can get in the pipes at overlap when the motor is off and the petcock open and the needles are leaking.

Exhaust temps should be higher ,,,a lot , by the engine. 1000 deg. Unless wet.

still thinking. not getting much else.

If you wanta call and talk,,pm me.

Thanks Stan.

I agree it sounds like a rich problem. The needles should be fine. The carbs were rebuilt well, I think. I did use a infrared temp tester and saw up to about 212 at the header pipes. The cylinders were more like 196 F.

I am going to tear into it again tomorrow. It is sounding more like a stuck choke. It runs OK, not good when cold, but when it is warmed up it is way too rich. I'll let you know what I find out.

Stuck choke/something not right is a good suspect... it's running rich.

And if you haven't... synch the carbs.

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Stuck choke/something not right is a good suspect... it's running rich.

And if you haven't... synch the carbs.

I agree Hobi. I will sync the carbs next, that should smooth it a bit more. I did inspect the choke system. The cable actuates the linkage fine and all the plungers on each carb operate as they should. Possibly internally at least one choke is causing some richness? But all plugs look rich. Here is what I said on the email list:

Well I think I made progress today. First I connected the fuel pump back up. In working with it I noticed I still had the original fuel filter inline below the fuel pump. I had another one up by the tank. So I replaced the stock one with a larger auto gas filter, and took out the second filter. With the pretty fouled plugs I tested the bike without the airbox on. It didn't seem to be much improved. I was able to watch to make sure the slides were moving up like they are supposed to with vacuum. I made sure all fuel lines and breather hoses were clear. I didn't ride it in this config as I had the gas tank setting backwards where the seat goes.

I picked up a couple sets of new plugs. I decided to try some hotter plugs to see if that would help at all. I put the stock paper air filter in and re-installed the stock exhaust pipes. I put the tank and seat back on and fired it up. It did rev up as if on choke, even though the choke was off. Well I still see a bit of lighter black (dark grey) smoke while idling and revving up. Still seems a bit rich. I jumped on to take a spin. Wow, the idle and over all running of the bike feels better. Then on my first run up the street before the bike warmed up it felt much smoother in mid range. Much better. But as I rode it I could feel become not quite as smooth. But it was an improvement! The bike didn't feel like it would foul out. I decided to play with the pilot air screws. They were at 3 turns out, and I moved them to 3.5 turns out. This seemed to improve the low speed running of the bike. It never felt like it would die, held idle well.

I rode the bike for about 15 minutes and it the performance didn't deteriorate. The plugs would have fouled out by this point previously. I took the bike up a big hill near me and it pulled up the hill well under load. When I got home I pulled a plug to see if it was any better. Shoot it looked the same as before. Maybe slightly less sooty, but still black like before. I have included a link to a very poor picture of the hotter DPR7EA-9 on the left (the last set of plugs) and on the right the way all plugs have looked in the past. They look the same in the picture but are slightly different. Very slightly.

http://picasaweb.google.com/VF700F/Interce...052327925720082

So what I don't understand is: With the stock air filter and exhaust pipes and stock needles and main jet the bike still runs rich. How would I make it leaner? Go with leaner than stock needles? Possibly the choke circuit is causing the richness, but externally all the linkages and plungers are operating correctly. Would the slightly larger holes in drilled in the slides for the Dynojet kit cause richness?

At least I know it is rich and not lean. Also I have eliminated other possibilities, the ignition coils and spark boxes work fine, and fuel flow seams fine. I will take it for a ride and see how long it runs before fouling plugs. Hopefully it won't.

Thanks for all the ideas thrown out there guys. I appreciate the help. If the bike doesn't foul the plugs, I feel the bike runs good enough to enjoy it. Probably not the fastest Interceptor, but pretty good. It does feel like a V4 should.

Here is a snapshot of the VF700F:

84VF700F_Interceptor.jpg

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Stuck choke/something not right is a good suspect... it's running rich.

And if you haven't... synch the carbs.

http://picasaweb.google.com/VF700F/Interce...052327925720082

OMG,those plugs indicate insanely rich conditions.Lower those Dynojet needles two notches.I`m wonder about pilot and main jets.Do you still have OEM jets and neddles,or do you know what were the factory setting vs.what is in the carbs now ?.

It seems you have to tune the carbs again here is excellent guide http://www.factorypro.com/ ----> Product Support---->Motocycle Tunning -----> CV carb tunning.

BTW,that model is known for whipping out camshafts,I would start with valve clearance and inspection of the cams.

EDIT.You do have stock hardware in the carbs now.Cruising conditions are mainly effected by pilot or idle circuit,mains and needles don`t matter much here.

You need to lean it by adjusting pilot screw.I don`t know specifics of your bike,it depends,usually turning out the screw richens the mixture but sometimes it is the opposite.

Anyway,this is the area you should concentrate.

One more thing,on worn out carbs needle seats might be oval instead of round,it can cause rich conditions under certain loads.

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One more thing,on worn out carbs needle seats might be oval instead of round,it can cause rich conditions under certain loads.

+1 all good information, and I agree. I just got this same info today from a mechanic at a local shop, and on the SABMAG email list. I have all stock stuff installed now. But my theory is that the emulsion tubes are ovaled. I do have good condition newer slide needles installed. But for years it had been running the Dynojet needles. They do looked kind of warn. Oh and to confirm that the emulsion tubes may be worn is: while revving the bike and looking down at the slides, I saw one spit a little bit of fuel around the slide needle as it was opening. I think this raw fuel is what is contributing to the rich condition.

Thanks for your comments, it really helps!

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I should have picked up on a couple of things said. When you mentioned the drilling of the slides I thought that could be a major contributor. With the larger holes the slides rise too fast and give a richer mixture than what`s required. I know it`s not the same bike but a friend of mine is the Eastern Canadian director for the V-Max owners. Whenever someone puts in a Dynojet kit in one of those bikes everyone says the same thing. "Don`t drill the slides!"

Also, on my FJ1200 I replaced the emulsion tubes with ones from FactoryPro. What a difference! I got back all my missing midrange and picked up 30-50 km range per tankful.

Another thing, I can`t remember if the float seats are screwed in or are held in with an o-ring and retainer. If it has an o-ring I`d check those rings to see if fuel is getting by. (Although that would have a greater effect at low speed as you`re not using as much fuel. Never mind, online mental ramblings)

Were the needle and seats ever chacked for sealing? How about the float height/fuel level?

Ray

My `84 V65 Sabre has over 100k km on the original needles and still gives reasonable economy. But I`m going to be looking for replacements.

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