engine vibrations

[54chevybelair]

Last fall I had joined this site to get help with a problem and learn more about my new to me 2004 RSV. I had a problem with my RSV stumbling under a load and V7Goose gave me great advice on cleaning the carburetors and synchronizing the carburetors. I thought I had things working well, so I set out on a 3700 mile trip. On my way out things seemed good but after a couple days the problem returned. The engine vibrates badly under a load. This problem comes and goes; sometimes it would run ok and then others very bad. Most of my trip was at higher altitude and I thought maybe my problem was associated with that but it still did it on the way home. It acted worse in the heat but sometimes it would run ok in the heat. I ran in some rain and hail but most of the trip was dry.

In 4th gear at 60mph it will still vibrate and in 5th gear at 70mph it vibrates if I ask for power. At 75mph trying to climb a slight grade on the expressway it struggles to maintain speed.

This is a list of what I have done before the trip.

1) Removed carbs and cleaned

2) New spark plugs – twice

3) New spark plug caps – NGK only 5K ohms

4) Carb sync

5) Sea foam through tank.

6) New K&N air filters

7) New fuel filter

 

If someone has any suggestions I would greatly appreciate it. I really do like this bike, but this power plant I am unsure about. I may have never had it running good as I have never been impressed with the power, but my last bike was a GL1500 and that is what I am comparing it to. If I could just get this thing to run smooth I could deal with the fact it is less powerful than my old GL.

Thanks in advance

[V7Goose]

You still sound like you are only running on thee cylinders, at least at times. What have you done to verify they are all pulling hard?

 

Have you inspected the diaphragms? When you changed the plugs, did they all look identical? Have you done anything with you pilot mixture screws? Have you checked compression and done a leak down test?

 

Here is a relatively simple test that could help you pinpoint a problem cylinder, no matter what is causing it. Find a stretch of road about 5 miles long that is relatively straight and level so you can get similar results running both ways. Choose a specific gear and speed/throttle combination where you seem to find the worst problem, such as 4th/60/hard roll-on.

 

Now make a couple of runs to concentrate on exactly how it feels and just exactly how you will conduct the test, such as exactly where and what speed you will start it, how long you will hold the throttle open, how many times you will repeat it in one run, etc.

 

Once you are confident you can repeat the test and know what exactly to expect, stop at one end of your test track and pull one plug wire, then immediately repeat the test and concentrate on how it compares with the original runs on all four. Repeat this with each cylinder, looking for one that doesn't seem to hurt the test results quite as bad as the other three did. If you do find a particular jug that isn't pulling as strong as the others, we can start talking about what can cause it.

Goose

[54chevybelair]

Thanks V7Goose. The diaphragms all looked good. I held them up to a light and slightly stretched them and found no holes. It did run better after cleaning the carbs. All the plugs did look identical, I didn’t notice anything unusual, but both sets I replaced were relatively new. I have not done anything with the mixture screws but would be interested in trying to adjust them. The plugs in it now have 4000 miles on them so I should check them to see if I see a difference. I did check the resistance of the coils per the manual and all 4 were within spec. I was thinking maybe one of the plug wires could be broken and making contact some of the time.

I forgot to mention during the trip I plugged the AIS and capped the vacuum ports. I also tried running 91 octane but neither did anything so I went back to 87. The AIS is still disconnected.

 

Edited July 31, 2011 by 54chevybelair

[V7Goose]

I wouldn't bother to pull the plugs again unless you are going to do a hot-read by killing the engine during the problem and pulling the plugs right there on the side of the road. If your problem is intermittent, the plugs will almost never show it unless it was happening exactly when the engine was shut off.

 

I'm assuming you did a fingertip test on cold start long ago to verify that all jugs are hitting at idle, but that doesn't tell you anything about how well the spark is working under load and when hot - that is why I suggested the 3-cylinder runs to see if killing each cylinder in turn has the identical impact on the bike's performance. And you could still have a blocked passage in one of the carbs that is affecting how well it works - this is ESPECIALLY true with CV carbs which rely on differential air pressure on each side of the diaphragm to function. You did make sure the little o-ring is in place under the diaphragm cap on each carb, right? You can also get some idea if the diaphragms are workging properly by pulling off the air plenums on top of the carbs and reving the engine while watching the slides - not an exact test, of course, but if one slide is dogging it bad, it should be real obvious.

 

It will be a lot easier to find the real problem if you can determine it is only affecting one cylinder than just the engine in general.

 

How about your carb vent hoses - are they routed properly and not kinked or blocked? A CV carb cannot raise the slides if the vent is blocked. I have seen an occasional suggestion to rout the vent/overflow hoses down under the engine, and that is a very BAD idea - any change in air pressure or wind around the vent hoses will have dramatic effects on how a CV carb works.

 

Do you have any problem exceeding 85 MPH? These bikes tend to run amazingly well on just three cylinders, and often a rider can't even tell, but they usually won't go much over 85 unless you have all four.

 

The last thing I'll suggest is that you find a different Venture to test as a comparison. If you don't have any other members close enough to you that will help out, look for one on sale or find one at a dealer that you can test ride. This will give you a way to determine if your bike is really the dog you think it is.

Goose

[Rick Haywood]

Last fall I had joined this site to get help with a problem and learn more about my new to me 2004 RSV. I had a problem with my RSV stumbling under a load and V7Goose gave me great advice on cleaning the carburetors and synchronizing the carburetors. I thought I had things working well, so I set out on a 3700 mile trip. On my way out things seemed good but after a couple days the problem returned. The engine vibrates badly under a load. This problem comes and goes; sometimes it would run ok and then others very bad. Most of my trip was at higher altitude and I thought maybe my problem was associated with that but it still did it on the way home. It acted worse in the heat but sometimes it would run ok in the heat. I ran in some rain and hail but most of the trip was dry.

In 4th gear at 60mph it will still vibrate and in 5th gear at 70mph it vibrates if I ask for power. At 75mph trying to climb a slight grade on the expressway it struggles to maintain speed.

This is a list of what I have done before the trip.

1) Removed carbs and cleaned

2) New spark plugs – twice

3) New spark plug caps – NGK only 5K ohms

4) Carb sync

5) Sea foam through tank.

6) New K&N air filters

7) New fuel filter

 

If someone has any suggestions I would greatly appreciate it. I really do like this bike, but this power plant I am unsure about. I may have never had it running good as I have never been impressed with the power, but my last bike was a GL1500 and that is what I am comparing it to. If I could just get this thing to run smooth I could deal with the fact it is less powerful than my old GL.

Thanks in advance

 

OK My friend you sound like you copied a post I made a few moths ago. My bike did the exact same thing. Here is what fixed it to a certian point.

 

New diaphrams in carbs easiest thing in the world to change. Also found that the air box under the fuel tank has like 4 tubes that attach to the top carbs and one of them had worked off the back left carb. I cleaned up the area and put a new clamp on it and then resynced the carbs and it made a world of difference. Warning do not tighten the clamp to tight just snugg. If you tighten it to tight it will slide up and come off again. Now as for the thumping/vibration you are feeling. First what did you ride before? if it was a inline 4 or six they are so much smoother. Second: these bikes have that v-twin thump at lower rpms when you role back on ther throttle. My bike is running better than it ever has and gets about 41 mpg but it still has that little thump/vibration in 4th and 5th when I rollo back on the throttle. Now it goes away in 4th at about 63 mph and in 5th at about 75. If I am not under throttle just cruising it is not there. Again these bikes have some of that. If it get 40 mpg or better and starts easy and runs smooth in lower gears then this is probably the way it runs. As for 5th under throttle going up a hill, remember 5th is an overdrive so it will act like it is being lugged a little. Just drop to 4th and it will haul ass. Hope this helps.

[darthandy]

Rick is dead on with this. These bikes, as I have discovered, really do not like to lug. Even at 60 mph in fourth, rolling on the throttle will set off some vibration, particularly on a slight upgrade or into a strong wind. 75 mph uphill in 5th? You will definitely get some vibration, especially if you give it a lot of throttle. Don't be afraid to rev it...it won't bother the bike and you'll even (surprisingly!) get better gas mileage. If the vibration worsens as revs go up or you get strong vibrations in lower gears at more elevated revs, then you may have a problem. As Goose suggested, see if you can find another venture, or better yet, an experienced Venture rider with a Venture and see if he'll trade for a short ride. Then you'll have a much better idea of how things should feel and what an experienced rider thinks.

 

By the way...I had a '54 Chevy Belair in high school...a two door hardtop, in fact. Sure wish I had it now..they're actually worth something!

 

Andy

[54chevybelair]

Darthandy, I have come across a few people that used to have a old Belair. Every time I have it outside a lady down the street comes down to talk with me about the good times she had. This car is very special to me as it belonged to my brother that was killed in a motorcycle accident. In his honor, I finished what he had started on the car and I have brought it to a few car shows. It is something I will always have and hopefully my son takes an interest in it.

 

As far as my bike, maybe I am expecting too much from this engine. My last V4 was very smooth and powerful, I assumed this engine would be the same. I would think it should be able to hold its own speed at 75mph on a slight incline. The vibration is so bad I had to replace missing screws on my vacation. My HD buddies are going to have fun with that.

 

Anyhow, V7Goose and Rick Haywood gave me some things to try. I hate to admit it but I like riding motorcycles more than working on them. I am a full time worker and college student, my semester starts in less than a month and I have other things I want to get done, so I may be putting this thing away for the winter. Or I may hire a mechanic, but I have never had good luck with mechanics.

 

Thanks to all for all the suggestions and I will post whenever I find the results.

[darthandy]

Thanks for the pic. Sure does bring back some memories. It looks quite nice. Very sorry to hear about your brother. As for getting your son interested, see if you can dig up some old HOT ROD magazines from the late 50's or early 60's ... that's what got me going on the older cars and hot rods. Back then, it wasn't just to make them nice...it was also about having inexpensive transportation.

 

As for the bike, if it shook screws loose then it may be something a bit more serious. One thing I didn't notice in the list of things you have tried was a carb synch. You mentioned getting advice but not if it had actually been done. Out of synch carbs can definitely cause a vibration at the best of times and even more when you are lugging the motor. I know what you mean about smooth fours, but normally these engines are quite smooth, other than when being lugged. Try the other suggestions and synching the carbs, if it hasn't already been done. Also, just in case you didn't know, it is possible for the coils to spec out OK when checked cold, but one may be failing once heated up. On my Triumph, a quick and dirty check is to spray some water on the exhaust pipes when the problem occurs and see if one of them doesn't "sizzle". Not too sure how to check that on these engines but it may be something worth looking at. Triumph had a lot of coil problems in the early years due to one of their suppliers. They would run fine cold and start breaking down when heated up.

 

Good luck!!

 

Andy

[54chevybelair]

I just wanted to give everyone an update. I did park the bike for awhile, but I couldn't stand looking at it sitting anymore. I like the ergonomics and the appearance of this bike, I just needed to get it running better.

A FJR friend told me on his forum they recommend syncing the carbs at cruising RPM’s. I don’t have a tachometer (need one) so I’m only guessing I set the carbs about 2500 RPM’s. This helped tremendously. The engine vibration was almost completely gone and it would run 75 mph on the x-way even on a steep incline. The inconsistent running was also gone, doesn’t make any sense but it hasn’t returned.

Next a coworker had a used set of Vance & Hines pipes he let me have at a deal I couldn’t pass, so I put them on. This gave me much more power and sounds great. I was getting real bad popping on deceleration so I turned the pilot screws out ¼ turn. The popping is still there some, but not bad at all.

Now the bike runs great, I had it out for a couple hours today and it was flawless. I can even be in 5th gear at 60 mph and when I accelerate it just goes. Before it would shake and hammer very bad. I am now very happy with this machine and look forward to the next time I get to ride it.

I’m don’t know if something else is wrong because the high RPM carb sync is what fixed most of the problem. I have purchased a colortune kit and will learn how to use it and maybe next spring I will try it on my bike. For now I’m just going to enjoy the rest of the riding season.

I want to thank everyone for your suggestions and the time you spent to help me. V7Goose has been great both on this posting and the last one I had with the same problem, thanks V7Goose.