Bike running Different

[Rick Haywood]

OK Got another question, My bike seems to have a viberation of sort under throttle. When just cruising it is smooth but when you accelerate it has that old Harley feel. I don't know how else to explain it other than it isn't smooth. I changed the plugs and put in new air filter over the winter and other than that nothing has been done. It runs smooth when it idles and if you rev it up in nuetral it doesn't miss. I was wondering if maybe you guys think it could be one of the diaphrams or maybe something else. Also mileage has dropped from 41 to about 35 mpg but also remember I more than likely ran it harder trying to figure out what the heck is wrong. Open for suggestionsps, I have never changed the fuel filter. What does one run like when it needs carbs synced?

 

2000 RSV MM Edition, I bought it in july of 2010 with 18,000 miles on it and I now have 39,000 so I assume it must have set a bunch

[Freebird]

Rick,

It could very well need the carbs synched. That is exactly how it will feel if they need it.

 

There are a number of other possibilities.

 

A bad coil causing it to run on only 3 cylinders. It will run amazingly smooth on three cylinders but you could get that vibration and poor gas mileage.

 

Also...I'm sure this is probably not the case but are you SURE you aren't shifting too soon? These bikes to like to run at higher RPMS than a twin and if you shift too soon and run at too low RPM they can vibrate like that and since you are essentially lugging the engines, it can hurt your gas mileage too. Like I said, I doubt this is the case for you because you have owned it a while and your mileage WAS better until recently. So unless you've changed the way you ride it, this should not be the problem.

[Yammer Dan]

What Freedird said!!! Most likely the sync.

[Rick Haywood]

So you gius think I should sync the carbs before I replace the diaphrams? I guess the sync is cheaper than replaceing and then finding out they weren't bad.

[Rick Haywood]

Rick,

It could very well need the carbs synched. That is exactly how it will feel if they need it.

 

There are a number of other possibilities.

 

A bad coil causing it to run on only 3 cylinders. It will run amazingly smooth on three cylinders but you could get that vibration and poor gas mileage.

 

Also...I'm sure this is probably not the case but are you SURE you aren't shifting too soon? These bikes to like to run at higher RPMS than a twin and if you shift too soon and run at too low RPM they can vibrate like that and since you are essentially lugging the engines, it can hurt your gas mileage too. Like I said, I doubt this is the case for you because you have owned it a while and your mileage WAS better until recently. So unless you've changed the way you ride it, this should not be the problem.

 

Well I don't lug it but that is what it feels like when I am under power

It doest smooths out at really high rpms.

[Freebird]

Yes, I would be VERY surprised if the diaphragms are bad. They typically last for many years. We have folks here riding Ventures from the 80's who are just now changing them for the first time. If you truly suspect that you have a bad one, it is very simple to pull them out and check them. You don't even have to remove the carbs from the bike.

[Freebird]

Oh...and syncing the carbs is very simple. If I were closer, I would offer to do it for you. It only takes about 10 minutes.

[Rick Haywood]

Oh...and syncing the carbs is very simple. If I were closer, I would offer to do it for you. It only takes about 10 minutes.

 

 

 

I have never done that but EUSA1 I believe has the tools and knowledge on how to do it and he live about 90 miles from me and can be bribed with a couple of root beers at his favorite place in Oglesby, Illinois.

[V7Goose]

Don pretty much hit it all. Sync is the prime suspect to cause this, and something affecting the combustion on one cylinder (such as coil, plug, plug cap, carb jet, etc.) is next in line.

 

You didn't tell us what speeds/gears you were getting the problem when you rolled on the throttle, so no way for us to comment effectively on that. But for the sake of other potentially new members I'll just explain that a little - we assume you know that trying to roll on the throttle at too low an RPM will produce the EXACT symptoms that you describe.

 

Just to sum up - vibration in this engine under acceleration is cause by one of two things - either the RPMs are too low, in which case the engine will shudder and vibrate even if all is set up perfectly, or at lest one cylinder is not pulling an equal load. The solution is to sync the carbs, make sure the RPMs are above 2,500 (minimum of 65 MPH in 5th), and do a hot reading of the plugs to evaluate how the combustion is working to spot a possible problem. But do not forget to do the cold start finger tip header test - that is the best way to find a dead cylinder without a bunch of other tests!

Goose

[Rick Haywood]

Don pretty much hit it all. Sync is the prime suspect to cause this, and something affecting the combustion on one cylinder (such as coil, plug, plug cap, carb jet, etc.) is next in line.

 

You didn't tell us what speeds/gears you were getting the problem when you rolled on the throttle, so no way for us to comment effectively on that. But for the sake of other potentially new members I'll just explain that a little - we assume you know that trying to roll on the throttle at too low an RPM will produce the EXACT symptoms that you describe.

 

Just to sum up - vibration in this engine under acceleration is cause by one of two things - either the RPMs are too low, in which case the engine will shudder and vibrate even if all is set up perfectly, or at lest one cylinder is not pulling an equal load. The solution is to sync the carbs, make sure the RPMs are above 2,500 (minimum of 65 MPH in 5th), and do a hot reading of the plugs to evaluate how the combustion is working to spot a possible problem. But do not forget to do the cold start finer tip header test - that is the best way to find a dead cylinder without a bunch of other tests!

Goose

 

Well I know that all the plugs are firing and I get the worse shudder when I am running around 65 mph and roll the throttle an it keeps the shudder all the way up tioll about 85 or so. It acts exactly like I am lugging the motor but I am not doing that. I will try the carb sync and work from there. Hopefully this solves all my problems. I hate it when they don't run perfect like they should.

[Dbeck]

I have an 84 VR that is doing the same exact thing. Cruises fine until I hit the throttle, between 3k and 4k rpms. Accelerates fine until I hit 3300 rpms through 4k rpm's then smooths out. I bet it's the coils! I have already have doon these things:

 

Have run sea foam in it several times, disconnected the yics, Carbs cleaned and synced, new plugs and wires, TCI has been resoldered along with new diodes, diaphrams are good and slides are moving in sync, have cleaned connections and added dielectrical grease to tci, and other connections from stator and pickup coil.

When I had it all tore apart I did not check connection at coil. Whoops.

I just bought an ohm meter but do not know how to use it really; bet I can test the coils and see if they are bad with this new gadget with a little advice.

 

Bike has been running like this since I bought it last year, just couldn't figured it out.

It would be great if this was it (though they look involved to get out).I still get 40 mpg.

 

Thanks,

Doug