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A follow-up to a question I had earlier...

3K views 25 replies 10 participants last post by  smltownr 
#1 ·
Got pretty much all the bugs worked out of my '02 VN750. I had asked a previous question regarding how the bike feels in 5th gear, at higher speeds. It seemed to hesitate when I was cruising around 60-65 mph.

I took it back into the shop, and they took it for a ride. They told me something that explained it, but I'm paraphrasing here. Want to see if anyone else has heard such a thing. They said that because the bike is carburated and not fuel injected, there are certain RPMs where, basically, the jets have to kick in where something else isn't, and there can be a slight lag while the bike is deciding which way it wants to go. (I wish I could remember exactly what he said) But, apparently, I should adjust speed to slightly above or below where that's happening, and that's supposed to "fix" the issue.

Does any of this make sense? Does anyone else experience this?
 
#3 ·
No. Bike is pretty stock. No ear shaves, or any other mod that I'm aware of. I just had the carbs cleaned, new float bowl and needles.
 
#4 ·
Does it do it when you are just cruising at a steady speed or is it when you try to quickly accelerate at that speed? And have you noticed if a gust of wind can make it happen at that speed?

The reason I ask is if the carb vent hose isn't stuck in the slotted hole in the back of one of the ears (air filter box) it can behave like that with a gust of wind or accelerating. The best way to make sure that isnt a problem is to cut the end of the carb vent hose at a 45 degree angle and stick it in that hole. Then it shouldn't cause any issues.

As far as what the shop told you...maybe. But I would think that would definitely only happen on really quick acceleration and only if there is something else causing a brief lack of fuel. I never had any trouble with my vn accelerating quickly or hesitating except when the carb vent hose fell out of the hole. :)
 
#7 ·
It seems to accelerate (and decelerate) just fine. It's when I'm "cruising" that I sometimes seem to get it. When I first noticed it happening, I actually assumed that it WAS wind causing it, and I still think I get a little of that. But, when I'm cruising, trying to hold the throttle at a constant speed in that range, that seems to be when it happens.
 
#5 ·
NO, not right. At 60 you are doing around 4000 rpms. After 2800 rpms the carb is already running on both the pilot and main jets. The problem is either a fuel delivery issue, an ignition issue, or as simple as a carb vent issue.
 
#8 ·
Now, when I had the carbs cleaned, this reminded me, I had the...crap..now I'm trying to think of the damn word....the little thing on the left side of the bike that turns the fuel on and off replaced.

Even with dirty carbs, I don't recall the bike doing this before when I was cruising. I figured that since this was the first time I rode with the carbs cleaned, that his explanation was reasonable.

I'll check the vents, and I'll see if I can look at the fuel lines, but why would ignition cause this? Do you mean the plugs?
 
#9 ·
I've seen 4 cylinder cars do this exact thing when the plugs and wires need replacing. Accelerate and everything just fine, but would sort of lose power, or hesitate at cruising speed. A "mechanic" told me that the insulation on the wire loses resistance after awhile, but couldn't explain why it would only affect performance at specific speeds.
 
#11 ·
I also think it could be electrical in nature. Even a shorting wire somewhere.
 
#14 ·
Do the easy, free stuff first. Check your grounds to make sure they're not loose, make sure the vent hose is in the ear, make sure the plug wires are snug and secure, etc. Then start looking at the cheap, easy things. And then finally start looking at more expensive stuff. The harness should be one of the very last things you look at replacing. That is neither easy nor cheap.
 
#15 · (Edited)
For giggles, I just changed the plugs, even though I changed them not too long ago. They actually look dirtier than I thought they would.

The vent hose being in the ear, can you go into a bit more detail than that? I see a hose on the right side of the bike going into the air filter. Is that what you're talking about?

Also, when you say check my grounds...how would I do that? What am I looking for?

I apologize. Up until now, I've never really been the DIY guy. I want to learn this stuff.
 
#16 ·
Also, when changing my spark plugs, I noticed that the bike is leaking coolant from the plastic reservoir that you actually put the coolant into. According to the mechanic, it could be a leak, or it could be something where the bike got too hot and it tried to backflow too fast, or something like that.

Anyone seen that before? Anyone know what I'm talking about?
 
#23 ·
but after about 1/8 throttle is reached the MAIN SYSTEM starts to put out an increasing percentage of the total mixture up to full throttle.
So even here, it says that the pilot is still being used after 1/8. It just gets used less and less, until the main takes over.

I still stand firm. Every other diagram I've seen has contradicted what you said.
 
#24 ·
I certainly didn't meant to start a debate!

Good entertainment, though. I'm getting my popcorn!
 
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