Rough cruizing

[johnny74]

My '02 FZ1 is having issues when cruising between 4-5k RPM, around 40mph. Acceleration seems OK, but just when maintaining the same speed it is not smooth. You can hear it, and feel it a little. Does this consisitently when the bike is warmed up.

Also, what is the average MPG you guys are getting?

Thanks!
Johnny

[eflyguy]

Shift up, or down?

I get 37-ish, but it varies a great deal based on how I'm riding..
..a

[grommet]

Mine is pretty smooth at any rpm. No fueling or intake mods at all. Slip on exhaust.

If you're getting over 40mpg you're going too slow.



Any number of things could contribute to roughness. More information would be useful. Particularly how many miles the bike has on it and how often you ride it. If your riding is sparse, or the bike has been sitting for any length of time (few months) without running, there is probably a little gunk in the carbs. That's my first thought.

Even without knowing anything else about the bike or your riding habits, I'll suggest Sea Foam first. I bet the roughness will go away.

[ski84]

Originally Posted by grommet

If you're getting over 40mpg you're going too slow.

Depends on your definition of slow. I don't drive conservative and I regularly get around 45-50MPG on the open road (non-city). I suspect your carbs need some work. RavenRider's carb job will give you a noticeable improvement at all throttle openings.

http://yamahafz1oa.com/forum/showthr...ht=shim+needle

[grommet]

Originally Posted by ski84

Depends on your definition of slow. I don't drive conservative and I regularly get around 45-50MPG on the open road (non-city). I suspect your carbs need some work. RavenRider's carb job will give you a noticeable improvement at all throttle openings.

While tuning his carbs, ski84 did not notice that his sarcasm sensor system had drifted out of spec.

[ski84]

Originally Posted by grommet

Grommet: point taken, I'll dial it back into calibration.

[johnny74]

22 or 23k miles, ridden often and started monthly during winter. Tried Seafoam.

I get about 36 mpg. Thought it should do better.

[grommet]

1. Have you compared it with another bike to see if it's normal?

2. Has it always been this rough? If not when did it change? Did it change suddenly or gradually?

3. Has the mileage always been 36? If not when did it change? Did it change suddenly or gradually

4. Have you cleaned the air filter?

5. Any other mods to the bike such as jet kit, intake mod, etc?

6. Have you pulled the plugs and checked color? If so do you know what to look for?


I could go on, but you get the idea. My bike runs rough, Why? is not much to go on.

[johnny74]

I'm sure it's not normal because it has been gradually getting worse since last season. Mileage has no changed. AF is still clean. Has a Yosh slip on, but I don't know if it's been jetted. Will check plugs again but they looked normal when I changed them a month ago.

[grommet]

Pictures of the business end of the plugs would be very helpful.

[hooligan998]

If it has a slip-on but has not been jetted, you may want to consider getting one. A slip-on leans out fuel delivery at every point. That lean condition would cause the roughness you say you have, especially if the floats have not been set correctly for a slip-on.

[johnny74]

Originally Posted by hooligan998

if the floats have not been set correctly for a slip-on.

I can understand rejetting, but how would a slip on, or any mod for that matter, require readjusting the float levels? Sure, there would be more fuel available in the bowls, but the fuel system should have no problem keeping up and preventing them from going empty, right?

[richard314]

Originally Posted by johnny74

I can understand rejetting, but how would a slip on, or any mod for that matter, require readjusting the float levels? Sure, there would be more fuel available in the bowls, but the fuel system should have no problem keeping up and preventing them from going empty, right?

The float level determines how much fuel a given amount of vacuum will suck into the carburetor venturi.

[hooligan998]

Originally Posted by johnny74

I can understand rejetting, but how would a slip on, or any mod for that matter, require readjusting the float levels? Sure, there would be more fuel available in the bowls, but the fuel system should have no problem keeping up and preventing them from going empty, right?

Slip ons or aftermarket air filters increase air flow through the carbs. Carbs then use more fuel. If the floats are set too low (I believe stock is 12.5 to 13 mm), the float needles will shut of flow of gas into carbs prematurely, causing a lean condition and rough running. Most jets kits require setting the floats at 14 mm which allows float needles to close later keeping fuel flowing into the float bowls longer. Research float level in here, you'll find all the info you need on this subject.

EDIT: Didn't see richard's post. But he's spot on with his reply.

[Falcon 269]

Originally Posted by hooligan998

Slip ons or aftermarket air filters increase air flow through the carbs. Carbs then use more fuel. If the floats are set too low (I believe stock is 12.5 to 13 mm), the float needles will shut of flow of gas into carbs prematurely, causing a lean condition and rough running. Most jets kits require setting the floats at 14 mm which allows float needles to close later keeping fuel flowing into the float bowls longer. Research float level in here, you'll find all the info you need on this subject.

EDIT: Didn't see richard's post. But he's spot on with his reply.

Float levels are set with the carbs inverted. Setting them to 14mm actually reduces the level of fuel in the float bowl which of course means the fuel flow is shut off sooner, not later.

If cylinders 3 & 4 are genuinely running 40c cooler than the other pair, either 1 & 2 are running too hot (indicating lean fuelling) or 3 & 4 aren't firing correctly (they share a coil) or they might be over-fuelling.

I'd start by fitting new plugs and trimming 1/2" off the plug leads where they go into the caps. Eliminate poor ignition first before fault-finding for a fuelling problem.

Oh, and the plugs will tell you what the fuelling was doing in the instant before the motor was shut down. As a diagnostic tool for fine-tuning fuelling that's not a lot of use. Extremes of lean/rich settings may be detectable from the plugs but you'd have other obvious symptoms, too.

[johnny74]

I found a couple spark plug boots I could still get another "snap" out of them if I pushed pretty hard. That seemed to help greatly, but the biggest difference was syncing the carbs! It was easy and the bike is way smoother now.

Checked the exhaust temps before and 3&4 were cooler by about 40 degrees. I'll check again as soon as I ride again. Not great weather here today in chitown.

All in all, it is getting much better, but I don't think 100% yet, but close. I thought this bike would be really hard to keep the front wheel on the ground, but it's always been the opposite. Even at the drag strip last year I thought it should go faster. The best I went was 11 flat at 130. It's all stock as far as the slip-on, and maybe jets. I haven't gotten that great at launching yet, my best 60' was 2 flat. I weigh 200.

http://www.youtube.com/watch?v=oxvL9...&feature=g-upl

Thanks everybody!
Johnny

[johnny74]

The issue I'm having is at like 10% throttle. Float bowls shouldn't be anywhere near empty.

[johnny74]

OK, so I made the bike stutter down my street and hit the kill switch and put it in neutral up my driveway. Here's the plugs. Maybe a little rich, but not too bad. Only about 1000-1500 miles on them.

https://picasaweb.google.com/lh/phot...eat=directlink

https://picasaweb.google.com/lh/phot...eat=directlink


Thanks!
Johnny

[Falcon 269]

Plugs look acceptable and similar to each other.

What did you use to check header temps? Just want to be sure we're working on accurate information.

Rough cruise at light throttle usually says 'lean surge'. Yours is a 2002 model with 2.5mm nylon spacers on the needles. Yamaha increased these spacers to 3.0mm on '03 models onwards in order to address the lean part-throttle fuelling on the first of the Gen 1s.

You might want to try raising your needles by 0.5mm with suitable shims.

[johnny74]

I was checking the headers with an infrared pyrometer. And I forgot to mention that 3&4 pipes are blued near the head since I bought the bike.