My TFOG experience

[McVaaahhh]

My YZF was running really rich so I decided to take it in to TFOG. I'd been to TK before but I thought I'd give TFOG a shot and see what they could do. They ordered a jet-kit for the bike and said bring it in on Tuesday when the kit was supposed to be there. I took it in on Tuesday and when I dropped it off I asked when it would be done. Was told probably Thursday. I took that to mean thursday or friday at the latest.

I called on thursday later afternoon and was told they hadn't gotten to my bike yet and would get to it on friday.

I called Friday at closing time - hadn't gotten to my bike yet would get on it tomorrow (sat)

I didn't bother calling on sat - they didn't call me either.

Finally got the scoop on Monday. The wrong jets were in the kit and Jim had spent a lot of time trying to adjust them before contacting Dyna-jet and finding out they sent hime a kit with bad parts in it. Jim was really nice and basically it boiled down to a mis-communication issue.

They'd have the kit on Wednesday and get back after it.

I call on Thursday and it was done. Jim said it was still a little rich on the bottom end, but that's the best they could do with that motor (I've heard that 750 motor is not that great).

Still running pretty bad on the bottom end. Wants to die when I'm sitting at idle and sounds like a twin when at cruising speed (little throttle) becaue it's still running really rich.

So now I'm torn. I'm trying to sell the bike and I don't know how much luck I'll have selling it when it's running like this. I don't want to take it back because it sounds like there's nothing more they can do, and I don't want to throw good money into it if it's not going to run better.

I'm not really pissed off at TFOG, but then again I feel like I wasted $300 getting it re-jetted because it still runs pretty rich. They were nice guys over there and the time issue wasn't their fault, just the lack of communication with me was.

Ah well, I'm done ranting.

[rforsythe]

Have you tried an aftermarket air filter to increase some airflow and lean it out a bit?

[McVaaahhh]

Think it would make that much of a difference? I guess it's worth a shot though.

[Mel]

yeah, it will make a difference...whether or not it will fix the problem I dunno. But when I swapped out air filters in my bike it ran WAY too lean afterwards.
Basically right now, your bike is getting too much fuel for the air it is taking in and it is drowning itself. You get more airflow coming into the mixture, it will bring the air/fuel ratio back up and *shoud* in theory run better.

[rforsythe]

Also check the air filter you have in there now. If it's dirty or plugged up no amount of jetting in the world is going to fix that.

[McVaaahhh]

Thanks a lot guys, I'll go grab a new one and see what happens.

[RAGrote]

You get more airflow coming into the mixture, it will bring the air/fuel ratio back up and *shoud* in theory run better.

Only if you increase the flow out as well. Otherwise you'll just be spending money for nothing. I can almost guarantee changing just the air filter won't do much.

Test it before you spend any money. Take a short ride with NO air filter. Don't worry, there won't be enough junk ingested by the engine to harm it. Idle it until it's @ operating temp and then drive it a mile or 2. You'll know right off the bat if the air filter's going to help.

Good luck.

I find it interesting that they couldn't come a little closer to "fixed". It's a time consuming operation and I'll bet they didn't want to hand you a $300 labor bill. (which is a good thing)

[Dr. Joe Siphek]

don't want to take it back because it sounds like there's nothing more they can do, and I don't want to throw good money into it if it's not going to run better.

Do you have some bad money i could have?

[McVaaahhh]

don't want to take it back because it sounds like there's nothing more they can do, and I don't want to throw good money into it if it's not going to run better.

Do you have some bad money i could have?

Kinda evil and possibly posessed, not too sure you would really want it.

You get more airflow coming into the mixture, it will bring the air/fuel ratio back up and *shoud* in theory run better.

Only if you increase the flow out as well. Otherwise you'll just be spending money for nothing. I can almost guarantee changing just the air filter won't do much.

Test it before you spend any money. Take a short ride with NO air filter. Don't worry, there won't be enough junk ingested by the engine to harm it. Idle it until it's @ operating temp and then drive it a mile or 2. You'll know right off the bat if the air filter's going to help.

Good luck.

I find it interesting that they couldn't come a little closer to "fixed". It's a time consuming operation and I'll bet they didn't want to hand you a $300 labor bill. (which is a good thing)

Good point, I'll pull it out first and see what happens. **Yeah I know, kinda sounded dirty - Pull and Pray.

[troythetroll]

Out of curiousity, why was it running rich in the first place? Did the carbs get messed with somewhere along the way, and you are trying to correct a past problem? And I usually thought jet kits were built to richen things up anyway because they usually aren't installed alone, the standard pipe-filter-jetkit swapout is more likely I bet. Which is why people recommended other pieces of the jetkit-pipe-combo.

Is this bike already piped?

Myself, I've owned more than a couple of sea level jetted, carbed, non piped bikes at altitude now, and besides not needing the choke much in the morning to start, running rich never has come up as a problem.

[rforsythe]

Only if you increase the flow out as well.

Not if his filter is crap to begin with.

Test it before you spend any money. Take a short ride with NO air filter. Don't worry, there won't be enough junk ingested by the engine to harm it. Idle it until it's @ operating temp and then drive it a mile or 2. You'll know right off the bat if the air filter's going to help.

I have no idea what this will do to his model of bike, however some don't respond well to this treatment. Airboxes are designed to resonate and create certain pressure waves, and taking out the air filter can mess with that process. It may or may not be a valid test...

The bike was likely too rich to begin with, but there is no reason a normally operating, properly maintained bike can't be rejetted for this elevation to get back to a balanced mixture. Something is wrong.

[McVaaahhh]

Already piped when I bought it - Vance and Hines. I don't know the history of any jetting that was done. Jim at TFOG agreed that it was running really rich.

Not being a mechanic myself I can't say that he diagnosed WHY it was running rich correctly, but it IS running better with the leaner jets in it.

It floods quite easily and is pretty much a bitch to start in the morning. It was getting really crappy gas mileage when I brought it in and I haven't yet gone through the new tank since I got it back so I can't yet say if that has improved.


Interesting note - after the bike is already warm and I put the choke on full the bogginess goes away and the revs go up to 5k or so. Obviously not rideable like that, but I thought it was interesting how high the revs go. I've had carb'd bikes in the past and never had the revs go that high.

Bad choke adjustment or bad idle speed adjustment?

[McVaaahhh]

Out of curiousity, why was it running rich in the first place?

it was running a little rich when I got it, but I just dealt with it. Over the last month though it started to get worse and harder to start in the morning and starting flooding easier. Any thoughts on why it would get worse as time goes on?

[FZRguy]

If the bike has been jetted down and is still running quite rich, very good chance that the emulsion tubes are worn. I replaced the tubes in my FZR at 25k, but I do a lot of touring. The info below is from the Factory Pro web site. They have tubes for your bike.


This is a picture of the needle jet area of an emulsion/needle jet tube from a stock 38mm CV Mikuni carb as installed on Yamaha TDM/TRX 850, YZF750, FZR/YZF1000, etc. Notice that the center hole is noticeably worn at the "V", the 12 o'clock position, which would be towards the engine, as installed in the carburetor. This causes 2 conditions. First, it allows more fuel to enter the carburetor, as in using a needle with a small base diameter AND the fuel that enters the carb enters in larger droplets, resulting in poor combustion. If you install a jet kit and it is much too rich at low rpm, and lowering the fuel level 1mm doesn't fix it, check the needle jet tubes for wear - it's not uncommon. The reason why these parts are often replaced is because they all contain the "needle jet" - that wears out and causes low rpm richness due to excessive needle / needle jet clearance. That wear is why some excessively lean bikes run better at 5,000 miles.... they "wore out" and got richer!!

Eventually, in the 36mm horizontal mount and 38mm downdraft Mik's, the carb body plastic insert, where it holds and guides the slide from rattling back and forth, will wear out - allowing the slide to rattle and bang the needle fore and aft in the needle jet orifice - causing accelerated NJ wear. This wear is biased towards the lowered slide position - as in idle and low rpm areas - as in "in-town", "stop and go" driving. The gist of that is that you may only get 5,000 miles out of your needle jets in your bike that you use for cruising 4th Street and hanging out at McDonalds - but your long distance highway cruising buddy might get 25,000 miles before mileage deteriorates to 25mpg or worse.

[~Barn~]

<snip...>but there is no reason a normally operating, properly maintained bike can't be rejetted for this elevation to get back to a balanced mixture. Something is wrong.

[rybo]

Have you had it on a dyno to verify that it's running rich? I had an fzr400 for a while and when the valves were going out of adjustment it would get very hard to start and flood easily. When was the last time the valves were checked?

[McVaaahhh]

Have you had it on a dyno to verify that it's running rich? I had an fzr400 for a while and when the valves were going out of adjustment it would get very hard to start and flood easily. When was the last time the valves were checked?

I haven't had them checked in the 4 mos that I've had the bike. Not sure if they were checked before that.

Thanks for all the input everyone, I guess I've got a couple of things to take a look at.