i just dont know anymore............

[Devinjordan]

2000 750 all stock

ok first things first i ride my bike just about everyday at least 10-15 miles and run berrymans b-12 in the gas every 3-4 tanks. so she hasnt been sitting

when i first got my bike i thought she ran great, i didn't know what running great was. i got a new oem air filter and she was running perfect... this was about 6 months ago. now its like it only runs good when it wants to. one day it will run perfect and then just all of the sudden run good up to about 5000rmp and start to like shutter and bog down, this also happens from time to time under WOT. but i just don't understand. i have rode everyday this week and it ran great. but 3 or 4 days ago, when i went for a ride it wasn't running good (bogging down around 5k) but i kept riding and about a mile up the rode it cleared up and ran great. and yesterday it was pretty cold out side and the bike was running great just loving the nice cold air, got about 20 mins into my ride and boom starts running like crap. so i turned around and started heading home figured it would clear up on the 10-15 mile ride back, but this time it didn't.
This has been going on for a while know about 2-3 months where its good one day and crappy the next. sometimes for the whole ride and others for maybe only a few minutes and im lost here. any help or suggestions greatly appreciated. thanks guys.

i also should mention sometimes it will go a week or two not running right or it will run right for a week or two with no problems. and the change happens fast it can be running great then get on the throttle and it will bog down, i dont know when its going to happen. also it idles fine and will rev fine with the clutch in or in neutral.

[Wild-Bill]

Fuel filter?

[Devinjordan]

i did notice a little trash in my tank a few weeks ago so i dumped the gas and refilled with fresh gas. i will pick up a filter later today. are the stone filters better than the screen types. it has a stone on it know.

still open to all suggestions. thanks

[Wild-Bill]

No filters on a pre-98 Kat. They tend to slow fuel flow enough that the bike starves for gas.

If you're troubleshooting and want to make sure you're getting clean, fresh gas, try running an aux tank. I made one from an old lawnmower tank. It hangs from a ceiling rafter so it's up, out of the way while I work on the engine and I installed a shut-off valve so I don't have to mess with dribbling fuel all over when I disconnect.

[Devinjordan]

No filters on a pre-98 Kat. They tend to slow fuel flow enough that the bike starves for gas.

mine is a 2000 but the tank may be from a pre, i no its not the tank that was originally on the bike. but not sure on the year if that makes a difference.

If you're troubleshooting and want to make sure you're getting clean, fresh gas, try running an aux tank. I made one from an old lawnmower tank. It hangs from a ceiling rafter so it's up, out of the way while I work on the engine and I installed a shut-off valve so I don't have to mess with dribbling fuel all over when I disconnect.

i will try this also when it warms up outside.

[Devinjordan]

Any other suggestions?

[diavolo]

If you had some gunk in the tank, it will take more than just one flush out to clear it - try cleaning it out again, or adding some gas line anti-freeze or some Sea-foam for a few tanks to see if that clears up the issue. I had a similar problem, except I took a major dose of water, and it took about 5 tanks of fuel to finally clear the carbs of residual water (after flushing the tank twice) for her to run smooth, once again.

[travg]

It may be worth taking a look at your petcock. If the rubber diaphram in there is starting to go, it may be getting starved for fuel every now and again. I know mine would just basically stop going until I reached down and turned it to Res or Pri, and it would run again, and then repeat the process. Rebuilt the petcock and no problems since. Just a thought, but sounds fuel related.

[kat600rdr]

Not saying its a Fuel Filter, but the post 600 has one inline from the tank to the carbs. Mine ran like crap with an aftermarket one, put an OEM one on it and it ran great. I would assume the post 750 has one as well.

[Wild-Bill]

mine is a 2000 but the tank may be from a pre...

The fairing fooled me. That's a pre fairing. :shrug:

You definitely want a free-flowing filter. One of the reasons pre bikes run so poorly with a filter is that the filters don't flow enough fuel to keep the bowls filled. If you don't know when the filter was last replaced then definitely try changing that out. Take a look at the lines while you're at it and make sure nothing's kinked.

[Devinjordan]

ok thanks and i rebuilt the petcock about 8 months ago so it should be good.

and yea i know i like the look of the pre fairings even if it makes my bike look older.

[ZukiFred]

I would also look for vacuum leaks myself.

[Kreylyn]

I dont' think it's fuel...

I think it's a spark issue. Poor connection on a spark plug boot, bad wire... something along those lines.

I would start with checking plugs, even replacing them if any question. Clip about 1/2" off the end of the plug wires and screw the boots on tight to make sure they have a good and new connection on the wires.

Ultimately... check the down tube temp on all four headers when it's acting up... the cold one will point you to where the issue is.

Krey

[Devinjordan]

ok i will check all of these tomorrow, i dont think its a vac leak bc it comes and goes. also i checked the headers yesterday and all four were hot. like i said it only happens sometimes under WOT or past 5k rpms

[Devinjordan]

Update

i worked on the bike today. first i got a new fuel filter. and set up a alternative tank with fresh gas. i let the bike warm up bottle feeding her. and there it seems to be running a little better. so then i took the airbox off and pulled the carbs away from the engine, took off all four bowls and soaked them in carb cleaner and scrubbed them with a small brush and used compressed air to blow it all out. then i stuck the carbs back on and started the bike and reved it up a little and held my hand over each one of the carbs for a few seconds. so then i but the airbox back on and put the filter back in, and went for a test ride.(still bottle feeding) and she ran great. so i put the tank back on and went for another short ride and it seems to be running perfect. i don't know which one of these steps fixed the problem, but its fixed.