Johnathan.fine

I need help with my 98 Hawk I have owned it for about a year and a half she now has 20k and hasn't ran smooth since the second day I have owned it. It's all stock pipes, jets etc. It runs like a champ until it gets up to operating temperature. At which point once I give her a good run she begins to spit sputter and backfire from the pipes and occassionally into the airbox, once this happens all power is lost at full throttle it will idle down and die, then she will run fine for a little while before starting the process again. I recently rebuilt the carbs changed the fuel filter and cleaned the tank. I have had to change the spark plugs 4 or 5 times all with the same result caked black fouled plugs. I was curious is there anyway to tell if its running too rich or is the spark not powerful enough to burn all the atomized fuel. I love the bike but cannot stand the hiccups in the way she runs. any ideas would be helpful

VTRsurfer

If the misfire occurs under load (on the gas), it sounds like ignition. Check the plug wires for burn marks, carbon tracks on the insulators, and check resistance...should not be over 30K ohms. Leakage at the coils is also possible. Check for carbon tracks or leaks.

Easiest way to check for ignition leaks (easier on a car due to access) is to hook up a ground wire (piece of wire with alligator clips on both ends) to a screwdriver and engine ground, do not ground to battery. Then start her up and run the screwdriver along side the plug wires and around the coils. If a spark jumps to the screwdriver blade, you found the leak.

The plastic insulators on the plug ends are a common source of leakage.

996SSVTR

I had a carburator problem with my bike, but in the end it needed to be re-jetted. But commonly, about 3/4 of the time carb problems are electrical. As far as running rich, check the forum for info, but generaly if they are black your running too rich and if they are white your running too lean. It does suck that the coil and the plug wires are attached.

VTRsurfer

I didn't know that. $$$$$

Johnathan.fine

would the electrical leak not show itself when the engine isnt warmed up under load this is what confuses me

VTRsurfer

Not so much the plug wires, but a coil can sometimes have internal problems in the windings that show up more when the coil heats up.

I've always envied the guys that worked at dealerships who could just go to the parts department and try installing a new coil or other part to see if that works.

However if BOTH plugs are carbon fouled, that points to rich mixture. If you are running stock exhaust, as I am, that seems unusual. But I ran into another VTR owner with stock cans once who said he had rejetted. I'm trying to think what could be disconnected (vacuum lines, etc) to cause what you describe, but not coming up with any answers.

Is it a California bike with the EVAP canister? I've seen cars with bad EVAP purge valves running rich as hell.

supermatt996

could a ignition problem cause the plugs to make it look your bike is running lean even if its not. my bike has the same back pressure blow up through the air filter

VTRsurfer

Carb farts are a common problem on VTRs and many big bore carbed v-twins. My 83 BMW R100RS (1000cc) did it too, but not as often. It had much smaller carbs.

Mine's all stock, but when the hic-ups got worse, I removed the EVAP (California emissions), and that has helped but not eliminated the carb backfires.

supermatt996

no evap on mine but ill check for ignition leaks and the timing tommorrow

Johnathan.fine

too my knowledge its a 48 state bike not a california spec one but as I didnt buy it knew in 98 I dont know for sure. I havent dug into it personally my mechanic knowledge is with cars not so much with a carbed v-twin. where is the EVAP canister for me to look for? when I had the carbs cleaned I was told they looked like the stock jets if my bike had aftermarket pipes on it and had the stock cans put back on for sale and not rejetted for them could it cause this much like running the choke on for too long? or is my best bet to order a new set of coils first and just continue to go down the line one part at a time

Little_Horse

+1 on checking the coils but make sure to test both primary and secondary circuits. I had both coils die at the almost exactly the same time so its worth a look

nath981

Your all stock and you did you all that work on the carbs. make sure all the vacuum lines are on correctly. Check your TPS(this was wreaking havoc with mine) and the air mixture adjusters are set according to specs.

VTRsurfer

If you had a CA emissions bike you'd see what looks like a black coffee can sticking out in front of the chin fairing. Sounds like yours is 49 states.

nath brought up another good point, check the TPS. It's on right side of rear carb with a plastic electrical connector.

gboezio

Black fouled plugs are from an over rich condition, make sure that the jets have not been drilled trough by an idiot, check for gas in the vacuum line of the petcock (if the rear plug only is fouled), if both plugs are fouled equally it sounds like a main jets issue someone re-jetted it too rich, have it checked or take the carbs out and read the numbers (178 front/180 back), if stock, change the jets for known good, just been cleaned with a steel wire is enough to mess up jets.
Needles....mmm check them anyway, look for washers inside the slide.

Johnathan.fine

thank you I will start checking everything today the carbs were pulled apart and cleaned by what i think is a fairly reputable shop close by but it wasnt a honda dealer so you never know I guess. sounds to me like the common guess for mine is what i thought its rich but could be electrical as well. But at least no one said it might be the I.C.U. which is the most expensive part i thought it could be.