hello lads, my name is Darren and I'm in Tipperary in Ireland. I joined this site tonight out of sheer desperation.

I have a 1998 VTR Firestorm that I bought about three months ago and has given me non-stop trouble that is literally driving me insane. I've spent money, I've spent time, I've had several people try and help me.

The bike stutters and and performs as if it has fuel starvation problems. It ticks over and pulls through the revs great, but if you cruise along at a constant rev, in around 3,500 to 5,000 rpm she stumbles and misses. If you crack open the throttle she will take off fine, but at constant speed is terrible.

Now before you start screaming things like vacuum lines on the spout facing downwards and PAIR valves etc - let me explain! this kinda talk is old news to me pal!

my bike is strange because when I bought her she had a half a PAIR system that was disabled poorly. My rear rocker cover had a mysterious hose coming from the little silver cover that houses the reed valve, a hose going nowhere and it looked as if there was nowhere it should go. So the obvious thing was to check the front rocker cover, right? well the front rocker cover has no reed valve, little silver cover or anything - nothing. the casting marks are on the rocker cover as if Honda had intended to put one there, but no PAIR, and obviously, no hole.

so, i noticed after sometime driving the bike that the PAIR at the back was venting out an oily mist. I drive the bike everyday, about an 80 mile trip to uni, and she was being made to work for a living. she was performing poorly consistently. so this is what aroused suspicion and I discovered the wonderful world of PAIR valves and subsequently closed the valve and drove off into the sunset.

she seemed to perform slightly better, i synced up the carbs and everyhting seemed well. she was noticably popping more on the throttle over run, but i like that and was happy.

however, today she is back to her old tricks and is driving worse than ever. i've gone through plugs, i've disassembled carbs and cleaned and balanced them a hundred times in the last few weeks. new airfilter. new Samco coolant hose kit. new APE cct's. new vacuum hoses etc.

but i am getting nowhere.

I notice that the owner of a page called 'Greg's Liter Honda Bikes' is on this site and I must say that I found all the info most helpful there and it was the best resource I could find anywhere on the VTR Firestorm and I tried hard, very very hard, because I need this bike. actually, while I mention it, the page seems to be offline tonight. Today I changed the routing of the little hoses under the carbs, I think its called 'VTR Carb Fix' on Greg's page. I wanted to come back and see if I definately did it right, but have had no luck getting into the page all evening.

Its 5am in Ireland and I should have been asleep long ago, but I'm back on the bloody net trying to get some info that can help. I'm getting desperate, i'm a student and i sank every penny i could milk into this bike that i waited for for ******* ages and now its a nightmare!

 

The pair valve allows frsh air into the exhaust... nothing more. I've seen them blocked off every which way and it's never made a difference in performace. To me, it sounds like it's running very rich. Does the bike have any modifications? If you're cruising along and it's stuttering, then you intruduce a bunch of air via the throttle and it clears it up... signs point to a rich condition. Try pulling the choke out and see if it gets better or worse.

 

thanks indie, what are the settings for the screws? if you happen to know?

 

zixxer;

If you're asking about the mixture screws, spec is 2.5 turns out from full clockwise.

 

thanks RK1, I'm going to give it a try tomorrow and will be back.

any other suggestions about what this could be would be great too

 

Is the air filter the standard Honda? Air box is stock? Which exhaust system are you running?

Are the carb internals stock or rejetted? And which main jets and needle position if rejetted?

Have you checked the TPS with a multimeter?

 

its a 98 bike with 46k miles, excellent condition

she has stock jetting and airbox and a brand new Honda airfilter

Art cans

 

i reset the TPS with the multimeter.

the first day I had the bike I fried the R/R and it took out the battery and the TPS with it. I replaced it with the Yamaha R1 unit and got a secondhand TPS which was functioning perfectly and that is all fine now. the electrics are all good, i'm positive of that. a friend who has another VTR let me swop out the ECU, the coils etc and it all made no difference.

the strange thing is it is erratic sometimes. sometimes the bike will drive well for hours and suddenly start performing terribly and it can last for days.

 

I was going to guess that the guy who botched the pair removal had buggered a carb rejet as well, but if the air filter is Honda and you know the jetting is stock, it must be something else.

If the vacuum line to petcock is fine, petcock isn't gummed up etc. and especially because it is intermittent it sounds more electrical than fuel, but I don't know what it would be.

 

Does the hesitation continue above 5K rpm?

I have a dent in my forehead from slapping myself while diagnosing my own motorcycle ailments these last forty years. (I am a slow learner)

Is the fuel tank vent clear?

Is the vacuum line to the petcock intact along it's entire length and doesn't collapse under hard vacuum?

Ireland? Moist ambient sea air? Have you made sure that there is no corrosion on any of the connectors to the CPU box or the ignition system? I found corrosion in the connection junction between the female pin and the red/white wire for the RR unit that prevented my bike from charging the battery despite installing a new RR.

Diaphrams in the carbs okay? My BMW had a slight tear in one that caused the same symptom that you describe.

As my dent grows deeper, I wish you luck over there. Having a touch of Irish in me, I've always had a slight yen to visit. Perhaps someday.