seafoam ?

hi all I'm having fuelling problems and hoping for some direction , the bike is a volusia 800k4 carbed model.        about a month ago I noticed the bike wouldn't rev to the max it was only getting to 60mph in top gear then holding back so I cleaned the carbs - no difference . so I cleaned them again and soaked jets overnight in carb cleaner - no difference. in fact it would now only do 50 in top and was misfiring aswell so I drained tank and put 15quid of super unleaded in (yikes that stuff is dear)rode it for 10 miles and it was slowly getting worse so I cleaned plugs (fouled)it went slightly better but would still only rev out to 50mph in top so next I put just under half a bottle of sea foam in the tank  run it for 20 minutes and left it for 2 days ,     when I started it up on choke it revved slightly higher than it used to on choke before , revved lovely on the driveway so I rode it for 5 miles under load - still only revved to 50mph , yesterday I put new plugs in and it now does 60 mph again like when it 1st played up no misfiring runs sweet in each gear to about 2/3rds of rev range then holds back .     its the 1st time ive used seafoam and was wondering if theres too much in the tank or not enough or maybe the problem lies elsewhere ?        should I keep riding it to use up fuel then put fresh  fuel in or does seafoam work pretty much straight away ?    if it does work straight away then next I was going to test coils leads and caps but they look a pain to get to,    somebody told me if it was vacuum pipes it would play up at tickover and bottom end of revs - is this true ?      am I missing something else       ?     it starting to drive me nuts now lol     if anybody could shed some light I would appreciate it cus at the moment I cant afford to book it in a shop       almost forgot the bike was running totally stock till February when I dumped oil and changed air filter to k&n cus old one was looking a bit choked   if it helps the mixture screw was set at 2 and a third turns out - sorry for the long post I think my brain hurts and need a lie down lol

dont you have to rejet when you put k&n filters on

Yep - I think there is a strong likelihood that you should have re-jetted the carbs when adding the K&N.

A good clue here would be to have a run at high speed then have a look at the spark plugs. They engine is likely to be running lean at high revs, and this should show on the spark plugs - they are likely to be whitish & possibly with a glaze on them. If so - you will need bigger main jets - try your 'supplier' of the K&N air filter. OR do a bit of web research .... such as  is there a Dynajet kit for your bike ? 

The other option is to put a standard filter back on (If you've not binned the old one/housing etc. ) & see if the 'original performance' is restored - which will indicate a problem with the carb set-up when the K&N is used.

Hope that might give you some low cost options to try out.

thanks for the replies I will check plugs the weekend and go from there                I didn't even think about rejetting cus its only a k&n that slips in the airbox and a few years back I did same to a Harley and that was fine but its worth looking into though perhaps its because the Suzuki revs higher than a Harley I don't know            I will let you know what happens     cheers

wow ive sorted it out at last .        I put a new stock air filter back in and set the mixture and it absolutely flies now I'm so chuffed , in fact its better than when I bought it       .  I did also end up testing coils and plug caps - coils were fine but resisters in plug caps were a mess and the little springs were rusty so I cleaned them .           not sure if that is what makes it better or air filter but probably both I would presume .        I want to thank you for pointing me in the right direction  I'm so chuffed I joined this site    cheers everyone   -   steve

Glad you got it sorted steve 

Steve, I know it's sorted now but do you have stock exhausts or aftermarkets just out of interest ?

exhausts are stock        jet sizes 127.5 main and 27.5 pilot    I think a lot of the problem with the k&n was the 2 inlet tubes that fit on the stock filter don't fit on the k&n so I had to leave them off       also I didn't want to rejet so I just put it back to stock filter with inlet tubes back on        I was wondering if anybody else tried a k&n without rejetting ?  if so did you have similar results to mine ?

I'm running stock filter, but when I had mine dynoed last year, the guys said that if you fitted a K & N, you'd need to rejet

katsd wrote:

I'm running stock filter, but when I had mine dynoed last year, the guys said that if you fitted a K & N, you'd need to rejet

I agree with you Dave, from what I understand, normally you can change either the filter or the exhaust without re-jetting, but not always, it depends on the bike and what you fit. I personally would get it dynoed if I changed the filters, not sure about the exhaust though, if a straight through slash cut then I would but if it was for a fully silenced CE one then probably not.

Glad to hear you've got it sorted. sounds like the issue could be one of jetting, or possibly flow - depending on what the 'tubes' you describe from the original installation actually do.

These could affect the airflow into the motor & there should be some advice on this from K&N. I remember that the K&N for the CBR600F - V that I had a few years back had an alternative deflector plate  for inside the air-box and it needed that to run properly.

I know on some other bikes there are adapters than should be fitted with the filter - one of the reasons being that a few years ago K&N seem to have streamlined some of their range, making one filter work for a range of bikes if use with the appropriate adapter/collar/etc. where the general overall filter size was similar.

Martin's Volusia ran like crap when he fitted a spiked come air filter with stock exhausts until he had it rejetted and set up properly.

when I bought the k&n the paperwork with it said no need to rejet but I have a feeling that the paperwork is the same for every filter they sell        if the inlet tubes were able to fit their filter then it might of been ok maybe , but the backing plate ? of their filter is far too thick to accept the tubes     anyway I'm just glad its sorted - thanks everyone  cus without this site id still be stumped   I'm now looking forward to riding it as much as poss

simbo wrote:

 Martin's Volusia ran like crap when he fitted a spiked come air filter with stock exhausts until he had it rejetted and set up properly.