I'm back w/ m'tail b'tween m' legs

Mikey D

I know, I haven't been around in a while and here I am ask'n ya'll for help, but my sweetie's sick!

         When I wack 'er @ around 6 - 6.5K there is (Just when the front wheel is supposed to start loft'n) a major drop in power.  She still accelerates but not like she love me.  She dosen't seem to be drop'n a cylinder, and there are no drivability issues up until that point.

         17K on the odo.
             She was dismanteled but I changed her to salvage (3 or so years ago and no problems 'cept for breaking 2 rear wheels)
                 Bone stock on Dynojet = 162Hp
                     Added 2 bros full system and it woke her midrange up! (2 years ago)

          I bought a set of plugs with the intent of swapping 'em but I havn't convinced myself that could be the problem.

          I've almost talked myself into it may be a really shiddy tank of Circle K (vs my usual Chevron) and when the shes up to speed the lack of octane is causing a knock and the spark retard is kick'n in BIG TIME and causing this distressing condition.


I've talked to the local dealer who said he's never herd of any drivability issues like this with a Busa.

        Would't be valve adjust
        Maybe fuel pump pressure? (or shiddy gas?)
        Operates fine up till 6 - 6.5k (no cylinder drop out)
        Air cleaner is clean.
        Tires are up
        Chain is adjusted properly
        May be gett'n just a tad harder to start.
        She has stalled out 2 or 3 times when the clutch is pulled after just taking off (light on the throttle) when she is cold. (could have been a clutch fluid level issue)

Wadda ya'll tink?  Anyone out there ever hear of sumptin like this before?

Thanks in advance!



Donating Member
Hey Mikey.. how goes it?

My first thought is fuel filter....

Might be getting plugged up and you dont notice it until it needs more fuel and cant get it...


Donating Member
dump out shiddy gas and run a bottle of techron and refill. that would be if you have water in the tank.


As well as that already mentioned such as fuel pump and filter...
1. Replace the plugs anyway... Just to eliminate the simple possibility.
2. Then check the charging system and battery. Could be that the amperage demands are not being met due to some power fault.
3. Check the ignition coils to see that they are lighting off a blue white spark with a plug grounded. If your plugs are eroded then that could cause an excessive draw on the coils. But at 6k that would be severe.
4. * As far as I understand it our bike's simple electronics don't have knock sensors (could be wrong though) and instead used maps programmed for various conditions.
5. Your throttle position sensor could be at fault. There should be a test procedure to see what voltage it reads across the leads compared to a given standard.


Oh yeah 90% of the time it is the lowest common denominator.. Such as a filter along the line...


Donating Member
I have been out to Mickey D.... Nice to see you are still around though...

I would second the changing gas idea, especially if it has been sitting a while... It is easy to drain the tank, just lift her up and pull the return feed line and let her drain on the floor...
It evaporates quick with no mess... hahahaha

What has changed on the bike is truly the question here. Did you mess with timing? When is the last time it ran right and has anything changed between the time it ran right and now...



The Shaver Immortal
Donating Member
Holy crap....Cloud9 and Mikey showin up!!

Mikey, you hairy lug...we've missed ya! Cloud...good to see ya back!

Now as for that problem, I think Projekt's got most of the stuff covered. I'm thinkin it could be a fuel pump or filter issue.

Either that, or it could also be a crack or hairline fissures on your fuel hoses.

Keep us posted on the prob, my bro...


Donating Member
just went through sort of the same problem with my 05 with 23000 miles , cleaned fuel filter with compressed air , all good now ! changed my plugs first helped a bit right up to where i was havin the problem but problem was still there check the o rings on the fuel pump and pressure regulator and before you re assemble put a little oil on the orings , hope you get the problem fixed !


MotoGP Wannabe
Donating Member
Hey Mikey...good to hear from ya  

How many miles do you have on your plugs
if it's over 10k...that's probably it

Mikey D

Thanks for the ideas Ya'll!

Good to hear from ya! I'll never forget our little jaunt down the canyon!
I still owe Bullet Train a pair of cans.

Rock -a- day! I had a similar idea. Shiddy gass from shiddy part o town.

Project - Good list! How much of Suzie do I have to dismantle to get to the plugs?
- I've replaced 2 batteries over the years but just figured it was the AZ heat cooking them. (Like everything else out here!)
- Plugs outside a compressed cylinder full of A/F could still spark bright with at defective or slightly shorted coil. Also it would be running crappy (or not at all) down low as well. But a good idea anyway.
- not sure about knock sensor either
- I too thought about the TPS. Should be a easy check.

Cloudy! - Good to hear from you as well. - Gonna do the gas thing, just not in the "environmental assassin mode"!
- The only thing that has changed was the rear tire (not a likely suspect for this though) Maybe it was happening before the change but I was prolly riding limp wristed because she'd just spin instead of loft'n.

Pac-Man - You hairless, gonad shav'n son of an islander! WTF's up?
- seems like I'm gonna have to figure out how to hook my automotive fuel pressure tester to Suzie to check the fuel pressure. When the bike initializes, the fuel pump takes the same amount of time (subjectively) to pump up to cutoff pressure so I mentally ruled that out. Good idea to check it though

Johnstein - That's what I've been waiting to hear. Someone with the same problem and a functional fix! Thanks!

BA - Back atcha! - You're right, the plugs are prolly stock & it would be a service to Suzie to change em.

Thanks again folks! I'll try to put uup another post on a more social note. Muchas Gracias!


Just check the fuel pressure @ the fuel rail supposed to be 40-42psi, if not start looking at the fuel pump, mine went bad @ 23575 miles... bought a low mileage pump off ebay for 40.00 with less that 3500 miles on it....Works like a charm..btw I did the clean of the filter w/compressed air it worked for about 500 miles then it went to bed....


Track Coach / TufPoodle Coach
I'm with trasherfox, sounds like you need to clean/replace your fuel filter? I'd do that first since it's simple and easy.


MotoGP Wannabe
Donating Member
With 17k on the ORIGINAL PLUGS that is the reason for the harder starting and the lack of performance

They are recommended to be changed every 7500 miles


As I've been through this myslf, I'd have to concur with the guys about the filter, especially the fine mesh screen at the fuel pump inlet.  

Latest Bikes

Forum statistics

Latest member