Shit bag

[killa]

Hi

I have mentioned this before but I need some more opinions as to find the fault is going to cost me and I don’t want to go in blind.
The VFR is running sweet, or very nearly, basically the bike is quick at high speeds, revs nicely up around 7Krpm and up. But the problem I am getting is when you come to corners that need you to go through gears etc at low RPM. The bike, especially when low’ish on fuel needs a good kick up the arse to get her past 4.5KRPM to about 5.5KRPM.
I am experiencing a burbling effect at lows speeds and rev, so you can imagine from the lights a quick launch requires a lot of stick which in turn is no good for my clutch. I have a large can on the back which I am reluctant to get rid of because of the sound it makes but I have been told this could be leading to the problem due to low pressure.
The problem is hard to nail because this could be anything from the Air intake, fuel and carbs, oh and the can. It does change when at different running temperatures.

Any thoughts?

Thanks

Killa
____________________
Cleverly disguised as a responsible adult.
Bike:- Yamaha TRX850 | Killas Biking History | Killas Gaming History | Killas autmotive history

[Kickstart]

Hi

Does sound like a possible issue with the carbs needing setting up for the can you have. At a guess at that point in the rev range the can is causing it to run lean (or possibly just working rather too badly at half peak power, ramming exhaust gases back into the engine).

Stick it on a dyno with an exhaust gas analyser and see what it has done.

You might be able to get away with shimming the standard needles up to richen the mixture. You might need a dynojet kit with some reprofiled needles. You need someone with good knowledge of setting bikes up.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[killa]

Thanks for that Keith, I am trying to avoid changing anything that Honda put in my baby.
I was hoping it wasn’t the can, I have heard some horror stories from people taking their bikes on Dyno’s and how they perform afterwards. Could be bullshit.
____________________
Cleverly disguised as a responsible adult.
Bike:- Yamaha TRX850 | Killas Biking History | Killas Gaming History | Killas autmotive history

[craigs23]

Have a look around 400greybike for a more detailed explanation. Sounds like a mixture of things.

How old are your plugs? Take them out and have a look at their condition if they haven't been checked recently (best to check the rears atleast - the fronts are a nightmare to get to).

There is a standard Honda flatspot around 6k which can only be ironed out with either a HRC CDi unit, an aftermarket system, or dyno retune (or best - all of the above).

The symptons do sound as if it's related to the fueling of the bike - presumably down to the fact of the end can fitted - it really is wise having the bike rejetted to suit the can as this is surely causing the problems.

Having said that, one other way to combat the problem is to ride through it - on a good balt down my favourite country lanes, my tacho needle rarely drops to under 8k, I like to keep it on the boil between 9 and 13 (over revving yields small rewards as the torque levels off after 12,000).

[Kickstart]

[killa]

Good info guys, I am 100% sure there is no non Honda bits in there.
TBH I have learned how to handle the bike with this and it does run sweet in the higher rev range, but it is increasingly annoying when a Golf GTI can have you off the mark because I am not getting the power to the floor I need. Sorry, not that I do this all the time, but it is annoying.
____________________
Cleverly disguised as a responsible adult.
Bike:- Yamaha TRX850 | Killas Biking History | Killas Gaming History | Killas autmotive history

[craigs23]

lol, gives them a head start and they think they're winning, until the power kicks in anyway, then, no chance.

Bye Bye GTi....