1996 F3 wont go over 40 mph, spluttering, juddery

SiKamon · 09-12-2007, 4:42 PM

hi again.

i have a strange problem with my bike and i'll try to be as accurate as i can with the description.

firstly i have been on 2 rides today first one, for about 40 miles, with no problems what so ever.

i then took it out again and when trying to accelerate nothing happened.

i was travelling at almost 40mph, went to overtake a car and the bike just felt like it did not want to go any faster, i could pull the throttle far back and it would just splutter, not increase in speed and make some small judder motions.
after this i took the clutch in and the bike just cut out. lights still worked fine and i managed to pull over. the bike then started up straight away without problems.

on the journey home i then tested some more.

when travelling in any gear the bike behaves normally but just does not want to get past 40mph, at 30mph it is fine, increasing it is different to normal to 40mph but it will get there.
after 40mph it just doesn't increase and just splutters.

so in 1st it accelerates normally to about 35 or 40 and you can just feel it loses all power and does not want to go anymore. this is the same in each gear.

if it helps at all, sometimes when starting the bike, for maybe 1 or 2 seconds holding back the throttle to help it start does nothing and then it will kick into life and go straight to high revs as the throttle is far back.

i have looked through the manual and there is a long list of things to start checking and i am nowhere near great at maintenance so any help or ideas on where to start would be very much appreciated.

thanks
Simon

Rider · 09-12-2007, 5:56 PM

Maybe your engine revs pick up - the rev counter sensor,( I can not remember the proper name) is not functioning properly.

I had an NSR that the cables to the rev sensor by the "flywheel" where breaking up, which led to a lot of misfiring and sometime the bike just going dead. After a while it would start again, no problems...

I would suggest you check the cables/connectors to the engine speed sensor and maybe cam pulse generator if there is one on your bike....

Good luck,

BDA116 · 09-12-2007, 9:39 PM

Check the fuel pump.

Rider · 09-13-2007, 3:21 PM

Quote:

Originally Posted by BDA116

Check the fuel pump.

+1 Sometimes the simplest is the best answer...

lanbrown · 09-13-2007, 3:43 PM

I don't it is the sensor as he said it happens in any gear, which would make the RPM's different. It is limited to 40MPH, which complicates things.

What mods are on the bike and any recent service/additions?

SiKamon · 09-13-2007, 6:23 PM

hey guys thanks for all the advice, as soon as i took the petrol tank off it was obvious what the problem was a hose had come off the air intake.

i've uploaded a picture, number 5 had come off number 3

thanks again for all the suggestions i really appreciate it.

Rider · 09-14-2007, 1:15 PM

Since I do not have an F3, can please someone tell me what these parts (3, 15) are? I can not understand from the diagram?

BDA116 · 09-14-2007, 3:54 PM

The F3 has a dual stage DAI system that changes the way the airbox breathes over 25 MPH. Part 3 is just a breather filter while part 15 is a valve that directs where the air goes.

LITEITUP · 09-14-2007, 4:21 PM

Thats a crazy thing about the F3 all those hoses NEED to be hooked up properly or the thing isnt going to run above 35-40mph. I was gonna tell you to check those but glad you figured it out. I had the same problem years ago.

BDA116 · 09-14-2007, 5:06 PM

You can completely remove the whole system by just hooking two of them together.
When I gutted the system on my first race F3 it did that. It was bad, get out on track and into third or so and suddenly it was like riding a bronco. Pull in, check things, go back out, same thing.
Finally found someone else in the pits that had done the same thing and showed me which hoses to connect.

It was a couple years later that the same behavior started again, this time after no mods to the bike. That was the fuel cutoff relay going bad and not powering the pump. Wired it directly with a different source and all was well.

Two different fixes for the same behavior. But both simple and cheap.

cbrbeanbag · 05-05-2008, 11:40 PM

after checking for the same problem i found missing 14 and forward in that pic to be my problem. would still like to know what you had done to hook the two together.