Carburettor/Air Flow Issue

Hi All,

I have a strange issue with the T80.

It runs fine nearly all of the time but I have noticed that when I am scooting along and I head into a gust of wind or the wind blows across the road, the engine splatters and sounds like it is missing and lacking fuel. When riding under normal conditions, it then runs fine again.

I am running 98 octane fuel in it, it has the original airbox with a cleaned and oiled air filter but he only thing I can think of is the tube connecting the carburettor to the airbox might not have a good enough sealed fit.

Very strange. Anyone ever experience this?

Any ideas?

Regards, Frank.

Never had this problem myself, petrol should not be an issue as the Townmate will run on normal 95 Unleaded perfectly ok. Suggest you check the petrol is feeding into carb ok, maybe the diaphram in petrol tap faulty (new tap needed as no repair kit available) Try running on the PRI position. Also could be an electrical fault, bad connection, ignition switch (have you a bunch of keys or fob that catches the wind a momentarily turns off ignition) plug, coil, CDI unit etc. Dont think it has anything to do with air filter or connecting tube.
Sorry cant help further.

mine does similar things feels like its run out of go I put it down to wind resistance your nearly flat out a strong gust of wind blows slows you down same if you were on a bush bike,drive a long at 30 and you have loads of throttle in reserve but at 50 you hav,nt

JohnW wrote:Never had this problem myself, petrol should not be an issue as the Townmate will run on normal 95 Unleaded perfectly ok. Suggest you check the petrol is feeding into carb ok, maybe the diaphram in petrol tap faulty (new tap needed as no repair kit available) Try running on the PRI position. Also could be an electrical fault, bad connection, ignition switch (have you a bunch of keys or fob that catches the wind a momentarily turns off ignition) plug, coil, CDI unit etc. Dont think it has anything to do with air filter or connecting tube.
Sorry cant help further.

Thanks John, I'll try the PRI position on the way home from work in a little bit but I did notice it yesterday on the way home from work as it was quite windy in Sydney. On the throttle, it was coughing and splattering erratically, bad throttle response, very rough running, but out of the wind though, it ran nice and smooth. Off the start and under load it is normal, I don't experience this bahaviour, only when cruising and just on the gas, it bucks and kicks. Seems like it leans out the mixture and it starves it for fuel. Very strange.  

I did as advised and I must say it did run slightly better but the symptom was still evident but not as severe. Could it be the fuel tap?

3hundredspartans wrote:I did as advised and I must say it did run slightly better but the symptom was still evident but not as severe. Could it be the fuel tap?

Could be if the diaphram is split so not creating full vacuum

Well, I did put on a new fuel tap and it was slightly better for a while but it was back to the same behaviour today commuting to work. It is very strange. It bogs down for a second as if it has no fuel when I apply the throttle while cruising, but as I apply slightly more throttle it then all of a sudden powers on. I will have to try another carby. My suspicion is the butterfly shaft bushes are worn and it is sucking in air from there. Determined to get to the bottom of this as it is a pain to ride.

"bogs down" also referred to as "bogging" check your pilot air screw setting

More likely to be the accelerator pump (seems similar problem to Barker's) Check that the setting is correct for the accelerator pump linkage (should activate at 1/3 throttle) also that the pump plunger is going up & down smoothly & that petrol is coming out of the spray tube (just in front of carb slide), you will need to unbolt carb from manifold to check this. There should be a squirt of petrol when pump plunger goes down. (See page 81 in Haynes)

Great, thanks guys, will get onto it tomorrow.

Thanks for your help gents! Made an adjustment to the pilot air screw and accelerator pump and the T80 purrs like a kitten now. Adjustments made were only slight but geez, it makes all the difference. Thanks again.   

Good .
let us know how it runs in crosswind now .

The issue is non existent now, cross winds, down winds, whatever wind there is. Thanks again!