tyre pressure and fuel tap

[ORourke]

Hi,

I introduced myself about a month ago when I bought my 1989 GSX400E (GS400E) twin. The weather has finally turned so I am going to have the opportunity to take a ride here and there, I have also ordered an owners manual but it has not yet arrived. Meanwhile I have two questions:

Does anyone know the appropriate tyre pressures with the bike running the original tyre size.

This is a little embarassing, but my first three bikes all had fuel taps with 'off' - 'on' - 'reserve' positions. The suzu has 'PRI' - 'ON' - 'RES'. Now I take it that this bike has a vacuum tap, so that PRI is prime, and allows fuel to run freely, ON is going to be controlled by the engine vacuum, RES is self explanitory. If this is right then when I park the bike I should leave the tap in the ON position.
Can you confirm that this indeed correct?

Thanks,

Tyrone

[tkent02]

Hi,

I introduced myself about a month ago when I bought my 1989 GSX400E (GS400E) twin. The weather has finally turned so I am going to have the opportunity to take a ride here and there, I have also ordered an owners manual but it has not yet arrived. Meanwhile I have two questions:

Does anyone know the appropriate tyre pressures with the bike running the original tyre size.

This is a little embarassing, but my first three bikes all had fuel taps with 'off' - 'on' - 'reserve' positions. The suzu has 'PRI' - 'ON' - 'RES'. Now I take it that this bike has a vacuum tap, so that PRI is prime, and allows fuel to run freely, ON is going to be controlled by the engine vacuum, RES is self explanitory. If this is right then when I park the bike I should leave the tap in the ON position.
Can you confirm that this indeed correct?

Thanks,

Tyrone

All correct about the fuel tap, what tires are you running?

[Billy Ricks]

Proper tire pressure is determined by the difference between hot and cold tire pressures. You want to see a difference of 10%, about 3 lbs, more pressure hot vs cold. Too little gain and you're running too much pressure which doesn't allow tires to heat up properly resulting in less traction. Too much of a gain and you're running to little air heating up the tire too much.

[ORourke]

All correct about the fuel tap, what tires are you running?

I've got Brigestone Mag Mopus L303 front (3.00/18) abd Mag Mopus S714 back (3.75/18)

Thanks,

[Nessism]

Those sound like the original tires for the bike. If so, do not ride on them farther than around the block at low speed. 30 year old motorcycle tires are not safe and need to be updated to something new- less than 5 years old or so.

In terms of typical tire pressures, old school tires typically take roughly 28 front and 32 rear (either up or down depending on usage). I have some modern Avons on my 850 and they call for 33/40.

[salty_monk]

That's interesting Ed, have always run my Avons at 28, 36. Where did you get your info on the Avons? Maybe I'll change pressure.

[Nessism]

That's interesting Ed, have always run my Avons at 28, 36. Where did you get your info on the Avons? Maybe I'll change pressure.

It's on their website. Not sure how critical this is though. I think your pressures are fine considering you are not exactly a heavyweight.

[BassCliff]

Hi Mr. ORourke,

I agree with Mr. Nessism, but I would ride on those tires just far enough to get to the tire shop and have them changed. Have a gander at the tire information that I've collected on my little BikeCliff website. Please don't ride around on 20 year old tires. They may have tread, but the rubber is compromised and could fail catastrophically.

You've got a great looking bike. It deserves some new shoes.



Thank you for your indulgence,

BassCliff

[salty_monk]

It's on their website. Not sure how critical this is though. I think your pressures are fine considering you are not exactly a heavyweight.

http://www.avon-tyres.co.uk/motorcycle/?page=fitment&method=fitments&manufacturer=57&id=1314&model=&year=1980

Hmm found it, you have to search for their recommended tyre first to get the info.

36 & 42 PSI recommended for the 77-80 1000E (prob ok for the G too) so maybe I will up the pressures a little to see what happens.

Dan

[C.V.]

Broke my rules and had the local sheisters change my rear again, they put 52lbs in the rear tire! time before that they left the valve stem loose, and I was down to ten in 2 days! Running steady now at 40/32.
Hi max's BTW

[ORourke]

Thanks for all the answers.
The tyres are not the originals, the bike is a german import, and in germany bridgestone still sell those very same tyres new. However I did take a look at the serial numbers, and from what I can see the rear tyre is 6 years old, and the front one 9 years old, so not quite as tragic as 30 year old tyres.

I am looking for a new pair, but having a little trouble finding a pair in the right size

[trippivot]

by yourself I say 36 front and 34 rear

with a passenger 40 and 40. bias ply tires with tubes? yep

under inflation is chronic problem with M/C tires