what fuel? hard starting

[fergie]

my 87 fzr 750 has suddenly got very hard to start, it fires but wont run properly until warmed up which takes alot of effort. once it's hot it runs loike a dream.

i have just replaced the plugs 2 weeks ago, (whats the correct gap?)

someone said it may be the combination off very cold weather and poor petrol, i use 91.

but the bike is garaged at home and outside at work. my questions are;

what gas do you guys and gals use? (street use)

have you had any problems with fuel? should i use/try 96?

any other suggestions?

thanks

[fergie]

one thing i forgot to mention was that when i pulled the plugs i found that they were dry and sooty,

what does this tell me?

cheers

ferg

[wari]

It tells you they were dry and sooty ... I dont know for sure though , but an uneducated guess would say running too rich or wrong plugs.

BTW , I use 96 from Gull.

[Antallica]

Did it start before or after you changed the plugs?

I use '96 from BP.. burns better.

[Marmoot]

If it's sooty, it's too rich.

Too-rich mixture is just like "wet air". They're harder to burn, especially when the combustion chamber is still cold. Once it is warm enough, the combustion is sweet.

[SPman]

The trouble with the current unleaded petrol is that it is harder to get a good plug reading in general road use, because even when all is well, the plugs tend to be sooty.

[fergie]

Good advice, thanks.  the bike started fine after i put the new plugs in. i only had problems starting on monday morning, i put gas (91) in on sunday in huntly(shell) the bike was sweet on the run back to jaffaland.

i think i will give the plugs a clean and try some different petrol  (GULL 98)

a friend talked to a yamaha mech who said i may need to replace the valve shims but i dont think it's that serious yet! apparently the fzr is hard on them and need to have them replaced every 40,000 ks

once again thanks for your advice and comments

ferg

[What?]

Originally posted by fergie
a friend talked to a yamaha mech who said i may need to replace the valve shims but i dont think it's that serious yet! apparently the fzr is hard on them and need to have them replaced every 40,000 ks

Methinks your friend might have got the wrong end of the stick, Ferg. FZR's are famous for having a very long service interval for valve shims - they only need checking every 40K, and it's odds on that they will not need replacing - or not all of them. Compare to the average big Japper from the early eighties; they had a service interval of 5K...

Anyway, he might have a point, but i think it unlikely that your valve clearance is the issue. Try draining the tank and refilling with some fresh juice. It sounds like you bought half a tank of goo.

[wkid_one]

Tend to agree with What's that it may just be shit in the lines if it an isolated case.

[SPman]

Coulda been bad fuel - I refueled at Te Kuiti once heading to New Plymouth, and ended up with a a 2 cyl. Trident for the rest of the trip!

My FZR750 did 85K  before I sold it and the last shim check at 72K showed no wear at all!

[Dave]

91 fuel is easier to burn than 96/98 so it wont be the grade-but like the other dudes said, could be a shitty fill.
Also might have some dirt under the needle valve in a carb causing to flood on one cylinder,iff your pulling the plugs out and they're sooty,its either because its been sitting idling with the choke on,or the carbs need attention.

[WanaGo]

Hey,

Im just new to the bike thing, but is it true that the BP 96/98 is better than other brands, like it burns just as well as 91, cos it has low benzene etc? Thats what I got told anyway.... BP 96 over the rest.....

WanaGo

[wkid_one]

If you are runnning 96 inner city - this can cause increases fouling of the plugs......apparently

[fergie]

well i drained the old fuel out of the tank and re filled with 96 from gull,cleaned and gapped the plugs.

it was a bitch to get her running as per the last few days but once warmed up it was fine.

i assume it would take a while to burn the gas that was in the carbs, the big test will be in the morning when it's cold?

will keep you informed

cheers

ferg

[What?]

Mate, I shoulda said - when you drain the tank, drain the carbs as well. If it still doesn't go right, then the carbs may have to come out for a clean. Could be some gunge preventing a needle valve closing, causing rich mixture.