GSX-R 250 Throttle problem

[Hitman]

When i start my bike (1989 Suzuki GSX-R250) it takes about a minute before i can use the throttle. It idles and wont rev at all. If i let the throttle go completely it dies. This also happens occasionally when im starting in 1st gear from a stop, i apply some throttle and i get nothing, i can wind it right around. Sometimes it will kick in and rev a few seconds later other times it will take 15-30 secs.

Anybody got any ideas?

Cheers
Andrew

[Posh Tourer :P]

Are you using the choke? Does this only happen when it is cold?

It sounds like a fuel mixture problem to me...

[Hitman]

It happens whenever it hasnt been used for an hour or so. Yeah fuel mixture was my guess too. When it will finally rev when starting it spits out a bit of smoke.

[riffer]

It happens whenever it hasnt been used for an hour or so. Yeah fuel mixture was my guess too. When it will finally rev when starting it spits out a bit of smoke.
Its running way rich Hitman. Check your choke cable - when they get old they tend to stick and don't go back, leaving the choke partly on.

Also, your plugs could be shot too. Or, you could have an old, dirty air filter thats messing with the air/fuel mix by not allowing enough air in too.

[Artifice]

or possily shite in the carby. maybe a sticky jet. give er some tlc.
i miss my old gixxer 250 :(

[Marknz]

It's a Suzuki... that's your problem :devil2:

[Magua]

Yamaha isn't much better, I have a laggy throttle and petrol hungy bike. Could be many things. Given it an oil change along with filter, next thing is the airfilter.

[Hitman]

Which fuel am i surposed to be using? I put 91 in it, but i think i was surposed to put 96 now. Could this be the problem?

[Magua]

Why are you supposed to use 96?

[Posh Tourer :P]

Which fuel am i surposed to be using? I put 91 in it, but i think i was surposed to put 96 now. Could this be the problem?

wont make that much difference.... 91 will do for your bike

[riffer]

Why are you supposed to use 96?
To eliminate pinking, or pre-detonation.

Detonation (also called "spark knock") is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.


Mild or occasional detonation can occur in almost any engine and usually causes no harm. But prolonged or heavy detonation can be very damaging. So if you hear knocking or pinging when accelerating or lugging your engine, you probably have a detonation problem.


The octane rating of a given grade of gasoline is a measure of its detonation resistance. The higher the octane number, the better able the fuel is to resist detonation. Most engines in good condition will run fine on regular grade 87 octane fuel. But engines with high compression ratios (over 9:1), turbochargers, superchargers, or with accumulated carbon deposits in the combustion chamber may require 89 or higher octane fuel.
How a vehicle is used can also affect its octane requirements. If a vehicle is used for towing or some other application where the engine is forced to work hard under load, a higher octane fuel may be necessary to prevent detonation.


If switching to a higher octane fuel fails to eliminate a persistent detonation problem, it probably means something else is amiss. Anything that increases normal combustion temperatures or pressures, leans out the air/fuel mixture, or causes the engine to run hotter than normal can cause detonation.

[Magua]

So how would I know if my 88 FZR would run fine with 96?

[Krayy]

Count me in there with my '00 VTR250. Coming up to first fill (damn the SWMBO for not giving me a free weekend yet), so I need to know if I should start feeding her 96 and stay there.

[riffer]

So how would I know if my 88 FZR would run fine with 96?
You probably wouldn't notice any difference at all in performance. Just in the back pocket.

Is the bike currently pinking? If so, is it pinking because the fuel octane is too low? Many things to look at first - if its tuned well, and still pinking under load there could be a case for higher octane.

My fzr750r pinked like crazy under acceleration when I first derestricted the airbox/exhaust without doing anything else. The solution was to go up in main jets as it was sucking in FAR too much air compared to petrol.

Look to replace your coolant as well Magua. A bike running hot tends to run lean as well. Your FZR should go fine on 91.

[Hitman]

Finally heard back from the mechanic, hes says its not compressing. and it will take about $600 in labour not including anything that needs replacing. What exactly does this mean? and is it something i could do myself with a workshop manual and a bit of time?

[Blakamin]

Finally heard back from the mechanic, hes says its not compressing. and it will take about $600 in labour not including anything that needs replacing. What exactly does this mean? and is it something i could do myself with a workshop manual and a bit of time?
Top end rebuild.... sounds like your rings are...F&^%ed

[Hitman]

What does it cost for new valves and rings?

[FROSTY]

The most common compression issies with the gsxr250 is either -badly set tappets or worn tappets needing a valve grind. Its much less common for the problem to be the rings. -Ya valves have heads not much bigger thab a 5x piece and have to open and close sometimes 14000 times a minute.
That said I would follow celtics advise first.
Id suggest hauling the plugs out and check em for color-if 2 ar black and wet/sooty and two are a good color then you'll know which cylinders are at fault. I'd as a matter of course toss a new set of plugs in.
Give the carbs a bbloody good clean out -blow out ALL of the jets and make sure the choke is operating properly.
Id maybee suggest winding all your mixture screws in tight then back em off 1.5 turns.
good luck dude

[Hitman]

Cheers XJ/Frosty

Just took the air filter and carb off, will check the carb out tomorrow, and maybe take the engine block out, c how the carb goes first.

How can i tell if the chokes stuck on?

I got the pressure readings from the cylinders, 65, 70, 65, 60 PSI, less than 1/2 of what they should be.

[Kickaha]

Cheers XJ/Frosty

Just took the air filter and carb off, will check the carb out tomorrow, and maybe take the engine block out, c how the carb goes first.

How can i tell if the chokes stuck on?

I got the pressure readings from the cylinders, 65, 70, 65, 60 PSI, less than 1/2 of what they should be.

Who did the compression test was it you or the shop?
It should be performed with the engine warm and full throttle(well thats how I was taught) and after its checked if you squirt some oil down the plug hole and recheck it the reading goes up then it indicates worn rings if there's no changes it's valves

[Hitman]

A shop did it for me, i asked if it was the rings or the valves but he just said i wouldnt know till i got the head off. Also i think its pretty common for 250's to get the valves covered in carbon and loose a good seal that way. Borrowed an engine winch of a mate today and well take out the engine block tomorrow. It wont cost me anything to check the valves anyway cause im doing it myself.