Suzuki GP100 won't rev when more than 1/3 of throttle

[cb1rocket]

Hi all

Again more GP100 problems.

The bike basically won't rev above 1/3 of throttle. The bike happily revs highly at below 1/3 throttle but anymore than 1/3 and the bike sputters and dies. I have cleaned the carb (not a great clean but will do properly with an air compressor later, but have taken apart and use carb cleaner).

Choke cable and throttle cables are fine.

Its really annoying as the bike idle really well, but when you want to set off it can't pull my weight as it won't power up any further 1/3 throttle - help!?

[27cows]

Decoke the baffle, for starters, and change the plug.

If your GP is a points model, may well also be worth checking the timing.
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The RXS100: vehicle of choice for Chuck Norris

[cb1rocket]

Thats what I don't get. I can rev the bike to 7k rpm freely (and more if I wish) when under 1/3 throttle. Its a points ignition so will have a look at that. My air filter is missing too, but the air housing is there. Funnily enough I can't see why it has an air filter as the carb doesn't even connect to it! Its an expose carb mouth which is mounted to the side of the engine.

On another note, i can get the bike to pull me when below 1/3 throttle quite well, but as soon as you approach a hill, you need more throttle obviously. Basically the bike is unrideable.

The carb has been tampered with before. Is the pilot jet setting likely to affect above 1/3 throttle opening? I thought that was for slow running only (ie tickover speed).

Cheers

[Blau Zedong]

[cb1rocket]

oh i see. So i wondered why there holes on the bottom of the engine side cover that covers the carb?! I thought that was the air inlet. Weird design.......

Anyhow any more thoughts as to why i can only open the throttle to 1/3 without killing the engine.

I might have to youtube this......

[Blau Zedong]

[cb1rocket]

cheers blue will find some suitable foam as the original is missing. Had a tinker with the pilot jet screw on the carb mouth and reset that back to 1.5 turns as the book says. I can now rev freely past 1/3 throttle but when i let the clutch out it doesn't like to pull that well. I also put a bit of choke on and that has help dramatically. So i know the engine is running quite lean.

So i will conclude with getting the air filter sorted. And replace the carb side cover and try again.

Still need to check the timing, but I thought these were fixed? And that the only thing that will poor sparking is the contact breaker system.

This is my first experience tinkering with a points model, all my bikes except this has been CDI ignition.

[gearboxkart]

if the carbs on the side of the motor i take it its a disc valve engine (sorry not familiar with the gp100) if so you may need to check the valve tining of the disc, i used to run rotax engines in my karts which were disc valve and they were a pain in the arse.
Also had an rd400 which did the same as yours, when it was just started and cold it would red line within 5mins thats it max 4000rpm turned out the previous owner had changed the carb jets and were way way oversized, changed to std size jets and all was cured.

[cb1rocket]

I did check the main check size and was the correct size.

I'm going to go along with Blue's opinion and get the air filter sorted. I just hope the previous the owner hasn't bugger about with the timing/disc timing!

[Blau Zedong]

Assuming the GP100 is a bit like the earlier A100 then the disc valve is keyed in place so I wouldn't think it the problem.
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18:54:48 Rob Fzs: jews don't give away stuff for free

18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

[gearboxkart]

so are rotax's but they still move for adjustment and bear in mind 16000rpm does give them some grief lol (rotax that is not a gp100), and theres also the possibility some1 has took a file to the disc and over done it !

[cb1rocket]

Thanks to Blue's suggestion and everyone else, I have bunged in a car cleaning sponge for the time being in the air filter housing and reset the fuel mixture screw. Ordered a genuine filter element mesh for the foam to wrap around.


Its also has passed it MoT

Now I just need to give the bloody thing a good service.

New plug and decoke the baffle.

And re check the carb, I think the previous owner really has buggered it about.

I get 40mph on the flat and a struggling 30mph up hills and it does feel it wants to die as I step down the gears.

The power is rather flat until you get to 7k rpm so it does suggest to me that the carb is buggered? Also you have to change gear until you reach 9k rpm giving me 2k rpm range of power, pah!

Cruising is a pain as i'm on full throttle at 5k rpm to maintain a decent 35mph!

Hints?

Cheers

[Robby]

[cb1rocket]

will do, just got hold of an original filter mesh and foam wrapped round it. Will give that a go in the morning and see how that performs.

Although my money is on something else...........

[smookz]

hi . . . . . . .

I know this is an ancient thread, but did you ever resolve the issue OP?

Have veeerrrrry similar issues, starting to suspect the points . . . Although i have an air filter Carb has been cleaned thoroughly as well, all jets etc.

Curious . . . .

[Pete.]

My dad's bike was the same. Would barely rev and had no power. I loosened off the exhaust at the cylinder head and it made a lot of noise and revved easily, so I removed the silencer and de-coked it. Good as new.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[bikenut]

:D does the xhaust "fizz"???????????? ie : blocked?? also check exhaust port...........eliminate that first as its a 2 stroke.......

[cb1rocket]

[smookz]

Ooooooh, timing. I keep coming back to this in my fault diagnostics.

Bummer, don't fancy trying to sort it, looks scary! Fair play on fixing it, thanks for the reply

Viva lé 2smoke!!