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Soften My 280

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does anyone know if i retard the timing on my 280 gasgas it will softening it a little if so does anyone know how i would do this

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Yes it would but a 280 is a firey beast, why dont you try a base gasket, flywheel weight or slow action throttle.

If its still too fiesty, buy a 250!!!!

Plenty of good 07's around, just picked up a beaut for

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does anyone know if i retard the timing on my 280 gasgas it will softening it a little if so does anyone know how i would do this

What year and model is your 280?

Jon

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its a 2007 model

There are a couple of things I've done to my 280 and other than the special long headpipe I made, should be fairly easy for you and all mods are reversible if you don't like them. The stator plate is fixed on the Pro and although you can slot the Hall Effect sensor (magnetic trigger) mounting bracket, you may want to try that as a last resort.

The black tube Domino helps a lot. It has a lower ramp that pulls less cable per degree of turn of the throttle tube.

Boyesen dual-stage reeds smooth out the low RPM delivery.

Lowering the gearing often helps. I tried the 10-T countershaft sprocket, which helped but now run the stock 11-T countershaft and a 44-T rear

sprocket, used for the 125/200 models. Helps me to not get where I'm going before I'm ready. The Montesa 4RT guys love the 44 and have scooped up much of the GasGas dealer stock around here. I think the 07' comes with a 43-T rear (my 02' came with a 42-T) and you can get the GG sprockets in 41-T, 42-T, 43-T, 44-T, 46-T and 48-T, so you might want to try a 44 or maybe even a 46. I like to use the 11-T front as I think the 10-T coils the chain a little too much for the 520 chain.

Straight race fuel will soften the low RPM response by lowering the IMEP (Indicated Mean Effective Pressure).

Jon

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I've just gone from a 2002 280 to a 2008 250 and the softer bottom power is just what I needed for better traction. I had a 10tooth countershaft and slow throttle on the 280, but the 250 with an 11tooth and fast throttle is sweet. Its easier to control the lowend power and even my wheelie balance distance instantly doubled.

Jon,

I've only got a few hrs on it, but with premium pump gas (91 octane in my area) and the ignition in rain mode, when pulling higher rpm it sounds like its pings a bit. In sunny mode, it doesn't sound near as bad. It looks like its got a thinner base gasket. Have you noticed this ? Should I try a thicker base basket or a head spacer ?

btw - I changed to the 120 mainjet that also came with it and the plug looks good. It was shipped with a 118 in it and looked a bit light. I'm also using 50:1 Ipone at the moment and would go back to 80:1 like I was using on the 280 but the manual is now suggesting 2% (50:1) Whats your view as this would also richen the fuel mixture ?

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Jon,

I've only got a few hrs on it, but with premium pump gas (91 octane in my area) and the ignition in rain mode, when pulling higher rpm it sounds like its pings a bit. In sunny mode, it doesn't sound near as bad. It looks like its got a thinner base gasket. Have you noticed this ? Should I try a thicker base basket or a head spacer ?

btw - I changed to the 120 mainjet that also came with it and the plug looks good. It was shipped with a 118 in it and looked a bit light. I'm also using 50:1 Ipone at the moment and would go back to 80:1 like I was using on the 280 but the manual is now suggesting 2% (50:1) Whats your view as this would also richen the fuel mixture ?

The 250 is a sweet bike, they are still kinda rare here but once you ride one it's easy to fall in love with the power delievery. 91 Octane is just about tops for pump fuel where I live also. As I remember, the recommendation is for 92 Octane, but I would think that a "good" 91 should work well if the jetting is correct. As pump fuel octane is an average of Motor Octane Number and Research Octane Number (R=M/2) all pump fuels are not created equal and theoretically, pump fuel with a higher MON that results in the stated average would be a better fuel for our use as the MON research is conducted under more "severe" conditions.

A 120 main sounds fine, especially during break-in when frictional heat will be a little higher (I run 118/38 jetting in my 280, but that may be a little "rich" for other 280's and each engine is different). You might want to raise the needle a notch or two (lower clip) to try to clear up the ping as I'm assuming that the "higher rpm" is around mid-range, where the needle setting would have an affect. The base gasket will look thin and I wouldn't worry about it. Gaskets of differing thickness will be used at assembly to set the squish clearance. I don't see any problem with sticking with the 50:1 during break-in (as for premix ratio, you can always change later, within reason, to what suits you) and not make any decisions about gaskets or spacers until you get some solid hours on the bike. It will usually run better (and smoother) as time goes on so your performance baseline will evolve (and any modification decisions during that time will be static) during break-in. Most riders I know are very happy with the 250 without any modifications.

This is just "top-of-the-head" stuff and I'm sure that riders that have more experience with the 250 can give you some better advice.

Jon

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Thanks Jon. As it says you are a site supporter, I was assuming you are Jon Stoodley ??

I would have tried lowering the clip a notch, but it came with it 1 notch lower than the middle already.

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Thanks Jon. As it says you are a site supporter, I was assuming you are Jon Stoodley ??

I would have tried lowering the clip a notch, but it came with it 1 notch lower than the middle already.

Yep, that's me, but don't tell anyone, my reputation is bad as it is....

I wouldn't worry about lowering the clip (meaning, go ahead and do it). Each engine is a little different and the same jetting you are running might not work as well for another bike. Same for the air/fuel screw adjustment, it's not a static number of turns but really needs to be set for that specific engine running under those specific conditions.

I was riding with a friend today, (helping set up next weeks Trial) that also has an 07' (280, not 250) and he had been having some jetting problems and I machined a #120 jet for him last week for him to try (118s were the largest I had). He said the 120 fixed the jetting problem and the bike runs great. This was a little surprizing as a 118 I run in my 280 would be a little rich for some other Pros. I don't know if this is specific to the 07', but some apparently run better with the 120 and maybe yours is one. I'm not aware of any 07' features that would dictate that jet size, which is larger than "normal" for most 280s.

Cheers.

Jon

Edited by JSE

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