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2010 GasGas 4stroke

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A guy wants to trade me his GG 250f (has the yamaha wr250 motor) for my 2007 KX250

Heres the problem: it has a really bad bog to it. He says its a jetting issue but im not real familur with 4strokes i have only ridden 2strokes my life. It has a Boyseen pump on the carb and i was thinking maybe its starved for fuel??? When cold it takes 12-15 kicks to start. When sitting it idles fine and if you twist the throttle from idle it boggs and will die if you dont let go of the throttle.

The bike needs bearings,fork seals a battery,pegs and little misc things.

I know little about GasGas and even less about 4strokes and would like some advice.

Thanks!!

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1. Check fuel tank vent.

2. Take off fuel line from carb and make sure plenty of fuel is available to the carb from the tank.

3. Pull the carb and make sure that there is fuel being squirted when the throttle is opened.

4. Take carb apart and pull all of the jets. Make sure that all of the passages in the carb have no restrictions. Carb cleaner, compressed air, and small wire could be required to remove clogs.

This should be a pretty easy fix. Keihin Carburetors are very easy to work on. It sounds to me like the pilot jet is clogged. Or, the Boyseen pump is not set up correctly.

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Perf wise you might be dissapointed coming of a two stroke 250 mxer.The gg is an very good trail bike but a yzf might be a better choice if your thinking going 250 four stroke and are a serious rider. P.S, I've riddin all three.

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how can it be that much different, it's a yamaha 250 motor?

I would much rather have the yamaha motor in the gasgas frame

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Im buying a 4stroke on purpose it will be my son's 1st "big boy" bike. He is going to learn on it next year and i will give it to him in a year and buy myself a new bike. The Kx250 is way too much for him to ride next year

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how can it be that much different, it's a yamaha 250 motor?

I would much rather have the yamaha motor in the gasgas frame

Ok so you've got the I own a gasgas their the bestest I'm gonna get all defensive :lol:

Yam. Much better forks.no contest

Yam YZF. Lighter weight, no contest

Yam Parts pricing and availability better, no contest

YZF mill much more power than WR engine, can be somewhat remidied with exhaust cam swap.

Complexity, Yam easyier to work on than GG, no contest.

I also own a gg, my fifth one the latest a 011 gg xc 250. My buddy Flash has, and I've worked on as well as riddin his 2010 gg250f and his kids 2011YZF 250, no contest!

The OP has asked for opinions I'm assuming he implied educated opinions based on real world experiance .For a Kids first real bike ,sure go for it if you can make the deal work.

Edited by widebear

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I own a yamaha and a gasgas two stroke, I have no brand loyalty. Forks on both bikes need a revalve to work, the gasgas forks are better to start with offroad, yz forks offroad are terrible harsh

any weight penalty is totally worth it for gasgas handling

I do not think yamaha is any more or less complex, why do you say this? in my experience all the euro bikes are easier to work on, they simply things like airfilter access.

for parts pricing, motor parts are the same, obviously, wear items are also the same, the airfilters are from honda's, the brake pads are generic japanese MX pads, the bikes share parts with other brands, this makes sourcing parts pretty easy unless it's something like a frame, cant say I have broken a frame since a honda steel frame.

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I own a yamaha and a gasgas two stroke, I have no brand loyalty. Forks on both bikes need a revalve to work, the gasgas forks are better to start with offroad, yz forks offroad are terrible harsh

any weight penalty is totally worth it for gasgas handling

I do not think yamaha is any more or less complex, why do you say this? in my experience all the euro bikes are easier to work on, they simply things like airfilter access.

for parts pricing, motor parts are the same, obviously, wear items are also the same, the airfilters are from honda's, the brake pads are generic japanese MX pads, the bikes share parts with other brands, this makes sourcing parts pretty easy unless it's something like a frame, cant say I have broken a frame since a honda steel frame.

Any serious rider will need to replace the base valve pistons on the gg zokes to get enough oil flow for a stack to work properly, kyb forks dont need expensive pistons and will go longer between oil changes because of the cc designe and better quality control.

Replacement yam plastic should be around $100 for everything excluding graphics. GG relacement plastic with graphics is around 450.00 . i've seen polisport kits but cant seem to buy anything besides blue.

The gg fuel tank is purpose built for the thumper but still uses the hokey sheet metal screw fasteners for mounting the shrouds to the tank. It's not a matter of will, but rather of when the holes get damaged by stripping, to the point were you need to relace the tank, prob not cheap and for sure not available used, there are fixes but none of them permanent enough.

Weight wise the YZF will be lighter than the gg. the wr engine is supposed to be 15 pounds heavier than the mx version according to a yam forum stickey somewhere on this site. The gg has all kinds of lighting and wiring, battery, and such.

The Yam is a purpose build race bike where as the gg is a hybrid based on a 125 chassis and off the shelf suspension components, triple clamp and fork leg offset and is not engineered to world class for that engine , chassis combo.The yam will handle better than the little gg in most situations.

Fit and finish on the Yam is very good, gg not as good.

Resale value no contest.

The gg is a nice little bike and I would'nt mind having one as a play bike but not as my principle ride, for sure.

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To the op, the bog is likely due to the carb needing to be cleaned (especially the pilot circuit) however tight (adjustment) valves can create a bog and hard starting. Does the bike have an aftermarket exhaust? Just putting a slip on muffler on my 426F creates a horrid bog that requires re-jetting and altering the accelerator pump timing.

Sounds like it will be a nice bike with a little bit of work. If it doesn't smoke or make noise I'd probably jump on it. I would not ride it until you are certain the valves are adjusted properly. Pretty easy to do once you figure out how. Should be an excellent project and learning experience for you and your son :lol:

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