650sx bogging on take off

[booski]

I have a 87 650sx with duel cooling full aftermarket exhaust and 44mm mikuni. It starts fine every time but when I go to take off it bogs for about 15-30 seconds before it shoots off like a rocket. It runs good as long as I am halling tail but when I slow down its starts to bog again. It seems like too much water is running into the exhaust when it is not running. If any of yall could help me I would greatly appreciate it. Just bought this thing friday under the impression it ran like a top.

[TOR*P*DO]

Re: 650sx bogging on take off

it sound slike it is lean on the lower end.
turn out the low speed screw 1/4 turn (first note how many complete turns you are at on the carb and record)
and see if that improves it

[booski]

Re: 650sx bogging on take off

alrighty, I'll try it. Is there a certain temperature range these things like to run at? I've got a temp gun I use to tune my r/c cars with. I didn't know if that would work on skies too.

[TOR*P*DO]

Re: 650sx bogging on take off

not really and hard to measure combustion temp due to raw water cooling

[Hill858]

Re: 650sx bogging on take off

You know it could be too much water running through waterbox. How are ur water lines runs?

[booski]

Re: 650sx bogging on take off

Ok, I took the ski to the test pond and set the carb to default settings and still bogged, tried leaning and richening the lowspeed all the way to 1/4 turn in each direction, still bogged. also messed with the high speed needle a little. no improvement. however i discoverd it runs better with the hood off, and the exhaust is dry piped. any ideas before I tear into the carb?

[booski]

Re: 650sx bogging on take off

I rebuilt the carb and took the ski back out. It's still bogging on the low end. It seems to be loading up with fuel when I slow down. It runs better without the flame arrestor. please help.

[twalker8204]

I had a pretty bad exhaust leak recently and would choke it out and just bog like crazy. I would check to make sure your exhaust/couplers are all tight and that they aren't leaking. Even wrap in heat tape for now to make sure it isn't a leak

[booski]

Re: 650sx bogging on take off

I already checked for exhaust leaks. Whole exhaust system is sealed up tight.
Thanks for the reply though. I am really starting to get bummed. Im going to try the ignition system next anybody have tips on checking the stators and what not?

[alphamale3]

Re: 650sx bogging on take off

Im not 100 % sure but I wouldnt think the electronics would have anything to do with your problem. But if it makes you feel any better my 650 is doing the same thing, did you ever figure it out?

[Element3488]

Re: 650sx bogging on take off

i also have an exhaust leak in mine, easiest way to test to take the hood off and run it if it runs better then you know you have an exhaust leak.

[waterhappy]

Re: 650sx bogging on take off

Get a flow control valve to dry out the water box, mine is set to 1/4 throttle and it made it stop lugging at low rpms. I too have fuel cooling.

[Auto86]

Re: 650sx bogging on take off

Im not 100 % sure but I wouldnt think the electronics would have anything to do with your problem. But if it makes you feel any better my 650 is doing the same thing, did you ever figure it out?

hi guys .. I’ve had the bog many times .. 2 strokes can fowl plugs.. I always rev it up a bit in place to warm it up before I drive.. I like to run it full blast at start and just before I shut down just to clear it out.. how’s your plugs?? They can tell you lots! While idling remove one plug wire ... if it stalls your only running one cylinder if it keeps idling try the other... you’ll hear a difference . Sometimes just plugs go bad.. any weeds in the grate??

exhaust leaks , clamps and gaskets, maybe replace.. try torque the bolts to spec .. look up your specific ski.. also the intake can also do this.. torque bolts or maybe even replace gaskets on intake manifold and carb .. sets are cheap on e-bay if your intake is sucking air from a bad or loose gasket it is leaning it out and robbing the gas. If gaskets bad on exhaust side your loosing your pressure which affects the combustion process of the two stroke .

carb settings could be off but if 1/4 turn don’t fix it I’d put it back.. you need to read your plugs to set the carbs.. at mid to top.. too dark too rich too light to lean I like my plugs to look light tan colour.

bottom end I like to turn 1/4 at a time until I hear motor start to rev up a little. Then drive slow with new plugs and check the colour.

gas lines... are they old ?? Loose , see lots of bubbles?? Maybe sucking air.. I had to replace a primer once after replacing all my fuel system ! Parts get old and start to fail . How’s you filter?? I like to run clear inline filters about 3 bucks and replace when I see junk inside. How’s your fuel pump ?? I had a bad diaphragm, again cheap rebuild set on e-bay
could also have a loose pulse line going to the pump making it weak or just not run nice ..

I also have had it bog if I didn’t pump my bilge often enough. I guess the water spray inside causes isssues.. weird to me because it’s all supposed to be water proof lol.

hope that helps guys!

[550headache]

650sx bogging on take off

When was the last time your carb was rebuilt/cleaned? The small filter in the mikuni SBN carbs will and do get clogged with crud. Will drive you crazy. If you haven’t already take the diaphragm cover and remove the small filter on the pump side. If its clean move on. If its dirty you might have found your problem.
Also, cut your plug wires back and screw them back in. This will ensure your getting good spark. Is it the same plug that goes bad every time?


Sent from my iPad using Tapatalk