Major Bog, Hanging RPM's MM700

L

Ltprose

New member
Joined
Dec 3, 2008
Messages
18
Age
41
Location
North Pole, AK
Hey All,

I'm trying to help my buddy troubleshoot his 01 MM 700. It is in pretty rough shape and heavily modified. No radiator, clutched, modified head, drilled out airbox, and I'm sure a whole bunch of other parts are missing.

It starts fine but idles at about 3,000 rpms. The choke is necessary to start it and is a little sticky, but once it is started the choke has no effect on how is runs. I checked the choke cable and made adjustments, I also loosened the throttle and oil cables to the way they are supposed to be, and it made no difference.

No matter what, this thing idles at 3,000. Hit the throttle and it bogs heavily, but it still hangs at 3,000 no matter what feathering technique is used. Sled will not move. Brakes are free and track spins when pushing it. Compression is 130 on all three. Plugs are black black black! Probably jetted for the upper atmosphere and we're at 1,000 in interior Alaska. Aparently it has always idled at 3,000 since the mods were done, but the bog is new. I pulled the carbs and cleaned them and it made no difference. Needles are set rich.

I don't need it to run great, being perfectly in tune. It's a beater, I'd just like to be able to make it move. :o|
 
Did you look/adjust the throttle cable? Maybe the TORS system is kicking on due to the messup idle.

Can you adjust the idle down, and have it idle at a lower RPM?
 
The throttle cable is set up correctly and has a few mm slack in it like it should. The "limiting screw?" on top of the throttle assembly was screwed out so much it wasn't even touching, so I'm not sure why it would be idling that high. I readjusted for minimal contact with no difference in idle. The fuel screws are set at 1.75 out, but since it idles so high that probably doesn't matter.

How else would I go about lowering the idle?
 
Take the air box off and look at the front of the carbs, make sure the slides are closed at idle with the idle screw loose like it is. If there closed, there is an air leak. Hose clamp on the carb to the motor, carb boot cracked or bolts loose, gasket leaking or even a case leak. I dont want to scare you but if the carbs are closed and it idles high it is definetly an air leak (Extreamly lean condition). You can start it up and spray some carb cleaner (lightly) around the carbs and such if the idle changes your getting close to the leak. Keep looking, Fix the lean condition first then work on the bog. Also check the pulse line going to the fuel pump, it may have a crack in it.
 
Found it

Well,

Minus the fact that this sled is (fill in the blank) rigged, I finally got it acting within reason.

Throttle return spring had unwound a half turn, so I tightened that up and now the carbs actually close. The tors switch and idle control screw were both broken. So they have been removed/replaced. TORS now bypassed which got rid of the bog and high idle. Nominalled the jetting for a little closer to the conditions here so now the plugs are a lighter shade of black. Also found a couple cracks in the carb boots and fixed them with some JB weld. Hey, the guy I was helping had a budget, that budget happened to be zero (Unlike a certain president I know) :bash:

Thanks for the assistance.
 
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