flat / bog in mm700

My sled has a mid range bog when I first try to bring the rpm's up if it's not warmed up and you jump on it. Blows all sorts of smoke while the extra fuel
In the cases clears out. Do you get any smoke when it bogs? How do the plugs read, rich or lean?
 
Not really

The machine runs well, I may have misspoke. Anyway it does not really seem to bog bad, it is more like a dull or flat spot in the acceleration curve. The sled is really responsive, up or down. When you pinch the throttle a little before or after this range (5000-5500) it perks right up and gets on it. In this range it sounds a little blubbery, and is not as responsive. It is much improved since I started this thread, but still there.
To answer your question, I have not noticed a cloud of smoke or anything. And temperature does not seem to have a pronounced effect. I will try and keep watch next time I am out.
Thanks for your time and thoughts :letitsnow
 
If its happening when it's super cold do you have the carb hear on or off? The carb heat will have the effect of richening the mixture. Likewise if the carb heat Is on you may be too rich because of it. I believe 20 degrees is the poInt for carb heat iirc
 
ok

It has reed spacers and the notch. I was running carb heat the last time I was running it. It was also 0 deg F.
 
If its happening when it's super cold do you have the carb hear on or off? The carb heat will have the effect of richening the mixture. Likewise if the carb heat Is on you may be too rich because of it. I believe 20 degrees is the poInt for carb heat iirc
 
maxco said:
To be clear you are talking about the needle jet, or nozzle, not the needles. I do not have my Slp cheat sheet in front of me, but I recall a 499 Q-2 something. I will look at that. I have never changed the needle jet, I searched around about it. It is apparently a press fitting? Any words of wisdom on how to do this?

Also where do I go to get a decent price on needle jets? Thoughts?

The clutch is set per SLP piped (no spec on ported). SLP install sheet. they recommend for 7-10,000 ft, 100 deg or 1-9 for a black/silver spring. I need to clean my primary, so I will look at that later this week, and get back about the arms/ weights. I have them written down somewhere, but lost it. ;(

All help is appreciated. Thanks ;)!
Click to expand...

Yes, I'm talking about the nozzles. They are easy to change. Remove the bowl and main jet. Open the slide all the way and push the nozzle up from the bowl side into the venturi. May need a slight tap to get it loose, but very easy to do. I don't know of a good place to get them. SLP stocks them, but they are pricey.
 
Need to take apart carbs

I do not know what nozzles I am running. I tried to contact the guy who sold me the sled, and ask him if he changed the needle jets, no response yet :(. Anyway I called quite a few distributors, and no one has or can get these nozzles (499 Q-2). Sudco, Slp Parts unlimted, Westernpower. Mukunipower.com. Carberator parts. I may have a line on a set, but they may just not have updated there web-site. So I guess I am going fishing. I will open up the carbs as soon as time, and weather cooperate. Any help on finding 499 Q-2's?
:2strokes:
 
try shopping oem parts and you will find your needed nozzles. most the 600 triples ran a Q-2 and dont be surprised if you have staggered nozzles as typically the pto side ran a larger number. surprised slp didnt point that out. the old guys must be gone.

8CH-14141-52-00 for the Q-2's. simply substitute the -50 series for the appropriate nozzle. -58 for a Q-8, -56 for a Q-6, -54 for a Q-4 , etc.

map your carbs prior to popping dollars, you will want to adjust accordingly and allow an extra option for the pto side.

i highly doubt a nozzle change is in your best interest as the difference between the numbers is the hole diameter and/or the amount of holes. as mentioned, map what you have.
 
overlap

I was thinking this area could be at an overlap point. Maybe I am getting a little rich where the pilots/needles/mains hit. So I thought I would lean the pilot a touch 65 down to 62.5. See if that helps. They were at 62.5 before I did some engine work. I wanted to make sure I was too rich and tune down. If that does not help, I will try dropping the needles a shim. put 2 on top insted of one up, and one down. Small adjustments, very incrementally. I dont not feel this is a big problem, but is a bobble.
 
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Needle jets

I took the carbs apart. The jet needles are 798 8-4. And the pto is 798 8-8. Can anyone tell me is this stock? ;)!
 
if your calling jet needles what i refer to as nozzles, yours are stock for the sled.

pto would have the Q-8, center and mag Q-4's, according to my manual for the mtn max.

Q-2's across the board i believe for slp pipes. to my knowledge, the differences between the nozzles is usually the number of holes or the sizes of them, or both.

a larger inside diameter nozzle allows more fuel/air flow richening the circuits from mid to wide open throttle. fewer air bleed holes also richen the mid to wide circuit. larger air bleed holes in the nozzle will lean the circuit from mid to full throttle.

i never had a grasp on the numbering vs sizing, i counted the holes and checked the diameters with an old school welding tip cleaner set using the aformentioned affects as a guideline for fine tuning on grass. your air jet can also have an effect as well. far from being an expert, just used to dabble a bit as i had the parts readily available.
 
So tests today

I did some plug tests today. looked good accept the pto midrage pulg test. this past week I changed the needles, I shimmed them up 1 shim. It seemed to run better. I have a question though. The pto midrange looked rich. Is it ok to set needles differently. I think I should drop the pto needle back down 1 shim. To lean the pto in midrange, but leave the topend the same. And leave the others the same. Is this ok to do?
 
Thanks snow dad

I appreciate the information. From what you said it sounds like you do not think the nozzles are a big deal. Wether or not I change them. Is this correct? I was going to look into the OEM nozzles for the 600. Did not know if it was worth the time Sorry to be a pest.
 
sure, its ok to stagger the needle settings. Usually when it does a blubbering sound its fat, meaning rich and the increase in rpm makes it go away because the carb slide opens up more and the velocity of the air incoming changes the air/fuel ratio.
I would simply play with the needle settings. One thing to note is you can go in between the settings for example, the needles are set to lets use #3 as a example, that would be 3rd groove down with the steel clip with both washers under the clip, going to 3.5 would be 4th groove down with 1 under and 1 on top of the clip. However you can go in between that setting and go to a 3.25 setting by using the 4th groove down and both shims on top of the clip.

what I would personally do first is take the sled out and get it to do the blubber and hold it there for a little bit, reach over and hit the kill switch and pull the plugs and read them and the piston tops. So you know which way to go, dont be alarmed if its only 1 cylinder that needs changed, its common, some cylinders can run richer/leaner then others.
 
Sunday jan 27 plug

So this is a mid range, 34 deg plug. It looks rich,but safe to me. This photo is the center cylinder. The plug on pto was wet and black at both wot and midrange. So i am considering changing the pilot. I went richer on pto one size, as recomended by the yamaha manual, but the plug test is indicating it is to rich. Thoughts?

Thanks :letitsnow
 

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Midrange, IMHO, is influenced more by the needle position. Especially if the bog is from 1/2 to full transition. The testing I did, showed very subtle peroformance difference between the Q-2 and Q-4 in the PTO. When I ran this motor with the SLPs, I found that on my motor, I could get away with 2 sizes down from SLP specs on the mains at any altitude. I would venture a guess that you could possibly drop the needle on the PTO by at least 1/2 position for some testing. Mind you I was running BR9EYA plugs. Shouldn't make a huge difference as long as you are running a 9 range plug.

Once you have nice plug and piston wash achieved, if the issue is still there, I would be looking at the clutching. It has been seen before.
 
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