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Discussion Starter · #1 ·
This winter has been pretty crappy, so I havnt had many chances to test my 600VES conversion. I got out for an hour or so tonight and it ran pretty well. I just installed an almond/red primary spring with 10-62 weights. I am riding ~1000 feet and have 410 main jets in the 38mm stock carbs. Needle clip is 2nd from the top and mixture screws are 1.25 turns out.

The sled always starts up on 1st or 2nd pull. It needs very little choke. 2-3 seconds tops or it will stall out. The thing idles good at around 1500 RPM and feels pretty good up to the engagement point, which is around 4200. Tonight I noticed that I could rev it right around 4000 rpm and then go WOT and it would jump out of the hole, but go to about 7000 (I think) but sort of sound like it was bouncing off of a rev limiter. After 1-3 seconds, it would feel like the mains were kicking in and it pulled great. I don't think it would pull above 7500-7700 RPM. It may have gone higher, but the thing was pretty fast and I didnt have the room to stay on the throttle and look at the tach. I'm guessing I could drop the weights a bit to pick up more RPM's.

I need some opinions...does this sound like an electrical or a carb problem? I am used to working on 4 cylinder motorcycle engines, and it gave me the feeling of hitting a rev limiter, but I'm thinking that I was wrong. Would this be a main jet adjustment because I was going WOT, or a mixture adjustment because I was stopped and just getting on the gas? I dont have a flex light yet (just ordered one) to check the piston wash, but I pulled the plugs when I got home and they looked to be a real light tan color. Maybe I am just too lean???

Thanks for any info...just looking for some opinions on what to try next.

Arik
 

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your too lean on the needle , put it back in the middle slot . Depending on your airbox type you may need one larger on the main jet (440 is stock on most 600 sleds) You should see a peak of 8000 rpm so you may need to back off to 10-60 in the primary , very few stock 600 will pull 10-62 unless they dont run a pile of helix angle.
 

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Arik,

This sounds just like my sled this Tuesday. I finally got my 600HO conversion fired up and took it out for its maiden voyage. My motor came with 380 mains and the needle was set at 2nd from top. My sled was responding in a similar way and just felt like it lacked some power. Pulled the plugs and although they were brand new, I could see they were trying to turn a light tan color. Came home and swapped the needle position to the stock setting (middle or 3rd slot down) and took it back out for a spin. HOLY SHIZNIT...I could barely hold on. Granted, I still have the stock gearing in there but the motor would spin right up to 8000-8100 without hesitation.

I am running the peterepeater recommended "Gulla" set-up in the 440 clutches which is a Team Silver and 62's in the primary and Red/Black with a 66-44-42 helix. I do have the Dynoport pipe and can on my HO, which is supposed to be +9 HP (if you believe their claims) but all I know is that now with the lean bog gone, my sled can throw 62's around no problem. One last check of the plugs and they were already starting to get a little chocolate colored and if anything, were a tad on the wet side.

I plan on doing a better write-up after a good a good shake-down run on her but I would agree with xc-mark...you have a lean bog in the mid-range, which is confirmed with your plug readings.

BTW, I am also in a low altitude area (Illinois) so our settings are pretty similar even though you have a VES.
 

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You could also be feeling "pipe surge" from too rich jetting on the main, or too light of clutching. I doubt the clutching is too light.
 

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mine does the same damn thing with twins.... i have a 600ho and im running 2nd needle clip, 370 mains, and fuel screw .75 turns out. if you hammer it, it does ratatata for a few seconds and cleans out right? and if your braaping the throttle at a slower speed and hammer it, it doesnt do it?

do this, take your sled out for a ride down a ditch or trail.... get it running reg temp. stop and let it idle for a minute and take off. does it feel like its loading up? and when you first start it and let it warm up, is it hard to take off for the first 3-4 seconds?

i tried 3rd clip, it just stuttered the whole time. dropped to 2, got alot better, but still lightly there. turned fuel screws in, got better, and if i hold it at 5000, then mash it, the stutter is gone. going to turn in the screws some more.... \

would a different needle be in need? something that is leaner at bottom and same rest of the way? cuz im thinking when i go out west, i dont want to have the fuel screw turned all the way in....
 

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I had a similar problem. Everything ran fine up to about 7/8 WOT. Then if you would absolutely pin it, it felt just like there was a rev limiter. Upon closer inspection, I realized I needed new reeds. They were chipped up and cracked. A new set of them and I was amazed by the power of the 600 at WOT. Great sled!
 

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I had a similar problem. Everything ran fine up to about 7/8 WOT. Then if you would absolutely pin it, it felt just like there was a rev limiter. Upon closer inspection, I realized I needed new reeds. They were chipped up and cracked. A new set of them and I was amazed by the power of the 600 at WOT. Great sled![/b]
i think were talking about from a dead stop or very slowly moving. while moving anything over like 10 mph and i gun it, its fine. its dragging from a stop or creep that it does the thing that sounds like a rev limited. its from fuel buildup. i moved needles to clip 3 and it did the stutter the whole time and would not clear out. moved to 2, still there, not as bad. turned the fuel screws 3/4 turn out from seated, seemed to help, need to lean it out more. i think im gunna see if the rr needle and the 600ho RMK needles are the same or different...may get an rr needle to try
 

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Discussion Starter · #9 ·
I had a similar problem. Everything ran fine up to about 7/8 WOT. Then if you would absolutely pin it, it felt just like there was a rev limiter. Upon closer inspection, I realized I needed new reeds. They were chipped up and cracked. A new set of them and I was amazed by the power of the 600 at WOT. Great sled![/b]

THanks a lot for the info guys. I went out today and put the clip back into the 3rd slot and it seemed to run worse. It felt like I had moved it the wrong way, so I decided to try to go the other way and put it in the top slot. Well this definitely didnt work and I really couldnt go past 1/8-1/2 throttle or it would just break up. Way too lean I'm guessing. I'm starting to get frustrated with this motor. The motor runs good, but I cant seem to cure the flat spot....it just moves around on me. I guess I'm going to try to go back to 2nd or 3rd clip position and richen up the mains a bit. Maybe the 410's are just too lean for me.

Arik
 

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how do you know the mains arent too rich already? richening the needle made it worse, maybe you should lean out the fuel screw and lean out the mains? im my stock HO motor, i have fuel screw 3/4 turn out from seated, needle second clip, and 370 mains with twin pipes....going to check wash and plugs at WOT. so far i have held for a few half mile pulls and it didnt burn down, so i am guessing i am still okay....guys with single pipes have been running 340's and 350's
 
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