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I have heard you can adjust the idle by turning the idle screw.  Is this all you need to do? or are there other things you have to do.. to adjust to the adjust you just made to the idle?

My sled idles really low, so that it doesn't stall, but the lights are soooo dim.

Thanks
 
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I think that is a draw back with some of the early Indy's.  But you can bump up your idle on the carbs.  Make sure they are syncronized though.
 

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Does your sled ilde good for about 30 seconds and then go down (once engine is warm, of course)? I have seen this due to excessive oil setting on idle. One thing to check.

If everything is OK and you want to bump up the RPM a little, follow this plan

1.  Remove airbox
2.  Set your (rough) new slide height using the idle screw
3.  Insert 2 same size pieces of drill rod in the carbs under the slides for the new height.
4.  Make sure the heights are as close to being the same as possible. When you crack the throttle the rods should become loose at the same time
5.  Use the "Uni-syn" carb sync tool to synchronize the carbs
6.  Crack the throttle and place a shim between handle and throttle
7.  Re-sync your carbs by making sure both slides lift off at the same time - this is done with the cable adjustment on top.
8.  Re-adjust oil cable if needed
9.  Install airbox and go ridding.

This needs to be done at normal motor temp, as well as normal ridding temp. You might find that if you set it for 2000 RPM today (+30 deg C), your idle will be around 2200 RPM at  -20 deg C.

Don't set idle so high as to let the clutch start to engage,
Don't set idle so high that the engine can have a "cold seizure"

good luck
 

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madsledhead, where did you learn to sync. carbs?

The cable on top of the carb is used for one thing and one thing only "adjusting the bottom of the slide with the top of the intake" On fan cooled sleds this would be the top of the carb intake closest to the air box and liquid machines the closest to the engine.
Never mind the drill bits and uni-sync they will just confuse you.
I found a simple and easy way to make it idle and so the throttles leave at the same time is too: Screw out idle stops until they no longer 'just' touch the slides. Next, start the machine and start screwing them back in equal turns until your rpm is close to where you want. Shut the machine off and set a mirror between the carbs so you can see both slides at the same time. Next adjust the slide that is moving first by turning the idle screw in until it matches the movement of the other slide, lock brake and start sled and set idle to desired rpm by screwing both idle screws equally. Re-check and adjust until idle and or slide movement is perfect. Sounds harder than it is but really quite simple....
 

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Actually, Mikadoo, the cable adjustment is more for "off-idle" synchronizing.

You cannot turn your idle screws to match the slide height. This is going in reverse. The slide height is independant of idle demand. There is different combustion properties for all cylinders and they must be adjusted independantly. If you simply relly on the "top opening", you will essentially set all three carbs identically - but the airflow requirements are NOT identicle.

There are several good articles I have found on this subject that are similar to the method I use.

The first is an acticle to sync 4 mikuni roundslides:
http://www.650motorcycles.com/CarbSync.html

The third is an article from Snow-goer on carb sync and set-up:
http://www.snowgoercanada.com/tech_carb.shtml


Both of these reputable institutes feel that the same procedure I described is OK.

If you are happy about your performance on your sled, keep doing what you are doing.

I'm sure there is different way to do it, but my way is effective so I will relly on it.
 

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As I stated, the cable is for one thing and one thing only, adjusting the bottom of the slide with the top of the carb intake or throttle bore. Why would you not want all slides adjusted perfectly the same? If each cylinder requires different air flows you have some serious problems going on ie: broken rings, cracked head or cylinder, seals worn etc.

Funny this subject has come up, I just recieved my Sept. issue of Snow Tech and as always I turned to 'Dear Ralph' immeditaly and the last article was on carb sync.
This was just a quick spec. but here it is from Ralph: You want to make sure ALL carbs are set to the SAME height, that they ALL start to open at the EXACT same time. One easy way to do this is to sync them at wide open throttle. Open the throttle to wide open,and set the cable adjusters so the bottom of the slide is flush with the top of the throttle bore.
Hmmm, I think that is what I said.
Sure, your way will make it run, but not very good I'am afraid.
Enough said on that subject.........
 

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What are you saying, "enough said on the subject"

Or implying my sled probably has a cracked head or something, were here to offer friendly advice and your bad mouthing my methods?

If I'm wrong, big deal. But Every single tech report I have read clearly says to balance the air flow. And all jugs have different fuel demands. Just look at your jets, are they the same across all jugs? Setting the same slide height is "rough" tunning of your sled, individual cylinders need to have idle screws tweeks just slightly after to balance (sync) the carbs.

Most tech manuals even tell you to LOOSEN the top cable adjustment to ensure the slide is sitting on the needle. After which you adjust your cable so the slide move in unison.

I like this forum, It's a good place for advice, but when it comes to bashing I feel like just staying out for good!

By the way, here is a quote from snowmobile magazine
" The purpose of synchronizing the carburetors on multi cylinder motors is to balance the intake on each cylinder. This gives better throttle response, a smoother idle and better mileage. On a twin, match the carburetors together. On a triple, do two, then match the third to one of the other two.

Note: If the carburetors are way out of adjustment, you will need to do a "rough" adjustment first. If the carbs are close, skip down to the "Fine Tuning Adjustment" section.

Rough Tuning Adjustment:

- Remove the airbox for free access to the carburetors.

- Unscrew the idle speed screws, (big knurled knobs on the side of the carburetors you can turn with your fingers), so they are no longer touching the slides. You will feel the resistance change as you are turning counter clockwise. The slides should bottom out in the carburetors. If not, the cables may be too tight. In that case, use a wrench to loosen the locknut on top of the carburetor, and spin in the adjuster so the slide comes all the way down, and the cable is slightly loose.

- Adjust the idle screw in on each carburetor until it just touches the slide. Now turn it in another four (4) turns. The carburetors are now roughly balanced at idle. (Another way is to lift the slide, install a pencil, turn the idle screw in till it just lifts off the pencil on each carburetor.) The actual idle speed will need to be adjusted when the motor is running.

- Now squeeze the throttle slightly, (just off idle is enough), and look/feel the slide lift. Adjust the throttle cable up on the "slower" carburetor, until they both lift at the same time. Now you are done with the rough "off idle" adjustment.

- Next test the "freeplay". Squeeze the throttle slightly until you are just lifting the slides. How much clearance is there on the throttle lever? The manufacturers specify this as it affects the throttle safety switches on many models. The width of a credit card is about right. You will need to loosen the nut on each carburetor, and adjust in/out the same amount to get the freeplay correct. Now go back and check the synchronization at "off idle".

- For the final test, squeeze the throttle full on. Feel inside the carburetors; are the slides all the way up? If not, check the throttle cable condition, routing, and your previous adjustments. Also check for interference with grips, thumb warmers and the like. Repeat for 3rd/4th cylinder, then move on to fine tuning. "

Sorry guy's, don't care for the bashing.
 

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Mikadoo...If I had to get my info from 'Dear Ralph', I think I'd just stay home and watch the Disney channel!! He's just another guy with an opinion.

For the last few days I've noticed that you seem to know everything and everyone else is an idiot. Why are you wasting your time on here when you could be making $millions$ showing people what they are doing wrong. Why don't you just chill a little and let a discussion happen and join in if you have something to add. Sometimes there are different ways of getting to the same solution. Your way isn't always the right or only way. (neither is Ralph's)


In my opinion, madsledhead is absolutely right about different requirements per cylinder due to different stages of wear. I don't think it plays a major role in how your carbs are syncronized, but it is a factor. You don't think that cylinders wear differently? Then tell me, why is it that it's usually the ctr cylinder on a triple that goes first and the pto cyl on a twin that always shows the most wear?

I think that you should stick to trying to help out and quit trying to find an idiot. There aren't any here.
 

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Chill guys!! I'am only trying to make a plain and simple solution to carb tuning for the guy! madsledhead your making it sound  like you have to have 10 years of college to do a simple 20 minute job. You will have most people so confused they wont even try to sync. them.

idooski, I surely dont get my gospil info from Ralph but thought maybe as popular as Snow Tech is some of the people would believe him.
I try my best to inform people on a whatever help I can give them to save them the kick'in and cuss'in not to mention lots of money I have been through. I have doing this for 30 years, longer than most on this site have been on this earth so I do have a little knowledge, not an expert by any means. I do admit I get carried away at times but that's me.
 

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idooski, I think your right. the carb on the mag side that is closer to your can is going to be warmer than the carb on the pto side therefore creating different fuel to air ratio's based on the fact that different air temps have different air density.  which would create a need for two (or three) different adjustments for your carbs.
 

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Actually, the PTO side runs a little warmer due to the heat build-up from the clutch. To that end, the PTO side is usually the side to need the larger jet. In recent years the manufacturers have done well too do away with this problem.

Mikadoo...I've been at it for over 30 years myself. That doesn't make me the expert. Lots of these guys know more than me. And I believe lots of them know more than you as well. But that's not the point of this forum is it? I know more about some things, you know more about other things, and someone else is the expert about something else. That's why we all come here. To learn something we don't already know. I don't need to prove I know something. I just throw the information out there and the people here can use it if they want to.

By the way easy_does_it, are you Mikadoos neighbor or are you mikadoos other side?
 
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