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Discussion Starter #1
OK so let me try this again. Which should I trust more, reading plugs or piston wash? I've been adjusting my carbs and have 2 plugs saying the adjustment is spot on for 1/2 throttle but the wash looks almost entirely black? So is it set correct or is it lean? My other cylinder is a diff story wash on 1 sides edge of 1/2" or more but the plugs shows a rather white insulator...is it rich based on wash or lean based on plug? Anyone able to help me understand this? Thanks.
 

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Right!!! The plugs are a temporary window into what was happening for about 30 seconds. The piston top is a picture of what is happening all the time. I would like to see a clean dome next to the trandfers about the size of your thumb nail. The rest a nice charcoal black.

PS..... Buy a digitron EGT gauge!!!!!!! It'll save you lots of money and give you some insight on what lean and rich actually sounds and feels like. plus you'll never have the wrong tune.
 

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Discussion Starter #4
Right!!! The plugs are a temporary window into what was happening for about 30 seconds. The piston top is a picture of what is happening all the time. I would like to see a clean dome next to the trandfers about the size of your thumb nail. The rest a nice charcoal black.

PS..... Buy a digitron EGT gauge!!!!!!! It'll save you lots of money and give you some insight on what lean and rich actually sounds and feels like. plus you'll never have the wrong tune.[/b]

Thats the info I was looking for, thanks!!!! So, what your saying is that if I leave the carbs set the way they are (the 2 that are correct)....then it will eventually lead to proper wash being seen on the pistons. How long does it take for wash to change? One other thing, are plugs readable after simpling letting the engine idle for 10mins? Mine always show wet...should I adjsut air screws?
 

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the truest way to read plugs is to do a plug chop. run at wide open throttle and cut ignition this will give a true reading of plugs. i.e lean or rich.
 

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One thing that I would like to interject here is that you can't get a good plug read or get a decent read on the wash when the machine is on a stand. (pretty sure that I read your post yesterday about running it to 100 k/hr with slight brake pressure) The engine has to be loaded down in normal circumstances to get accurate readings. I wouldn't even trust readings taken while on a dyno unless it was in a climate controlled room.

I use both, plug chops and piston wash in order to get the mixture set right. I don't believe that you can use just one or the other to get there. I don't believe that you can get away with using just EGT gages either. You need to use chops and wash to develop a base line for your EGT's. Then you can confidently use the EGT's to monitor conditions while riding.
 

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idooski is right. I might trust my plug readings on the dyno, provided it is a load type. using a jet chart I would then correct the jetting to the cooler temps. knowing what temps you have in the dyno room will make it pretty easy. mikuni used to have a nice little slide rule chart that was great for this. they may still have. this may help http://www.mikuni.com/fs-tuning_guide.html
 

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Discussion Starter #10
OK, so let me get all this straight. Just to make sure I'm getting the correct answer here, my intention with my sled is to set it correct (not rich or lean) and leave it for the entire season. Basically get it back to exactly factory spec so I can hop on it and ride all season without worries. I'm not interested in rejetting everytime I ride so my sled performs at its peek all the time. I figured that if I got it set right once I could live with the peace of mind all season that I am not going to melt a piston any moment now. Is this not a proper way of looking at the situation? Also it was a guy who used to race MXZ's all over the country who told me I could test the sled on a stand, so I guess I assumed he knew what he was talking about. So, your saying I have to wait until we actually have snow to test it? So, all my tests were plug chops where I cut the engine while the throttle is still engaged. Basically does anyone have any advice on how to do this properly? I find it frustrating researching on the net, especially wash cause I always see 2 way different stories. So, please help me! Thanks.
 

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So why don't you jet it for the coldest temperature you expect to ride in and install a Holtzman Tempa Flow to take the worry out of the warmer days. $272.00 and your done.
 

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Discussion Starter #12
So why don't you jet it for the coldest temperature you expect to ride in and install a Holtzman Tempa Flow to take the worry out of the warmer days. $272.00 and your done.[/b]

That is a good idea and definiately something I am interested in getting at some point, maybe next season. However, I would also like to know how to set my carbs properly. I think thats basic vital snowmobiling knowledge, especially if you buy used sleds (like myself) and are unsure of what the guy before has done to them.
 

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I do not have it on hand, but it is info the deale can give you. if the guy before you did some work and it requires the jetting you have now? if that is the case doc's way is the best. but to get the factory specs call your favorite dealer.
 

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Discussion Starter #15
I do not have it on hand, but it is info the deale can give you. if the guy before you did some work and it requires the jetting you have now? if that is the case doc's way is the best. but to get the factory specs call your favorite dealer.[/b]
First of thanks everyone for the posts it is greatly appreciated (after getting rippedoff hardcore last yr when I took my sled in to stealership, i've vowed to do everything myself from now on), I'm learning here so please be patient. Now this may be taking the thread in a diff direction but still it will help me ride comfortably knowing mine and my fiancee's sleds are running properly. I have a tech manual and it says the carbs should have 300 mains, 50 pilots, and I pulled a needle to find it was something-4 which meant its supposed to be set at the 4th slot. The carbs have all these exact settings, but the wash I was seeing told me I needed to take a look at the carbs. MAG piston has much more wash then PTO and center. So, I took carbs off and cleaned then (they were already clean), then reset the slider gap to the recommended .051" opening, adjusted the throttle cable, and then began performing plug chops. The result was that the PTO and CTR plugs were spot on (and I learnt recently from here that the wash will not reflect this for a longer period of time). So, my question now focuses why the MAG isnt the same even though the carbs are set the same? What steps should I take to correct this? This is where my initial question stems from.....the fact that the piston shows plenty of wash (rich), yet on plug chop the insulator is white (lean) or am I reading the plugs wrong?

PS This sled is a 1999 MACH 1, 699cc
 

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Attached are the carb specs from the 1999 service manual, the 1999 high altitude spec book and the 1999 racing manual (final). You will note that all specs reflect 300 mains and 50 pilot jets except the racing manual. The best advice I can give is to recommend using mineral oil to do a plug and piston wash test. Synthetic and synthetic blends tend to burn more cleanly and skew test results. Other factors are setting the idle / low speed screws according to each cylinder's needs. Float level is also critical and running it up to high speed on a stand just vibrates the heck out of the carbs as well as being extremely dangerous. Having a track or belt explode is deadly. Now that I've made the public safety announcement let's get on to other things.

1) Get some masking tape and make a scale on your throttle flipper aligning 1/4, 1/2 3/4 and full throttle.
2) Run some mineral oil through the system until you observe it in the injection delivery lines
3) Take the sled to a field with level ground and wet grass (about 1/2 mile) Bring soapy water for slides
4) Bring a helmet (too easy to break your neck on grass)
5) Warm up motor until the gage just starts to move then do a full run at 1/4 throttle chopping at the end, Observe plugs and correct Idle screw to attain close coloration on subsequent runs allowing the motor to cool down each time
6) Same as above at 1/2 throttle. This time if plug color isn't good check jet needle for defects (scraped or bent needle)
7) Same as above at 3/4 throttle. This time if plug color isn't good check needle jet for elongation or scratches inside
8) Same as above WFO. Check main jet for erosion or beveling on the under side

NOTE ***The above tests should read on the rich side when temperature is above 0 C (32 F) due to jetting requirements

This way you can isolate the various circuits of the carbs to determine whether there is a rich / lean overlap from one circuit to another. Be prepared to spend a full day doing this and take notes after each run. This is assuming that the engine compression / leak down is fine, the reed valves are seating well, the boost / resonance box is not cracked and the crankshaft seals are doing their job. Bottom line, you need to follow "real world" test scenarios to access "real world" results.

[attachment=40566:1999_Mach_1_carb.doc][attachment=40567:1999_Mach_1_carb2.doc][attachment=40568:1999_Mach_1_final.doc]
 

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Discussion Starter #17
TD thanks again for the info. Lots of good info included there. Now I have a clear outline how to check my plugs and wash and adjust accordingly. I greatly appreciate you sharing your knowledge with a novice like myself, you may not realize how valuable your knowledge is to beginer tuners like myself, but it is! So again thanks a bunch. Now for one last question before I leave you be (for a few days anyways!! haha)....Inregards to the pics I have of my plugs in this thread, are they good examples of what I am looking for on each test I do? EX. the MAG is not set correct but the CTR and PTO look good for that throttle setting. Basically, is what I see on the CTR plug what I am striving for in each test? THanks.
 

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I would target the plugs to read like the centre cardboard to chocolate brown. Another thing came to mind here about the triples, check to make sure the choke plungers are seating fully and inspect the rubber seal underneath them for cuts or dents. One just has to be a tiny bit off it's seat to show rich on a plug test. Make sure the enrichment cable has some slack in it in the off position.

As annoying as it sounds, I find the best way to check triple Rotaxes is to remove the pipes and observe the colour of the 3 exhaust manifolds because the ball joint is about 100 MM away from the pistons which is where egt probes are usually installed.
 

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Discussion Starter #19
Alright, its off to do some testing and setting. We got snow lastnight!!!!!! 5" of the light soft stuff, I hope it stays. Atleast its better for my tests. Thanks again for all the info everyone, especially TD.
 

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Why are you even worring about the jetting in the first place?
I gather from what I have read that the sled is completly stock?
If your @ 0-2000 feet above sea level leave it alone its plenty rich in stock form.
You have the stock specs, go over the carbs and make sure/set accordinly.
I suggest 45 pilots as the only change, cleans it up on the low end and idling.

A tempaflow is a great item to have, I love mine and would'nt be without it. They cost around $150.00 or less not $250.00.
 
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