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Discussion Starter #1
I just got my indy 400 fired up for the first ride today after being stored indoors. I ran the sled out of fuel last season and drained the carb's, then left it until now. It wont start on its own, not even with the choke....I have to blow on the vent tube connected to the carbs and it fires, but the engine races to clutch engagement then it dies...Sure sign of being lean. I got it warmed up a bit and the idle died down, took it for a 2 minute boot up the road and back...it didn't take long for the engine to become very unresponsive and I struggled to keep a moderate speed. Turned it off pulled the plugs and the one cylinder's plug was overheated (white)...What would be a first suggestion? Clean the carbs?..

thanks for any suggestions...
 

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Definitely clean the carbs!! And while you have them off, shine a light in there and look at the piston skirts. always a good idea to do this when you have em off. -Polaris Doc
 

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Discussion Starter #5
Whats your guys take on re-using headgaskets? I pulled the head over the summer and put it back on without replacing the gasket. I know its not recommended, but I used to re-use headgaskets in my dirt bikes over and over without issues...and my friends XCR 600 has a re-used gasket in it with no signs of leaks.... Mine is not leaking or burning antifreeze as far as i can tell, and the compression checks out the same as it was last season...could it still be that gasket causing it to go lean? I torqued the head down to 22 ft/lb following the torque sequence in the manual. Also when i took the head off, one of the head studs came loose before the bolt did...I just got it back in as tight as i could with vice grips but is this tight enough? should i have used silicone or loctite? Forgive me i dont work on sleds for a living im a car & bike guy so the process is sometimes very different...

thanks in advance
 

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as long as the gasket looks good i wouldnt worry. The stud will be fine. After you run it a while it doesnt hurt to retorque the head either. Hope you didnt burn up your pistons doing all that lean running. Hows your compression look? Stop running it till you fix it. Are both sides lean or just one?
Causes to run lean:
Water in fuel,
Iced carbs,
Dirt in carbs,
Jetting wrong,
Carb not clamped to boot,
Boot not sealed to Jugs well,
Cracked Boots,
Crank seals bad,
Crank case halfs not properly sealed after rebuild
Plugged fuel filter cant supply fuel fast enough.
Fuel pump going bad

Start narrowing things down. Clean carbs, pop off the fuel line and give your cord a rip to see if it flows well. Inspect the carb boots. When you drained the carbs did you cap the sediment tube off good so its not leaking out? Is there oil around the crank seal? Check it all out.
 

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Discussion Starter #7
yes, it was just one side....I think the carbs must be dirty so I'm gonna clean them both....another thing is that when i pulled the head off i lost antifreeze (obviously) and i just filled up the reservoir...but I'm thinking i should have topped it up through the pressure cap aswell?
 

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Discussion Starter #8
well, my latest compression check scared me. I got 40 on cyl #1 and 60 on cyl #2.....but before I verify I have fried my engine i have to knock out a few variables first....For one, my compression tester doesn't seem to be working perfectly (although i did work fine a few weeks ago)...the gauge falls slowly without releasing the pressure....Also, There were no carbs on my sled when I did the test (but I'm sure that wont make a difference) Also, I re-used the head gasket...I'm thinking maybe somehow this is leaking on me...ill have to check that out...lastly it was -20C and the sled has not run in a week...and I really cant get a fast couple pulls on the recoil because its not retracting fast enough...I'm hoping the gasket gave out on me. I checked the compression before it ran a bit lean and it was ok...It ran for no more than 5 minutes and I shut it down after it started to run crappy and loose power. Pulled the plugs and ONLY one of them showed signs of overheating, the other was dark and wet...I cant see both cylinders loosing compression simultaneously.

When I shut the engine off to check the plugs, it was not hot (in fact, I took the plugs out with my bare fingers 30 seconds after I shut it off...and it wasn't hot.) The insulator on one plug turned a white color, the other seemed fine. Could the white color be antifreeze from the gasket??
 

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pull the carbs and clean them, maybe spend the $15 or so and get new mains and pilot jets to be safe. once you pull the bowls, you will be able to tell if they are "green" or not. had an older 600 that sat for one summer and the carbs varnished up so bad the dealer had to soak them in an acid tank for a couple days. and that was with stabil in the tank and fogged. far as compression, you sound unsure of your tester, maybe get a couple testers and compare results. whenever i do a top end, i allways use a new gasket, whether the old one looks good or not.dont get me wrong, i have heard a lot of people re-using the old gaskets without any problems but do it once and do it right is the way i try to do things . an extra few dollars now, saves a lot of headaches down the road.
 

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I'll tell you what, if you want to save yourself some money do it right. Check the pistons for holes, then get some new head gaskets. Sled gaskets once compressed do not seal up anymore. Follow the torque procedure with some slight changes, instead of going straight to 22 ft-lbs, go half way and then go to 22. Then run the sled for 15 minutes, can be out riding, and retorque. Clean the carbs and be sure there is no crap in the mains and pilots. Also check the jet and make sure they are not different from what you have on the jetting charts. And if you can check the crank seal on that side it would take care of all your basic malfunctions.

If it's anti-freeze then you take care of that issue, if it's compression then you take care of that issue. If it's fuel you take care of that issue.
 

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Discussion Starter #11
thanks for the replies...

I'm gonna go out and change that gasket...and I usually torque the head half and then go around bringing it up to 22 lb/ft...following the torque sequence..... Pulled the carbs out and they looked...well...pretty clean. I sprayed carb cleaner in all the little holes and jets...
 

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Discussion Starter #12
well, nothing seems blown up or melted down...so i may have a hint of luck left...what do you guys think of these pics....the pistons look the same way they did when the compression was fine...Notice the black on the head of the cylinder that was running lean...head gasket?...I also took a peak at the piston skirts through the intake...no scores or burn marks...seems good to me?!...




I dunno...I really don't wanna pull off the block so i think I'm gonna see if i get my compression back with a new gasket....
 
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