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Discussion Starter · #1 ·
So, last year about this time I managed to burn a hole in my #2 piston by running lean....

So, one year later (and apparently non-the-wiser) the bike is finally back together and was started saturday. Runs identical to last year just before burning that piston. I did some investigating and noticed #4 cylinder is not firing while idling, but does so under throttle. Checked the carbs, spark and compression, all good.

I sprayed some carb cleaner on the intake monifold boots, and bam, about 2-3k rpm increase. Here is my thought, and feel free to tell me I'm wrong, but under idle I am pulling in so much air through that boot that I'm not even getting enough gas to fire. Under throttle, more air is coming through the carb, so I at least have enough gas to fire, but still lean.

Either way, I need to seal this up. I used some tar/honey looking gasket maker that is resistant to gas and temperatures, but I am not sure of the quality of the seal job (my buddy did it while I was working on something else). Is there something special I should be using to seal these manifolds up? I have been kicking around the idea of just buying new ones, but I'm a cheap a$$ and the boots I currently have aren't cracked and actually feel pretty soft. (the one that bit me last year actually was cracked, but has been replaced with a used good one).

thanks,
Andy
 

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Navy Vet Search & Rescue
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Unfortunately, I'd agree with the "none the wiser". :cry: Those manifolds are almost certainly the same age and have been exposed to the same wear and tear. How long do you think it's going to be before the other 3 develop more cracks to the point of possibly losing 3 more pistons? You've already lost more time, labor, and money than it would have cost for a new set of manifolds. At what point do you say enough, and park the bike until you have the money to fix it right? I'm all for fixing things the as cheaply as possible as long as that route isn't going to lead to doing more damage than good.
 

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Discussion Starter · #3 ·
Good point Mike. Should have mentioned too that the only person I even met more stubborn than me is my wife :). Anyway, the bike is in fact parked, and I do like the idea of fixing it right the first time. However, even if I do buy new ones, don't I still have to use something to seal the mating surface between the manifolds and head?

Didn't you have an issue with these being cracked on your bike and it took you a while to track it down? Did it make a big difference once you replaced them?
 

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Navy Vet Search & Rescue
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You shouldn't need anything between the new ones and the head. Just be sure the surface of the head where the manifolds mate up to is clean and smooth. Yes, that mating surface is the same place I found the cracks in mine. The difference in mine after installing the new manifolds was like day vs. night.
 

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Discussion Starter · #5 ·
Ok sounds good to me.

I'll be ordering a new set of those manifolds.
 

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Ozone,heat, and the poor quality of the stuff called "Gasoline" all contribute to rubber bits failing after a few years. The Alcohol mix used here in the U.S. has caused more trouble with cars fuel systems developing problems.

It dosen't really work well in some of the lawn equipment engines either(mowers,tillers, and blowers).
 

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Discussion Starter · #7 ·
So I just ordered the manifolds from Z1. Shameless plug here, but I manage to talk to Chris everytime I call there, and I feel as though I should pay more just for the great service and advice they always give...

Anyway, speaking of gas... around here they have some of the high octane gasolines (offhand, v-power from shell) that has no ethanol added, but is something like 92 octane. my manual calls for 87, but I am assuming 92 will be ok, right?
 

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Machinist For Sale/Rent
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I bought all 4 intake boots for my wifes KZ550 about 12 years ago. I only used one or two, can't remember exactly. Any way I am quite sure 2 of them are still up in my closet if you need them.
 

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Discussion Starter · #9 ·
Thanks for the offer Bob, but I know I at least have 2 bad ones, so I am just going to replace all 4 of them with brand new ones to make sure I don't have a major issue again like last year.
 
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