AC 900 twin EFI Boondocker Trim Setting
- Thread starter cokingcat
- Start date
Are you running pipes? If not why are you running a boondocker box? I mean, yeah the efi 900 is a little rich out of the crate but if you gut the air box and get a can on them it runs pretty good. I would almost think you have a crank seal leak or air leak some where on that side of the motor.
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cokingcat
Active member
Long story short, learning the hard way through this- I’ll just tell you what it has now. SLP ported cyc and milled heads. Vforce reeds and D&D pipe/can. Nothing has been changed with the air box. For some reason the wash on the top of the piston always looks good on the mag side. It’s the side the cyc that gets the streaks and melts the rings into the piston. PTO side is always ok top and this time it had one small streak on the piston. I’ll post pictures of the cyc tonight. How would I look for a leak on just this one side? Also what’s a safe starting number for the trim since the mag side is always a little leaner?
look and timing. efi has way more timing then cab, my sled burn down intake
side of piston on may every time, try retarting timing and or run better fuel
side of piston on may every time, try retarting timing and or run better fuel
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cokingcat
Active member
I am for sure going to run better fuel, I am going to try to run 92 oct and mix some race fuel (the next time I can get to Denver to buy some).
The timing was great idea to bring up. How and where to I check the key on my King Cat? Because I bought the sled used, I don't know if it's been changed. I take it that's what your taking about. And that's the only way to change the timing right?
The timing was great idea to bring up. How and where to I check the key on my King Cat? Because I bought the sled used, I don't know if it's been changed. I take it that's what your taking about. And that's the only way to change the timing right?
You might have a crank seal out Ross causing an air leak. Post pics of the other piston.
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cokingcat
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also if it's a leak, how come it only goes bad at the start of the second season? Maybe were over thinking it. Is that normal for a leak to take that long?
The first time was because there was no boondocker (previous own didn't tell me about the milled heads/porting), then the second time because it was too lean after I set up the boondocker when I got it back from boondocker?
The first time was because there was no boondocker (previous own didn't tell me about the milled heads/porting), then the second time because it was too lean after I set up the boondocker when I got it back from boondocker?
An air leak can affect only one side. If the other piston looks good then it is more than a trim issue if this one was that lean.
Almost looks like a lubrication failure to me. The efi sleds have a oil line that goes to each individual reed boot. There is a chance that that cylinder is not getting the oil it needs? I am not sure if the oil pump has two separate out put lines or if it has a t in the line after the pump. Maybe the line to that side is plugged or off ?? Maybe not just a thought. It is all the scuffing on the side of the piston that makes me say its lube related.
i dont know what you guys are seeing on the mag side but to me it doesnt look like there as any wash on there at all.....looks like your running waayyyy lean. its getting hot and expanding...your mag side is typically gonna run hotter than the PTO side. even the PTO side looks a bit lean. judging by your pistons i would say you need to throw some fuel at it
To check air leaks, start up your sled and spray brake cleaner on each side to see if it will rev up a bit...if it revs it is bad if not then your good. give each side a solid 1 second blast. Brake cleaner is less volitile than ether but you will still see an elevation in RPMs if the seal is bad
To check air leaks, start up your sled and spray brake cleaner on each side to see if it will rev up a bit...if it revs it is bad if not then your good. give each side a solid 1 second blast. Brake cleaner is less volitile than ether but you will still see an elevation in RPMs if the seal is bad
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cokingcat
Active member
Thanks Meatman for the reminder on how to do that. The first time this happened I did do that after the rebuild, and I didn't find a leak. I am going to do it again when I am done with this rebuild.
Boondocker directions say don't set the trim over 7. Do you (or anyone) have an educated guess looking at these pistons what I should set this number to, so at least they are running equal?
Boondocker directions say don't set the trim over 7. Do you (or anyone) have an educated guess looking at these pistons what I should set this number to, so at least they are running equal?
The exhaust edge being burned off has nothing to do with lubrication. Does the "good" piston have any pitting or goes it look sandblasted or dull?
Right, I have never seen a piston with that much scuffing on the sides. Thats why I say maybe lube. I was wondering about the wash also. Looks lean to me also, hard to say, how many miles on those pistons?
ok after drinkin a few more beers and lookin at the pics I have come to the conclusion that maybe the boondocker book didnt take into consideration your porting because when you port your cylinders you are increasing the airflow through the motor (2 stroke is basically a pump creating high and low pressures of air blah blah blah) now by increasing the sizes of transfer ports, boost ports, intake ports and exhaust ports you are able to flow a higher volume of air through the case. Increased airflow needs to be matched by putting more fuel in. I think a good investment for you would be an Air/Fuel ratio gauge.
i mean you have no wash on your pistons whatsoever....i put a little tech sheet awhile back and posted it up here and a couple other sites...ill throw it up here again
i mean you have no wash on your pistons whatsoever....i put a little tech sheet awhile back and posted it up here and a couple other sites...ill throw it up here again
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