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Old 02-04-2010, 07:10 AM   #166
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Amain also has those restrictors.

I had to replace the rear bearings on both of my JPX engines. I used the TKO ceramic bearings (should be the same size as the Vspec bearing) and they have worked great ever since. First engine last a couple of gallons and the 2nd engine barely made a gallon. Both have ran a few gallons since then with no issues.

I am convinced I had a fuel problem since both bearings went at the same time although one engine was six months older. What fuel are you running?
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Old 02-04-2010, 07:24 AM   #167
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Hi guys, I have about 2.5-3 gallons through my JPX Plus. The engine runs awesome, but last night I heard the main bearing. I am going to order a TKO replacement bearing for it, but wanted to get your input. Is a ceramic bearing better for this application or just a standard bearing?

Also, has anyone else had to replace the main bearing and if so, how many gallons did you have through it?
i replaced both bearings after about 3 gallons. thats when i saw that the front bearing was starting to leak. so went ahead and replaced both of them at the same time. they helped a lot. TKO ceramics by the way.
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Old 02-04-2010, 08:13 AM   #168
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I am convinced I had a fuel problem since both bearings went at the same time although one engine was six months older. What fuel are you running?
Interestingly enough, I am running Maxy fuel. He was at the track last night so I got his input and he confirmed it was the main bearing and said it is because I leave fuel in the tank between races. I race, at a minumum, weekly so fuel never sits longer then 1 week. He said that is all it takes.

Other experienced racers say that has nothing to do with it, but Maxy knows fuels so I am not sure what to believe.

My front bearing seems to be okay. Do you guys think it needs to be replaced too? I rather not touch it unless it is really the smart thing to do. I will inspect it once I disassemble the engine but do you guys always replace both or just the one that is bad?

Thanks for the input guys.
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Old 02-04-2010, 08:27 AM   #169
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When you take the engine apart you can check both bearings. Replace them if they fell rough or have play between the inner and outer races. I am still on my original front bearings. Only the rear bearings went bad. I was running Byron's gen2 at the time and everyone was having rear bearing issues on that fuel around here at the time. The fact that I had two go bad very close together not long after switching to the Gen2 tipped me off.

I also have a Vspec that had a front bearing go bad and the rear is still good so it is worth it to check. I have never run Maxy's fuel and since you got 3 gallons on the original bearings it is probably ok fuel. I run OD fuel now, and I am not sure you can beat it for wear protection.
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Old 02-04-2010, 02:30 PM   #170
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another question..
do i need to remove or add any shims to this engine if i run 30%? i run 20% now and have one shim in it now i think. or whatever comes in it stock.
thanks
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Old 02-04-2010, 02:49 PM   #171
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Add one more shim and you'll be set. If you don't and run 30% it will die quick it might not last two more gallons. I have seen people not add a shim and theirs made it about 2 gallons.
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Old 02-04-2010, 02:56 PM   #172
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My JPX has 3 shims in it stock and 1 extra for 30%
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Old 02-04-2010, 03:21 PM   #173
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you do not need to add a shim to run 30%...LOL..I actually remove 1 shim and run 30% and my engines last just fine !!!
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Old 02-04-2010, 03:23 PM   #174
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Add one more shim and you'll be set. If you don't and run 30% it will die quick it might not last two more gallons. I have seen people not add a shim and theirs made it about 2 gallons.
ew lol i think ill add another
thanks
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Old 02-04-2010, 03:32 PM   #175
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My manual say's to add 1 shim .01 mm in thickness to run 30 % But from what i have heard maximo knows this engine . I have talked to a few people who said the engine only lasted a couple gallons & the common factor is they were running 30 % without adding a shim . Mine is just starting the fourth gallon & other than a leaky front bearing i have had no problems . I run 20 % with stock shimming . Hope i'm not jinxing myself LOL .
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Old 02-04-2010, 03:38 PM   #176
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uhhh yea i think im just going to stick with 20% for this engine lol

or wait.. would switching to 25% need any shims?
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Old 02-04-2010, 05:11 PM   #177
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uhhh yea i think im just going to stick with 20% for this engine lol

or wait.. would switching to 25% need any shims?
im pretty sure the manual says that you can 25% with stock shims but im not 100% sure so if you have the manual look threw it and it will give you all the info.
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Old 02-04-2010, 05:17 PM   #178
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im pretty sure the manual says that you can 25% with stock shims but im not 100% sure so if you have the manual look threw it and it will give you all the info.
ok ill try to find it. thanks for all the info
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Old 02-04-2010, 05:25 PM   #179
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you do not need to add a shim to run 30%...LOL..I actually remove 1 shim and run 30% and my engines last just fine !!!
I run 25% in my stock Jammin no problem at all, Listen to Maximo he knows these engines .
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Old 02-07-2010, 05:35 PM   #180
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Can someone please confirm the size for the main bearing? I am looking at the Amain website, but don't see it listed. (DISREGARD, JUST FOUND A POST WITH THE SIZE. THANKS!)

Thanks.
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