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Discussion Starter #21
I couldn’t find anything on led website for a 68 mm all I could find was things for a bigger bore any one got any suggestions I’m still not sure which piston I need either and not wanting to order the wrong parts
 

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Give LED a call he’s is real informative and will take the time to explain things to you.Regardless if you’ve ever done business with him or not..
 

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I couldn’t find anything on led website for a 68 mm all I could find was things for a bigger bore any one got any suggestions I’m still not sure which piston I need either and not wanting to order the wrong parts
before you go and order something, you need to determine your cylinder clearance. Just putting another 68mm piston in there may be a short term fix if there is too much cylinder clearance. The piston skirt will break and potentially trash your whole motor. The next size larger piston is a 68.50, 526MO6850 for wiseco. plenty of them for sale on ebay. However, once you go past the 2mm overbore (68mm) the standard headgasket will not work and ideally you would need to get your head rechambered to account for the increased surface area now part of the chamber on a 2.5mm overbore.

no quick fixes if you want it done right.

also you have a long rod per the HA2, so use the spacer plate with the 85/86 250r piston
 
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How do u check the cylinder clearance
you dont. take cylinder and old piston to a quality machine shop to have them measure. Like a place that would build a performance auto racing engine, if you dont have a good local dirtbike repair shop. You want clearance in the 0.0035-45 range. maybe a little bit more figuring some might be worn off piston as well as the cylinder.
 
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Discussion Starter #26
K we don’t really have any shops around here that build race engines we have a Honda dealer I will go in there tommorrow and c I’d tgey can check it out for me does anyone have a head gasket recommendation for the 68 mm or would stock b fine
 

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as other said you cant just order a piston and hope it works.it need the bore checked then usually a larger piston needs ordered then they bore and finish hone for new piston.if you dont have a shop around you send it to a shop.as for headgaskets oem is pushing it with a 68mm bore.and anything bigger the head gasket also needs bored...bdt motorsports can do all the work and also has the needed headgasket in stock.
 

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Discussion Starter #28
K thanks for all the help I will get it checked out and c wat all is needed to get it back together does anyone know what might of caused the piston to melt
 

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do it right n send 2 bdt motors carlos. bdt can measure n bore. cut head. cut gasket. they have everything in stock.


Sent from my iPhone using Tapatalk
 

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This is how I ID OEM stock crankshafts
KA4 1985 Honda ATC 250R Short Rod
HA2 1986 Honda ATC TRX 250R Short Rod
HB9 1988-1989 Honda TRX 250R Long Rod
Now 1987 I really don't know much about that year was already morphing into an 88 so it has many differences from an 86 and allot of similarities from an 88
Good luck
 

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Discussion Starter #33
Could the carb on it have anything to do with it I noticed it had a larger carb on it by Eddie sanders racing
 

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I'm guessing that your engine has an air leak like crank case seals. Other than cleaning don't mess with the carb. Do yourself a favor and research for a local mechanic and request a leak down test after rebuild. It will save you money in the long run.
 

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Where are you located? There are skilled mechanics all over the country. You don't need a high dollar specialist on the other side of the country. You need a full service mechanic near your home.
 
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Discussion Starter #36
I’m in Kentucky near Elizabethtown I know it had an exhaust leak for sure when I tore it down it didn’t even have the O-Rings on the pipe
 

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The leak would be on the intake side which includes the crankcase on a two stroke. Leaky crank seals seems to be most likely. I don't know and know one can without getting hands-on. If your goal is running 250r on a reasonable budget a local mechanic will be able service you and your 250r best. If your budget allows send your complete engine to a respected builder.
 

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What about Wilson Cycle in Elizabethtown? Google says that they have been in business since 1989.
 

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Discussion Starter #40
K so I got my piston and stuff and was checking on crank seals and noticed there is oil where the crank and rod is every time I turn the crank over it will come up with oil on it so I am assuming the crank seals have to be bad I have the other bottom end from the 88 motor if that will work but if it’s not a really big job I was thinking bout putting the seals in the 86 motor if I don’t have to split case or anything does the case have to be split for the seals to be replaced
 
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