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290 or 280??

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I broke a valve not too long ago and messed up my entire motor. Instead of buying a new cylinder I was thinking of going with a big bore. Anyone use a 280 or 290?? Any complaints?? I heard that the 290 uses a steel sleeve instead of nikisil plating..does this create problems?? Also I have heard when boring out to 280 the cylinder walls become skinny and cause the water pump seals to go out and the cylinder to sometimes crack?? Anyone know how reliable these big bores would be or any other info I should consider before going with one??

Thanks Alot

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I have used thumper racing 280 kit and I just put a athena 290 kit on my 03 wr250f. The 290 kit runs cooler and seems to have more power. It is a brand new cylinder also. :naughty::naughty::D

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A steel sleeve that is simply pressed into a machined bore has a natural heat transfer barrier built in where the two metals (sleeve and cylinder) meet. It doesn't stop the transfer of heat from the sleeve to the cylinder, but it does slow it up. There are bonding techniques that were used in most of the better aircooled two strokes before stuff like nikasil came out, but they are costly and complicate the process to the point that small run operations don't usually use them. A plated cylinder generally won't have this problem. A plated cylinder can be fit to the piston tighter than a steel one because of the similarity of the expansion rates of the piston and cylinder. This will make them quieter when cold.

Just general info, for what it's worth.

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I have used thumper racing 280 kit and I just put a athena 290 kit on my 03 wr250f. The 290 kit runs cooler and seems to have more power. It is a brand new cylinder also. :naughty::naughty::D

I've been running a Thumper Racing 280 for a couple years with no problems "love it". TR's 280 is an overbore then recoated, theyr'e 290 is a sleeve, I'm not a fan of sleeves.

Hey bocephus is the ATHENA 290 a sleeve?

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The Athena 290 is a new cylinder not a sleeve. I just picked up a 04 YZ250F and ordered the Athena 290 kit for it. I also have an exhaust on the way. I pick up my suspension on friday. I will probably ride sunday without the motor kit and then put that on before the next time out.

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Thumper Racing 290 kicks ass! Not as powerful as a 450 but an incredible increase in torque. :naughty:

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Second season on a Thumper Racing 280. No problems, no complaints, just a more powerful powerband in all areas with a NOTICEABLE increase in the low and mid rpms. I researched the 290 vs. 280 and found the Thumper 290 kits higher compression requires race gas :naughty: and I did not want that in a trail bike out in the middle of (where the hell are we). Gary at TR also recommended the 280 if reliability and longevity were more important to me than maximum power.

dd

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could some one post the web site for the 280 big bore..im thinking about getting one, and i dont want to have to run race gas. thanks a lot.

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Since owning my 2002 YZF, I have run a stock piston, Wiseco high compression std bore, Thumper Racing 80mm 270cc (not 280cc), and I recently upgraded to the Thumper Racing 290cc kit with the cast iron sleeve. A few comments on my evolution:

1. Each upgrade made progressively better power that was noticable from one change to the next. By far, the 83mm 290cc kit makes the most power and is the most fun to ride.

2. The 270cc kit is probably the most reliable, but only because it is the largest bore size you can stuff into the stock cylinder by boring and replating. No sleeving is required. My new 290cc kit has a sleeve, but Thumper Racing did an incredible job sealing and decking the sleeved cylinder, and after 2 hours of hard riding, it hasn't leaked or burned a drop of oil or coolant. Zero problems with reliability, and it still starts on the 1st/2nd kick!

3. None of these piston/big bore upgrades require high octane gas over 93 octane. I will repeat that (in case there are any Honda riders reading trying to learn something) - none require the use of high octane (over 93) fuel. Since you run high octane fuel to RESIST DETONATION and PREIGNITION, it is not required in these applications. The compression is just not high enough to require using high octane gas. I have never tried any racing fuels that contain additives and oxygenated agents, etc., so I can't say anything about how they work. I have tried a high octane (110) mixed with pump gas and it turned my bike into a complete pig. :naughty: I run my 290 on the same gas as when it was stock, and it runs like a champ. :naughty:

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Since owning my 2002 YZF, I have run a stock piston, Wiseco high compression std bore,

this the STD/+.75 compression ?

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I found this, $630.00 is a good price for everything.

http://www.procycle.us/main/bigbore.htm

Thanks for the link!! The website lists it as a "bolt on kit". Is this true? So there is no machining to be done? I assume not since the cylinder is included. Does the wrist pin on the piston have to be pressed? I just want to make sure that if I buy this kit I can do it myself without having to make a trip to the machine shop. Also will stock exhaust work well on a big bore motor?

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Thanks for the link!! The website lists it as a "bolt on kit". Is this true? So there is no machining to be done? I assume not since the cylinder is included. Does the wrist pin on the piston have to be pressed? I just want to make sure that if I buy this kit I can do it myself without having to make a trip to the machine shop. Also will stock exhaust work well on a big bore motor?

I have the 290 kit and it rocks!!It is a bolt on kit.So do not be scared.My hot cams should be in this week.I will also port the head.This bike will fly. :naughty:

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so let me get this straight. the thumper racing 290 kit is a steel sleeve and is stock compression. while the athena kit is a new solid alum cyl w/coating? and the athena is higher compression? or are these the same kits,just different distributors? :naughty:

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Goog question NC man!!!!

I too have been studying these kits and have gooten mixed info.

Is Thumper racing the same as the Authena Kit? The cyl. on the latter kit appears to be a stock cyl. from the outside. What are the doing to insure enough interior cyl. wall to keep it from grenading?

I am sure there is many more questions that will need to be answered!!

Mark

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I would never use a steel sleeve if I could get a plated cylinder.

BTW a buddy bought an RPM Ice Cube cylinder for his CRF250 and the instructions said to use 93 octane fuel and on a supercross style track to use 91 octane. They said the bike would pull harder out of corners with the 91 octane.

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