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'84 XT600 is now bored to 2nd oversize and new OEM pistons and rings installed. No more smoking.

Claims aside, has anyone installed one? Noticeable performance improvement?
I'd like to get more pop instead pulling like a tractor.
Thanks

I think we all like more power. It can be had for a big price. Higher compression, more agressive cam timing, heavier valve spring to handle the cam, better breathing with larger valves and ports cleaned up, bigger carbs, free flowing air filter. It takes a concert of cooperating changes to achieve a sizable power increase. The down side is, shorter engine life, and just a more cantankerous bike.

I like the longevity of the current engine and can do with a little less power. We'll see how my 86 and 84 compare when they are on the road together.

Steve

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'84 XT600 is now bored to 2nd oversize and new OEM pistons and rings installed. No more smoking.

How much shorter life do you get by adding high compression piston, cam+++? I can recomend the KTM if you want action and power, with 75hp it will take on the rear wheel on all gears.

Seems like KTM has really come to the front and are really hot. I'd say a bike built to todays standards will last a long time. Materials and engineering are much improved today over 30 years ago.

Improving an old XT is not the same thing at all and may compromise the engine with mods.

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'84 XT600 is now bored to 2nd oversize and new OEM pistons and rings installed. No more smoking.

These motors are plenty stout for adding hp. All a person needs to do is put in the new oil pump that adds volume and run quality oil, changed before it breaks down from the shearing in the trans. I've had several of the 660's apart and they aren't any higher quality than the old ones (which they are designed out of). There are guys running turbos or high comp pistons, bored to the max and run at high rpms without much issues. usually problems arise from simple abuse or poor maintenance .

All motors will have somewhat shorter lives when built up however with good habits it wouldn't be a measurable difference. A person just can't let it idle for 10 minutes @350F or let the it scream at 7000rpm for 20miles just to beat or keep up with your buddy on his crotch rocket. Keep it sane and no problems.

As for the new tci running the older curve(good idea to help them out but mostly will add on top end due to more advance), welllllllll, the motors are the same, just with a starter added to one. I have an '85 jug,head,and valvetrain on my 3TB, an '89 jug & head on the 660 bottom end, all cams are the same, valves are the same, piston is the same. the trans is the biggest difference and it has nothing to do with combustion. Jetting as always will need to be tuned for proper mixture, no black magic involved. The newer heads have just a little smaller intake runners and the carb bore are smaller, there is where most of the 3-4hp loss is on those. Using the older carbs may be a good choice.

If a person wants to know where any power gains can be gotten with these motors, just ask those that installed bigger/better carbs. The stock carbs are whats holding them back, they're just a pain to change over. Then and only then will a person get all the benefits from high comp pistons , taller cam profiles, porting , timing curves, and exhausts.

Very good dissertation and explanation. As you said, good maintenance is vital and certainly much more important if the engine is taxed more. It is just amazing how much abuse these old bikes can take and still come back for more. Thank you for the good information, we all can learn from those who know...

Steve

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'84 XT600 is now bored to 2nd oversize and new OEM pistons and rings installed. No more smoking.

I have an 86 and a 90. The biggest improvement I got was from air pods and jetting up. a lot. The top end rockets with that change. I put old carbs , same pipe and jetting on the 90 and while bottom and mid improved , the timing advance kept the top end a dog. Just ordered a 90 box with the 86 curve in it from HPI. We will see what happens. Application, no guessing.THUMPTHUMP