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2003 DR650 - New piston - your opinions

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So my DR has just under 70,000km on the clock (not all mine) and I am pretty sure I will have to replace the rings at least. Now the question, IF I do need to replace the piston as well (heard I might as well since I wouldn't want the thing to disintegrate on me because of age :moon:), how big a difference will the high compression piston (JE kit) place on the engine?

Personally I find my bike with US gearing (15.45) pretty darn good and a nice compromise between slow and touring speeds. So I don't want more power, no need for it.

But what I would like to know, how much of a difference does the high compression piston make? Is it worth it apart from the power increase? Will it place so much more stress on the bike that other problems or issues will start popping up?

Or, should I just pop in a new standard piston and leave the John Deere standard knowing that it lasted 70,000km so far, it should last another 70,000km without hassels from increased stresses.

Happy trails

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WOW! Thats the first time I have ever heard a DR owner say they dont need more power. As for me without question I say JE Piston and A cam at least, I'd be thinking about the big bore myself, Ok I only have 4500km on mine and i'm already dreaming about the big bore. just my two cents.

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I am with you on this one. The DR in stock form has plenty of low end grunt and really does not need anymore. Just remember a motor and only has so many miles in it so why use it all up in a short amount of time. Increasing the compresion on the top end is gonna put more stress on the bottom and wear it out quicker. Just mt two cents.

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The Testosterone addled DR newbs here on TT are always going to tell you to go for more power :cheers: .... but you're instincts are correct. Stay with stock. :moon:

All the high compression kit will do is use more fuel. JE pistons are good but Suzuki stock is even better. Sure, you'll get more power ... do you really want it?

70K kms. is a bunch of mileage for a DR650. Someone has been taking good care of your bike ... BUT ... are you sure it needs rebuilding?

Using a lot of oil at present? Leaking Oil? Smoking? Have you done a proper leak down compression test? How do the plugs look?

If compression is OK and oil use is moderate ... don't touch it! Change the oil to Mobil One synthetic, put in a new set of Denso Iridium plugs and go riding.

If it truly needs a rebuild, here is what I would do:

1. take all apart and measure everything. Let a pro do it if possible/affordable. Check out the condition of the cylinder wall .... make sure the Nikasil type coating is in tact and has no unusual wear or oblong shape. An experienced Pro needs to see it and MEASURE IT.

2. If cylinder OK (If not OK ... then things could get expensive labor wise)

(lets assume it is OK for now) then replace piston and rings using standard Suzuki parts, lightly hone cylinder carefully. (let a pro do it) Install new parts carefully with new piston pin and snap retainer rings, and aligning end gaps on rings and such.

3. Check the top end completely. Let a pro look at the head, valves, valve seats, Valve stems, valve guides, Valve springs, Cam. Good time to rebuild the entire head, buy new valves/springs/guides and maybe even a new Cam. Check cam chain too and cam chain adjuster.

4. As long as you're in there, replace that large brown plastic gear (it can crack) on the clutch side and remove the NSU (neutral sending unit) and Loc-Tite it in (replace Phillips with allen heads and use RED loc-tite .... if the NSU bolts come out ... by bye gear box.

Beyond this not much you can do. One long term weak DR area can be the gear box. Do not be shocked if you lose a gear. But if the bike has never been abused .... then you've got a good chance to do another 70K kms. once rebuilt.

Good luck!

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..... your bike ... BUT ... are you sure it needs rebuilding?

Well, I have a suspision that it needs at the least new rings. I have noticed that it uses oil, the only problem is that I can't say if its because the rings are shod or because I ride hard-ish (don't think I get close to redline revs, just twist wide open and run up the gearbox quickly). What I have noticed is that the oil has a petrol smell to it, faintly, which could be a faulty petcock. The exhaust fumes also have a faint oil smell to them when idling. We went out riding in the forest roads yesterday, and at one spot I was kinda stuck on a log (the trailwings don't always grip that nicely) and my bud behind me for a moment smelled something and wondered if it was his DRZ that smelled that way. Suffice to say, the smell of an engine using oil. But there is no smoking of any kind that I or my bud noticed. As for leaking, not that I know of. There is some weapage on the base but I think its a paper gasket since I don't see a notch. Cam chain is good from last I checked, tensioner, I suppose its just something you replace. The plugs: Running lean as they are black carbon-ed, but not heavily (I get about 23km/liter if I ride no more than 80km/h, and about 18km/l if I ride normally to hardish - hitting reserve). Should maybe lift the needle a notch.

Other than that, I haven't done any checks what so ever. I should I know just to be sure, especially before I buy parts.

The cylinder I might be able to have measured on a CMM machine....might, could be interesting.

I could go check it out on the net, but parts wise, except for piston and rings, pin, gasket set etc (about $190), what would the top end bit set me back as well as that gear you mentioned?

I am more than happy with the bike's power delivery.

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If you are going to replace the piston anyway then go for the JE.

It's lighter than the stocker and 10.5:1 isn't really high compression anyway.

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All the high compression kit will do is use more fuel. JE pistons are good but Suzuki stock is even better

You've got those two things backwards. :moon:

All things being equal, raising the compression ratio will increase fuel efficiency. The JE piston is forged which makes it both lighter and stronger than the cast OEM piston.

I'd say the main issue for Inprogress would be availability of higher octane fuel. The JE piston will need a few points higher octane to avoid detonation as compared with the stocker. If higher grade fuel is commonly available in SA then there is no downside to going with the JE piston. If not stay with stock or have a JE piston machined to bring the compression down to stock level.

Until the motor is disassembled and inspected this is all speculation. At 70,000km there is a very good chance the cylinder itself is worn and will need to be re-plated or re-sleeved.

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+1 Fuel economy on my DR650 has improved since installing the J&E piston and Web cam. With a lighter piston the directional change stresses that are placed on the rod/bearings, crank/bearings are reduced any time the engine is running. True... the stresses on the rest of the drive train are increased as torque/HP increases but how often are most riders pushing the bike to it's limits in those areas? IMO the decision to install the forged HC piston is a no brainer if you are going to have the engine tore down anyway. :moon:

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So this is a bit besides the point, but, when you think of South Africa, what do you see in your minds eye? We do have R1200GSA's here as well. Ok, given, I hear our diesel fuel is atrocious, so much so that all modern diesel cars sold here get fitted with additional filters....but that is what I hear.

When talking HO fuel, how high just so that I can check, in-case I live in a more back wards country than I expected.

My only concern with the HC piston setup is the stress in the engine. I realize the compression isn't that much more, but when it comes to what is more an what is to much, beats me. Its a 70k bike, I don't want to put in a HC piston only to have to replace more parts in the engine a couple of months down the line because I installed a HC piston. If it aint that much more, then I will go for it. But like it was said, all this is just speculation until I actually do the tests to see if I do need to replace, and then as well, do the tests to see how much of a replace. I've heard of a DR here locally with 140k on the odo and the cylinder was still good. Yes it might be an exception, but still comes to show.

Thanks for all the help and advice guys, I am taking it....under advisement ;D

Happy trails

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My bike runs fine on regular grade fuel. (87) The only time I've been able to get it to detonate was in very tight stop and go riding where the engine temperature was quite high... high load, low rpm, high temp.

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I am new to ThumperTalk and wondered if someone could help me... I just picked up a 2003 Suzuki RM 85 that needs some repair. I am told I can download a FREE service manual? Does anyone know the web address that I can download one from? I found free service manuals for a couple Yamaha's but no luck with the Suzuki. Would appreciate an email to cphdrider@aol.com if anyone knows... Thanks in advance.

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A stupid question: Detonate? What does this mean in terms of normal engine running? How would I know if it "detonates" whilst riding?

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A stupid question: Detonate? What does this mean in terms of normal engine running? How would I know if it "detonates" whilst riding?

Pinging... rattling.... pink... death rattle, etc. are other terms for pre detonation. You'll certainly know when it occurs in the DR650. It's quite a pronounced sound resonating from the fins. It sounds similar to taking a screw driver shank and tapping it on the cylinder head fins. It can be quite the destructive process within your engine so we certainly want to avoid it.

Wikipedia says: Knocking (also called knock, detonation, spark knock or pinging) in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel-air charge is meant to be ignited by the spark plug only, and at a precise time in the piston's stroke cycle. The peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive.

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When you are checking available quality of fuel be sure to keep in mind the difference of RON vs. MON etc (google it if you have no idea what I'm talking about :moon:).

I don't think you will have any problems in SA. But if you are planning on ever crossing the continent or riding to neighboring countries, I'd fit a forged piston with the same compression as stock.

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Now this pinging, is it a once of thing or do you hear it a few times in succession? Reason I asked is that I did hear a "ping" type noise twice on my bike now, but if I had to describe what I thought it was from, I think is a stone nicking the header pipe. Its a once of short ping noise, and only once a ping. Like I said, heard it twice now on the bike, the first time being about 2000kms ago.

LukasM, where do I find a forged standard piston? My searches always only showed the HC pistons; maybe I'm an idiot but my searches also only showed me the J&E one's.

Now, regarding the testing, should I start a new thread or has it been discussed properly and extensively in another post here on TT? What is the proper procedures of testing to see if you need to strip her down and start the replacement process?

Happy trails all.

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