DR650 FAQ - Engine

Q:

Installed 'Performance Kit' and WOW!

For 1996 to 2009 DR650SE owners – I recently installed a standard bore J&E High Compression piston along with a Web Cam camshaft and must say the results were fantastic. My goal was not to destroy the best part of the big DR's power... the awesome low to mid-range torque. I decided to go ahead and do some head work while I had it apart but only matching and cleaning work, no port hogging. The head certainly needed some TLC in its stock form. The valve seat to cylinder head transitions are pretty bleak and there are the typical casting goobers in both the intake and exhaust ports. I matched the intake manifold to the head but, other than clean up and polishing, I did not open the exhaust port any more. I had a nice multi-angle valve grind job done as well. Fresh valve seals were the only new parts required.
The standard bore J&E High Compression piston and Web Cam were bought from ProCycle and I went to my local Suzuki shop for the gasket set (I just went ahead and bought a complete set). I used Permatex copper coat on the base gasket, head gasket and head bolt washers. It sure is nice to have a totally leak free dry engine again.
I know... shut up and get to the good part! I put 65 miles on the bike yesterday after getting it all back together. Torque is the big word! The stock powerband doesn't seem to have changed, it just moved up the food chain a ways. From thump-thumping out from a stop to roll-on torque there is just more on tap everywhere. Obviously more power is available up top as well but, just like the stock engine, it’s not the strong part of the powerband. The roll-on torque is a riot out of turns and my nearly new rear tire was no match for the power, breaking away easily. I can see this being a huge asset for the SuperMoto guys shaming all of those superbikes in the tight twisties.
I have made no jetting changes or adjustments on my FCR from how it was before the engine mods but I noticed even less deceleration popping than with the stock engine internals. Not that it did much of that before but it seems even better. I'll keep an ear on this but I'm wondering if the increased vacuum generated by the smaller total combustion chamber volume is holding the Air Cut Valve open wider... or at least for a longer duration before the spring closes it. Heck, maybe it’s a cam duration thing.
Oh yeah, If you’re thinking of doing these mods anyway don't wait for the dyno report... just do it. My recently calibrated seat-o-the-pants dyno says you won't regret it.

A:

Glad to see you finally got the parts assembled! We now sell that complete kit!) Yeah, the cam behaves better around idle than the stocker. You'll probably notice it pulls a little bit better and smoother right off the bottom in addition to making more power through the rest of the range.
For anyone replacing their piston I recommend a visit to the Mototune web site for a good explanation of proper break-in of a motor.

Q:

Lots of 725 kit installation questions

I have a few questions regarding the 725 kit I recently purchased from ProCycle.
1) Can you confirm that the 725cc sleeve has to be bored out to fit the supplied CP piston? The CP piston supplied has a bore diameter of 4.17 inches and the inside bore diameter of the Northwest Sleeve part, although it says 106 mm (Part# 0229-C6), measures approximately 4.1 inches (104.14 mm). The only way the CP piston can fit into the sleeve is if the sleeve diameter is increased to a larger diameter.
2) Assuming that I have to increase the bore diameter of the sleeve, how much larger than the diameter of the piston should I increase the sleeve diameter to and where should the measurements be taken?
3) The two compression rings appear to be made of different materials as one is of a lighter color than the other. Which one is the top ring and which one is the bottom ring?
4) The installation instruction sheet says that Web Cam Racing Cams "do not recommend any type of synthetic oil". Does this mean that I should NOT use synthetic oil after break-in or that they do not endorse a particular brand of synthetic oil?
5) Web Cam Racing Cams also says "for the first 10-15 minutes of use, we recommend setting your engine at a high idle (2000 RPM) to ensure proper lubrication". Does this mean that I should observe this period with the engine in neutral or can I ride the bike with this high idle (2000 RPM)?
6) At the bottom of the installation sheet it makes reference to "installation information on your enclosed timing card". I did not receive a timing card with the camshaft.
7) The thermocouple enclosed with the Vapor Trail Tech appears to be too small to fit into the recess of the DR650SE spark plug hole without me having to bend and re-shape. Which spark plug should I fit the thermocouple under? I would prefer to fit the thermocouple under one of the spark plugs rather than another place on the head as I think it would give the most accurate readings. 8) After installing the big bore kit and stage 2 camshaft how many miles should I do to consider the new parts fully broken in?
9) One day while riding the DR650 I inadvertently hit the kill switch. After a few seconds I switched it back to the "on" position with the throttle in the closed position. When the switch was positioned to the "on" position there was a loud back firing sound resembling the discharge of a gun. Would this have done any harm to the engine? The engine continued to perform normally.

A:

These are good questions!
1) Yes, sleeves are always made smaller then the finished size. Shrink fitting a sleeve into the cylinder distorts the sleeve. If it came sized to fit the piston then after installing it into the cylinder it would be too tight on the piston. Any machine shop that is capable of installing the cylinder sleeve will know all about this.
2) The sleeve should be bored (after installation in the cylinder) to .002-.003 piston clearance. Again, any machine shop that is capable of installing the cylinder sleeve will know all about this. These measurements are not to be done with feeler gauges! These are precise measurements that should be done with an accurate bore gauge. It is essential that this bore be completely round and straight from top to bottom. If the machine shop you take your cylinder to asks too many questions, they are probably not familiar with the process and you should immediately take your parts and go to another shop! If there is any question, send your cylinder, new sleeve and new piston to Northwest Sleeve in (of all places!) Boring, Oregon and let them do their usual fantastic job on it.
3) Lighter color on top. Don't forget to check the ring gap and adjust it if necessary.
4) Synthetic is fine after break-in.
5) Just don't let the idle speed drop below 2000 rpm. At low speeds the rockers are effective at wiping the oil off of the cam lobes. Higher RPM during break-in assures plenty of lubrication while the cam breaks in. It's better to ride go ahead and ride it.
6) The timing card is only useful on motors that have adjustable cam sprockets. Be sure to check valve to piston clearance.
7) The thermocouple is just soft copper. It will form itself to fit. Just be careful putting in the first time. It also fits better if you put it between the gasket and the spark plug body. I have mine on the outer spark plug.
8) See the mototune break-in method: www.mototuneusa.com/break_in_secrets.htm. When he says "open the throttle hard" he means to open it all the way, or as they used to say, "WFO" (Wide Frickin’ Open). With this method the motor will be completely broken in by the time you reach the 200 mile mark.
9) That caused no harm to the motor. The BANG happened when unburned fuel ignited inside the exhaust pipe. This can be a fun trick to pull in a tunnel. :)
Thanks for the great questions. I hope that you found my answers helpful!

Q:

More re-sleeving questions

I want to install a big-bore kit in my motor. How do I put the bigger cylinder sleeve into my motor?

A:

The new big-bore sleeve is a 'shrink fit' in the cylinder. This means that first the old sleeve is bored out of your cylinder. Then the cylinder is machined to an inside diameter slightly smaller than the outside diameter of the new sleeve. The cylinder is then put in an oven and heated up to expand it. Once the cylinder is fully heated up, the new sleeve is dropped into the cylinder. As the cylinder cools, it contracts to form a very tight fit onto the new sleeve.
After the new sleeve is installed it is then bored and honed to the proper size to fit the big-bore piston. Some folks are puzzled about why the sleeve isn’t sized to fit the piston to start with. The reason is that the stresses of the shrink fit would distort the final size of the cylinder bore, making it unfit for use requiring machining anyway. The only way to fit the bore precisely to the piston is to do the bore and hone last. Naturally, this is all precision work and should be done by an experienced machine shop that fully understands the process. Though most good automotive machine shops will understand all of this, if you have any questions, you can always send your cylinder, new sleeve and new piston to Northwest Sleeve in Oregon and let them do their magic on it.

Q:

Questions about the 725 kit.

I am interested in your DR650 725cc big-bore kit, and have some questions:

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Q:

Another question about the 725 kit.

I am inquiring about your 725cc big bore kit and have several questions about it.

A:

Will do my best to answer your questions!

Q:

Even more questions about our fantastic 725 kit!

I have a few questions about the 725 kit that I don't see asked as of yet.

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Q:

Does the 725 kit work with the stock cam?

I'm thinking about doing the 725cc kit this winter but have a couple questions.

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Q:

Big bore vs. high performance kit?

I'm trying to decide between the just the big bore kit or the complete kit with the high performance cam. What is the difference in power & performance between the two? Or, am I comparing apples to oranges to some degree. Should I be thinking of the big bore vs. the high compression, and figure the cam should be used for either?

A:

It is somewhat a case of apples and oranges. The high compression piston and cam will give you crisper engine response and a motor that is more willing to rev and makes more power everywhere with a better top end pull. The big bore kit by itself will give you a motor with a powerband similar to stock but with the biggest gains mostly in the low end and mid-range. For the best of both worlds add the cam to the 725 kit.

Q:

The BEST way to break-in a new motor!

Should I follow the stock, recommended break-in for a new top-end or is there a better way?

A:

Yes, there is a better way! Go to mototuneusa.com and follow his break-in method. I started doing this a few years ago and have never had a problem. It just makes sense. The factory does us all a disservice recommending a slow break-in. I think the real reason for this comes from their legal department. They want you to ride your new bike cautiously until you get familiar with it. The break-in period is for the new owners brain - not the mechanical parts in the motor.

I was recently watching a documentary showing sportbikes coming off of a Kawasaki assembly line. Every bike was gently warmed up then went right onto a dyno and did a 'full throttle through the gears' dyno run. Then went off to have the oil drained and get crated up. They wouldn't be doing that if there was some harm to be done to the engine without a slow break-in.

Q:

Are you working on a big-valve head?

I recently saw on a forum that you were working on a DR650 big-valve head. Is that true, and if so can you tell us when it might be available?

A:

We are working on it! We hope to have the first head sometime before summer 2010. Then it will take a month or two to do testing and such. The stock valves for the 1996 and newer DR650 are the same part number as the DR200 valves! The stock valves are 33mm intakes and 28mm exhausts and those seats will only accept a 1mm oversize valve which we have already installed and tested. These are not nearly large enough for an engine of this size. Our plan is to have 36mm intakes and 32mm exhausts which should give us power gains across the board without requiring more RPM’s and not losing any bottom end power.

UPDATE! The BIG VALVE HEAD is here! We have put it through some tests on the dyno and going to be running it hard on the roads and trails as soon as the weather gets slightly better! Stay tuned as we should have big news about the big valve soon!

Q:

Best way to get more compression?

Is machining the barrel a cheap or cost effective way of gaining some more compression?

A:

Milling the top of the cylinder is the easy way to get the squish clearance set up properly but you won't be able to raise the compression ratio any significant amount. Taking .010" off the cylinder is only good for an increase of maybe .2 or so. Take off much more and the piston will contact the head. Not good! If you do increase the compression ratio much you definitely want to set the squish clearance properly. The squish area creates turbulence during combustion which speeds up the burning and decreases the tendency toward detonation. Though milling the head is the easy way of raising the compression, I would suggest welding up the sides of the combustion chamber instead. Why? First, you would increase the available squish area. Second, milling the head (and cylinder) will retard the cam timing. Retarded cam timing can be good for top end power but maybe at the expense of bottom end torque. You could slot the cam gear bolt holes and leave the pin out, but for some reason Suzuki decided it needed a pin in addition to the two sprocket bolts, but there must be a reason it is there.

Q:

Is a high-compression piston going to cause problems?

I have a 2003 DR650 with approx. 8,000 miles that has a leaking base gasket. I have the top-end off of it and am trying to determine how far I should go on the rebuild. I know it was running rich for the last couple of months as I grew tired of always fiddling with the main jet, needle position and mixture screw without ever getting it completely right. The bike ran well enough, although I knew it was definitely rich. The exhaust system is coated will black soot.

Anyway, the carbon and crud build-up appears to be more than just a rich fuel/air mixture. While it looks like an oil burner to my untrained eye, the bike never actually used any oil until the base gasket began to leak, but even after that, I only added about a quarter of a quart after about every 2,500 miles. It's been about 15 years since I last pulled an engine apart like this, and most of my 1/2 dozen engine rebuilds were on 2-strokes. While I like performance gains as much as the next guy, I'm not interested in trading performance for reliability. One thing that drew me to the DR was it's reputation for having a no frills, reliable, long running, low maintenance engine.

After all of that, here are my questions:

A:
Q:

Adjust valves when noisy, or before?

Do the valve's always make noise when needing adjustment? My used 1997 DR650 has 6,000 miles on it but I'm not sure if someone has adjusted them. It runs great and there is no noise, but I was wondering if I should check them?

A:

Yes, check them. Valves typically tighten up over time and this makes them quieter.

Q:

How cool does motor need to be to adjust valves?

Tonight I'm doing the first valve check on my DR650, and I read in the shop manual that the bike should be cold. I plan on letting the bike sit for at least an hour or so before checking the valves. Is this sufficient time? It's pretty cool out here now (low 70s, 60s at night).

A:

An hour is plenty of time. If it's not too hot to touch it will be OK.

Q:

Should shop adjust valves on initial service?

I would like some feedback on this. I called the local dealer to set up my 600 mile service, was speaking to the service manager and inquired about checking my valves cold, well, he said that they normally don't check the valves on the first service? I don't have my manual handy, but I thought that was one of the items they should look at? He also said that normally the valves are in check at the 600 mile mark. I thought that most of the adjustment would be due early on.

A:

The valve clearances definitely should be checked after the break-in period. I would recommend talking to another shop. These guys apparently don't want the work.

Q:

Stock vs. aftermarket gaskets.

Can you tell me the difference between OEM Suzuki gaskets (specifically the DR650) and aftermarket gaskets (Moose Racing for example).

A:

While the Moose Racing gasket kit for the DR650 is good quality, it still comes with just a paper base gasket. A few years ago, Suzuki updated their base gasket to a metal sandwich type gasket, not just paper. With the kits that we sell including gaskets, we use the Moose Racing gasket kit, but also include the newer metal sandwich OEM base gasket.

Q:

Do they make copper head gaskets for the DR650?

It is my understanding that copper head gaskets are usually used for high performance applications where you want to adjust the squish/compression ratio. (Top fuel dragsters use them.) They are probably not available for a DR650, are they?

A:

Sure they are! I have a big box full of them. We use copper head gaskets for our 725cc DR650 big bore kit. I spray them with Permatex 'Copper Spray-a-gasket' to assure a good seal.

Q:

What do you use (if any) for a gasket sealer?

I have a full OEM gasket set from Suzuki and it includes the metal cylinder base gasket (the reason for the tear-down). I planned on using Permatex high-heat silicone for the valve cover (as from the factory), but then I got to wondering if people use anything else for the base & head gaskets in particular, or if they just assemble the parts dry, with only the gaskets.

A:

Paper case gaskets we don't treat with anything. The head and base gaskets usually get a quick spray of Permatex 'copper spray-a-gasket'. You don't have to do it, but let's just say it gives you a good feeling.

Q:

Can I use a head cover from a different motor?

I have a 2002 CCM 644 which uses the Suzuki DR650 engine (or the XF650 Freewind). The cover to my cylinder head (the top cover with mount on it) has cracked and is leaking a little. If anyone has a spare cover in good un-cracked condition that they are willing to part with, I would like to buy it, pretty please.

A:

Using a cover from another head is risky. The bore for the camshaft in machined with the head and cover assembled. A cover from another head may not match well enough for proper alignment of the cam bore or proper cam bearing clearance.

Q:

Oil in the stator OK?

I finally got around to checking valve clearances on my DR650 today. Anyone who has ever done this knows that one step in the process is getting the engine to Top Dead Center (TDC). To find TDC, you remove the 8mm and 10mm hex/allen bolts on the left side of the engine. When I removed the 10mm hex/allen cover on the left side of the engine (when looking forward on the bike) oil poured out. This can't be right, can it? The flywheel must have been spinning in oil and I really can't see how the bike even ran because I would have thought that the magneto wouldn't have worked correctly if it is swimming in oil. All total I'm guessing that about a cup of oil poured out; some of it came out just by removing the 10mm hex cover; more came out when I tilted the bike to the left. I even ran the bike with the 10mm cover off and some oil sprayed out. This is a 2005 DR650 with about 3,000 miles.

A:

That said, your engine oil must have been over-filled for oil to pour out just by removing the cap. The bottom of the inspection plug hole is a couple inches above where the oil level should be. Either someone put too much oil in it or you have a carburetor problem allowing fuel to overflow the carburetor and drain into the crankcase. (You would know this was the problem if the oil smelled like gasoline.) One last tip is to be sure that you check the oil with the bike in a totally upright position. If you check it with bike on its side stand, it is not a good reading.

Q:

Best way to monitor motor temperature?

My 1996 DR650 has a Web Cam, 10.5:1 piston, 36/32mm valves, FCR 41mm carburetor and a FMF Q2 exhaust. My question is should I be concerned about it getting too hot? I know these motors are pretty much bulletproof when stock, but how much can you do to them before you start worrying about dependability? The bike runs absolutely great, and I’d like to keep it that way.

A:

The DR650 is very good at shedding heat. When we're running one on the dyno we have to run the fan on the low setting and turn it off between runs in order to keep things up to full operating temperature. If you are concerned - or just curious - add a Vapor unit which has a nice temperature gauge function.

Q:

Performance parts for 1990 - 1995 DR650s

I am trying to locate a supplier that makes a high compression piston and high performance cam for my 1992 Suzuki DR650. It seems 1991 to 1995 DR650 performance parts are hard to find. Any help would greatly be appreciated.

A:

Web Cams can re-grind your stock cam and Wiseco makes a replacement piston but I don't know if it is higher than stock compression. Another option is our big bore kit for the older (1990 - 1995) DRs. This makes your current 650 a 670.

Q:

What happened to that dang missing neutral switch screw?

I removed the side cover on my DR650 in order to change the clutch disks and I realized that one of the two screws that hold the neutral switch in place is missing! I know that this often happens to DRs, but can you tell me what happened to the screw? Is it destroyed? Is it playing around inside the motor? Shouldn't the screw break the motor? Or will the motor break the screw?

A:

You need to find it before something disastrous happens. You may be able to fish it out with a small magnet on the end of a piece of hose or stiff wire. If not then engine disassembly will be required. Yeah, what a PITA but it's a lot better to take it apart now than to let it do it all by itself! When it happens you could be hurt or killed. Suzuki should have done a recall to address this problem.

Q:

Cold wet weather + short rides = milky sludge.

I went to change the oil in my DR650 today and was a bit surprised to find my fill cap covered with the white sludge indicative of moisture in there. My bike sleeps outside in the street every night and then gets a 15 minute commute in the wee hours of the morning. I usually take it to grab lunch mid-day as well, which is about a 5 minute ride.

Could the moisture buildup be from the hourly weather changes we have here in Seattle? Or from the short commutes I do? Perhaps both? I'm clearly inexperienced with this issue, so if anyone wants to point anything out to me, I'd appreciate it.

A:

Cold wet weather + short rides = milky sludge. You want to get the oil hot enough for long enough that the moisture can evaporate out. The DR650 is so good at shedding heat that it can take some long hard riding to keep the moisture out. At least during winter weather. If you can't get out for a long enthusiastic ride you might consider an early oil change to get the moisture out of it.

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