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Stubborn DR350

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My buddy bought a dirt model 94 DR350, it has a few problems hard to figure out. Someone supposedly recently overhauled the engine. Something very weird is going on. Compression 135lbs. It uses the very small thread spark plug CR9E like the DRZ400 or DR650. When kicking it, will kick back hard sometimes like it is trying to fire on the piston upstroke of the compression stroke. I kicked it about 500 times yesterday bruised my foot. It will run if pulled or rolled off the hill and runs decent at lower rpm but misses badly when throttle is wide open. It will idle a while but when it dies it will not start with or without choke. The piston is at top dead center when the T mark on flywheel lines up. The valve tappets are then free and set at .004 and .006. The carb is a pumper carb and someone has worked on it lots of times, half stripped screws and such. It will barely idle if the fuel screw is full in, but dies immediatly when the screw is backed out any at all. Also the full throttle miss goes away for a few seconds when choke is applied. When idling you can spray carb cleaner all over the carb looking for air leaks, none can be found. These are some theories: The cam sprocket timing is off 1 tooth, The carb is in need of all new parts, maybe the carb body has been ruined by former too much wrenching by ham fisted mechanics, The CDI is bad and causing it to fire at the wrong time. Have you ever heard of such a stubborn DR? Any ideas?

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Just thinking out loud here: That spark plug was for a 350SE...not sure if it's supposed to go into the dirt model. Does it have a manual decomp lever? If not, you may have a bigger problem here.🙂

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Sounds exactly like my 350 when I first got it back in the day.

First off make sure the carb is clean and the float is set correctly, if the PO were in there alot they might have been playing with the jetting so verify the sizes as well. I am betting the float is set incorrectly, that's what caused mine to "miss" on wide open throttle. On the topic of the carb, how high is the idle when the engine is warm? I noticed a higher set idle made starting the bike harder.

It doesnt sound like a CDI problem, and really doesnt sound like the CAM timing is off either, but that can be checked easily enouph if you want to verify. Just make sure you have some high temp silicone sealant for when you put the cam cap back on.

I am still apparently the only person who can start my DR350. My method is to use the decompression lever and give it a few easy kicks to "clear" it out. After that pull in the decompression lever, slowly kick the bike until the lever pops out, then just a couple degree's more after that. Return the kickstart to the top position and then jump on it with all your weight. Normally starts within the first few attempts this way.

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The service manuals call for DPR7EA9 but this one has got the small threads like the CR9E. Maybe someone switched the heads? Its the dirt model with pumper carb and manual compression release. I used to have a 99 Dirt model, it started with 1 or 2 kicks every time. On the carb there is a small brass pipe going from bottom of carb to inside the carb bore, looks like someone tried to remove it at one time or another and the rubber seal is gone, and the seal is gone on the accelerator pump rod. The guy that bought my trusty old 99 DR is bringing it over this evening, so we can switch carbs and CDI if necessary. Carb first. Probably need to look at the cam timing before he gets here with the other DR.

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The service manuals call for DPR7EA9 but this one has got the small threads like the CR9E. Maybe someone switched the heads? Its the dirt model with pumper carb and manual compression release. I used to have a 99 Dirt model, it started with 1 or 2 kicks every time. On the carb there is a small brass pipe going from bottom of carb to inside the carb bore, looks like someone tried to remove it at one time or another and the rubber seal is gone, and the seal is gone on the accelerator pump rod. The guy that bought my trusty old 99 DR is bringing it over this evening, so we can switch carbs and CDI if necessary. Carb first. Probably need to look at the cam timing before he gets here with the other DR.

I'm befuddled by the rocker/valve cover with the smaller plug hole...at any rate, shouldn't be causing a problem unless the CDI is programmed for the different plug...and I'm not even sure CDI's are that "smart".

Anyway, it very well could end up being a carb problem. It sounds almost like a clogged pilot or the needle is set too low...like it's starved for fuel. Could be that the carb is just Fubar and needs a replacement.

Another thought is that the decomp could be hanging a valve slightly open. A compression of 135 *seems* a little low for a fresh rebuild to me. That could be the culprit. Could you do a leakdown test of the head to be sure all valves are closed maybe?

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More of the same crap. This time I have a great running, easy starting 99 DR350 dirt model sitting right next to the problem maker 94 bike. Switched carbs, same problems. Switched CDI, same. Switched coil, same. Switched voltage regulators, same. Checked both stators with ohmeter side by side, same readings. Double checked cam timing and manual and auto compression release, looks fine. Dirt model cam with a 5 stamped on the end. The cam chain may be stretched a bit, there was only 3/16 left of travel on the auto tensioner. I don`t really think the timing of the cam could be off enough with a stretched chain to do what this bike does which is this: Kick like Chuck Norris 100 times, won`t start. Occasionally during this great fun session it will pop and backfire against your foot and bruise it good. If you tow it with an atv, it will eventually start and run ok in the lower revs, but anything above 1/3 throttle craps out bad. Better not let it die, or your atv buddy will have to hook on again for another tow. This is all with the other carb and CDI from the great running 99. Nothing we have done to this bike makes any difference at all! The only thing left is switch stators (not so easy) and take it to another shop who can do a leakdown test of the engine check for leaky valves or cracked heads. I have seen some atv`s run fine with 100 pounds of compression and this thing has 135 pounds or more. No wonder the previous owners left it in the barn for 2 years after working on the carb til all the screws and jets were wore out!

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Sounds frustrating for sure.🙂

1 more stab here:

Any blockages in the exhaust? Are you sure you've got good fuel flow from the petcock? Could still be that the valve cover/rocker system is the wrong one.

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Clymer has been known to have bad info scattered thru out the shop manuals such as the wrong wire colors to troubleshoot the stator and the DPR7EA9 plug called for in Clymer. The genuine Suzuki manual does indeed call for a CR8E spark plug gapped at .025 for the dirt model 94 and 99 which both bikes have. This 94 problem bike has many different colors of gasket sealer thru out the engine and the screws, bolts have been worn out from numerous attempts over the years to get this bike running right. I found some missing parts here and there like rubber seals missing or wore out on the carb, the Cam C-Ring is gone, the last mechanic forgot to put in the C-ring on the cam and bend over the tangs that keep the cam sprocket bolts from backing out but it appears to have not done any damage yet. Against all better judgement, and after reaching the end of my diagnostic rituals finally decided there was nothing else to do except switch the stator plates, even though the ohmeter readings were identical on both bikes and met the specs in Clymer and Suzuki shop manuals. Reluctantly pulled the stator and cover from the running 99 model, carefully looked it over, looked at the way it is made. Then went to the 94 removed it. Layed them both together on a bench to stare at a while. Ah, what do we have here? The bad running 94 has one of the 2 pickup triggers installed upside down so it don`t line up with the magnetic bump on the flywheel. Someone, either a crooked dealership or a disgruntled empoyee at Suzuki motor in 1994 had went to great pains to install this upside down. No way to get a wrench or socket on the small bolts but can use an open end wrench standing on end with a screwdriver thru the box end to turn it a few degrees. Finally got it off, when reinstalled no problem getting a wrench on it while in the right position. I suppose the Suzuki tech that done this has been laughing for years over this little trick. Maybe sold lots and lots of parts and labor, engine overheating, mechanics wearing out and stripping screws. Since the ohmeter readings were right, I doubt anybody would ever pull the stator and buy a new one since they cost over $400 and the readings were fine. Monday will order the new carb gaskets and missing parts and such to put her back together. I`m now confident the bike will finally run like never before! Been working on bikes since a kid in 74 and never saw such an effective sabotage method. although a couple months ago found a Z400 Suzuki that had been worked on by the nearby large dealership, will save that story for another thread.

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🙂

Wow! Please post up your results here once you've got the new/replacement stator in. Interested to see how this turns out.

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