I got a 2000 ds i bought used dec 23 2001. seller said it only had 4 rides on it. I owned 2 400ex's nice bike but my love lies with my DS. Any way latly its been backfiring through the carb. it doesnt do it all the time. when it acts up it acts like its caming out, at idle and at 1/4 throttle then rips hard to full throttle. the dealer said it was running lean. I took apart the carb (what a bitch those cab bowl screws) and cleaned every jet every screw I could get off. the butterfly valve was black from backfiring.I put a large fuel filter on and shortend up the vent hose. It still wants to back fire this time after riping down the road and choping the throttle. It will almost blow the carb right off the boot.
I live in Michigan and its been betwen 38 to 15 temp. out side. would that be a factor? Any one rejeting for cold weather?

I got 3 ideas but I want some feed back first

1) go to larger pilot
2) raise the needle (how exactly do you get that needle out from the slide?) HELP
3) valves need adjusting (I dont think its had its 10hr check up.)

By the way shes all stock except ohtsu tires.

any help would be great!!!!

 

Check your air screw, this will cause your ds to backfire.

 

To get the needle out, You use needle nose plyers and reach down into the slide and pull the little black round plug out. Be careful of the tiny spring under it.The needle is under it and ready to come out.Stock setting is fourth slot from the top.As far as your backfire. Check to see if you have a leak in the rubber boot going into your motor.Good luck>>[img]i/expressions/face-icon-small-happy.gif[/img]

 

Check all the simple stuff, and all the maint. shcedule stuff, before you drop any cash yet.
Make sure the plugs are correct - they should be DR8EA.
Make sure all ignition wires are connected well - plug wires, coils, etc.
Make sure the carb needle and jets are actually set correctly - the previous owner may have screwed with stuff. 4th groove on the needle, stock main jet is 165.

Make sure the air screw is adjusted correctly - this can be tricky more some people. Turn screw in until motor starts to bog, then start turning back out, counting each 1/2 turn, until it bogs again. Position screw exactly half way between the two pints of bogging. Position of this crew can have an effect on idle speed, so after you do the above positioning, you may have to reset idle speed - roughly 1300rpm - and then re-position air screw again.

I have around 70 hours on my motor, on my last 50 hour valve check they still needed no adjustment. I expect they will at 100 hours, but if your bike only has 4 rides on it then it is doubtful the valves are out of wack enough to cause a problem. You never know though, so since you unsure of its break-in treatment and 10 hour service, I'd have it done if I were you.

Above all - don't continue riding until problem is solved.

One more thing - 92 octane or higher only. Low octane + high compression = pre-ignition.

 

10-hour service!!!

Sam:

Take the quad in for the 10 hour service. The dealers charge way too much for this but, when you go to sell the quad you can tell the prospective owner you took it in for the 10 hour service. Not many people do this and it is a testimant to how well you treat your bike.

Sounds like you are on the right track and have some good advise from others.

I will PM you with some .pdf documents you may find helpful.

 

Thanks every one for the help. I went through her with a fine tooth comb, every thing looked good. I got to the air screw and it was 1-1/2 turns out. I turned it all the way in and it started to burble a bit I turned it out and out I thought it was gona fall out. it was about 6-7 turns b4 it started to act up it wasnt as noticeable as turning it all the way in. I settled at 2-1/2 to 3 turns out. took her for a spin and it runs awsome!!
again Thanks for your replies.

PS any one from Michigan on these forums?

 

Not from Michigan, but I go to Silver Lake at least twice a year.

 

On the stock carb, which is the air screw that you are talking about? Is it the same as the fuel mixture screw on the bottom of the carb, toward the front, encased in the aluminum sleeve? I was having the same problem last weekend and want to give it a shot.

 

Yes that is the same fuel/air screw in question.
dynojet.com has a cool site with instructions for their jet kits. This link in pdf format is for the ds650. It shows the location of all the stock parts and the ones to swap out if your using their dyno jet kit. It will also tell you what you should / may find in yours.
Here is their main site in case you want to check on another bikes jet kit.

 

hello everyone im sad to say the back firing came back and this time it fouled my plugs black! I couldnt get it, it ran great the day I adjusted the air screw and the next time I went out it ran good for about 20 min. then started the same thing.
I came back on line and searched this site and came across DS650Bill thread about streching the carbs return spring. It sounded what mine was doing and made sence. I streched the return spring 25mm, went riding for a hour or so and ran great! cross my fingers. NeoSirfir you said your ds was doing the same thing you might want to try this. Ill keep ya posted if it comes back.