Jump to content

Looking for a little help

Recommended Posts

Hey everybody I haven't posted in quite a while. Mostly due to not having thumper to talk about. A couple of weeks ago I bought a 99 Dr350SE with low miles. Didn't really have time to ride it thoroughly but it ran okay. Well, with all my bikes I have tinker. The bike was running really rough popping, stalling while stopped and such. So today I pulled the carb which I've done before on a DRZ400 so I'm not new to tinkering with carbs. But the PO did some stuff to the carb that I don't quite understand. So I took a few pictures and was hoping someone would know if he used the right parts and there's a few things I've not seen before that makes me scratch my head. So here's the Mods


- Hole cut in top of airbox (using stock air filter, it's in good shape)

- Aftermarket Petcock (not sure which brand but it works well. 

- Supercrapp after market pipe. (Not to offend anyone but I don't like Supertrapp)

- Rejetted not sure if the right jet was used but a quality kit was used ( I think).

- Aftermarket fuel mixture screw.


That's about it for mods. So below you'll see pictures with questions and hopefully I'll get a few suggestions from someone out there.


So the first 3 pictures is making me scratch my head. What purpose does this serve?







Sorry for the unusual picture sizes, I haven't done this in a while.


Here's the jet kit they used.




Here's the jet that was used.




Here's a picture of the air box mod.




This is the slide needle and the order in which the parts were installed. 




And here's a picture of what the white blob was covering. Why would someone do this? did they think air was escaping? 




And last but not least is a picture of the float bowl. It didn't look dirty to me and the bottom of the bowl lid wasn't gunky either.




So I know this is a lot of info but I just need some advice. Should I use a different jet kit? By the way according to the jet kits instruction sheet it looks like the PO jetted it to a stage 2 setting.


I know these carbs can be finicky and I have all winter to tinker with it so this is just my first step in gathering knowledge.

And yes I used fresh gas and the tank is clean as can be. I know I could just switch it out for a pumper carb but I don't have an extra $400 laying around at the moment so fixing this one is my only option for now.


In advance I'll thank everyone for any suggestions or knowledge they can give me.



Link to comment
Share on other sites

What size are the jets? With the opened up airbox and exhaust you should size up a few on the main and maybe 1 size up on the pilot. The red vacuum cap is doing nothing. The blob is also useless. I would replaced the screw and hose with a properly sized vacuum cap (I tried the screw block off method on my bike after swapping petcocks and it made the bike bog until i put a cap on it).

Link to comment
Share on other sites

Hey thanks for the info already. The main jet is a 136. I'm below 1000 ft elevation. So if I need to go to a bigger jet do I need to buy a new kit or can I just buy the individual jets themselves? And I know this may sound like a dumb question but where would I start looking for a vacuum cap? I didn't think the blob was doing anything good to know I was right. 

Link to comment
Share on other sites

You can get an assorted pack of vacuum caps at your local auto parts store or hardware store.


You can just buy individual jets and it will be fine. The cheapest I've found is on eBay with the seller nichecycle. They are not OEM mikuni. Shipping is out of Florida and they charge a flat $3.15.


JetsRus is a great source for OEM jets (they also have nonOEM), but shipping is $7-8 so you end up paying double for the jet.

Link to comment
Share on other sites

Thanks for the info. I just happen to stop by the automotive store on the way home and picked some up. I have a 140 I think I'll try other than that I have Idea where to start. If I have a 136 now should I just order the next size and see which runs better? Should I leave my pilot jet as is? 

Link to comment
Share on other sites

I figured out what the blob was for. There should be a circlip on the end of that shaft. Which holds the butterfly valve and allows it to rotate. I guess the previous owner lost the clip or couldn't get it to stay. Either way it's jerry rigged. Check the parts fiche to see what I'm talking about.

Link to comment
Share on other sites

Hey guys almost there. I cleaned the carb really well and installed a 140 main jet. Don't know what size the pilot jet is PO installed it. Now it starts right up and once warm rev's nicely. But....and there's always one of those. When warm it idles between 2800-3300 rpm. And turning the knob pictured with the arrow I'm guessing is the idle screw but no matter how much I turn it the idle doesn't change. Is this due to my pilot jet?  




Like I said I'm almost there. It idles high but has no popping sound just smooth acceleration but won't idle down.



Edited by fergy1008
Link to comment
Share on other sites

Try adjusting the air idle screw it is right above the starter on your carb, you will have to rotate the carb or take it off. Certain carbs have brass plugs covering the screw, if you do have a plug it can be removed by drilling it out or poke a screw trough and pull it out.

Link to comment
Share on other sites

  • 2 months later...

Well it's been an challenge with this bike. After some frustration trying to adjust the carb I finally made the plunge and purchased a pumper carb from Jesse @ Keintech Engineering. After a discussion about how my bike was set up with the airbox and exhaust Jesse insured me the carb would be and improvement and all the adjustments and settings would be good. I installed it this afternoon, it took me about 40 minutes and a few swear words but when it was installed I anxiously filled the tank with fresh gas and hit the starter. With full choke and a few turns of the motor the bike fired to life. And man does it sound good! The difference between the stock and the pumper carb is night & day. The throttle is instant, no hesitation what so ever. The pumper carb was worth every single penny. Running a FMF slip on pipe and the new pumper carb is simply amazing. I'm really going to enjoy the DR this summer. I also bought the UFO front fender from Jesse and it bolted right on with no problems. I only had to drill a hole for the brake line bracket. Honestly a 5 minute job. If anyone is on the fence about doing this mod and wants to talk with someone who is more than satisfied with the results email me @ winger1008@gmail.com. Honestly it's a whole different bike. In a good way!

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

  • Create New...