1991 DR650 mikuni carb question

[noslenam]

Ok first off I am new here so please be patient.? I have a 1991 DR650 which has been sitting for a few yeas with probably less then 50 miles over that time. I took the bike in and had the carb cleaned and suck. I got the bike back and it fired right up first kick and has run great for the past few weeks. All my riding is local and probably 5-10 mile round trip with little to no problmes. I did notice from time to time the bike would bog down and seemed to run rich. Top speed would be around 65mph . So I did a trip that was about 60 miles and I noticed that on the way back it started to bog down again. We stopped to drop off on of the rideres and I noticed the carb was leaking gas from the drain hole at the bottom of the carb. I checked the drain screw and it was tight. I would say that it was like I pulled the fule line and just watched the fule drain out.

It stopped after a minute and I proceded to ride the last few miles home. When I stopped at home it continued to drain. It was running rich I believe. Is it possible there is a pin hole in the float assembly?

I am hopping to get some ideas on what to look for. Any help is appriciated.

Thanks,

?

[DoubleD650]

Kinda sounds like you got some junk in the needle valve that cuts off the gas when the flote, flotes up....

What ever the problem is your gonna have to take off that carbi and give it the once over.....clean,clean,clean it....

But don't go ape S%&* and ram wires into the jets,,, just carb cleaner and a little tooth brush action........

Take it off and work on it at a bench so that those tiny ass parts don't get lost....... IMO

Good Luck !

[noslenam]

Kinda sounds like you got some junk in the needle valve that cuts off the gas when the flote, flotes up....

What ever the problem is your gonna have to take off that carbi and give it the once over.....clean,clean,clean it....

But don't go ape S%&* and ram wires into the jets,,, just carb cleaner and a little tooth brush action........

Take it off and work on it at a bench so that those tiny ass parts don't get lost....... IMO

Good Luck !

Thanks for the quick responce. I actually have the carb off and when I took it in about a month ago they did a carb clean and needle valve and such. I am wondering if I may have had some rust or other debri in the tank from it sitting for son long and it has worked its way back into the carb.

I had someone mention a bad fload assembly with a possible pin hole leak.

I also checked the float assembly and it looked good but I may have to replace the two O-RING's on the float assembly. If my thinking is correct, if I have 1 or 2 bad o-rings will that alow gas to flow into the carb and thus flow out the drain. I just replaced the drain srew which looked top be worn.

What are your thoughts on this hopefully simple fix?

[DoubleD650]

Yea,,,, I could go with that...

The crap in the needle that is.....

All it takes a rust as small as a tick turd to mess it up.......

Give the flotes a look, shake 'em (once out) if they rattle, it's bad.......

O-rings would be nice at the year scooter,,, but flowing out of the carb means that gas is not getting cut off.......

[noslenam]

Yea,,,, I could go with that...

The crap in the needle that is.....

All it takes a rust as small as a tick turd to mess it up.......

Give the flotes a look, shake 'em (once out) if they rattle, it's bad.......

O-rings would be nice at the year scooter,,, but flowing out of the carb means that gas is not getting cut off.......

OK so I pulled the carb off and gave it a good cleaning. The bike fired right up and ran better than it has in a while. So now after about a week or so I noticed that the carb is leaking gas out the drain hole once again. The bike still seems to run good. My question is, is the carb presurized? Could I be getting a buildup of pressure that is forcing gas past the drain screw? I replaced the screw with a new screw. Is there something I can do to the screw that might help reduce the amount of gas that flows past?

I also replaced the gasket and 2 o-rings which gave me a much better seal.

So I am just left with what is causing the gas to leak/pour out the screw drain whole?

Any suggestions ideas are appriciated.

[mxrob]

OK so I pulled the carb off and gave it a good cleaning. The bike fired right up and ran better than it has in a while. So now after about a week or so I noticed that the carb is leaking gas out the drain hole once again. The bike still seems to run good. My question is, is the carb presurized? Could I be getting a buildup of pressure that is forcing gas past the drain screw? I replaced the screw with a new screw. Is there something I can do to the screw that might help reduce the amount of gas that flows past?

I also replaced the gasket and 2 o-rings which gave me a much better seal.

So I am just left with what is causing the gas to leak/pour out the screw drain whole?

Any suggestions ideas are appriciated.

Not sure of which model Mikuni you have but many of the bowl drains also double as the float bowl vent. You probably are not leaking fuel past your drain screw...... but have a fuel level issue which would drain out of the same small line. Since you've cleaned the carb you either have a float level that is set too high or the needle and seat are toast. ?

[pardus]

This may be obvious but do you have a fuel filter on? If a speck of dirt from the tank gets between the needle and seat it'll stop the needle from closing therefore letting fuel through. That would also explain that it would run for a week after a clean then get clogged again causing the fuel leak to start again.

Just my 2c worth ?

[mxrob]

This may be obvious but do you have a fuel filter on? If a speck of dirt from the tank gets between the needle and seat it'll stop the needle from closing therefore letting fuel through. That would also explain that it would run for a week after a clean then get clogged again causing the fuel leak to start again.

Just my 2c worth ?

+1 Good point.

[noslenam]

This may be obvious but do you have a fuel filter on? If a speck of dirt from the tank gets between the needle and seat it'll stop the needle from closing therefore letting fuel through. That would also explain that it would run for a week after a clean then get clogged again causing the fuel leak to start again.

Just my 2c worth ?

Good point, other than the filter that is in the tank from the petcock there isn't one. I guess I better get one. Any suggestions on what the best type of filter would be to use?

Thanks and I will try that as well as another good cleaning.

[mxrob]

Good point, other than the filter that is in the tank from the petcock there isn't one. I guess I better get one. Any suggestions on what the best type of filter would be to use?

Thanks and I will try that as well as another good cleaning.

The OEM petcock comes with two fine screen filters.... one for reserve at the base of the petcock and one sitting up on an extension tube for on. They are not replaceable without buying a new petcock. Yours have been removed??

[noslenam]

Not sure of which model Mikuni you have but many of the bowl drains also double as the float bowl vent. You probably are not leaking fuel past your drain screw...... but have a fuel level issue which would drain out of the same small line. Since you've cleaned the carb you either have a float level that is set too high or the needle and seat are toast. ?

Thanks for the feedback. So I am looking at the diagram of the mikuni carb located at-

http://houseofmotorcycles.bikebandit.com/partsbandit/oem_schematic_view~schem_dept_id~707292~section_dept_id~1~section_dept_name~OEM+%28Stock%29+Parts~dept_type_id~2~model_dept_year~1991~model_dept_mfr~Suzuki~model_dept_id~703250~model_dept_name~DR650SM.asp

You mentioned that the fuel level might be to high. If I am seeing the diagram right the bottom portion of the bowl/housing has a brass tube that comes up. This would be the overflow drain I imagine? So if the float is not calibrated correctly or is maybe work out ove the years, the fule level may be getting to high and reaching the drain tube? So my best bet would be to do a good carb cleaning and adjust the float high as recomended. This sould solve my problems. If I am still having problems after that would it be safe to say that I should replace the float assembly?

Thanks

[fl-cracker]

Thanks for the feedback. So I am looking at the diagram of the mikuni carb located at-

http://houseofmotorcycles.bikebandit.com/partsbandit/oem_schematic_view~schem_dept_id~707292~section_dept_id~1~section_dept_name~OEM+%28Stock%29+Parts~dept_type_id~2~model_dept_year~1991~model_dept_mfr~Suzuki~model_dept_id~703250~model_dept_name~DR650SM.asp

You mentioned that the fuel level might be to high. If I am seeing the diagram right the bottom portion of the bowl/housing has a brass tube that comes up. This would be the overflow drain I imagine? So if the float is not calibrated correctly or is maybe work out ove the years, the fule level may be getting to high and reaching the drain tube? So my best bet would be to do a good carb cleaning and adjust the float high as recomended. This sould solve my problems. If I am still having problems after that would it be safe to say that I should replace the float assembly?

Thanks

By George, I think he's got it.?

[mxrob]

Thanks for the feedback. So I am looking at the diagram of the mikuni carb located at-

http://houseofmotorcycles.bikebandit.com/partsbandit/oem_schematic_view~schem_dept_id~707292~section_dept_id~1~section_dept_name~OEM+%28Stock%29+Parts~dept_type_id~2~model_dept_year~1991~model_dept_mfr~Suzuki~model_dept_id~703250~model_dept_name~DR650SM.asp

You mentioned that the fuel level might be to high. If I am seeing the diagram right the bottom portion of the bowl/housing has a brass tube that comes up. This would be the overflow drain I imagine? So if the float is not calibrated correctly or is maybe work out ove the years, the fule level may be getting to high and reaching the drain tube? So my best bet would be to do a good carb cleaning and adjust the float high as recomended. This sould solve my problems. If I am still having problems after that would it be safe to say that I should replace the float assembly?

Thanks

Yes, that's the overflow drain/vent. Certainly start with the adjustment check. If that does not do the trick and you are sure you are not getting contaminats back into the needle and seat, that could be keeping the needle and seat from fully closing, then you'll need to replace the float assembly. #18. Be sure to get the two o-rings #19 and 20 as well. It may be possible that the assembly comes with the o-rings though. You will need to check with your dealer on that. Good luck!

[DoubleD650]

Yes, that's the overflow drain/vent. Certainly start with the adjustment check. If that does not do the trick and you are sure you are not getting contaminats back into the needle and seat, that could be keeping the needle and seat from fully closing, then you'll need to replace the float assembly. #18. Be sure to get the two o-rings #19 and 20 as well. It may be possible that the assembly comes with the o-rings though. You will need to check with your dealer on that. Good luck!

Here this will make it easyer.....

[noslenam]

Thanks everyone for the feedback.

Well I wonder if the petcock is an aftermaket. The one I have in my tank in one solid filte that is about 4-6 inches long with a fine screen. I am sure it contains both the main and reserve intakes but it is a single unit. I think I will still add an inline filter as well.

Thank again everyone for the help.

[noslenam]

Ok I have another question for you all. So I recently pulled the carb and adjusted the float assembly. I have not noticed that there is any fuel flowing from the overflow as of yet. I am noticing that the bike seems to start better with out the choke first start of the day. The bike also seems to run a bit different.

So I imagine that after adjusting the float I may need to adjust the needles some? If the bike start better when cold with out the choke does this mean the bike mixture is richer? When at speed the bike seems to run good but it does seem to be a bit off sometimes. How is the best way to tell if the bike is just a bit on the lean side or rich side.

Thanks again for the help.

[keysandslots]

If it starts fine without the choke, it's probably running a bit rich. Easiest way to tell is to check the sparkplug colour. Run it for awhile at or near idle, then kill the engine and pull the plug. If it's light tan or white, you're lean, really dark tan or black, you're rich, and if it's a nice tan colour, you're just right.

You can do this at multiple rev ranges but in order for it to be accurate, you need to kill the engine after running for a few minutes in the range that's giving you problems. When I did the work on my '91 DR650, I eventually got everything sorted out accept the very top end, near 150 KPH (almost 100 MPH indicated). So, I would head down the QEW at full throttle, then kill the engine (still on the highway) and coast to a stop at the side of the road. Then I'd pull the plug and check the colour.

It worked but I don't recommend this.

Randy

[noslenam]

If it starts fine without the choke, it's probably running a bit rich. Easiest way to tell is to check the sparkplug colour. Run it for awhile at or near idle, then kill the engine and pull the plug. If it's light tan or white, you're lean, really dark tan or black, you're rich, and if it's a nice tan colour, you're just right.

You can do this at multiple rev ranges but in order for it to be accurate, you need to kill the engine after running for a few minutes in the range that's giving you problems. When I did the work on my '91 DR650, I eventually got everything sorted out accept the very top end, near 150 KPH (almost 100 MPH indicated). So, I would head down the QEW at full throttle, then kill the engine (still on the highway) and coast to a stop at the side of the road. Then I'd pull the plug and check the colour.

It worked but I don't recommend this.

Randy

Randy thanks for the help. So I have adjusted and installed a new float assembly. The bike starts greta and seems to be running rich when at 1/2 to 3/4 throttle or more. If I understand correctly I need to adjust the needle jet at this point? A few months back I had the bike worked on and carb was cleaned and adjusted after sitting for about 4 years. There was some old gas in the tank that was used by the shop to get the bike back in running order. can this be causing problems as well? If the bike had very old gas in it and they tuned the carb to the crappy gas it had in there could I need to re adjust the needels at this point?

I would imaging I need to but I want to make sure befor I start playing around.

1/2 to 3/4 throttle seems rich so how do you lean the needle jet at this point?

Thanks everyone for being patient.

[mxrob]

1/2 to 3/4 throttle seems rich so how do you lean the needle jet at this point?

Thanks everyone for being patient.

Tuning the bike with old stale gas would certainly be counterproductive.

The 96 and up DR650's have a needle that has only one clip position. Not sure what you have on the 91. The jet needle can be richened up by shimming on the 96 and up units but you can't lean it out without cutting down the white plastic spacer. If your model has multiple clip positions like are shown in the diagram above you can lean out your needle by moving the clip to a higher clip position (lowering the needle). That being said a flaot bowl fuel level that is set too high will richen up your mid throttle positions... and main. Double check that you have the correct fuel level before making any major changes.

[cyron]

I also have a 1991 DR650, & was having the same issue. I rebuilt the carb, but I'm a carb novice. I finally in a last ditch effort ordered a new manual fuel Petcock.

I put it on last night & no more peeing out the float drain, no surging, etc...

So, for ~$30 buy yourself another fuel Petcock, & a manual one at that.

I had to put a note on my tank to remind me to turn off the fuel.