Mikuni BSR36 carb rebuild problem

Dont know what else to do. Guess I will take my DRZ400s to the shop. I have been unable to ride for a few years so my DRZ has sat for quite a while. Got new battery. No surprise bike would not start. Would turn over and hit a few licks and that was about it. Figured carb was gummed up so pulled it (Mikuni BSR36 CV Carb) and took apart and cleaned all the jets, put it back together and still would not start. Ordered a rebuild kit pulled carb again and replaced the following:

 pilot jet (23)

 main air jet (24)

main jet (14), main jet holder (12) and o-ring (13), needle jet (11)

pilot adjustment screw (36) and o-ring (33)

Diaphragm (15)

O-ring (37)

Needle valve assimbly (18) including o-ring

My first time rebuilding a carb. Made a few mistakes no doubt. The one I know of was I didn't know about counting the turns until bottoming out on pilot adjustment screw so set it at 3 1/2 turns per Clymer manual. I measured the float bowl height at 13mm from gasket surface to highest point on float. Checked the throttle sensor resistance which is a little off. Closed it was 6270 ohms, open it was 5020 ohms or 80% of closed value. Manual said should be 78%. Don't know but hope that's close enough.

Put it all back together and it fired right up and ran for several min. Turned ignition off and then started it back up several times and seemed to run and start well.

Decided to take it for a short test drive down my 1/4 mile long driveway. Got to the end and it died and would not start back up. Would turn over and run for a sec or two and then die. Had to push it back to the house. Noticed that it was trying to backfire a little when trying to start it. Did a little more reading and saw there some said to set the pilot adjustment screw to 2 1/4 to 2 ½  turns out from the bottom. I tried to adjust with carb on bike but wasn’t having any luck so I pulled the carb again and turned the pilot adjustment screw in one full turn to 2 ½ turns out from bottom. Put it back together and bike started and ran for 15 min. Turned the key off and tried to restart with no luck. Would not hit a lick.

Heck I dont know my problem may not even be the carb. Im not much of a mechanic. Pulled the plug and it looks great and has spark. Guess thats no surprise since it ran for while.

Dang thing has done this to me several times. Put everything back together and it fires up and runs. I think COOL I finally got it. Come back later and it wont start. Will run for a sec or two and then die.

Guess I should mention I also put a raptor petcock on bike and added an inline fuel filter. At one point I thought the new petcock might be causing problems so switched back to original stock petcock. After doing so once again the bike fired right up and ran for several min. I thought COOL, I got it now! Went back out next morning and it wouldnt start. This seems to be a recurring theme. Many times after I reinstall the carb it seems to start and run but then an hour or so later or the next morning it wont start.

So what did I do wrong? Could it be something else rather than the carb. Could it be timing related? Did I miss something with the carb? Im out of ideas. Guess I will take it to the stealership.

Edited by llbaker2
spelling

Have you checked for gas in the oil?? 

I had the SAME EXACT ISSUES with the bike starting, getting warm, then dies and wont start till it cooled off a bit. If you do indeed have gas in the oil, check the petcock as its usually gone bad and letting fuel bypass without the vacuum line running. (provided you have the vacuum petcock and have not already done the common raptor swap)

In addition, the needle seat o-ring is usually bad as well letting the gas past the float valve. If you already replaced the needed seat o-ring you should be fine there as thats normally the culprit.

Just pop the dip, take a good whiff when its warm and if you have enough gas to stall and shut her down... you should be able to smell it pretty good. Let us know what you find!

Edited by RC_ichard
19 minutes ago, RC_ichard said:

Have you checked for gas in the oil?? 

I had the SAME EXACT ISSUES with the bike starting, getting warm, then dies and wont start till it cooled off a bit. If you do indeed have gas in the oil, check the petcock as its usually gone bad and letting fuel bypass without the vacuum line running. (provided you have the vacuum petcock and have not already done the common raptor swap)

In addition, the needle seat o-ring is usually bad as well letting the gas past the float valve. If you already replaced the needed seat o-ring you should be fine there as thats normally the culprit.nJust pop the dip, take a good whiff when its warm and if you have enough gas to stall and ut her down... you should be able to smell it pretty good. Let us know what you find!

Thanks RC_ichard for your response.

I replaced the petcock with a raptor petcock just before rebuilding the carb. Not sure what you mean by needle seat o-ring. If you are referring to item 13 in the carburetor parts diagram (see image below) I already replaced it. Also replaced the entire needle valve assembly (item 18 on carb parts diagram) which includes the o-ring. I changed the oil at same time I replaced stock vacuum petcock with manual raptor petcock (and yes I blocked off the vacuum nipple on the carb with a rubber vacuum cup). 

partdia.jpg

Check the oil again anyway. You may have inadvertently knocked the float level out of range during the rebuild. If the float level is too high it will also flood the engine.

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Just left Walmart. Picking up some oil. Not sure if it was my imagination or not but thought  I smelled a hint of gas. Better safe than sorry.

rc is referring to assy 18 in the diagram, it attaches to the float and when the carb bowl is full (and the float is floating) that assy shuts off fuel, when it leaks the carb bowl overfills and it can continually leak filling your engine w gas albeit slowly.

Typically w gas in oil the bike wont restart hot but will run fine when cold.

I would also drain your carb bowl into a container and se if there is any water present (even a drop) water will show up as specks (of dirt like material) on the bottom of the container or droplets on the bottom if there is more than  a little water is heavier than gas so it collects down low like the bottom of your tank and the bowl of the carb, if water is present it gets stirred up and essentially blocks the jets and keeps the bike from running till it sits a bit then it may restart and stall and not restart etc.

 

if you find water drain the tank and refill w fresh gas.

1 hour ago, RetroRanger said:

rc is referring to assy 18 in the diagram, it attaches to the float and when the carb bowl is full (and the float is floating) that assy shuts off fuel, when it leaks the carb bowl overfills and it can continually leak filling your engine w gas albeit slowly.

Typically w gas in oil the bike wont restart hot but will run fine when cold.

I would also drain your carb bowl into a container and se if there is any water present (even a drop) water will show up as specks (of dirt like material) on the bottom of the container or droplets on the bottom if there is more than  a little water is heavier than gas so it collects down low like the bottom of your tank and the bowl of the carb, if water is present it gets stirred up and essentially blocks the jets and keeps the bike from running till it sits a bit then it may restart and stall and not restart etc.

 

if you find water drain the tank and refill w fresh gas.

This has been a long process for me. I have pulled and reinstalled the carb 4 or 5 times. At least Im getting pretty good at it. I also installed an manual Raptor petcock and inline fuel filter. First time I just cleaned the jets and installed the petcock with no luck. Thought maybe the new petcock was the problem so as test switched back to original with no luck. Second time I pulled just to look it over to see if I had missed anything and reinstalled the Raptor petcock. In the process saw that I had pinched the diaphragm between the carb body and the top plate so redid that. Still no luck, Ordered a Moose racing rebuild kit plus a pilot jet (23) and main jet holder (12) and a new diaphragm. Installed all the new jets and o-rings etc. Still no luck. Did some more reading and decided that I didnt set the pilot screw properly. Tried to adjust pilot screw with carb on bike but couldnt get to it. Pulled it again and set it to 2 1/2 turns out from bottom. Still no luck. Checked the throttle position sensor resistance which as a little out but close enough (I hope). So you see its been a long convoluted process. Since I switched back and forth between the stock and Raptor petcocks I may have got more gas in my freshly changed oil. To be safe and because I think I may have detected a slight gas smell on the dip stick,  I will change the oil again tonight.

Early in this this process I dumped all the old gas out of the tank and have screwed with this so long Im positive whatever old gas that was in the lines has long since been drained out. Pretty confident in saying there is no water in gas.

This has turned into quite the project. At least I've leaned a little about carburetors. Hope the oil change does the trick.  Frustrating because it starts and runs and I think COOL, I've finally got it and then it dies and wont start time after time. 

Tell me about the in-line fuel filter you installed.  Brand, type, (paper or brass filter element), clear plastic or metal body?  Why did you add the filter?

When it will not start is there gas in the carb? (you can determine by opening the drain screw)

2 hours ago, Noble said:

Tell me about the in-line fuel filter you installed.  Brand, type, (paper or brass filter element), clear plastic or metal body?  Why did you add the filter?

When it will not start is there gas in the carb? (you can determine by opening the drain screw)

This link to filter I used: https://vod.ebay.com/vod/FetchOrderDetails?itemid=322069477016&transid=1783020306011&ul_noapp=true

I think the filter pictured is larger than the one I used from above link. I suspect the one in pic (larger one) would be the better way to go.

Got the idea from a Thumpertalk post. Below is a screen dump of image showing installation. Sorry dont have link (if your eyes are good you can get the link from top of image which is screen dump of web page).  I didn't do it exactly the same way but pretty close.

I originally got the filter because I broke off the screen filter on my stock petcock (plastic brittle from ethanol?)  and couldn't find a replacement (dont think Suzuki makes one). Decided to just replace stock petcock with Raptor manual petcock. Already had inline filter so figured it wouldn't hurt to add it.

Yep Im positive its got gas in the carb. I did just as you said several times because I suspected I had just the opposite problem. I suspected I was getting to much gas. It seemed to help when trying to start if I drained fuel from the bowl. Sometimes after draining it would hit a few licks and maybe even run for a few secs before dying again.

DRZ_Fuel_line_routeing.jpg

Edited by llbaker2

Some filters can be a problem for fuel flow with gravity systems.  But that filter should be OK.

So many parts replaced at one time with the carb kit makes me wonder. Kit brand? Source? Price?  Not aware of a kit that complete.

Gas contaminated oil is a possibility.  But generally only shows up after the motor warms up.

Main jet and starter jet mixed up?? (they will interchange) The man jet is the larger number, perhaps 142. It goes directly below the slide needle.

Defective float valve or float valve O ring or the body where the O ring seals??

Did you adjust the float setting? 13mm to the float when the float touches but does not depress the float needle.

7 minutes ago, Noble said:

Main jet and starter jet mixed up?? (they will interchange) The man jet is the larger number, perhaps 142. It goes directly below the slide needle.

Not to hijack baker's thread but my bike will only run on choke and dies when I touch the throttle. Did I make this mistake?

main.JPG

needle.JPG

9 hours ago, Noble said:

Some filters can be a problem for fuel flow with gravity systems.  But that filter should be OK.

So many parts replaced at one time with the carb kit makes me wonder. Kit brand? Source? Price?  Not aware of a kit that complete.

Gas contaminated oil is a possibility.  But generally only shows up after the motor warms up.

Main jet and starter jet mixed up?? (they will interchange) The man jet is the larger number, perhaps 142. It goes directly below the slide needle.

Defective float valve or float valve O ring or the body where the O ring seals??

Did you adjust the float setting? 13mm to the float when the float touches but does not depress the float needle.

I used rebuild kit from Moose Racinghttps://mail.google.com/mail/u/0/#inbox/15d9a47b37afc72f). In addition to the kit I ordered a few OEM parts from Babbitts (http://www.suzukipartshouse.com). 

Bike will start and run. Let it run for 15 min just fine. Decided to turn key off an restart but would not do so.

I read some place that jets had same threads and could be mixed up so when installed made sure that didnt happen. Jet with larger opening went to main and small to starter.

Replaced entire float valve assembly (part of Moose Racing kit). I suppose the new assembly could be bad.

I did not adjust float height setting but I did check it. It was right at 13mm perpendicular from gasket surface to highest point on float. 

 

 

 

Edited by llbaker2
Not to hijack baker's thread but my bike will only run on choke and dies when I touch the throttle. Did I make this mistake?
main.JPG.8a8d041f6a4583de616923b836a74066.JPG
needle.JPG.cee2494e9712d1949d3eca290060f1e9.JPG

Yep

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On 8/10/2017 at 2:51 PM, RC_ichard said:

Have you checked for gas in the oil?? 

I had the SAME EXACT ISSUES with the bike starting, getting warm, then dies and wont start till it cooled off a bit. If you do indeed have gas in the oil, check the petcock as its usually gone bad and letting fuel bypass without the vacuum line running. (provided you have the vacuum petcock and have not already done the common raptor swap)

In addition, the needle seat o-ring is usually bad as well letting the gas past the float valve. If you already replatheced the needed seat o-ring you should be fine there as thats normally the culprit.

Just pop the dip, take a good whiff when its warm and if you have enough gas to stall and shut her down... you should be able to smell it pretty good. Let us know what you find!

RC_ichard YOU DA MAN. Changed oil again. Fired right up and seemed to run fine. I say "seemed" because dang thing seemed to run fine several times before only to fail me again. I was so skeptical that that I was afraid to get to far from the house on first test ride. Last time I had to push it 1/4 mile back to house. My neighbors must have thought he's finally lost it because I was riding my bike around the house over and over and over and over.  After about 20 round-the-house trips I went for it and road around the perimeter of my 30 acre pasture over and over and over again. Must have covered at least 4 or 5 miles. By god I think its actually running this time. Idle seems to be a little off. Sounds about right when I first start it but when I crack open the throttle and then back off again it idles fast for a 5 or 10 secs and then settles back down to normal idle. Not sure what thats about. 

I was kind of surprised that to find gas in the oil (or should I say oil in the gas) again. Think that was the first thing I did (change oil) when breaking the bike out of storage. Changing the petcock was an after thought plus after changing petcock I was still having issues so I switched back to stock and then back to Raptor in attempt to eliminate petcock as culprit.  Guess that was enough to contaminate the oil again. Didn't take long.

Thank for your help RC_ichard. and to all that were kind enough to offer your assistance. 

I guess I lost track of the symptoms.  I though you said it would not start in the morning cold.  Yes starts cold, runs 15 min, will not re-start hot is classic symptom of gas in the oil.

36 minutes ago, Noble said:

I guess I lost track of the symptoms.  I though you said it would not start in the morning cold.  Yes starts cold, runs 15 min, will not re-start hot is classic symptom of gas in the oil.

This process was a long and convoluted one. When I first started trying to get bike running after setting for years the initial symptoms were different from from those near the end (gas in oil). I suspect I was dealing with multiple issues. When I first tried to start it up it would not start. It turned over and tried to start (sputtered a few times) but would not do so. I pulled carb and cleaned it. Cant remember the exact order but near the beginning I also changed the oil. Not sure if it was before or after the first time I pulled the carbs.

In the process of tearing the bike down to remove the carb I removed the gas tank. Rubber insert on inside of  gas cap had deteriorated and parts of it fell into the tank. While I had tank off I poured out the old gas and pieces of rubber from old gas cap. Got new gas cap (IMS tank). IMS also sent a new gasket for petcock. They said it would be bad too (ethanol thing). Pulled petcock and in process broke off in-tank screen filter (brittle from ethanol/age). Decided to add in-line filter because dont think Suzuki sells replacement in-tank screen filter. Thought that made more sense than spending $95 for new stock petcock. After doing some reading on Thumpertalk  decided to just replace stock petcock with Raptor petcock because of the gas in oil thing. After cleaning carb installing petcock Bike would start and run for a few secs and then died. Slight improvement but would still not run. Was not sure if problem was carb or petcock so switched back to stock petcock to see if that helped. Didn't seem to help so switched back to Raptor. Decided to rebuild carb. After rebuild and assembly the bike started right up and ran for 15 min or so until I turned the key off. Tried to restart and would not do so. Did some more reading and decided that I didnt have the pilot adjustment screw set correctly. Set pilot screw to  2 1/2 turns as suggested in Thumpertalk post. Started right up and ran for several minutes and even restarted a time or two. Next morning would not start at all. Thats when I made original Thumpertalk post asking for help. 

Think the stock petcock was bad as well as at least one o-ring in carb and gas was getting into the oil. I changed the oil but afterward I switched back and forth between the stock and Raptor petcocks in attempt to eliminate petcock as cause for not starting. In doing so I suspect the oil got contaminated with gas again. So now I have a rebuild carb with all new jets and o-rings and a new Raptor petcock and it still wont run.  RC_ichard said to remove dip stick and give it a good whiff. When I did so I thought I could smell gas so changed oil again. I think the problem is solved.

 

Still doesn't sound right , gas in oil will always start fine cold , it'll only refuse to start when the motor is hot due to fuel vapors filling the intake and displacing 0² , but it'll be fine again once the motor has cooled off . You keep saying it wouldn't start the next morning or later thus the motor is cold so should start if the sole issue was fuel in the oil. 

You will see in time if it is indeed fixed , always nice to finally get an issue fixed after a bunch of headscratching.

 

.

8 hours ago, jjktmrider said:

Still doesn't sound right , gas in oil will always start fine cold , it'll only refuse to start when the motor is hot due to fuel vapors filling the intake and displacing 0² , but it'll be fine again once the motor has cooled off . You keep saying it wouldn't start the next morning or later thus the motor is cold so should start if the sole issue was fuel in the oil. 

You will see in time if it is indeed fixed , always nice to finally get an issue fixed after a bunch of headscratching.

 

.

Cant explain why it wouldnt start "the next morning" after adjusting the pilot screw. Maybe I flooded it. I dont know. All I know for sure is that yesterday after changing the oil it started and I road it for 4 or 5 miles without any problems except the idle seemed to be a little off. Im gonna ride it some again today. Im skeptical after the problems Ive had. Wont be getting to far from the house until I get a little confidence back.

 

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