Jump to content
Sign in to follow this  

XR650R ROUGH IDLE

Recommended Posts

Hey guys i'm new to my XR but have had many bikes over the years. I have a 2006 XR650R that has been uncorked, baja kit, stator upgrade, XR400 CDI etc.

My problem is:

It will fire right up and idle perfect, throttle blips and calms right down sounds and feels good. Once i'm riding for a few minutes the idle becomes erratic, hangs and then falls right off and the bike stalls. it'll fire back up but the idle hangs. I can up the idle speed but then it's way too high. I've checked for intake leaks and none are present. I did read about a vacuum port to the left of the manifold but I couldn't locate it.

Couple questions:

My battery is toast- would this cause this issue?

Could the coil be cutting out once the bike is warmed up? Any quick easy way to test if the coil is bad?

Would a bad CDI cause this behavior?

thanks for any replies.

Share this post


Link to post
Share on other sites

First thing to do realistically is get a baseline like.

A: Is the carb clean/any blocked passages. (If not I recommend simple green)

B: Are there any vaccum/intake/exhaust leaks. Check vac hoses and make sure they're routed correctly.

C Does gas run freely to the carb when you pull the line and turn the petcock.

D I'm sure you checked but is the filter clogged/ extremely dirty.

E: Yeah check that ventline on the tank and the side of the carb.

F: Read the plug.

G: After it dies have a spare plug ready, pull the boot, insert new plug, ground on engine, and see if you get spark.

As far as testing the coil you can test resistance somehow (youtube) if not they're like $12 on ebay and you'll have a spare. Don't think it's the battery and I've had no experience with bad CDI's also yours is different. Also an erradic idle makes me think its lean, especially since you said it hangs.

Edited by Timm91

Share this post


Link to post
Share on other sites

I would check the pilot jet and ACV on the side of the carb, sounds like it going lean. Battery has no affect, they didn;t come with one on this model.

Share this post


Link to post
Share on other sites

Thanks for the replies guys. I should add that I swapped the carb to a brand new TM-40 and had the same issues so I ruled out the carb and am thinking the coil or CDI. I think i read that a bad coil can behave this way when it gets hot. i'm ordering a new coil and CDI just to rule them out which I don't like doing but I want to ride this bike...I wondered about the battery because of the upgraded stator and the baja kit with lights signals etc. I opened the petcock and lots of fuel but I will check the bowl once I get it back together just in case but I can blow air back into the tank from the vent hose so I assume it's working. I also used a propane torch to check for intake leaks and no change. thanks again for any help- this is driving me nuts. ..

Share this post


Link to post
Share on other sites

UPDATE:

 installed the new coil and CDI- no change...

Answers to the questions above in bold:

A: Is the carb clean/any blocked passages. (If not I recommend simple green)- I have cleaned a few times but next is with simple green. carb was quite clean as it is.

B: Are there any vaccum/intake/exhaust leaks. Check vac hoses and make sure they're routed correctly.- checked for vacuum leaks and found nothing- used propane.

C Does gas run freely to the carb when you pull the line and turn the petcock.-gas runs freely

D I'm sure you checked but is the filter clogged/ extremely dirty.-brand new filter

E: Yeah check that ventline on the tank and the side of the carb.- tank vents properly and I can get air past/through all carb hoses

F: Read the plug.- installed a new plug but haven't run it enough to get a proper read.

I checked resistance at the exciter coil and got 77ohms, which I think is on the low side. I tried to test the pulse generator but couldn't get a steady reading- it would flash 179 then the multimeter would die...( new battery going in today) would a bad PG cause this idle issue? this bike hasn't run right since I bought it and the spare box of parts had 2 extra stators in it so i'm thinking the PO got fed up and I gotta figure this out...

in case it makes a difference, the bike is/has:

electric start added

uncorked with stock header

valve clearance checked twice

BD dual sport kit

TM-40 installed and no change- stock carb is back on because it won't idle long enough to tune the TM-40

thanks again for any help- this thing is driving me nuts...

Edited by perrito

Share this post


Link to post
Share on other sites

According to the manual you should check peak voltage (100v.minimum) on the exciter coil. I have no idea how its done but would say 77 Ohms is high for a winding. Lighting is around 1 Ohm.

Share this post


Link to post
Share on other sites
7 hours ago, perrito said:

UPDATE:

 installed the new coil and CDI- no change...

Answers to the questions above in bold:

A: Is the carb clean/any blocked passages. (If not I recommend simple green)- I have cleaned a few times but next is with simple green. carb was quite clean as it is.

B: Are there any vaccum/intake/exhaust leaks. Check vac hoses and make sure they're routed correctly.- checked for vacuum leaks and found nothing- used propane.

C Does gas run freely to the carb when you pull the line and turn the petcock.-gas runs freely

D I'm sure you checked but is the filter clogged/ extremely dirty.-brand new filter

E: Yeah check that ventline on the tank and the side of the carb.- tank vents properly and I can get air past/through all carb hoses

F: Read the plug.- installed a new plug but haven't run it enough to get a proper read.

I checked resistance at the exciter coil and got 77ohms, which I think is on the low side. I tried to test the pulse generator but couldn't get a steady reading- it would flash 179 then the multimeter would die...( new battery going in today) would a bad PG cause this idle issue? this bike hasn't run right since I bought it and the spare box of parts had 2 extra stators in it so i'm thinking the PO got fed up and I gotta figure this out...

in case it makes a difference, the bike is/has:

electric start added

uncorked with stock header

valve clearance checked twice

BD dual sport kit

TM-40 installed and no change- stock carb is back on because it won't idle long enough to tune the TM-40

thanks again for any help- this thing is driving me nuts...

You can test resistance to the pulse generator. Don't know the specs but some have reported intermittent failure after it heats up. Also I believe you can test peak voltage while cranking, again I'm not sure the spec but I'm sure you could find it. However, I would try option G as mentioned to confirm a no spark issue before you go pulling side cases to replace the pulse generator. You just pop the spare plug into the boot and lay it next to the engine to ground it, when you kick it over you'll either see a spark jump or not... Also you mentioned it's uncorked/ if you have a slip on or baffle out this might put you a little lean in the event you're running stock jets. (Hanging issue) What size jets are in the carb out of curiocity?

Share this post


Link to post
Share on other sites

I know you said you had a different carb on there and it made no difference, but then you switched back to stock because the bike wouldn’t run long enough to tune the carb. To me that wouldn’t rule out a fuel issue if the new carb isn’t known To be set up right to begin with. High or erratic idle is a symptom of a lean condition. I have the same question as Timm. What size jets are in it, also where is there mixture screw set. Have you verified float height? I’ve never messed with an XRR so don’t know what carb is on there. The same as an XRL?? Could be the bowl isn’t filling up fast enough to keep up once you start riding it, running it low on fuel causing a lean condition maybe??? Keep us posted I’m interested to see what you find

Share this post


Link to post
Share on other sites

So I pulled the carb completely apart and cleaned with simple green, checked the ACV for holes- (none), slightly adjusted the float level and re-installed- same issue. The carb has  175 main, 68S pilot and af is 2.5 turns out and i'm at sea level. as soon as it started to die I cut the fuel off and emptied the float bowl and there was a good amount of gas in there... I swapped batteries in my multimeter and had a exciter coil resistance of 77ohms and pulse gen at 224ohms which seemed ok, exciter coil was a touch low but not sure if this would cause my issue. Once it dies it will fire right back up again for a few seconds then die again. I'm stumped here...

Share this post


Link to post
Share on other sites

These still could be symptoms of a clogged idle circuit. When you had the carb off for cleaning did you squirt carb cleaner (using the little red spray tube) up the idle circuit (with the jet removed of course)?  The carb cleaner should also be blown into the mixture screw circuit and the small hole in the back where the air comes in for the idle circuit. All three of these passages should also have a guitar string inserted and wiggled around then follow with more spray. This is important, especially for the mixture screw circuit because I've seen pieces of that small o-ring stuck up in there.  Sorry if this is redundant advice, but it has worked for me when I've had idle issues.

 

Edited by exaresix
  • Like 1

Share this post


Link to post
Share on other sites

DCcycleworks: it will act the same way if it's just idling- it fires right up with no stutter at all- sounds good then as it warms up the idle starts to act up and then she stalls.

exaresix: there was one passage I couldn't get into because I didn't have a guitar string but i'll get one this weekend and try again. this is a low miles bike and the carb was pristine when I took it off the first time- but i'm willing to get back into it and try anything. my gut tells me fuel too.

Share this post


Link to post
Share on other sites

Yep, give it a try. The other thing you'll see recommended is to use compressed air after all is said and done. I never got the feeling that this added anything, but if you've got the compressor with pointed rubber tip, and the carb is off, it won't hurt to do that too. Looking forward to hearing the results. 

s-l300.jpg

Edited by exaresix

Share this post


Link to post
Share on other sites

i'll go through it again next week. I did blow it all out with my compressor- I really hope the little passage is clogged up and I can put some miles on this thing. thanks again for the replies.

Share this post


Link to post
Share on other sites

How long does it have to sit before it will fire back up and run normal. A few minutes, or does it have to cool back off to like room temperature? I’ve seen coils go out like that, they run fine while the bike is cold but once everything heats up the coil starts to act up. You could put a heat gun or hair dryer to the coil and see if it happens faster, or spray something cold on the coil and see if it keeps it from happening

Share this post


Link to post
Share on other sites
15 hours ago, DCcycleworks said:

How long does it have to sit before it will fire back up and run normal. A few minutes, or does it have to cool back off to like room temperature? I’ve seen coils go out like that, they run fine while the bike is cold but once everything heats up the coil starts to act up. You could put a heat gun or hair dryer to the coil and see if it happens faster, or spray something cold on the coil and see if it keeps it from happening

The Stator does the same. My 600r had the be bump started when hot. 

Share this post


Link to post
Share on other sites

coil was my first thought so I did replace it. here's the drill: cold motor will fire up with a couple kicks no choke and runs strong for a few minutes until it's warmed up then it'll sputter and then die. jump on and it'll fire right back up again and only run for 10-20 seconds and stall, one kick and she's running again for 10-20 seconds.

Share this post


Link to post
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:

Sign in to follow this  

×
×
  • Create New...