07 xb9r hot start issue?

[CodyG]

So to start off i just rebuilt the motor new flywheel, mainshaft bearings, cyclinders, pistons, valves, lifters and oil pump due to previous owner blowing it up...whatever anyway i have 2600 miles on the motor so far and it runs great, i usually work on harleys so this motor was very familiar to me but i did notice the vacuum line on the throttle body was not capped and figured it was for a charcoal canister so i just went ahead and capped it. i noticed though from vidoes other peoples bikes seem to fire up real quick while cold as to mine you have to crank it two times then it starts right up. But the main issue is after riding for hmm 25 miles and getting the bike nice and hot i stopped to get gas or just stop and turn the bike off for a second i go to restart the bike it starts right up then immediately wants to die and sounded as though it was running on one cylinder so i gave it a couple revs and kept the motor running with higher rpm then just your normal idle and it sounded fine till i let off the throttle again. so i just took off and it seemed to clear up and just went away after riding. It only does it after being hot and trying to start after a long ride, no check engine codes or anything. i tried to call the local harley/buell dealer down here in sothern california to see if they could help but they want me to bring the bike in which isnt going to happen. i am new to this forum but i have tried to find someone else thats having this issue as well but i cannot find anyone else, hoping to see if someone could help me out. i would post pictures of the build but i cant figure out how to post pictures

 

[thrstrmech]

It only does it after being hot and trying to start after a long ride, no check engine codes or anything.

I have experienced this, before after getting gas in Borrego Springs before heading up to the look out, somewhat hard riding in the triple digits with some locals

kept the motor running with higher rpm then just your normal idle and it sounded fine till i let off the throttle again.

maybe a TPS reset is due, but that's just guessing without physically being there to see and hear it. could be a fuel delivery issue as well...

 

[thrstrmech]

BTW... welcome to the forum

 

[CodyG]

figured if i needed help this would be the site. But yeah i was wondering about the tps reset and ive read up on it but i dont think thats the issue because it idles fine at start up and while hot but after long rides its almost as if its not getting fuel or getting too much. The roller has about 17k on it.

 

[Theycallmecrash]

I have experienced this, before after getting gas in Borrego Springs before heading up to the look out, somewhat hard riding in the triple digits with some locals

I remember when that happened. Really weird. Never happened again did it?

Anyways Welcome Cody? What part of Southern cali? Im in san diego North county, and i hobby in repairing Buells. I have all the tools to service and or diagnose issues, if close enough im willing to help. The issue you described sounds to me like a possible head temp sensor or even leaky injectors when hot. More than likely head temp sensor, a common failure it seems. Considering it got a rebuild poor ring seating might be a factor but again not likely

 

[CodyG]

San bernardino area, that would be quite the hike to drive out that way but im not sure if the plug to check the computer or what not on these bikes are similar to harleys or not but i have both the scanner and wire for a computer. besides that wouldnt the head temp sensor throw some kind of check engine code? And how would i check for a leaking injector. And the ring seating issue i highly doubt doesnt burn any oil and i babied it for over 1000 miles and did and oil change two times within that period, oil was still clean no metallic flakes.

 

[CodyG]

And can someone tell me how to post pictures on here.

 

[DualSportDad]

What fuel map are you running? See my old start thread on here. My bike does similar after flashing the stock fuel map back to the bike.started fine with the race map but the stock map after riding and letting the bike cool just enough to cool the o2 sensor so its not being read anymore the bike won't idle without giving it throttle. One the o2 sensor warms up again and it goes into closed loop the bike will idle fine. I have verified this with ecmspy.

 

[Theycallmecrash]

The head temp doesnt always throw a code, the self diagnostic systems on these bikes are ****. Unless the sensor is disconnected or shorted out no code. The sensor often gives in accurate readings, the manual states a 20% variation +/- in the temp sensor is acceptable, i call BS.

As for the harley/buell equipment, im not sure. But there are 2 free programs running around for tuning buells and diagnosing them. ECMspy and Tuner pro RT then a $30-50 cable for communication.

To check for leaking fuel injector, well thats difficult especially if they only leak when hot. Again not likely pretty rare

 

[thrstrmech]

hasn't happen since and after the rebuild she ran a bit off 'til the tps reset, she runs fine now. the idle somehow was higher than norm and it took two-three times of hitting the switch to crank her over.
I used the plastic handle of a small screwdriver to hold the detent back while marrying the case halves to avoid ruining the threads in the case where the neutral switch mounts.

 

[Theycallmecrash]

I used the plastic handle of a small screwdriver to hold the detent back while marrying the case halves to avoid ruining the threads in the case where the neutral switch mounts.

Wrong thread buddy haha

 

[thrstrmech]

can you tell I just had a blonde moment today is Thursday right? I need a beer or two...my brain is frozen like my nads here in Nashville,TN. brrrrrrrrrrrrr

 

[CodyG]

i am using the stock computer i didnt want to get into mapping it, the original plan was to rebuild it and flip the bike but then i fell in love with it since i like harleys and know how to work on them very well but yet still wanted a street bike it worked out perfect.. but back to the head temp sensor, isnt that the sensor that tells the fan and all that when to turn on and off since it is the head that is stuffed up in the frame. the 02 sensor is the original i do believe im not sure like i said only thing i did was rebuild it didnt replace electrical stuff. but maybe ill check to see what the plug looks like i forget though where is it located. my other possible question is the fuel line getting hot since it runs basically on top of the motor, after it getting so hot and sitting could it possibly be vapor lock?

 

[Theycallmecrash]

Vapor lock is next to impossible on fuel injection.

The temp sensor does quite a bit more than turn the fan on and off. It affects cold start enrichment, and a temperature factor for fueling, a temperature/ ignition spark factor, as well as a bunch of really complicated things like hard and soft rev limiter modifiers, and like what thrstrmech expirienced was a factor to reduce engine power when too hot.

 

[CodyG]

thats what i was figuring with fuel injection but someone had mentioned it so it had me wondering. but now its starting to make sense to me that it might possibly be the temp sensor then because of the different starting issues i have been having. takes long to start cold and doesnt like to start easy after running for a while when the motor is nice and hot. also i noticed when i was riding during the summer which got into triple digits the bike would ping a little if i tried to get on the throttle at a low rpm.

 

[CodyG]

 

[CodyG]

posted pics of the build so it might help some people see how tore up it was and see the internals of the motor.

 

[Theycallmecrash]

[up] very nice

Couple things, you are aware push rods are different lengths?
And your grounds, how do you feel about them? I ask this one cause its common knowledge Buells have **** grounds. As science and **** tells us, as temp goes up so does resistance. Ive experienced this, and ive installed redundant grounds from sub-frame to frame, frame to engine in multiple locations. Some argue this is a ******** mod, i dont care im a fan of redundancy.

 

[thrstrmech]

nicely done[up]

 

[CodyG]

Thanks! And yes i do know push rod lengths are different but i havent really thought about grounding issues. Totally blew passed thinking about that, but like the other gjys said that temp sensor causes alot of malfunctions if and when it goes bad. So i want to try and track a temp sensor down and try it does anyone have a clue where to find them to purchase?