bike dies when breaking

03 VFR, pcv, leo vince exhaust, K&N air filter

symptom: when travelling ~50 mph, hard break (front only) and pull in clutch, no downshift, bike dies. push starter and it starts again. i can almost replicate it, seems the harder im breaking the more likely it is to die. besides the bike dying its running really well.

most recent change to bike was new chain/sprockets and new plugs, installed by power sports. I've put about 100 miles on bike since those additions and it's been dying since.

before the chain/sprockets i put in a pcv. have about 100-150 miles on pcv prior to chain/plug work, never died. yesterday i changed from power commander map to the cozy map thinking with zero throttle the engine starved and died, bike died 3x today w/ cozy map.

other change was asian levers and K&N air filter, again though these levers have been on since pcv was installed and bike didn't show symptom then.

to note: the clutch fluid is under the line in the window on left handlebar, going to have that replaced shortly by honda dealer. i dont feel like the clutch has any issues, starting from stand still or up/down shifting normally, clutch seems fine.

so any suggestions on what is causing bike to die? seems most recent change would be cause but not sure, could a plug cause the bike to die like this? i would see other symptom if a plug was bad correct? sputtering? could it be fuel? i had stabil in bike thru winter but have since ran tank low and filled at least 2x, probably 3.

right now the plan is get this clutch fluid changed since it's low, then take off pcv and see if bike dies without it.

 

Might need to boost idle speed up.

 

just update, i dont think my clutch fluid is low, when i put bike on center stand and turn handle bar to right its even with the line where it should be.

 

Ok, but a clutch that's not fully disengaging (air in system or warped clutch plates) can drag engine revs down enuf to stall engine out at low power. Test by gliding into a stop in neutral (at east 50 feet, time enuf to drop to idle) at idle speed and not squeezing the clutch lever. If clutch is normally dragging, bike won't stall in neutral.

 

I also installed PC-V over the winter and am having the same issue. Issue being, when pulling in the clutch to downshift for a turn or to stop the engine stalls. I believe this happens at moderate revs on up. Cruising and gently rolling off the throttle doesn't seem to produce the same effect. I can avert the stall by continuously blipping the throttle while the clutch is, letting the revs come down as I do. Once stopped, it'll idle. Also, the problem seems exacerbated by the summer heat. I've tried a few different fuel maps to correct the problem to no avail.
That said, I'll be happy to get this corrected or else I'm going to have to get comfortable "backing into turns". [kinda cool, I guess. Completely NOT what I'm going for.]
-Ed

 

See the thread below for more info. When installing the PC-V I also did removed the pair valve stuff. Maybe I didn't seal the system up well enough and it's drawing in air. (I does still crackle on decel, and my cans are gutted - [though lined with packing for sound quality]). Or maybe I pinched a fuel hose or something.

http://vfrworld.com/forums/showthre...ower-stall?highlight=stall+while+downshifting

 

Kind of confusing as to who did what to the bike. If this condition was after a dealer worked on the bike, then take it back to that dealer.

 

Just an idea. Fire up the bike in park and play around with the kill switch. Slightly rock it without fully setting it off. Maybe tweak the grip like you would if you were braking

 

Maybe also check your sidestand to make sure it is not loose and moving which would cause the automatic safety mechanism to engage.


Rollin

 

Godspeed, check your idle RPM. The manual says 1200-1300RPM but many (including myself) have found that 1350RPM is better and will stop from stalling. I had to do it within a few weeks of purchasing my VFR and I was experiencing the same issues as you are.

Also, did you sync the starter valves when you de-pair'd and put the PCV on? That goes alone more with holding a steady idle and starting well but also does play a little bit into your issue as well.

I would highly suggest that you check your idle and bump it up a tiny bit and see how that goes for a few weeks. I would wager that it reduces or eliminates your issue. If it only reduces, I'd move on to the starter valves. If it eliminates it, I would plan for the starter valves the next time you're digging into something else in that area.... like spark plugs, cam chain tensioners, thermostat, etc. It isn't hard to do, just time consuming and requires a manometer plus patience.

 

Meatloaf, thanks for the reply. (BTW, love the flat black model) I bumped up the idle as per the suggestions. It seemed to help initially. Upon removing the pair valve plumbing and installing the PC-V, I did in fact sync the starter valves. I have tried different fuel maps and even tried subtle changes to the fuel map on my own. Not much of change really. The plugs, while stock, seem fine with about 18,000 miles on them.

Cam-chain and thermostat are two new ideas. The fans kicks on around 221 or something like that, and I thought that was somewhere near normal for these bikes. But this is an interesting suggestion because heat seems to be the common denominator. Hot days cause it to stall more. I am inclined to check the voltage regulator/rectifier thinking that the heat induces early symptoms of failure.

Perhaps it is related to the PC-V, since it didn't do it beforehand. Throughout the process I am learning what others have said already about fuel maps - dyno tune is probably the best solution for the PC-V. I'll try to quit riding long enough to look into your suggestions. Thanks.

 

At 18k, your plugs are due for a change. I think the service interval for them is 16k. While they may look fine, I suggest you compare them to a new one and you will find that the iridium tip is worn more than you think.

A dyno tune is most certainly the best. I run two maps. Stock and dyno-tuned. I run the stock for the fuel economy and the dyno-tune for when it is time for fun. You have another option with the PC-V and that is the auto-tune module. It will run you about the same as a dyno-tune so whichever way you want to go.

As for the thermostat, CCT, etc... I only mentioned them as they are common failures and it is easy to get in to do your starter valves while doing any of those jobs.

Make sure that your de-PAIR job is still in good condition with no leaks and whatnot.

 

Innit great how perfectly fi works compared with carbs, huh ?? Not exactly, as almost any carb problem can be fixed with some adjustments while fi is digital and some running problems caN't be fixed.

 

Meatloaf, thanks for bringing my attention to the 16k interval. I was thinking of their life-span in terms of a four-wheeled (trucks/cars) applications. I'll get them installed and try to report back. I still need to check over the other suggestions. Then, I think I'm gonna get the tune. [I loaded the "zero" map and the stalling has abated. But at the same time, the air temps haven't been as hot as the stall conditions, nor have I taken any longer rides.]

 

My bad. My bike has over 21,000 on the clock. 16 vs. 21??? Potato / Potahto.

 

It makes a difference believe me, especially when you are trying to sort out tiny things like this. Run the zero tune, get your maintenance up to spec, get a dyno tune or auto-tune. Live the dream.

 

Have you downloaded the factory service manual yet? It is available on VFRD.

 

Yes, I have the service manual. So, I'll refer to it for the other procedures.

 

Yes, I have the service manual. So, I'll refer to it for the other procedures. I installed the new plugs (NGK 9's) last night. I only took a quick ride around the block and didn't notice much difference. I'm excited to this sorted out and get the tuning done. I think I'll call today and make the appointment because they're booked a few weeks out.

 

Here's an update for the benefit of others, hopefully. I am 99% sure the problem causing the stalls was a defect in the plug I made to block the pair valve over the front cylinders. I cut a piece of automotive hose about 1.5" inches long and filled 1/3 of the end with household caulk/silicone. Once it dried (I thought), I put the homemade plug over the pair-valve 'nipple' and used a spring/pinch style clamp to keep the hose on. I was relieved - sort of - to find that caulk/silicone that plugged the end had a big hole through it! Maybe it was the heat, or maybe I didn't let it dry long enough initially. Either way, I replaced the caulk crap with a piece of round stock steel I had around. While I haven't ridden it yet, it seems likely that's what was causing the stalls. If I'm lucky, maybe it'll reduce the small amount of deceleration pop the bike has too.

For the record, I checked the R/R, battery, and harness connections. Battery voltage is good. Connectors are healthy. The R/R seems fine but the meter says it only charges at 13.6v max at 4000 rpm. I'm guessing that's at least adequate, if not good. (I saw other threads talking about 14.1v?) I haven't found what charging voltage specs are in the manual yet. (lil help, if anyone knows off-hand).

Attached is my homemade plug gone wrong.