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Power Loss....Need Help

11K views 181 replies 17 participants last post by  larryg 
#1 · (Edited)
Ok. I had my ECU flashed and the bike was running wonderfully. I recently just got my bike back after having the Graves Clutch Kit and Graves CCT installed.

The Issue: I noticed immediately that the bike wants to jerk in 1st with the clutch lever completely pulled in. The mechanic told me my clutch lever was too tight and that he had adjusted it. I new it wasn't right so readjusted it myself and it was riding fine after that.

The ride home was great. The next day (today) it was riding great also until I parked it shut it off and then started it back up again in about 5 minutes. On my way to Cycle Gear, I immediately noticed a loss of power.

The bike revs high but doesn't seem to be pulling like it was with the ECU Flash.

I've also noticed that when I launch from 1st and then click up to 2nd, it goes to neutral instead. And I NEVER miss shift.

I've also noticed that shifting down into 1st from neutral while holding the clutch is really hard.

Any ideas?

My bike was riding like a dream and then all of a sudden I have a power loss. I've check for fuel line kinks already. And just to let you all know, I never beat on it (burnouts, clutch wheelies, etc.).

:dunno

Mods that I have:

Graves 3/4 system (no 02 sensor)
Graves Clutch Kit
Graves YEC Springs
Flashed ECU
PC5 (removed after 2 short rides prior to the power loss)
 
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#45 ·
So I dipped all the plates back into oil and assembled the clutch back together and went for a test ride.

The power loss is still there.

The only thing I can think of is the Power Commander. The power loss happened the day I removed The Power Commander but thats was after a few rides later that day.

It seem like it could be fuel or electronic related do to the fact that it happened so suddenly. My bike goes from unintentional power wheelies then after I shut it off and then start it back up in less then 1 minute, I have a huge power loss.
 
#48 ·
Neither do I.

What I did when I removed the PC was leave the posi-tap right where it was when I removed the green wire. I screwed the top of the posi-tap back on and filled the hole with silicone.

I will check the TPS wires when I get a chance.

Question: Whats else could it be if the clutch is good? Could the PC + SBK flash have given me the really aggressive power I was feeling? I did experience the power loss after removing the PC. Not immediately but almost. After like 2 short 3 mile rides.
 
#53 ·
you have isolate the problem, when you say power loss, I'm thinking the engine is not running good, but reading through, it sounds like the engine is fine, but the power is not being delivered to the wheels..which in that case, sounds like the clutch..
Have you adjust the bolt/nut right by the clutch cover/case?
When i replaced my clutch, i forgot to adjust it and the bike would get to 7-8k rpm then It felt like It stopped accelerating while it continued to rev to 11-12k rpm. So the power from the motor was there, it just wasn't getting to the wheel (clutch slipping)..that what I mean by isolating the problem.
 
#64 ·
damn one2 this sucks... i wish i could help but my knowledge on these bikes is not vast to say the least... i am doing reseearch to see if i can find any info that may help tho
 
#65 ·
Thanks man. I appreciate your concern.

I was just looking for video of fouled plugs online. I can't find anything good. Out of all the symptoms I found, the only one I'm really having is slow acceleration.

I have once during all of this experience a dying idle when my bike was cold. It never completely shut off because I gave it a little throttle. It started idling fine once a temperature registered on the dash.

I'm learning. I have good electronic knowledge but not engine mechanical.
 
#67 ·
Sounds like two different issues?:dunno
Replace the fuel line. Quick easy cheap fix, you can pick it up at like autozone for like $5. You're not going to be able to tell if it's kinked or not by looking.

And it's still seems like there is an issue with the clutch by your description. Check stack height.
 
#69 ·
are the upper injectors firing? it's a bit hard to diagnose i would start there. the upper injectors only work after a certain RPM. you've got the clear plastic connector that's 6 pins and then you've got the orange fuel line. triple check all of those. it sounds like a fueling issue to me and not a clutch problem. that clutch looks fine. the initial bogging sounds like you just dont have the clutch adjusted properly but the rest of it sounds like a fueling issue.
 
#74 · (Edited)
does it free rev fine?
how easy would it be for you to have the ECU flashed back to stock (just for diagnostic purposes)?
have you checked the TPS readings? resistance and voltage range?
have you taken the air box completely off and checked all connections below the air box.
is the actuator for the velocity stacks plugged in? (white 2 pin connector, it's on the left hand side of the bike)

tilt your gas tank up and take as many detailed pictures as you can of everything.
 
#78 · (Edited)
It's extremely unlikely it's the ECU, given that the symptoms manifested well after the install. An ECU flash doesn't change in any way, unless somehow an electrical short on the bike damaged it, which I also think is unlikely. We've never had any customer experience these issues with an ECU flash of ours, of hundreds done.

I think the fuel line and plugs are a good place to start, along with checking all fuel and electrical connections under the tank.

The last thing to mention is the cam chain tensioner - who installed that? If it's not tensioned correctly, the bike can jump timing. It will still run, but like hell and it could be causing damage to the valves/pistons. Probably not your problem, but this did happen to a local customer who tried to install his own incorrectly.

Hope you get it sorted!
 
#80 ·
It's probably not the CCT. The customer who's bike we had to diagnose actually ran and wasn't ticking, but when we pulled the valved cover, the cams were not aligned properly. It's possible he tightened the tensioner prior to bringing the bike by. Fortunately it had only jumped a tooth or two and we were able to get it sorted and he suffered no apparent valve damage.

It definitely sounds like the bike is not getting the fuel it needs to rev or the spark is insufficient. Double check all of the connectors you used for the PCV and make sure no pins are bent, check all fuel lines and connectors under the tank. Hopefully it's as simple as the fuel line. The plugs may also be fouled from the PCV fuel map adding fuel on top of our ECU flash prior to it being pulled. Has the same fuel been in it from when it ran well to now?
 
#81 · (Edited)
No. The same day the power loss happened, I got the fuel light a few miles later on my way back from Cycle Gear. Ran it for a little while before fueling at a different gas station and I don't get very far after the fuel light.

As far as fuel lines, I checked those. I checked connections too. I'll check them again today. I'm willing to bet my plugs are fouled. I spoked with an old NCO that said he use to ride a Suzuki years ago that fouled plugs often. He said my disruption matches all that he exeperinced. Different bikes, I know, but same symtoms.
 
#83 ·
Oh yeah buddy. Never use anything less than 93 Shell/Exxon and occasionally fuel here on post when in a pinch but only enough to hold me over until I get to Shell/Exxon.

How do I check timing? Pull the cover? And did that customer have issues right after the install?
 
#84 ·
I'd have to ask - I think he rode like that for several days, but realized how bad it was when he did a whole track day on the bike with the timing off. His symptoms weren't as bad as yours. Checking the cams is a bit complicated, you have to pull the valve cover off and make sure the marks on the cams are flush with the top of the head. I'd definitely put that towards the bottom of the list, it's probably not your problem.
 
#87 ·
So I ran the diag mode on the bike. No current malefaction codes present. No CEL and there hasn't been one this entire time.

TPS voltage: 15 completely closed, 100 completely open (according to the manual, these seem to be well within spec.)

Air filter: Well well well....I'm kicking myself in the ass right now. When I bought the bike. The previous owner told me it had a "new" filter. My dumb ass assumed it was a stock filter. I just learned tonight that it is a BMC Race filter and it could use a little clean.

Do I need a new map with the BMC Race filter implemented? :dunno And is it safe to do the "air box mod" while I'm replacing the spark plugs? :dunno

Fuel lines: With visual inspection, they look fine. I'm still going to replace them.

Upper






Lower



 
#88 ·
why don't you just take those fuel lines off and blow through them? i mean its pretty obvious when a fuel line is kinked. i'm crossing fuel line issue off the list. those look fine.

i'm not sure what 50 and a 100 means. i would be looking for a sweeping voltage range starting with the base voltage below. Also as well as these resistance values.

Throttle position sensor resistance: 1.2-2.8k ohms
Accelerator position sensor resistance: 1.2-2.8k ohms
Output voltage at idle: 0.63-0.73 volts.

i'm sitting here staring at the FSM (obviously) and there are a TON of sensors that can mess with all of this stuff.

do we know what the fuel pressure is? stock is suppose to be 47psi. you said it was weird after it went low. any chance your fuel pump died?


just trailer this thing down here, i'll get it running right. lol
 
#89 ·
No, the power loss came before the low fuel.

Can find those resistance values and idle voltage in diag mode? If a sensor was off or bad, would I normally get a CEL?

Hey....I'll be in Kenesaw this weekend. It's like less than 20 minutes North of Atlanta. I'll be there helping my girlfriend move though.
 
#90 ·
i would take it out of diag mode. technically you SHOULD get a CEL but that's not always the case. right now i'm focusing on everything that's been touched.

poor cold idle may be from a bad coolant temp sensor which could also throw off the ecu too over the whole range. lets check that too.

Coolant Temp Sensor
Resistance @ 0c (32f) - 5.21-6.37k ohms
Resistance @ 20c (68f) - 2.45k ohms
Resistance @ 80c (176f) - 290-354 ohms

so resistance will be getting lower as the coolant temp rises. if you're already experiencing poor idle results when it's cold and it's getting better when it's warm you should most definitely check the CST.


i'm about 20 minutes north of Kenesaw. I work Saturday but if you bring the bike by on Sunday I wouldn't be opposed to looking over it for an hour or two. offer is on the table for ya.
 
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