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Can’t rev above 7k after cam chains replacement and starter valve adjustment.


Kochan

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Hi guys,

 

Something weird happened to my VFR. I’ve replaced the cam chains and adjusted starter valves. After that the bike can’t go above 7k (if adding throttle slowly, if not it happens around 5-6k). It struggles and the revs are jumping (dropping and rising) but not above 7k. It’s a little bit like maxing our the throttle. Any ideas what can be a problem?

 

I will be grateful for any suggestions.

 

 

 

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Given what was touched on the bike 2 things might be incorrect cam timing or a vacuum leak.  BTW - do you mean you replaced the cam chain tensioners rather than the chains themselves? 

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Given what was touched on the bike 2 things might be incorrect cam timing or a vacuum leak.  BTW - do you mean you replaced the cam chain tensioners rather than the chains themselves? 

Thanks for the quick reply!

I’ve replaced both. Didn’t mentioned the tensioners because it’s irrelevant. I’ve checked the timing today with Honda manual and it’s correct. I’ll try to diagnose the vacuum leak. Any hints on that?


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Do you have any Fi codes? As Cogswell mentioned double check the Vaccum lines you would have removed to do the Starter Valve synch. Make sure the vacumm lines from the five way joiner are good and the MAP sensor Vaccum hose is good. Make sure the electrical connectors for both MAP and IAT sensors are good post starter valve synch. Also check you haven't disturbed or damaged the Vaccum hose to the FPR (fuel pressure regulator).

Good Luck.

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I had this fault on my 5th gen, without doing anything to it at the time it started, but it was intermittent. On random starts it would refuse to rev above 6500rpm. Turned out after checking everything, it was caused by corrosion in the return earth wires at the hidden wire join block in the harness. Since I cut the block out (it looked perfect by the way) and cleaned the green copper corrosion off all the strands then intertwine wrapped them together & soldered them all together the fault has not reappeared.

 

So if you are certain that all wires & cables around the throttle bodies & airbox plus engine timing is correct then as a last resort look at the earth block. I’d tried everything else including checking the earth block visually before ! 

 

Good luck.

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22 hours ago, Kochan said:

Would the vacuum issue cause problems only on low revs?


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Vacuum leaks usually cause issues with slow return to idle or inconsistent idle. Not usually at higher engine speed where there are no restrictions in the throttle bodies. You didn’t leave a rag in the airbox or airbox snorkel did you ? Don’t ask me how I know about this one 😞

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  • 3 weeks later...
Vacuum leaks usually cause issues with slow return to idle or inconsistent idle. Not usually at higher engine speed where there are no restrictions in the throttle bodies. You didn’t leave a rag in the airbox or airbox snorkel did you ? Don’t ask me how I know about this one


No, no rags :) I just came back from vacation. Honda Service just called me and said they have no time to investigate the issue any further. I need your help guys. Here is how the issue looks like:

http:// https://www.dropbox.com/s/3r8kv1guiwzujbs/Video%2023-07-2019%2C%2015%2039%2015.mov?dl=0

I’ll appreciate any help!


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2 hours ago, Kochan said:

 


No, no rags 🙂 I just came back from vacation. Honda Service just called me and said they have no time to investigate the issue any further. I need your help guys. Here is how the issue looks like:

http:// https://www.dropbox.com/s/3r8kv1guiwzujbs/Video%2023-07-2019%2C%2015%2039%2015.mov?dl=0

I’ll appreciate any help!


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Wow, thanks Honda...

 

Just tossing out possibilities... My first thought is to agree with Mohawk. Time after time, weird intermittent problems with the VFR800 turn out to be electrical in one way or another. Check your grounds, check your charging voltage, etc...

 

If that doesn't clear it up, I do wonder - especially since you've done the cam chains - could it have something to do with the VTEC engagement? You seem to be right there...

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Probably a useless bit of advice BUT, your bike did not have this issue before you did the Cam Chains and Starter Valves.

Can you pinpoint the issue to after the Starter Valve Synch or after the Cam Chain replacement OR did you only notice it after both jobs were done?

There must be something you've done! Backtrack over everything you've touched. Are you sure the single Vaccum hose to the MAP Sensor is not cracked or leaky? Are all the electrical plugs you removed properly plugged back into the devices?

 

That is pathetic that Honda are not looking into this for you. Did they even offer any suggestions?

 

Good luck and keep us posted with anything you find. 

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Hi Grum,

 

Thanks for the reply. It's definitely not useless. 

 

I've noticed the problem after both Cam Chains and Starter Valves unfortunately. It was a mistake to do both things at once but here we are... The vacuum hoses were checked few times already. It does not seem like they're the problem for now. 

I was in a hurry before the holidays but now I'll take my time, go back to square 1 and investigate each piece, one by one. What Honda guy suggested was to check VTEC valves, shaft position sensor, the camshaft position sensor, fuel pressure regulator. Will do that. I will keep you guys posted. 

 

Best,

Kochan

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  • 4 weeks later...

Hi guys,

 

Current situation - No changes so far... Beside the fact that the problem occurs even on the lover revs - 5k, 5,5k, 6k... (Video)

 

What I've checked so far (replaced from the other - running bike):

  • Vacuum hoses
  • Fuel hoses
  • Fuel pump
  • Fuel pressure regulator
  • Camshaft position sensor
  • PAIR sensor
  • Purge control solenoid valve
  • PAIR solenoid valve
  • Air sensor
  • One way valve
  • MAP sensor
  • Vacuum sensor & chamber
  • voltage regulator rectifier
  • compression test

What left to be checked:

  • Ignition Pulse generator
  • Ignition timing
  • Valve timing
  • ECM

My questions:

 

1. Am I right thinking that it's not V-Tec related since V-Tec is activated when the engine reaches 6800 RPM AND the coolant temperature reaches 65°C/149 °F?
2. My current bet is that's valve timing but can the valve timing be "slightly" off? I'm mean - can it look good on timing marks but be not perfect and cause this kind of problems? What do you guys think?

 

Best,

Grzegorz

 

 

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Wow... that video looks like it's hitting a rev limiter, as if the ECM thinks it's at the red-line. It's really hard to diagnose things like this remotely, but that doesn't seem to me like it could be a vacuum problem. It seems to me like one of the cam or crank sensors is seeing a pulse at the wrong time for some reason.

 

I've gotta say (and I mean no disrespect): problems that suddenly show up after a major maintenance project like this almost always turn out to be something hooked up incorrectly, or damaged during service. It's just amazingly unlikely that you ECM just chose that particular moment to break. I've been in your shoes before!

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Can anyone please verify if the timing is correct?

1. 3rd cylinder in TDC on compression stroke

https://www.dropbox.com/sh/utvikk4i6qot3l7/AAAhzzkOJuu6x0B98G6pOFF8a?dl=0

Turn the shaft 450 degrees clockwise

2. 4th cylinder in TDC on compression stroke

https://www.dropbox.com/sh/k7skyfxa45h9o7l/AAD1TBeVZkNJBStVXtHkTrFxa?dl=0

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  • 2 weeks later...

Hi guys,

I just want to let you know that I’ve solved the problem and the bike is running well!

The problem was the valve timing. When I set it as the service manual says it was not working and I couldn’t align the marks perfectly.

What I finally figured out is that the cluch cover on my bike is not original, and the timing mark in the inspection window is in the wrong płace... I had to turn the cam shafts forward to make it work. I don’t have to tell you how much time it took me to figure it out...

My main mistake was that did’t properly documented the position of the shaft l, only the camshafts and then I tried to set it as in the service manual...

Always look at the bright side so the good thing that I got to know the bike inside out now ;)

Thanks for your help guys!

Stay safe!



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Great effort Kochan. Sounded like a very tricky one to sort out, so many hours of checking and re-checking your valve timing. Hope you can now enjoy many miles of trouble free riding, you deserve it!

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7 hours ago, Kochan said:

Hi guys,

I just want to let you know that I’ve solved the problem and the bike is running well!

The problem was the valve timing. When I set it as the service manual says it was not working and I couldn’t align the marks perfectly.

What I finally figured out is that the cluch cover on my bike is not original, and the timing mark in the inspection window is in the wrong płace... I had to turn the cam shafts forward to make it work. I don’t have to tell you how much time it took me to figure it out...

My main mistake was that did’t properly documented the position of the shaft l, only the camshafts and then I tried to set it as in the service manual...

Always look at the bright side so the good thing that I got to know the bike inside out now 😉

Thanks for your help guys!

Stay safe!



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Wow! That had to be a bitch!

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55 minutes ago, Kochan said:

Did you experience problems like this?

I can’t remember if I did the valve clearance check before or after I swapped covers. 

Ever since Sebspeed started making clear clutch covers we’ve all been telling people they are interchangeable for all 800s, even the RC45. If I recall the part# hasn’t changed, so I’m not sure exactly what could have happened to yours. 

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  • 4 weeks later...

Did it even need Cam chains?

 

I have 115,000 miles on mine, and never have any intention of replacing cam chains.

 

The cam chain tensioners, can become notoriously noisy, but not the cam chains fault.

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