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Discussion Starter #1 (Edited)
Hi Guys, I'm another victim of having a stutter on my 929, its that dangerous for over taking, cornering there's no point me riding it till i sort it :(. Any help would be MUCH appreciative..
I only have a end race can and K & N air filter, the flat spot comes in after engine is warmed up (been ridden for around 15 or 20mins) and reliably happens at 5500-6000rpm, it feels like trying to accelerate when ya running out of petrol.
The bike has new plugs, I've fixed open the air intake flap in the air box, fixed open the exhaust valve and the servo cables are disconected. I did this mod to originally sort the stutter flat spot and still no joy. I originally thought machanical because of it happening when its warmed up ridding, so I read alot of posts on the HTEV and tried the mods. Not sure if it could be injector issue, but i have no faults showing on dash and it only happens when bike has warmed up, from starting from cold its full power right through the rev range and smooth delivery. after about 15-20mins it breaks my heart ...:crying:
 

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Hi Guys, I'm another victim of having a stutter on my 929, its that dangerous for over taking, cornering there's no point me riding it till i sort it :(. Any help would be MUCH appreciative..
I only have a end race can and K & N air filter, the flat spot comes in after engine is warmed up (been ridden for around 15 or 20mins) and reliably happens at 5500-6000rpm, it feels like trying to accelerate when ya running out of petrol.
The bike has new plugs, I've fixed open the air intake flap in the air box, fixed open the exhaust valve and the servo cables are disconected. I did this mod to originally sort the stutter flat spot and still no joy. I originally thought machanical because of it happening when its warmed up ridding, so I read alot of posts on the HTEV and tried the mods. Not sure if it could be injector issue, but i have no faults showing on dash and it only happens when bike has warmed up, from starting from cold its full power right through the rev range and smooth delivery. after about 15-20mins it breaks my heart ...:crying:
It's not overheating at all and the radiator is full of coolant?
Is it only when you are at full throttle or is it the same when cruising?
If you keep it above 6500rpm it's fine?
Are you running a PC3?
Have the valve clearances been checked recently?
Have you checked all the headers are similar temperatures?
Have you checked the vacuum line to the fuel pressure regulator?
 

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Discussion Starter #3
Hi Bladeracer, glad you've picked me up.

It's not overheating at all and the radiator is full of coolant?
Temp is normal, coolant level is ok
Is it only when you are at full throttle or is it the same when cruising?
Half throttle or full accelerating, then its like hitting a rev limiter at 5500-6000rpm, but some times when i hit it, i can feed it past 6000rpm very gently but it will knock me back to 4500-5000rpm. It will cruise at 4500rpm at 70mph, and it doesn't matter what gear i'm in, it still happens at 5500-6000rpm.
If you keep it above 6500rpm it's fine?
If I gently feed it past 6500rpm, the slightest bit of heavyness on the throttle knocks me back below 6000rpm (sensitive to knock me back once past 6500)
Are you running a PC3?
Not fitted, but do have one.
Have the valve clearances been checked recently?
No, how do I do this. Or am I best getting a garage to.
Have you checked all the headers are similar temperatures?
No, how do I do this. Or am I best getting a garage to.
Have you checked the vacuum line to the fuel pressure regulator?
No, I can do this.

Thanks BladeRacer, I'll get on with the checks not been done, and get back to you. I'll check back later if you have thought of anything else..
 

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Hi Bladeracer, glad you've picked me up.

It's not overheating at all and the radiator is full of coolant?
Temp is normal, coolant level is ok
Is it only when you are at full throttle or is it the same when cruising?
Half throttle or full accelerating, then its like hitting a rev limiter at 5500-6000rpm, but some times when i hit it, i can feed it past 6000rpm very gently but it will knock me back to 4500-5000rpm. It will cruise at 4500rpm at 70mph, and it doesn't matter what gear i'm in, it still happens at 5500-6000rpm.
If you keep it above 6500rpm it's fine?
If I gently feed it past 6500rpm, the slightest bit of heavyness on the throttle knocks me back below 6000rpm (sensitive to knock me back once past 6500)
Are you running a PC3?
Not fitted, but do have one.
Have the valve clearances been checked recently?
No, how do I do this. Or am I best getting a garage to.
Have you checked all the headers are similar temperatures?
No, how do I do this. Or am I best getting a garage to.
Have you checked the vacuum line to the fuel pressure regulator?
No, I can do this.

Thanks BladeRacer, I'll get on with the checks not been done, and get back to you. I'll check back later if you have thought of anything else..

You checked the coolant level in the radiator, not the reservoir, right?
So it's not a stutter then, it actually won't pull any higher than 6500rpm at all except at very slight throttle?
Valve clearance check is detailed in the manual. Basically take the valve cover off and use feeler strips to check the clearances between the lifters and cam lobes. If the clearances are too tight, as the valve expands with heat it will hold the valve open. I would definately check the cam timing is correct as well while you have the lid off. The tensioner may have failed allowing the chain to skip a tooth. How much mileage is on the engine?
Infrared thermometer is the best way. It'll need to read to at least 300C.
Pull the vacuum line and turn on the ignition to pressurise the rail - no fuel should come out.
 

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Discussion Starter #5
You checked the coolant level in the radiator, not the reservoir, right?
Nope, will do though..
So it's not a stutter then, it actually won't pull any higher than 6500rpm at all except at very slight throttle?
Correct, but it feels & sounds like a rev limiter
Valve clearance check is detailed in the manual. Basically take the valve cover off and use feeler strips to check the clearances between the lifters and cam lobes. If the clearances are too tight, as the valve expands with heat it will hold the valve open. I would definately check the cam timing is correct as well while you have the lid off. The tensioner may have failed allowing the chain to skip a tooth. How much mileage is on the engine?
I will print off your reply and carry out the checks.
Milege is 26000k
Infrared thermometer is the best way. It'll need to read to at least 300C.
Pull the vacuum line and turn on the ignition to pressurise the rail - no fuel should come out.
 

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You checked the coolant level in the radiator, not the reservoir, right?
Nope, will do though..
So it's not a stutter then, it actually won't pull any higher than 6500rpm at all except at very slight throttle?
Correct, but it feels & sounds like a rev limiter
Valve clearance check is detailed in the manual. Basically take the valve cover off and use feeler strips to check the clearances between the lifters and cam lobes. If the clearances are too tight, as the valve expands with heat it will hold the valve open. I would definately check the cam timing is correct as well while you have the lid off. The tensioner may have failed allowing the chain to skip a tooth. How much mileage is on the engine?
I will print off your reply and carry out the checks.
Milege is 26000k
Infrared thermometer is the best way. It'll need to read to at least 300C.
Pull the vacuum line and turn on the ignition to pressurise the rail - no fuel should come out.

The reservoir is not part of the sealed cooling system. It only catches any coolant lost when the pressure valve in the radiator cap opens. As the system cools it then creates vacuum which opens the return valve and draws the coolant back into the radiator. The level of coolant in the reservoir is not relevant to the cooling ability of the cooling system, you must check that the _system_ is full of coolant with no air trapped in it. I doubt this is the problem but it's worth ruling it out.
I had a problem with the sidestand switch on my '98 GSXR750 once. It would hit an electronic limiter right on 9000rpm. Luckily another guy in the pits had encountered this before. We bypassed the switch, problem solved. I never bothered investigating further so I don't know what was actually wrong with it. I don't think this is your problem either though as you can actually rev higher.
My reply doesn't explain how to take the measurements, refer to the manual. The Haynes and OEM manuals can be found online via Google or Torrents.
26000kms is fairly early for the tensioner to fail in my experience. Was anything done to the bike just before this problem appeared?
 

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Discussion Starter #7
The bike has always had a race can and air filter nothing else and has riden fantastic for years, then its just decided to do this? after reading up on it a bit i thought i'd try the HTEV mod, which gave the bike and me another wow feeling again. but the 6000rpm limiter feeling was still there after she had warmed up.
I'm going to check the valve clearences today and see if i can get hold of a timing light. Also carrying out the rad, side stand and fuel line checks. I'll get back with the results. Thanks for this, its great help and informative.
 

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The bike has always had a race can and air filter nothing else and has riden fantastic for years, then its just decided to do this? after reading up on it a bit i thought i'd try the HTEV mod, which gave the bike and me another wow feeling again. but the 6000rpm limiter feeling was still there after she had warmed up.
I'm going to check the valve clearences today and see if i can get hold of a timing light. Also carrying out the rad, side stand and fuel line checks. I'll get back with the results. Thanks for this, its great help and informative.

You don't use a light to check valve timing, that's for ignition timing.
The manual shows how to check the valve timing when installing the cams.
 

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So I have a 01 929 and im having the same problem. I probed the exhaust for temp and found out the 1st cly wasnt firing so replaced the plugs and coil.
Ive check the fuel pressure regular
Valves
And ideas their guys
 

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So I have a 01 929 and im having the same problem. I probed the exhaust for temp and found out the 1st cly wasnt firing so replaced the plugs and coil.
Ive check the fuel pressure regular
Valves
And ideas their guys

Did you check if there's spark at the plug?
 

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Here's my input.
About a month ago I had an issue where it would bounce off 7k like hitting a brick wall.
I didn't know exactly what I did to fix it, but in doing so. I found a few things wrong.

When I raised the tank, I heard like a bubble noise rising up the fuel return hose, which seemed to dissapear after I raised the tank all the way up.

The vaccum hose connected to the fuel pressure regulator was split at the regulator end, and was full of fuel, which leads to cylinder 1 and 4, so those plugs could be fouled.

The fuel pressure regulator was leaking (naturally) which has been ordered.

Anyway, I replaced that little hose that was split, and now she revs all the way, so I'm ASSUMING it was fuel related.
 

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Like I said I done all of that
Coils
Plugs
Checked exhuast temp
Checked for. Vacuum leak visualy and with starting fluid

I think my problem started when I dropped the bike im wondering if the inertia switch maybe be causing some of our issues because of gforce put on it by acceleration
 

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Like I said I done all of that
Coils
Plugs
Checked exhuast temp
Checked for. Vacuum leak visualy and with starting fluid

I think my problem started when I dropped the bike im wondering if the inertia switch maybe be causing some of our issues because of gforce put on it by acceleration

Inertia switch?
Do you mean the bank angle sensor?
Bypass it if you want to rule it out but I can't see how that could cause your problem. G-force under acceleration really isn't that much, deceleration is way more.
 

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And a side not when the problem occurs its only under load.condtions never when being reved in with the clutch in. ?
 

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What ever it is its electronic a module for the injectors or cdi somthing is heating up and breaking down because mines good for like an hour of constant riding its when u stop and the bike heats up is when ot starts to act up
Im not sure if these bikes have a module or cam/crank sensor. I am an automotive mechanic not a motorcycle one
 

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What ever it is its electronic a module for the injectors or cdi somthing is heating up and breaking down because mines good for like an hour of constant riding its when u stop and the bike heats up is when ot starts to act up
Im not sure if these bikes have a module or cam/crank sensor. I am an automotive mechanic not a motorcycle one

You already said that #1 is not combusting so you either have a spark or a fuel problem on that one cylinder.
Have you checked that it does have spark?
Have you sprayed starter fluid into it to see if it fires up?
It doesn't matter if you're a car or bike mechanic, the technology is the same.
If there were a problem with the cam or crank sensors you would expect a MIL on the dash, since you haven't mentioned any MIL I assume it is not throwing anything?
 
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