Slow burn 5th gen build - old skool kool!

[Stray]

Could use some advice on a few things: 

 

1. The bike shudders at the end of a long hard braking straight. Not at the start, just at the end. I overcame this by releasing and re-applying the brakes. Any idea why this is? How can I fix it? 
 

2. The combined brakes make the rear chirp and skip when braking hard (I THINK it’s the rear - hard to tell when hanging on for dear life). Sometimes the rear fishtails a bit as weight transfers forward. Does anyone have experience with CBS in track/race conditions? Anything I can do to stop this (other than ditch CBS)? 

 

3. Exhaust pops and bangs on closing throttle. Is that because of the PAIR system? 
 

4. Throttle response can be a bit snatchy at low RPMs. Can this be fixed (without a power commander)? 
 

All advice warmly received. 

 

Stray

[Cogswell]

I'll start off by saying I've never expeirenced any of that with my 5th gen.  I'll offer my $.02 - YMMV.

 

1.  If you believe it to be the brakes, do not confine your search for answers to that.  I would go over the bike with a torque wrench, checking all components' fasteners for correct torque, from front suspension attachments, swingarm, engine mount bolts, everything including caliper mounting bolts, etc - eliminate all possibilities.  It's free.  Then get a dial indicator and check wheels for runout as well as brake rotors.  If no improvement look for worn components - steering head bearings, front wheel bearings would be top of my list. Finally, what pads are you using?  Are they glazed?  A.M. pads can be of any unknown compounds.  Complaints abound about cost re: OEM pads, but I always use them and have never had a problem.  If still an issue, it will need other diagnosis. 

 

2.  CBS or not, the rear can fishtail with forward weight transfer.  Generally mine has hunkered down and not lifted the rear wheel with the CBS, I've never had that happen no matter how hard the braking.  Even with CBS, both wheels can skid - I've witnessed it.  A sudden rate of brake application can unsettle any chassis.  Maybe chat with a track instructor about that or have an instructor ride your bike and give you an opinion.

 

3.  No opinion on that.  Mine's never done it - tho my 4th gen sure did. 

 

4.  I've seen very few complaints about 5th gens with that issue, particularly the early ones with no cat.  6th gens are another matter, they seemed to be tuned very lean and a PC or Rapid Bike helps them significantly.  On my 6th gen, removing the injectors and having them cleaned made a huge improvement in that.  The ECU has no way of knowing if the injectors are not flowing per specification, so provides what it thinks is the appropriate fuel amount but when the engine does not get it, performance suffers.  These bikes are now over 20 y.o., there's bound to be some varnish / fuel residue in the system.  Injector bench cleaning would be a good maintenance practice.  It is a PITA tho, b/c the throttle body must come off to do that.  On 6th gens that was revised and all that's req'd is to raise the tank and remove the airbox.  YMMV. 

[Thumbs]

Brake judder - have you spun the buttons on the discs recently?

[Skids]

2 hours ago, Thumbs said:

Brake judder - have you spun the buttons on the discs recently?

Is that a thing? Never heard of it before. 

[Thumbs]

1 hour ago, Skids said:

Is that a thing? Never heard of it before. 

It sure is, I put a washer either side and a bolt through them and put the drill on it for a few seconds, part of my spring time routine now 

[Mohawk]

Squirt some brake cleaner in the disc bobbins & spin them, this ensures full floating disc. Check the disc alignment & that they are centred on the wheel hub, there is a little wiggle room. Also check the calliper sliding pins work as intended. 

For the throttle on track, just set a high idle of 2-3K rpm, then you never go on to the starter valves, its always on the butterfly. 
 

The rest as advised above. 

[bmart]

Describe "how" you're riding it, please. 

[Stray]

On 7/30/2023 at 12:28 PM, Thumbs said:

Brake judder - have you spun the buttons on the discs recently?

On 7/30/2023 at 5:42 PM, Mohawk said:

Squirt some brake cleaner in the disc bobbins & spin them, this ensures full floating disc. Check the disc alignment & that they are centred on the wheel hub, there is a little wiggle room. Also check the calliper sliding pins work as intended. 

For the throttle on track, just set a high idle of 2-3K rpm, then you never go on to the starter valves, its always on the butterfly. 
 

The rest as advised above. 

Thanks for the suggestions, gents. How could I forget about the bobbins!
 

Used an old centrestand nut and bolt with some brake cleaner and a few of them were a bit gristly. Well worth doing!
 

 

 

Discs spin true and I can’t see any runout. No lip on them either. Pads are OEM Honda with 90% life left. Sliding pins were polished and greased just before going on track. 
 

Also checked headstock bearings and that’s spot on: handlebars fall to either side under their own weight with a nudge. Yoke/triple clamp bolts also properly torqued.
 

This judder thing has me beat. It only happens at the end of a long, hard, emergency brake. If it was brake related it would happen from the start of the braking session, no? 
 

Good tip on setting a high idle for track - nice one mate. I’ll definitely do that next time! 

 

On 7/31/2023 at 1:37 PM, bmart said:

Describe "how" you're riding it, please. 

 

Bmart, this thing was being flogged HARD at Mallory Park race circuit. To give an idea, I was coming out of Gerard’s bend doing around 110-115 MPH (indicated) and accelerating towards Edwina’s after. No idea how fast as eyes glued to chicane thereafter. Braking hard on a downhill for the chicane make it rumble, just before turn in.
 

After Edwina’s there’s a nice curvy back section where you can get up to triple digits again, followed by some really hard braking for the 1st gear hairpin. Here she shakes real hard at the end of the breaking section, just before turn in. Quite unnerving. Had to release the brakes and reapply.
 

Knuckles white, butt clenched and eyes open wide…HA HA HA! 
 

I’m a very smooth rider and apply brakes, throttle or lean progressively. No sudden twitches or ham-fisted brutality. I’d be surprised if the judder was down to rider input. Tyres look shredded just like they should after a track day. No odd wear markings or discolouration that I can discern. 

[Stray]

Despite my intentions to mistreat this machine as a winter donkey, I’m really enjoying her. 
 

Looking to start spending on a pair of pillion grips, seat cowl and maybe a new front fender as the old one is quite battered/cracked. Thinking about a new shock too. 
 

This wasn’t supposed to happen…

[Stray]

Now back to the 5th gen race bike project: making a plug to fill the mechanical water pump hole in preparation for an electric water pump. 
 

I had an old water pump in the parts bin and decided to use its stem as the body of the plug. It’s made from cast aluminium and has the correct taper/step for the hole. A piece of old Ducati 848 brake torque arm leftover from the rear wheel conversion would fill the centre. This is also cast aluminium but must have been a different grade as you can see the difference throughout the fabrication process. 

 

You can see the water pump hole we are trying to plug in the centre of this picture, just below the clutch slave mount. 
 

 

This pic shows the step in the hole, and the corresponding step in the water pump stem. 
 

 

Tickled it with a hacksaw and used a crowbar to prize it off the shaft. Now we have the rough shape of a plug. 
 

Incidentally, if anyone ever wanted to remove the impeller from their mechanical water pump, you can just hammer it out. It’s an interference fit. 
 

Plug piece removed. 
 

 

Coin shaped centre piece cut out from Ducati 848 rear brake caliper bracket and roughly shaped with grinder to fit tightly in the plug centre. Got some aluminium brazing rods ready to “solder” the two pieces together. What a chore that was! 
 

 

 

Heating up the part, not the rod. You can see the solder along the inside edge. What o didn’t realise is this stuff leaves pores, and when it’s heated it just runs through the cracks between the parts and drips down the vice. 
 

 

Looking OK and oil tight from the inside…

 

 

…but not sure about the outside. 

 

Quick tickle with a file to see if it improves and you can see it’s not good enough. 
 

 

So back to apply a little more rod…but it just dribbles through the gaps and onto the vice again. 

 

So plan B: solder it facing down on a flat steel surface. 

Finally, it worked! Now we have a well filled plug with a flat surface to smooth. First phase is to file it flat, followed by a flap disc to smooth. Going for a domed shape. You can still discern the different grades of aluminium and the filler material. 

 

Smoothing with sandpaper. 
 

 

Followed by hard buffing wheel. 
 

 

And medium buffing wheel. 
 

 

Final polish with Autosol and a hard cloth (denim works great). Quite pleased with the dome shape and I even like that you can still make out the soldered bits. 
 

 

Plug inserted with Threebond and left to cure overnight. Made sure to wipe everything down with acetone beforehand. 
 

 

Also fitted PAIR block off plates while here (no Threebond needed as internal gaskets were still solid). 
 

 

Two steps closer to completing the race bike project! 

[Stray]

Back to the 5th gen Donkey: how to re-key your fuel cap if the key doesn’t match the ignition. 
 

First step is remove the cap from the tank. Undo the 3 bolts pointed at by the keys and Allen wrench. That’s the foremost one and rearmost two. The others are dummies. Unlock the cap to lift it off. 

 

Next you need to split the locking mechanism from the cap. First you remove the metal washer under the rubber rand. Don’t worry, the rubber is really thick and strong so no need to go easy. Washer has a cutout that slides over the lock if you orient it right. Sorry - no pics but you’ll be fine. 
 

Next, remove the three screws holding the lock to the flap. These are also under the rubber and below where the washer was. You’ll need a magnetic screwdriver or you’ll hate your life! 
 

Once separated, a quick twist of the key and the barrel slides right out. This pic shows the correct key inserted and the lock pins are (almost) flush. They stick up a bit because the key is old and worn. 
 

 

Next pic shows the incorrect (ignition) key inserted. The pins are no longer flush with the cylinder so it won’t turn in the housing. This is how the lock stays closed if the wrong key is used. 


 

Note how much longer the top key is to the one just above (5th gen regular ignition). I suspect the flap is from a HISS model with longer key. Their blade section is similar though - simply a longer shaft for HISS. 

WARNING 1: if you pull the key out of the barrel now you may end up with pins and springs and impossibly small ball bearings flying all over the place. Put a finger over the pins if you’re swapping keys round. 

WARNING 2: the rubber rand needs to be pressed down to release the locking tangs and let you take out the key. Imagine it’s pressing against the fuel tank when you close the flap. But when the barrel is removed the locking tangs (and their springs) can shoot out all the way so you need to hold them when doing this. 
 

Pins can be pulled out individually. 
 

 

From this point you have 4 options for a re-key job: 

 

1. Pull out all the lock pins (along with the springs and tiny ball bearings. This will make the lock work with any key or a screwdriver. Don’t leave the springs and ball bearings in as they can jam it all up. Great for race bikes but not good for street

 

2. Get yourself a Honda rekey kit. They exist! Then pull out all the pins that don’t work and replace them with pins that stay flush with your key. Expensive and time consuming but there is a way to match pins to the serial number of keys

 

3. Pull out only the pins that aren’t flush and leave in the ones that are. You can also swap pins around to see if you can achieve a better fit. This works, even if you only have a few of the pins left in the barrel at the end
 

4. Lastly you can file down the keys that stick out until they are flush (provided there’s enough meat on the bones). Use light pressure as the pins are spring loaded
 

I took a combination of 3 and 4. First I swapped a few pins around to get as close as possible, then tickled it with a fine stone on the bench grinder until it was flush. You can also use a Dremel or hand file but don’t press down as the pins are spring loaded

 

Before: 

 

After: 

 

Clean out any swarf and lube the lock well. I used graphite lube but you can use anything good in your workshop. 
 

Reassembly is the reverse of the above. The lock tangs need to be retracted (pushed into the housing) for the barrel dowels to locate correctly. Unlock it a few times before buttoning everything up, just to be sure. 
 

All in, took me 25 minutes and I now have matching keys for the ignition and fuel flap. I’d imagine you could do the same with the seat lock but haven’t needed to so you’ll need to look into it yourselves. 
 

Have a good day! 

 

[timmoer]

Damn... I wish the PO of my bike did that. He lowsided and fixed everything including replacing the tank. I'm stuck with carrying around two keys now - a minor annoyance, but still

[Captain 80s]

Just now, timmoer said:

Damn... I wish the PO of my bike did that. He lowsided and fixed everything including replacing the tank. I'm stuck with carrying around two keys now - a minor annoyance, but still

 

You can also have one key cut with each number.  Only one side does anything, they just cut both so you don't have orient the key before inserting.  We did it at the Honda Dealership quite often.  We'd paint a tiny color code on the key right below the plastic with touch up paint for a quick glance legend.   

[Stray]

4 hours ago, timmoer said:

Damn... I wish the PO of my bike did that. He lowsided and fixed everything including replacing the tank. I'm stuck with carrying around two keys now - a minor annoyance, but still

Now you can re-key your tank using this guide. Takes less than 30 minutes! 
 

3 hours ago, Captain 80s said:

 

You can also have one key cut with each number.  Only one side does anything, they just cut both so you don't have orient the key before inserting.  We did it at the Honda Dealership quite often.  We'd paint a tiny color code on the key right below the plastic with touch up paint for a quick glance legend.   

This is genius mate. Never thought of that - thank you for the tip! 

[timmoer]

On 8/8/2023 at 2:05 PM, Stray said:

Now you can re-key your tank using this guide. Takes less than 30 minutes! 
 

 

Ha, I stupidly didn't read closely and thought new parts for the barrel was needed. If it's just a matter of shaving the pins flush, sounds like a good small project on a weekend. 

 

Weirdly enough the key for my tank is the suspected HISS version (with two grooves running along the length of the key), whereas the ignition key just has one. The HISS tank key doesn't even go into the ignition, but the ignition key does go into the tank - luckily it's not the other way round otherwise this wouldn't work!

[Stray]

On 8/10/2023 at 4:38 AM, timmoer said:

Weirdly enough the key for my tank is the suspected HISS version (with two grooves running along the length of the key), whereas the ignition key just has one. The HISS tank key doesn't even go into the ignition, but the ignition key does go into the tank - luckily it's not the other way round otherwise this wouldn't work!

Mine was the same. Twenty minutes tickling the cylinder pins as per the guide above and you’ll be laughing. 

[Stray]

Had a bit of clutch slippage on the 5th gen  Donkey and thought I’d ring EBC to see what the craic is as because the early 5th gen has a different clutch setup from the later 5th gen (and early 6th gen). 
 

EBC told me they do different spring kits for the two models: 

 

- 5th gen A: CSK135 - 44.7mm long with 19.57mm diameter (7 turns)

- 5th gen B: 46.5mm long with 19.7mm diameter (7 turns)

 

Of course these are EBC figures but it suggests the early bikes have shorter springs than the later bikes. 
 

Have just ordered a long set for my early model, hoping for more positive engagement. Will fit new Honda friction plates and scuff the old steel plates. Also will give the master, slave and pushrod some love whilst in there. 
 

Let’s see how we get on! 

[Stray]

Folks, the clutch on my bike makes a bit more noise when in neutral than when the clutch lever is pulled in. Is this normal? If not, what do I look at first?

[Captain 80s]

NORMAL.

 

Put in your new clutch and springs, it will still be there.  It's 99.99% not a "problem".

 

[Stray]

14 hours ago, Captain 80s said:

NORMAL.

 

Put in your new clutch and springs, it will still be there.  It's 99.99% not a "problem".

 

Thanks Captain - really appreciate the reply! 

[Stray]

Captain’s reply above notwithstanding, noticed today with the clutch engaged (lever pulled in), the bike is quieter and smoother. When I let the clutch out (in neutral) it gets slightly rattlier. 
 

Do you think I need to change the clutch bearing too? Or something else? 
 

If I’m doing clutch plates and springs, what else should I do whilst in there? 
 

Bike has 27,500 miles. 

[timmoer]

Mine is the same - it's hard to describe but with clutch lever out, there's this almost "digital" type of noise that you can feel in the handlebars, some sort of medium to high frequency vibration that's causing it. 

 

I'm at almost 39k miles, clutch doesn't slip and I have ample clutch travel before engagement. I didn't think it's a big issue and am just going to leave it

[Mohawk]

Clutch disengaged (lever in) the clutch gear drive is still engaged but doing nothing.

 

Clutch engaged (lever out) in neutral, the gear drive is spinning the gearbox & the clutch lash springs bounce about to smooth the clutch on the gear. I suspect this is what you are hearing. 

[Stray]

Thank you gentlemen for your input. Gives some comfort and shows I should have just listened to Captain in the first place. 

 

Having said that, I've never noticed this on any of my other bikes (including another 5th gen a few years ago). Maybe I just missed it but does make me wonder...

 

Will be changing the pressure plate bearing just in case anyway as it's only about £11 ($15). Let see...

[Captain 80s]

Once you know about it, you will feel/hear it on other bikes.

 

I own more than a dozen V4s from 10K to 60K and they ALL do it to some degree.  You can feel it come in as you let out the clutch lever.

 

I worked at a Honda Dealer for over 12 years and it was one of the most common questions regardless of what model, including CB/CBRs.