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Cobie Fair

Ask The Chief (Mechanic)

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Hi posters and lurkers,

 

I want to introduce you to the Chief Mechanic at the Superbike School, Will. He has agreed to answer any mechanical questions he can. He is the guy Keith and I go to with our mechanical questions.

 

A little background on him:

 

Started at the school in 1987, assistant mechanic, till 1993.

Did some coaching for us from 1996-98. (still rides at our CODERACE school as the cameraman).

Came back as Chief Mechanic in 2000, been here since.

Raced some AMA in the 80's. Came out of "retirement" and raced locally at Willow Springs about 2002.

In 2003 he entered a 636 ZX-6R in 5 classes (some against 750's). Won 5 championships, set lap record. Oh yeah, at the time he was 210 lbs, father of 2, and in his 40's.

If it has tires, burns gas and uses oil, he's likely driven it or raced it (from RC cars to tractor trailers).

Built houses.

Skilled painter (auto and motorycycle).

Expert fabricator and welder.

 

He does spend most of his time working so he'll get to your questions as he can. If this gets large enough, we'll start a section for him, like we did Steve.

 

Ask away!

 

Best,

Cobie

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I've been out in the garage looking over the 2005 GSXR 750 I recently bought. I'm now the third owner of the bike. The second owner had bought the bike as a track-only bike from the first owner. The second owner raced it for a year, then tried to convert it back to a street bike, then discovered he couldn't title it (salvage frame), so he rode it illegally for a while, then sold it to me as a track bike. I'm sure there are some details in there which could beg further questions, but that's the gist of what I know about the bike's history.

 

I'm a true beginner when it comes to working on motorcycles. I've done a few oil changes, installed a few aftermarket parts such as slip-on exhausts and PC III, and done the routine checks (fluid levels and tire pressures, charged batteries, cleaned/lubed chains, etc.), so obviously I'm only on the very basics. Part of the reason I bought this bike was to start learning more about maintaining a bike myself.

 

I believe I've found my first major problem: the front end appears to be twisted out of alignment (not sure if that's the correct term however). The bars are not centered when I put the front wheel in alignment with the rear wheel, but instead the bars are slightly off to the left. I'm not always certain I'm getting a clear look, but as I look down the forks (from the seat looking forward) it seems as thought the upper end of the right fork is just slightly further forward than the left. Also, the triple tree appears to be slightly further forward on the right side (perhaps it's slightly turned to the left - not sure which description is a better fit). I'm looking for suggestions as to what might be going on, and what it may take to fix it, and what else am I overlooking?

 

Edited to add: I just gave it another look after reading some posts on a couple other forums. I centered the bars as best I could. Looking down to the triple tree, it appears centered as well. Looking at the bike from the front, the front tire is about 15 deg to the right (my left as I looked at it). I didn't think this was good news; most other posts suggested this was bent forks, triple tree, or both.

 

Edited again: I talked to the guy who sold me the bike, and he believed everything was straight and true. In talking it through I wondered aloud if the forks could have twisted a bit when I trailered it home. The trip was about 2 1/2 hours on mostly highway, but with a few bumps. So, one of the things I suppose I want to check is if that could be the culprit, but on the other hand I've no idea how to check if it's true.

 

Thanks!

Edited by Brad VanHorn

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I'm even less knowledgable about bikes than Brad. I'm having to bleed the brakes on my '05 ZX6R just about every time I take it out (about 1-2 times a month to get used to it vs. my EX before a trackday). I literally just did it before I checked this site and found this post, and it's like there was a huge air bubble in there. What would help? I can't find a leak. There's plenty of fluid that isn't over a year old. Until I started riding it less, I never had this problem.

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Good questions both, I'll see if Will can get this today.

 

CF

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You shouldn't be able to get air into the system if it isn't leaking. It can still form from within, though.

 

When did you last replace the brake fluid?

Over time, brake fluid will absorb water. Water boils way earlier than brake fluid. When water boils, it will steam. This can again stay in the system, requiring a bleed job.

 

What condition is your brake system in?

If pistons doesn't move freely or if the return bleed is partially blocked, pads will stay in too much contact with the discs, creating heat. Also, using non-stock pads can raise heat considerably. Se below for results.

 

How hard do you use your brakes?

The hotter the brake system becomes, the hotter the brake fluid will become. And the hotter it is - or perhaps it is during the cooling phase, I'm no chemist - the more moisture it will absorb. Hence hard use will make the fluid deteriorate quicker. It could, in extreme cases, break down in 30 minutes. The result is the same as for the first point discussed.

 

Personally, if I used my bike for track days solely, particularly if they were infrequent, I would consider replacing the brake fluid after each track day. If you make sure it doesn't run empty in the master pump and you make sure no air is allowed to return through the bleed nipples, you don't have to worry about bleeding the brakes after replacing the fluid.

 

One little tip for those struggling to get rid of that last bit of air from their brake systems; turn the bars so that the outer tip of the brake lever sits higher than the pivot point at the master pump and zip-tie the lever firmly against the throttle grip. Leave for 12-24 hours and the brake should be firm and fine and free from trapped air.

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Any sign of Will? I know he stays very busy, and internet forums can be hard to get to when you're preoccupied with other things. I'm just curious when we might hear from him.

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The brake stuff was pretty well covered with one exception and it could be the trouble. When I bleed brakes I make all the lever movements slowly, I have seen pump the lever like the hammer on a single action revolver. Not good, what that does is little bubbles out of big ones. You think your done but what you have made the air into an emulsion in the fluid that you can't see. From there left sitting all the tiny little air bubbles will coalesce into bigger bubbles and the next time you crack a bleeder wala more air.

 

The one big thing of keeping the master high by turning the bars is a must.

 

Another little "trick" is to pull the lever to pressure and then let it go, pull slowly and let go. What this does when you have the bars turned so the master is high is suck the bubble out of the fill hole in the master piston bore. Not something you car see with today’s remote reservoir setups but with the old bike you can see the air come out.

 

If your starting with a dry system pull the lever slowly back and delay at full pull to give the air and fluid time to pass each other in the hose, 10 to 15 seconds a pull.

 

Put all that together and it should be no problem to get the air out.

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Brad you crammed a lot into that post. The bottom line is little things like falling over off the side stand can "twist" the forks up. However if you smack it against a wall, twist it in your legs or loosen every bolt and make it straight, and then after riding it becomes twisted again you have a bent part.

 

The most common thing is a bent lower tree, a fork tube after that.

 

If you can get it straight with the front end on a tree stand or jacked into the air remove the front wheel, loosen the forks and let them down just below the top clamp and retighten. if the legs suddenly don’t point at the holes they just came out of you have a bent triple tree. If they do you will need to remove the legs and roll them on a flat table or on a truing jig. It's about 50/50 inner or outer tubes, neither likes to straighten and stay round.

 

If you figure out what is bent there are many across the US who can straighten parts. If you are in the LA area I can give you a referral.

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That's good info, thank you very much. I'll post again when I get done with my next round of checks. (And sorry I put so much in my post; I have a habit of explaining things in excrutiating detail sometimes :) )

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Ask away!

 

Best,

Cobie

I have a question for Will- I just put a new set of Woodcraft rearsets on my 02 CBR600F4i. Everything went OK, but the new parts did not have provisions for a brake lever lift spring, and the brake light switch. (I use my bike for both track and street.) I unplugged the switch and taped off the connector; I rarely use the rear brake anyhow. The brake piston has enough spring to bring the brake pedal back up OK- is this alright, or should I try to get the secondary spring rigged in there?

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Ask away!

 

Best,

Cobie

I have a question for Will- I just put a new set of Woodcraft rearsets on my 02 CBR600F4i. Everything went OK, but the new parts did not have provisions for a brake lever lift spring, and the brake light switch. (I use my bike for both track and street.) I unplugged the switch and taped off the connector; I rarely use the rear brake anyhow. The brake piston has enough spring to bring the brake pedal back up OK- is this alright, or should I try to get the secondary spring rigged in there?

 

As a matter of fact that is exactly the way my ZX9 was set up, woodcraft with no switch and no spring = no problem. If you want an easy way to get a rear brake switch try Baja Designs, they make a pressure switch/banjo bolt that works very well.

 

The spring is really there to keep all the numb footed riders from inadvertently applying rear brake.

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OK I have one for the chief (or anyone else with experience in welding on bikes).

 

Couple of weeks back at the first race meeting for the year I was pulled up for not having a steering stop (or sufficient one at that) and they were tempted to sit me out for it. Note it is still on the frame just damaged from last time I came off (see avatar).

 

Hence, I now have to weld/repair to limit the steering and stop the bar touching the tank but before I do just wanted to check a couple of things as I have never welded on a bike or any other vehicle before.

 

Obviously, disconnect the battery and remove/cover anything that may be hit by spatter but is there anything I really need to know before i arc up?

 

One thing I am really concerned about is petrol vapour, spark and heat. Take the tank off only partially solves the problem as there is still the carby in there and I will without doubt spill some fuel when I take the tank off which can be cleaned up but can be missed as well.

 

Any advice much appreciated...

 

PS: Will be done outside with a fire extinguisher next to my feet!!!!

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OK I have one for the chief (or anyone else with experience in welding on bikes).

 

Couple of weeks back at the first race meeting for the year I was pulled up for not having a steering stop (or sufficient one at that) and they were tempted to sit me out for it. Note it is still on the frame just damaged from last time I came off (see avatar).

 

Hence, I now have to weld/repair to limit the steering and stop the bar touching the tank but before I do just wanted to check a couple of things as I have never welded on a bike or any other vehicle before.

 

Obviously, disconnect the battery and remove/cover anything that may be hit by spatter but is there anything I really need to know before i arc up?

 

One thing I am really concerned about is petrol vapour, spark and heat. Take the tank off only partially solves the problem as there is still the carby in there and I will without doubt spill some fuel when I take the tank off which can be cleaned up but can be missed as well.

 

Any advice much appreciated...

 

PS: Will be done outside with a fire extinguisher next to my feet!!!!

 

You definitely don't want to be around when I weld on bikes. For the first time in years I found myself wondering if I should take the battery out when I was TIGing a subframe two inches away from it???? No I didn't take it out or disconnect it. I worry more about hurting the paint than igniting gas fumes. The only fires I have suffered while welding was the contact cleaner that hadn't fully evaporated, LOL! nothing quite like wondering what that POOFFF was when your helmets down.

 

Go ahead and take every precaution you want and then just get to it. Like I said before the biggest thing i worry about is hurting paint and second to that is plastic and rubber, the heat from the arc and the radiant heat through the metal will melt stuff. I keep a squirt bottle of water to cool stuff off.

 

That reminds me of the scariest welding job I have done, the F800 S brake rig. The gas tank it in the tail and is the fender and part of the side cover. I had to make a plate to go from the top subframe rail to the bottom and then weld the rear mount to it with 1/4" of clearance from red hot metal to plastic gas tank!!!!! Needless to say it all went well but there was a lot of squirting the gas tank to keep it cool while the metal cooled.

 

Now a tip about the stop, if your welding it to a steel frame you might want to consider welding a flange nut to a hole in the frame and using a bolt with a jam nut to make an adjustable steering stop. Sometime there's enough meat in the bottom tree to drill and tap a hole in it and use the jam nut and bolt on the other side.

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The reason you want to disconnect the battery is to prevent the onboard electronics from the current on welding systems that are earthed to the frame. Welds with open flame, for instance, will not attack the electronics in any way other than if you manage to melt wire insulation that can lead to a short circuit.

 

Personally, I would be very reluctant to weld anything on the main frame, particularly one made from aluminium alloy. One important reason is that I cannot weld and don't own a welder :D I'd rather drill and tap the bent stopper and insert a bolt that could be adjusted to the desired stopper distance if that's an option.

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Thanks for the advice!! Sounds like I should just get to it and stop thinking about it.

 

Drilling and tapping a bolt through the stop on the tripple is definitely a good idea but a bit too much work as it is only a tracky (Very old one at that) and doesn't need a great deal of lock or adjustable lock so weld it is. Just need to add a bit of metal to the frame stop, 2 minutes work when I actually pull my finger out!

 

Old school Mild Steel frame so no fear there but will use the water bottle to keep it cool. Definitely disconnect the battery though.

 

Also Will, if I ever make it over to the US to do a school (hopefully CODE RACE) and you are repairing bikes with a welder, remind me to run a mile!

 

Here is the reason I gave it a bit more thought than I might have otherwise...

 

<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.c...bed/1nQy72y6lU8" frameborder="0" allowfullscreen></iframe>

 

Thin sidewalls on them Yammie tanks!!! :o

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Thanks for the advice!! Sounds like I should just get to it and stop thinking about it.

 

Drilling and tapping a bolt through the stop on the tripple is definitely a good idea but a bit too much work as it is only a tracky (Very old one at that) and doesn't need a great deal of lock or adjustable lock so weld it is. Just need to add a bit of metal to the frame stop, 2 minutes work when I actually pull my finger out!

 

Old school Mild Steel frame so no fear there but will use the water bottle to keep it cool. Definitely disconnect the battery though.

 

Also Will, if I ever make it over to the US to do a school (hopefully CODE RACE) and you are repairing bikes with a welder, remind me to run a mile!

 

Here is the reason I gave it a bit more thought than I might have otherwise...

 

<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.c...bed/1nQy72y6lU8" frameborder="0" allowfullscreen></iframe>

 

Thin sidewalls on them Yammie tanks!!! :o

 

 

Nice video, thats a different type of welding though.

 

I don't know how an open offer will go but if any of you are in LA and want to drop by to see or do technical stuff like welding on frame's im sure we can arrange a time when im in town. I'm not "A Welder" for a living but I am schooled in it and can on occasion lay down a good bead.

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Job done, easy as.

 

Thanks Will and I was only joking about running a mile, it is always interesting watching skilled tradespeople like yourself apply the technical aspects of their job. So if anyone has the oppertunity to watch you work they would be mad not to.

 

Many more questions to come....

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On Jason's brakes, it sounds more to me like the master cylinder seals have had it, or perhaps the pistons are sucking back too far into the calipers. In the latter case the lever would have too much travel but the brakes would be firm when they bite, but it sounds more like the former to me. What does Balistic Will think though?

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That's a very rare failure, it can happen and if I bleed it and then find air I might suspect the master. Really in the last 20 + years I have only come across two masters that would vacume air in on the back stroke. They are far more likely to leak out or bleed off pressure.

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G'Day Will,

last time we spoke, the topic of changing the Students suspension settings on the BMW's came up.

You said they don't change 'em, sure there's not much time between classes so Factory settings or whatever is midway makes sense.

Do the Instructors mess with their assigned bikes settings much?

Like, Pete weighs a bit less than Cobie, and you are a bit different in weight to John, yet you all seem to just jump on any old bike and whizz around.

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That's right, Pete is skinny, and I'm a real human size (er, that's my story and I'm sticking to it!). :unsure:

 

If the coach is a full timer, he'll likely mess with his suspension, if not, he has to ride what he gets. I messed with my bike a few times early on last year, and pretty much haven't touched it since. James and some of the other guys get the super fast guys (I'm not going to go ride with Leon Camier), so they work on the bikes a bit more to get them as they like 'em.

 

CF

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I am on one end of the scale with both rider weight and pace. I ran the stock settings all over, up and down and ended up right back in the middle as the best.

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New question about chains and sprockets. I read about 520 chain conversions kits and how wonderful that is- is this worth doing? I'm also hesitant to change teeth counts- if decreasing the front by one and increasing the back by two is great, why don't the OEMs do all this in the first place?

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New question about chains and sprockets. I read about 520 chain conversions kits and how wonderful that is- is this worth doing? I'm also hesitant to change teeth counts- if decreasing the front by one and increasing the back by two is great, why don't the OEMs do all this in the first place?

 

G'Day Stevo,

Interesting questions,

from what is printed in the mags and online, it seems that a lot of manufacturers over/under gear their bikes to pass noise tests.

With the 520 conversion, what's on it now?

is it for a street bike or a track bike?

How heavy,torquey and powerful is the bike?

180 rear tyre?

Cheers.

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G'Day Stevo,

Interesting questions,

from what is printed in the mags and online, it seems that a lot of manufacturers over/under gear their bikes to pass noise tests.

With the 520 conversion, what's on it now?

is it for a street bike or a track bike?

How heavy,torquey and powerful is the bike?

180 rear tyre?

Cheers.

I use my bike both track and street. What I have: '02 Honda CBR600F4i, stock, with 525 chain, 16 and 46 tooth sprockets. I have almost 20K mi on the bike so it's probably time to replace the chain anyhow. I did just order Dunlop GP211A tires (190/55 on the rear, up till now using stock size of 180/55).

 

Speaking of noise, my muffler is stock, although I'm dragging it on some turns if I'm not really careful about my body position. Some guys think I need a new can, some think my rear shock needs to be replaced- if anyone has thoughts on this, I'd like to hear it. The way I see it is most after-market cans look just as big.

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