Messages

481

Kawasaki / Re: Kawasaki KX125 KE125 help please

« on: June 05, 2015, 05:46:14 pm »

Expecting more than 15 hours wfo running from cast piston on a highly strung 125 seems pretty optimistic?
Perhaps 5 hours between pistons on an air cooled  MX bike would be safer?

482

Wanted / Re: Honda CR 125M1 1975 cylinder wanted

« on: June 04, 2015, 03:48:08 pm »

Those cylinders are a bit hard to come up with here; US Ebay is a better bet.

 The Yanks are much more ready to part out bikes.

 There are usually a couple with bores left floating around there . I picked up one with damaged fins for $25 bucks the other night.

I went through the MR175 CR125 thing for MX  last year.

As Big K says it is not easy. I eventually thought to buy a complete MR engine and swap the CR ignition and gearbox into the quite different cases and port the cylinder and make a pipe.

 In the end I canned the idea as having already reached the point of diminishing returns.

483

Yamaha / Re: sc 500 starving for fuel

« on: June 03, 2015, 12:42:15 am »

Check the needle and seat size; it could be in effect the main jet.

484

General Discussion / Re: Suspension travel limit - which bikes?

« on: June 02, 2015, 06:10:20 pm »

Several weeks ago I enquired of the VMX committee of AHRMA (and the silence is deafening) how to measure the travel on a leading link fork (LLF).  Teles are measured along the tubes, but that 7" of travel at an angle gives a smaller amount of vertical wheel travel. 

Do LLFs get measured 7" along the chord from full bump to full droop (somewhat like a telefork) or do you measure 7" of vertical travel as with a rear swing arm suspension?

Beats me.  I guess the tech committee doesn't know either.  Either way would be fine if I knew which one was preferred.

cheers,
Michael

You would logically measure the arcuate distance as the 7". That is the motion range through which the wheel is being controlled.  The same should apply for the rear.
However since we are not in the realm of needing space exploration and missile guidance accuracy, a standardised vertical movement measurement would be practical.

485

General Discussion / Re: Suspension travel limit - which bikes?

« on: June 01, 2015, 11:55:44 pm »

the good old tape measure probably has a millimetre or more of slop in the hook rivet.

Tape measures are supposed to have that slop at the hook
The movement of the hook is meant to be the equivalent of the thickness of metal of the hook so that you can get an accurate measurement whether measuring inside or outside of an object
[/quote]

I know.  Rivets and holes wear and hooks bend and people err in their ability to use tools as well. 

A steel ruler has a square end that is self supporting on the axle or swingarm and guides itself so to my thinking is going to be closer to foolproof.

To demonstrate my conviction on this to myself I have a Mitutoyo stainless steel ruler 2 metres long.

486

General Discussion / Re: Suspension travel limit - which bikes?

« on: June 01, 2015, 07:40:50 pm »

If you/MA are using  tapes, presumably printed,  for a precision measurement, that worries me.

Generally tape measures are for reference only.

Tape measures are used by tradesman it depends on the tolerance needed.
[/quote]

Mate, I am a tradesman and I sometimes make suspension parts for cars. 

For this type of work if you are going to measure 229 mm you reach for a steel ruler or calipers; the good old tape measure probably has a millimetre or more of slop in the hook rivet.

In your defense the tolerance is very generous but it also highlights the lack of precision and rigor in the whole exercise.

Not really.

I think if someone has an abnormally long bump stop I think that needs to be considered, but measuring travel without the bump stop is just not practical.

For rear wheel you are measuring rear wheel vertical travel. As I said the position of the wheel in the swingarm (chain adjustment) does have an affect. All the way forward less travel all the way back slightly more travel.

Either way a tolerance needs to be stated.

My bump rubber is off the shelf Ohlins.

Don't the AMA use 10% of the bump rubber's free length for their calculations?

Measurement logically should be in the mid point of the chain adjustment range.

487

General Discussion / Re: Suspension travel limit - which bikes?

« on: June 01, 2015, 06:30:09 pm »

Is Dave a MA licenced measured?  So the tape I borrowed from Michael Banford and still have wasn't used to measure suspension travel. Check your facts and then post your apology here. I wasn't measurer before the meeting, but apart from the Seward who can't do it I wasn't the only other one licenced to do it.

If you/MA are using  tapes, presumably printed,  for a precision measurement, that worries me.

Generally tape measures are for reference only.

I would like to think that certified scrutineers would at least be using an independently calibrated steel ruler or a set of certified Vernier calipers if there were a chance that things could go to the Steward or beyond.

When you say "... compress shock to bump rubber.  No need to try and compress bump rubber etc." that seems expedient.  The bump rubbers on my Pre 78 bike are urethane foam and about 35 mm long. They function as a rising rate auxillary spring with a little damping.

 I could have the legal 229 mm plus 50 mm in the stops allowing for the motion ratio.

Surely the test requirement should be a measurement with bump rubbers completely removed?

488

General Discussion / Re: Classic Dirt 11 - are you planning to ride?

« on: May 29, 2015, 06:44:21 pm »

 

Pardon my ignorance, and that I've been away from the sport for nearly 40 years, but what in detail is the Classic Dirt and why would I like to ride it??

Walk 100 metres down your street to my joint and I'll tell you all about it!

489

Honda / Re: 87 CR250 front brake

« on: May 29, 2015, 06:43:12 pm »

Ghetto brake refresh:

If there is meat on the pads and they are not oil soaked,  linish the top half a mm from them and give the disc a good scour with 120 or so wet and dry, then a clean with thinners or prepsol.

Should be a marked improvement.

490

General Discussion / Re: Classic Dirt 11 - are you planning to ride?

« on: May 29, 2015, 05:36:51 pm »

Pardon my ignorance, and that I've been away from the sport for nearly 40 years, but what in detail is the Classic Dirt and why would I like to ride it??

491

General Discussion / Re: Hangtown - AMA Nationals Round 1 video

« on: May 25, 2015, 06:25:13 pm »

Highlights from last weekends British GP are now linked:

 http://www.mxlarge.com/2015/05/19/ama-nationals-four-motos-5/

492

General Discussion / Re: Something we all should have in the shed

« on: May 23, 2015, 06:16:15 pm »

Multi tool only counts if you display something you made using it...

My suggestion is a couple of humble 100 ml veterinarians syringes with a clear flex tube attachment.

Invaluable for decanting and adding any workshop fluid.  Mine get used as everything from a burette for compression ratio checks to calibrated fork oil top ups/reductions to priming grumpy starting 2 strokes.

493

General Discussion / Re: Hangtown - AMA Nationals Round 1 video

« on: May 23, 2015, 06:09:28 pm »

I envy you lad bazza. A trip to Washougal is on my list.

Massively three dimensional race track Hangtown.

Some of the corners had 3 or 4 lines; each a rut about foot peg depth.

494

General Discussion / Re: Hangtown - AMA Nationals Round 1 video

« on: May 23, 2015, 06:07:04 pm »

My son went there and met the Chad, great photos and speed compared to down under really stood out,he thought that at Vegas supercross as well

Cheers.

Hopefully the same source will be good the next 11 rounds.

495

General Discussion / Hangtown - AMA Nationals Round 1 video

« on: May 22, 2015, 10:21:39 pm »

This link will get you both 250 and 450 motos from last weekends opening outdoor round.

http://www.mxlarge.com/2015/05/19/ama-nationals-four-motos-5/