Registration and Vibrations

[Vespa no more]

Bike is finally registered and on the road. Am quickly getting used to riding it. Am very pleased with low centre of gravity and ease of turning.
Opted for “Historical Vehicle” registration: $50 class bike club membership plus $95 (includes on road registration and compulsory third-party insurance) as opposed to $468 (full year third party) plus approx. $200 registration. I decided to take fully comprehensive insurance $161 in case.
So: 50+161+95: $300 versus 468+200+161:$829. I’m sure there are cheaper options. At this price – get two 30 year old bikes on the road!
Restrictions: am allowed to ride on all club runs (usually 2-4 per month) and 60 days during the year. Have to keep a log book – completed before departure in case police have to inspect it. This is enough of an allowance considering work, family obligations and that I have a car as well.

Some issues though.
Throttle body balance was out. Bike vibrated significantly after 3000rpm. Couldn't believe (at this point) that these bike rev out past 8000rpm.

Used recently bought Carbtune and balanced throttle bodies.

Q1 What is the best reading / setting for all throttles? Measurements are done in cmHG (ie centremetres of Mercury). Couldn't find anything in the Clymer manual. All throttle bodies are set to same amount. This setting was dictated by the least responsive air bypass screw. Basically all set at 19cmHg.

Q2 The air bypass screws ended in significantly different positions - one nearly fully out and the another nearly fully in. What does this tell me?... (am anticipating a chorus of “strip and clean throttle body assemblies”). I guess there is an o-ring at the bottom of the screw that could be replaced. One passing point – I noticed that the mercury tube for throttle #1 was not pulsating like the others (strangely stillish… some movement) … does this suggest there could be a blockage and that this cylinder might not be doing the work of the others. NB all levels on manometer set to same. Will check that spark plug cap is clean and spark is good – did this some time ago. All spark plugs brand new and gapped accordingly to specs.

Q3 Vibrations: how much is still acceptable? At 3500rpm … still vibrating too much. But bike did rev out to 5000 before traffic hindered the fun. But 8000+ ??

Q4 Hall Effect Sensor: from doing the sniffing around on this forum and ebay there are a number options. Dial gauge seems most common and will order one. Will make dial gauge disc adapter as per Sidecar Pauls specs ( http://www.k100-forum.com/t9867-ignition-timing-on-a-k1 however I am thinking a suitable bolt and deep nut welded to the top will work).
However, I am used to using the timing light on cars. Is there any way to dynamically set timing on K Bikes? Surely this is more accurate?
Will probably make Hall Effect Sensor setting device at some stage (see link). I know enough about electrics to get myself into trouble. But when some of the experts here get going I am errr… confused to say the least. Obviously an area for further study. http://advwisdom.hogranch.com/Wisdom/oilhead_timing_box.pdf
http://www.k100-forum.com/t548-timing-a-k100-to-find-the-sweet-spot



Then I discovered a couple of related gadgets:
a)   Timing retard device. Has anyone tried one of these so they can adjust timing while riding? Expensive -  but then they all are until you find a cheaper option

http://www.ebay.com.au/itm/CRANE-IGNITION-TRC-2-TIMING-RETARD-CONTROLLER-FOR-NITROUS-TURBO-FAS6000-6425-/361139672118?hash=item54159a1436:g:JwAAAOSwcLxYGTHp

b)   Also discovered piston micrometer: however these talk in terms of millimetres before TDC rather than degrees. Any opinions on these?
http://www.ebay.com.au/itm/PISTON-STOP-TOOL-TDC-14MM-SPARK-PLUG-IGNITION-MOTORCYCLE-CAMS-TIMING-TOOL-TDC-/142165396923?hash=item2119b7cdbb:g:i4YAAOSwmmxW1i27


And a couple of extras: I remember one regular here saying “don’t touch the preset screws (probably the ones painted with blue Loctite) or you are entering a world of pain”. Surely there is a standard calibration for these. If so how do we set them?

8000rpm WILL happen.

Thankyou again gentlemen for any assistance and ideas.

Regards

Guy

[kennybobby]

The fuel injection controller is built around having the throttle plate completely closed at idle, and the blue thread locker is from the factory setting where they all close at the same time and open uniformly.  The compound can be heated to loosen it if adjustment is needed.

Assuming the screws haven't been molested, the idle speed/synch is done using the brass bypass screws on each body and the overall mixture is adjusted at the bypass screw of the air flow meter.

Good luck with getting the vibration issue solved and sorted out.

[The Mighty Gryphon]

These engines are pretty tolerant of a wide timing range.  The factory setting is when the Hall Effect Sensor plate cutout is aligned with a cutout in the cover around it.  There a several photos on the forum showing this alignment.  The cutout allows you to use a timing light through it to see the timing mark.  The problem is that you need to remove the front wheel to use a timing light in there.   I just line them up and all my bricks run great.  My inclination is to think the problem lies elsewhere.

Don't mess with the blue screws.  They are set at the factory on a flow bench.  There are procedures on the internet that allow you to get them back to original, but I would only go after them if the paint seals were broken and I knew for sure that a previous owner was screwing around with them.  Otherwise you will only make things worse.

[Vespa no more]

Errrrr

I might have mucked around with them earlier - so, in this very rare case, PO is not to be vilified.

Will have a closer look at all options but think I only adjusted the centre screw to increase the idle to overcome output shaft spring rattle.

Will look at timing light - much prefer dynamic setting. The cutout are aligned at present and don't seem to want to rotate..

Anyway, am certain its the timing.

For now...

Guy

[The Mighty Gryphon]

Some issues though.
Throttle body balance was out. Bike vibrated significantly after 3000rpm. Couldn't believe (at this point) that these bike rev out past 8000rpm.

Used recently bought Carbtune and balanced throttle bodies.

Q1 What is the best reading / setting for all throttles? Measurements are done in cmHG (ie centremetres of Mercury). Couldn't find anything in the Clymer manual. All throttle bodies are set to same amount. This setting was dictated by the least responsive air bypass screw. Basically all set at 19cmHg.

Q2 The air bypass screws ended in significantly different positions - one nearly fully out and the another nearly fully in. What does this tell me?... (am anticipating a chorus of “strip and clean throttle body assemblies”). I guess there is an o-ring at the bottom of the screw that could be replaced. One passing point – I noticed that the mercury tube for throttle #1 was not pulsating like the others (strangely stillish… some movement) … does this suggest there could be a blockage and that this cylinder might not be doing the work of the others. NB all levels on manometer set to same. Will check that spark plug cap is clean and spark is good – did this some time ago. All spark plugs brand new and gapped accordingly to specs.

Answer #1: I don't worry about vacuum level.  I use a two bottle home brew balancer that only tells me which of two TB's has the higher vacuum.  I get all the TB's balanced to the TB with the vacuum takeoff for the fuel pressure regulator which is backed out 1 1/2 to 2 turns from lightly seated.  All three of my bricks are balanced this way and they are all silky smooth at all engine speeds.

Comment on question #2: All throttle bodies should have the bypass screw turned out approximately the same amount.  The fact that you mention having trouble balancing them and that they are set at different positions tells me(actually screams) that you probably have an air leak in the rubber bushings above or below the throttle butterfly, or that the screw you claim to have "adjusted" on the linkage has opened up one or more of the butterflies allowing so much air to bypass the idle air adjustment that you can't easily get a decent vacuum. 

If you have upset the air flow balance of the throttle bodies the cylinders will be firing with different fuel air mixtures because each cylinder receives the same amount of fuel.  That may very well be the cause of your vibration, especially at smaller throttle openings.  If the vibration peaks at a particular range of rpm it could be the result of an air flow resonance in the throttle body causing the maximum mixture imbalance.

It is possible that you may also have a problem in one or more injectors.  Based on what you have posted so far, I would consider this to be unlikely unless the vibration was there before you started messing with the air flow via the screw you adjusted on the linkage.

You say the cutouts in the Hall Effect Sensor plate are aligned.  That tells me that your timing is probably correct.  You can leave the timing alone and track down the problem in the throttle bodies or injectors, or you can screw up the timing too.

It's your call...

[Vespa no more]

Thanks very much for the reply. Will get onto it as soon as work permits.

Timing generally set as per suggestions.
Injectors serviced and clean. Fuel 98 octane. ...
Thanks for the throttle body to fuel pump regulator screw setting - that was the sort of basic measurement I was after (the good old "1 1/2 turns" - sort of universal)
Will wind the screw back in to set the idle speed to standard and put up with the rattle.

Ah... possible epiphany... the idle (despite being set higher re: output shaft rattle) needs throttle when first started (including choke) but changes later when warm... settles down to sit at 1,000 rpm (higher than when cold). I remember that rubber fan belts squeal less when hot because rubber expands. However, have suspected air leak around inlet rubbers - but have previously tried the gas bottle trick with no effect.

Will get onto it and post the results. Wont be til friday.

Regards

Guy