MB100 development

[Henk]

R2 are agents for TKRJ and Pro X so you should be able to order through a bike shop near you.

[dangerous]

For future reference. Are there NZ agents for TKRJ and Pro-X or do you order direct online?

Well this is what arsed TonyB up, KB's TKRJ suplyer, A Dorkland guy IIRC told TKRJ he wanted to be NZ's only importer and as he sold more than Tony he got his way, anyways... your MB already has a TKJR piston kit as does our old 250LC and the 350LS has a rod kit aswell, no issues with any of these items what so ever, good gear as is prox

[Hilleye]

Well this is what arsed TonyB up, KB's TKRJ suplyer, A Dorkland guy IIRC told TKRJ he wanted to be NZ's only importer and as he sold more than Tony he got his way, anyways... your MB already has a TKJR piston kit as does our old 250LC and the 350LS has a rod kit aswell, no issues with any of these items what so ever, good gear as is prox

Ta for the info.

[husaberg]

I had a man look through the post. I can't seem to find the bit where the ignition curve came up I think it was Speedpro who said the Ignitech was only really helping at one point on his engine.
I could remember seeing these donkeys years ago.
Delay boxs, old tech piggy back to CDI units.
This company is still in business too.
It was meant at the time to be a common Mod on proddy bikes.

I have an article bellow that explains how they work and how to basically map an old style cdi unit.

The Ignitech is the obvious top self bees knees set up, but it may be possible to provide a lower tech solution.

I seem to remember JayCar having a adjustable delay circuit.

http://http://www.jaycar.com.au/images_uploaded/LM555.PDF
http://http://www.ehow.com/how_4827785_build-time-delay-circuit.html


Here is an exert off the net from a guy that builds Ignitions He mentions Buckets on his site to in regards to a Ignition he makes for the Honda 4 stroke single.

Engine revs Timing advance

1000rpm 26.0 degree
2000rpm 27.0 degree
3000rpm 25.5 degree
4000rpm 23.5 degree
5000rpm 22.0 degree
6000rpm 21.5 degree
7000rpm 20.0 degree
8000rpm 18.0 degree
9000rpm 15.5 degree
10000rpm 13.5 degree
11000rpm 11.5 degree
12000rpm 9.5 degree

"But the advance and retard goes the wrong way!?" you say. (Well one or two of you have.) I queried this with Rex, as I also thought that engines were supposed to advance the timing as the revs progressed, not retard it.
Rex replied:
"Since the early '80s much two stroke research has focused on electronics. We have seen the introduction of power valves to control the point of opening of the exhaust port. Initially this was performed by mechanical means, then designers found that to enhance the power band a control by an electric motor, itself controlled by a computer gave far more scope for power increases, especially in the midrange, just where you need to accelerate from a corner. Part of the search for midrange power focused on the ignition timing. It was found that beneath the power band created by the tuned exhaust system, more ignition advance could be given than could be tolerated at the peak horsepower rpm. A study of a MK 3 TZ350 curve will illustrate this. (Diagram to follow)
Then it was found that a further retard of the spark timing caused the exhaust pipe to run hotter, which affected the speed of the sound wave in the pipe. The net result was the pipe stayed in tune longer after peak horsepower by keeping the torque up.
We have found that retarding a fixed timing setup, by say 2-3 degrees, will give more power after peak horsepower, but there will be a drop in power on the climb up to peak horsepower. There a tailored ignition curve can give gains over the fixed timings we were used to in the early days of racing two-strokes. With limitations in engines by piston crown temperatures it pays to approach the design of the curve with care and dyno testing sometimes has to be verified with actual track testing. The same applies to other settings on the engine and the whole picture is usually a blend of art, science and experience, with failures on the way, such as holes in pistons! Hopefully this will give a brief explanation of why the general two-stroke ignition curve differs from a four-stroke curve which normally has a rise in ignition advance with a rise in rpm. Further study is recommended by reading books on the subject such as "Basic Design of Two-Strokes" by Doctor Gordon Blair and " Two-Strokes Performance Tuning" by Alexander Graham Bell."
So there you are. Years of research and hard work summed up in on or two paragraphs, supplied totally free to all of you people out there....thanks Rex.

There is also a Kiwi that makes ignitions too. Here

[Hilleye]

Conrod kit, check with them to see if its slotted. http://www.trademe.co.nz/motors/moto...-415302675.htm

Be aware that the "Long" brand conrod kits do not come with thrust washers (just me or is this random). Original Honda thrust washers are $40 at cost, so just sent it back and ordered a TKRJ kit, which isn't necessarily a bad thing reading the comments on "Long" brand bearings.

Back up engines arrived today (big thanks to the provider). One a worked H100 in need of some TLC and the other a stock MB. Porting on the H100 gives me hope that my current MB cylinder can potentially be improved, without needing to be scraped. Will sort through properly tomorrow and maybe post some photos.

Who knows, might build another complete bike and have an engine in reserve/development (probably not though, no time).

[husaberg]

Be aware that the "Long" brand conrod kits do not come with thrust washers (just me or is this random). Original Honda thrust washers are $40 at cost, so just sent it back and ordered a TKRJ kit, which isn't necessarily a bad thing reading the comments on "Long" brand bearings.

Back up engines arrived today (big thanks to the provider). One a worked H100 in need of some TLC and the other a stock MB. Porting on the H100 gives me hope that my current MB cylinder can potentially be improved, without needing to be scraped. Will sort through properly tomorrow and maybe post some photos.

Who knows, might build another complete bike and have an engine in reserve/development (probably not though, no time).

I seem to have found a Eccentric pin which might work in the MB100/H100 motors that would allow the use of a Strike 52mm kart piston it alow the use of a STD style bearing as well the price looks ok.
I will post the pics and the links later.
Speedpro used this approach but the cost I guess was probably a lot more than an off the shelf mass produced solution.

http://www.lambretta-teile.de/Big-en...-62mm-Vespa-PX
http://www.lambretta-teile.de/Excent...espa-PK-PV-V50
http://www.lambretta-teile.de/Eccent...-54mm-Vespa-T5
http://www.vespa-lambretta-teile.com...nghub-625-mm_1
http://www.worb5.com/shop_de_7/start.php?P_2071.php

There are other option if you bore out the crank to 22 if there is enough room.
The Bearing according to the blurbs is ment to be able to wigggle on?

I am having trouble finding the widths the Vespa seem to be around 15mm not sure with the Lambrettas where scooterboy

[Hilleye]

I seem to have found a Eccentric pin which might work in the MB100/H100 motors that would allow the use of a Strike 52mm kart piston it alow the use of a STD style bearing as well the price looks ok. There are other option if you bore out the crank to 22 if there is enough room.

Could you explain the advantages of doing the above for those of us that are less mechanically inclined.

[speedpro]

Using a good quality 52mm kart piston allows you to build a motor that works well at high revs which should equal more horsepower. The problem is that using a 52mm piston takes the capacity over the 105cc upper limit. To get around that you need to reduce the stroke which also has the added benefit of reducing peak piston velocity and acceleration given any particular engine speed so you can rev it even more. Plus they are relatively cheap and you can go to any kart shop and buy as many as you want in any size.

The 20mm pin with offset centre might be good if the big end bearing can we wiggled over the step and also depending on whether the centre section width is right for the rod + thrust washers + clearance.

[Hilleye]

Just got the new engine bearings today. Compared play in new bearings to play in old bearings, which I had considered flogged out and there's negligable difference.

So my next question is: The engine was definitely rattling on shutdown, but not noticably when running. Bike was spitting out of the muffler and running for a few seconds before dying again everytime we tried to start it up. What else could it be?

When pulling the engine apart I noticed that a very small part of the flywheel key had sheared off the top (vast majority was still intact), but it still wasn't able to be spun independantly by hand. Surely this isn't the problem. You can see the crank seems to show signs of flywheel turning, is this normal?

[TZ350]

Bike was spitting out of the muffler and running for a few seconds before dying again everytime we tried to start it up. What else could it be?

When pulling the engine apart I noticed that a very small part of the flywheel key had sheared off the top (vast majority was still intact), but it still wasn't able to be spun independantly by hand. Surely this isn't the problem. You can see the crank seems to show signs of flywheel turning, is this normal?

Slipped timing, in the early days we sometimes had the same problem, an overly harsh or inadvertant change down when it should have been a change up and the top part of the timing/locating key shears of inside the flywheel when the grip of the taper is unable to accelerate the flywheel enough to keep up with the crank and the timing slips, backfires can cause this too.

We have had the flywheel spin backwards so fast that it has shared the key and completely undone the crank nut and left the flywheel rattling around in the side cover. Its the quality of the fit between the tapers that joins the crank to the flywheel that matters, the key is only there to get the alignment right. If you still have the big original flywheel, get rid of it if you can and use a smaller MX one.

[husaberg]

Slipped timing, in the early days we have sometimes had the same problem, an overly harsh or inadvertant change down when it should have been a change up and the top part of the timing/locating key shears of inside the flywheel when the grip of the taper is unable to accelerate the flywheel enough to keep up with the crank and the timing slips, backfires can cause this too.

We have had the flywheel spin backwards so fast that it has shared the key and completely undone the crank nut and left the flywheel rattling around in the side cover. Its the quality of the fit between the tapers that joins the crank to the flywheel, the key is only there to get the alignment right. If you still have the big original flywheel, get rid of it.

Hilley

I to have suffered problems with shearing of the Key that was cured by lapping on the taper.It took me a bit of time to listen to someone to tell me that though

I just kept on replacing the keys making stronger ones one year it came off completely at Greymouth and someone found it and gave it too me.

I couldn't get it that the key was only there for location.
The taper is what holds it on in place.
For instance all the HP in the KTM50 is delivered though a taper with no key 10hp or so.

[Henk]

Valve grinding paste works well for mating the crank and flywheel.

[Hilleye]

Slipped timing, in the early days we sometimes had the same problem, an overly harsh or inadvertant change down when it should have been a change up and the top part of the timing/locating key shears of inside the flywheel when the grip of the taper is unable to accelerate the flywheel enough to keep up with the crank and the timing slips, backfires can cause this too.

We have had the flywheel spin backwards so fast that it has shared the key and completely undone the crank nut and left the flywheel rattling around in the side cover. Its the quality of the fit between the tapers that joins the crank to the flywheel that matters, the key is only there to get the alignment right. If you still have the big original flywheel, get rid of it if you can and use a smaller MX one.

TZ you might be onto something. I'm sure I've changed down when it should have been up, but more likely my friend may have done this during test sessions he was riding prior to BoB. So timing may have slipped, but any ideas what the rattle would have been? Like I said flywheel was still firm on the crank, flywheel nut was up tight too, mind you I'm not spinning it at 7000+ rpm when I check it. Would it be reasonable to assume that the flywheel might have been getting progressively looser or slipping further around on the crank and that's why it deterioriated gradually.

Another symptom that kind of lends itself to the above is, bike normally idles at around 4000rpm, but this had dropped to about 2000rpm just before all this happened and my rev counter (Trail Tech Vapor) started going schitzo and kept resetting (I thought it was just the battery, but changed it and it was a little better, but still kept doing it).

I can change the flywheel no problems if its a bolt on with no other mods. If I have to start modifying the ignition pickup I'm going to need some help. So with this in mind any suggestions with respect to a suitable lightweight flywheel.

[husaberg]

TZ you might be onto something. I'm sure I've changed down when it should have been up, but more likely my friend may have done this during test sessions he was riding prior to BoB. So timing may have slipped, but any ideas what the rattle would have been? Like I said flywheel was still firm on the crank, flywheel nut was up tight too, mind you I'm not spinning it at 7000+ rpm when I check it. Would it be reasonable to assume that the flywheel might have been getting progressively looser or slipping further around on the crank and that's why it deterioriated gradually.

Another symptom that kind of lends itself to the above is, bike normally idles at around 4000rpm, but this had dropped to about 2000rpm just before all this happened and my rev counter (Trail Tech Vapor) started going schitzo and kept resetting (I thought it was just the battery, but changed it and it was a little better, but still kept doing it).

I can change the flywheel no problems if its a bolt on with no other mods. If I have to start modifying the ignition pickup I'm going to need some help. So with this in mind any suggestions with respect to a suitable lightweight flywheel.

Just lightly file off AND I Mean Lightly
The damage and remove the key add some valve grinding paste and Spit and lap on the flywheel

Check for full contact with bearing blue and off you go.
In the box of bits. you will find a new key or 2 as well.

I would also suggest to let someone have a look in the motor before slinging it back together Yowl ling or grumph would be a good start.

[TZ350]

Would it be reasonable to assume that the flywheel might have been getting progressively looser or slipping further around on the crank and that's why it deterioriated gradually.

I can change the flywheel no problems if its a bolt on with no other mods. If I have to start modifying the ignition pickup I'm going to need some help. So with this in mind any suggestions with respect to a suitable lightweight flywheel.

I dont know what the rattle was, I would have to hear it to know more.

Yes the flywheel could just creep gradually, moving a bit with each miss change. Others have made lots of good suggestions about how to fix the damage and get the tapers to fit properly again.

The taper on my Suzuki GP125 is much smaller than the MB so the KX80 ignition is out but the KX125 might be worth a look as it has a bigger diameter taper.

Speedpro recently converted his, it would be worth looking at his #6 thread to find out what the doner engine was.