High performance CDI box

[moes1badcat]

Has anybody installed a high performance cdi box to improve horse power/raise rev limiter? I've seen them on ebay for yamaha raptors, grizzlies etc. Are they the same for the mz baghira 660? I know it's a yamaha motor. Are they available? Is this worth looking for? Where would I go to get one?

[keithcross]

Yes these are available. Slipstream tuning in the UK and Competiitive solutions in germany sell them.
The unit off of the Yamaha TDM850 will also allow higher revs but some think it allows to many revs.

Keith

[Bill Jurgenson]

Occaisonally the "race" box from Over turns up on eBay.

The TDM 3VD box works fine with stock engines or with mild tuning, but is not recommended with high compression pistons due to the spark advance curve. The higher the compression, the less advance is used. (gerneralization!) That said, I have a couple of them running, mostly in entirely stock bikes, but also running well in one mildly tuned Skorpion: Mikuni, Hotcam #1, Wiseco 100mm 11:1, lightened flywheel and starter freewheel, no counter balancer, Barker 39mm pipes, SZR cluster.
The TDM box cuts out at 8400.
Too high revs is nonsense, however. The SRX had no limiter at all and neither does my racer. Too high depends on the rider. The stock CDI cuts out at 7200, regardless of what fantastic numbers are shown on the tach - if it still works. It can be modified (e.g. by Bernd Lischo at http://www.tunebike.de or http://www.slipstream.co.uk) to cut out at 8400. I use these modified boxes (from Bernd) on the street in both the stock SZR and my 60hp Tour.
Running 15/44 with a BT090 140/70 2.6 atm at the back, my DET 100 tells me that I shift into 3rd at 90kmh, into 4th at 125-130, into 5th between 145 and 150. I went out on May 1st and onto the expressway to wind it out. The DET showed 182kmh at 7900 and it was not flat out yet. Turning the grip further brought noticable power gain until the limiter cut in. IOW, The shorter final ratio coupled with the higher revs is actually faster in top speed than the stock setup. Granted, my Toy is anything but stock, but in my nearly stock red Sport, The bike would reach the limiter at 8400 in 5th with the 15/43 but not with 15/39. I have not seen a stock Skorpion yet, that will run into the limiter with the long final ratio. Except downhill. Attached is a gear chart of the stock setup (except for 1st which is the longer 1st of the SZR).
You can see that even IF the bike will run into the limiter at 7200, it cannot possibly be faster than slightly over 180kmh.
Above that is the chart for my Toy.

[keithcross]

Bill

With the greatest of respect, to high revs is not nonsense. The SRX may not have had a rev limiter fitted, but if allowed to rev well above that it was designed to do, are you suggesting that no damage would result. Of course it would.
The higher a an engine is allowed to rev, the higher the stresses are that are placed on it. An increase from 7200 to 8400 represents an increase in reves of 16.666 percent.
This type of increase must put a strain on an engine designed to run at its original design revs with a consequest effect on reliabilty. Probably not a concern on a race engine, but it definaltly would be on a road engine.

Keith

[Bill Jurgenson]

Of course higher revs put higher strain on some parts - and less on others. The notoriously fincky transmission ( in all versions of this engine) for example is aided by higher revs.

I may have not been clear. I was not talking about a race engine, not prmarily at least. Surface pressure and bearing load are the biggest stress factors and low rpm is a major culprit here for everything involved, in particular the conrod at both ends, but also gear teeth flanks.
Higher rpm means in terms of actual stress really only piston speed in m/sec.
The rule of thumb max for this is about 16m/sec. The XTZ (86mm stroke) reaches whooping 10.32m/sec at 7200, at 8400 12m/sec, at 9000 like the racing engines run, it is still only 12.9. Even a long stroke crank (usually 2mm more sometimes up to 4) gets oly to 13.2(13.5). You can see that try as you might, you just ain't going to get near that dangerous 16 m/sec.
Just for the records, a modern street legal 4 cyclinder (e.g. R6 or R1) does get near that speed and also exceeds it routinely.

I thought, too, that it was clear that I was talking primaily about my street-legal bike with over 80000km on it. Still running the same crank with conrod and bearings, same valves, same guides, same primary drive.
And routinely revved above 8000.
b

PS: maybe I'll see you here tommorrow:
http://www.engine-expo.com/

[keithcross]

Bill

You are of course right in you statements on stress levels on components, but may I make the following observations.

Your comment on `Too high revs is nonsense' referred to both a road engine bike and your racer so no your comment may not have been clear.

Piston speed is of course important, but I have always understood that an additional strain is generated by the piston changing direction. The higher the engine speed, the greater the forces generated on the piston (old racing Ducati engines used to experience piston failure, the crown of the piston would literally come adrift from the rest of the piston).

The above forces could, in addition create additional forces on the connecting rod bearings and the connecting rods as well.

Valve springs. If a certain engine speed is exceeded valve `bounce' may occur, although this is not as bad a problem as it used to. In practice it is possible for the valves to collide with the piston once this problem starts to occur.

The above comment could of course be completely wrong as I am an electrical engineer, not a mechanical engineer. My comment are based on what I have read and heard over the years.

Keith

[Bill Jurgenson]

Piston speed is of course important, but I have always understood that an additional strain is generated by the piston changing direction.

Yes, of course. That is what the piston speed mantra is about. However, at the top, there is a pneumatic "damper" called compression every other stroke. This compression is a design feature and of roughly always the same size until the rings/bore are worn beyond tolerance, whether at lower speed or higher. At higher speed the higher acceleration of the piston actually relieves the crown pin a bit. 2-stroke engines are better in this and that is one reason why they can rev more freely to higher design revs. At the bottom to a much lesser degree; crankcase pressure, for which there is a vent that is, in street engines, too small for good reason. In the old days, such vents were poppit valves that stayed shut under compression (downstroke).
Of course, large pistons have a larger mass acceleration per stroke than small ones. One reason why a single can never ever be smooth like a 4 cylinder or even a twin, given the same engine displacement, even if all other things like mass forces of 2nd, 3rd, etc orders are disregarded. The piston has for practical purposes only forces of the 1st order. That is why the counterbalancer in a single can only partially alleviate vibration. Being a revolving shaft with a counterweight, it has very little force of the 1st order and cannot really counteract the piston. That is only given in a multi cylinder engine, best in a true boxer like the BMW in which the pistons move in opposite directions. The Ducati Supermono was extremely clever in that it retained the two-cylinder crank with conrod for the vertical cylinder which was then connected to a weighted lever instead of the vertical cylinder/piston. An almost ideal setup and without a counterbalancer. The new BMW 800 parallel twin uses a similar third connecting rod for which they graciously take all the credit. As if the Ducati had never existed. Of course, fo the typical BMW client the Ducati does not exist.
In a single, the counterbalancer essentially offsets the counterweight of the crank which are generally balanced to the piston to a factor around 50%. In simple terms, taking out the counterbalancer in a single of course increases vibes, but not to the extent many expect and the increase is dependent on how well balanced the crank/conrod/piston assembly is. With its much lighter crankshaft but heavier conrod(Carillo) and heavier forged piston, my racer engine has less vibration than my street engine with its stock crank assembly which has also not been fine-balanced like the racer. In the stock engine, the counterbalancer is designed for a rpm range centered around 4000rpm, not because this is the maximum useful rpm range but because that is where the most legal speed driving was expected - and immisions tested. At idle and just above and at speeds above 6000, the engine actually vibrates more with the counterbalancer than without, quite a bit more. OVER used to offer counterbalancers with various factors i.e. lightened weights as well a solid gears (no damping springs which are the primary cause for the alltoooften sheared off woodruff keys). Slipstream offer these solid gears and may also have a selection of counterbalancers. Changing the mass of the counterbalancer changes the useful rpm range; lightening it moves the range up.
Just for comparison and before anyone gets the idea the bucket-sized piston might be extreme: the new MotoMorini Corsaro 1200 engine has a bore of 107mm which is quite a bit more than the 100mm of the xtz which can be taken to 102mm with the stock sleeve and to 104 with a larger sleeve. With a Mahle Nikalsil cylinder to 105. The Morini is rated at 140hp at 8500rpm. Across the counter, not race tuned. Wth two of those 107mm rain buckets.
My own pet project on the bench (wich probably will not ever actually get finished - TIME) is a such an engine with that Mahle cylinder and 76mm stroke = 658cc. This engine will have an aircooled cylinder and 4-valve head, possibly with injection from SilentHektik. BIG time-related problem is the manufacture of the forged crankshaft with plain big end bearing. The Mahle cylinder and piston can be had across the counter. I am thinking about a Ti conrod and Ti valves. Apart from the much higher useful rev range and thus higher output, the engine should be considerably lighter. A dry slipper clutch is also planned and straight-cut primary gears.

(old racing Ducati engines used to experience piston failure, the crown of the piston would literally come adrift from the rest of the piston).

True. But that is not a question of high rpm as such. That is just bad piston design, both thermic and mechanical.

The above forces could, in addition create additional forces on the connecting rod bearings and the connecting rods as well.

The highest forces are compression and ignition, especially ignition which put several tons on the kingpin and piston top and this load is dynamically higher at lower rpm with full throttle. Another reason for the manufacturer's preference for CV carbs.

Valve springs. If a certain engine speed is exceeded valve `bounce' may occur, although this is not as bad a problem as it used to. In practice it is possible for the valves to collide with the piston once this problem starts to occur.

yes and no.
As long as the design-parameter valve lift (mass acceleration again) is adherred to, it is nigh impossible to get floating valves in any relatively modern engine with 4 valves or more. The safety margin is in the order of at least 50%. Tuning cams like the Megacycle or Hotcams stage 1 (definitely not the same thing) do not use more lift but only more overlap.
They do not need other valve springs. Using hotter cams with the stock valve springs is not recommended 'cause of the higher lift, not the higher rpm. The OEM springs ar too short for the increase in lift. They have a severe increase in force at the higher spring compression meaning excess wear on the valve train, both the rocker arms mating the cam lobes and especially the chain and also on the valve seats. The really good springs (not all so-called tuning springs are good at all) like those from Kibblewhite are considerably longer than the stock springs. They are not much stronger, if at all, and they have Ti retainers to lessen the mass.
From all of this, it should be obvious that floating is not a problem, even in racing engines. Of course Ti valves have less mass but are not really necessary. Way back in 1990 EGU ws getting race dependable 85hp/9000 out of the SRX, enuf to win anyway. Today's quad tuners are also getting 90hp out of the 5-valve Raptor engine which is, except for the porkchop crank and different ignition, technically identical to the xtz; almost all parts are interchangable. Mine runs beyond 9000rpm easily without Ti valves.
Except when the timing chain broke, I have never experienced the valves kissing the piston crown. Not in the racer, much less in the street bike.

Bottom line: I am not advocating running at a constant 8000rpm.
The idea of the xtz being a thumper is the problem. It is in no way a thumper save for its being a single with large displacment.
Given its conception date, it is a pretty modern unit, much better for example than either the radial valve head Honda or the original KTM 604 which is much younger.
It likes to rev, is more at home doing it and potentially lasts longer doing so. The projected rev range of the counterbalancer at ±4200, the rev limiter at 7200, the CV carb and the excessively long final rato are all design features aimed directly at imissions ratings, noise and US -legal driving and driving habits. And US liability law suits. They are not necessary parts of the design for its own sake.
Using a short final drive ratio and higher set limiter makes more noise - most of us want that in fact and use aftermarket cans which are louder but probably not as good in terms of performance as the riginal L&W. It also makes the bike more lively in the same useful, legal speed range while using less(!) gas and not breaking down any faster, probably less as far as 2nd and 5th gear and drive chain are concerned.
I have several customers who have unanimously reported that the shorter ratio together with the 8400 limiter and the lightened flywheel assembly make a new, almost unrecognizable bike which is also more economical. It is not just my own tainted "experience."

b

[keithcross]

Bill

You state:

"It likes to rev, is more at home doing it and potentially lasts longer doing so. The projected rev range of the counterbalancer at ±4200, the rev limiter at 7200, the CV carb and the excessively long final rato are all design features aimed directly at imissions ratings, noise and US -legal driving and driving habits. And US liability law suits. They are not necessary parts of the design for its own sake. "

My understanding is that the XTZ and SRZ 660 bikes were not avaialable in teh USA and I doubt that Yamaha took MZ requirements into account when designing the engine. Only the derivitive engine fitted to the Raptor 660 has been avaialble from Yamaha and I dont think its possible to put this vehicle on the road their. As far as I am aware the latest version of this engine fitted to the Yamaha XT660X, XT660R Aprilia Pegaso etc are not available in teh USA either.
BTW on the subject of the newer 4 valve engine, I currently run an Aprilia Pegaso 650 that is fitted with this engine as well as my Baghira with the older type engine fitted. I find the newer engine reves a bit easier that the 5 valve engine. Not sure why, maybe its because of its later design, maybe because it has fuel injection and only 4 valves to move around.
You might want to try one out, as I am sure that this engine will fit into the MZ frames

Keith

[basser23]

Keith,
I think you are correct in that the XTZ and SZR not being "generally"available over here.There are a few SZR's and Mz
was the only one to my knowledge to have the XTZ motor.No we
did not get a Tenere or TDM for that matter.
My Skorpion does have a TDM CDI though...put on by another racer
some years ago......
Chip

[keithcross]

I thought not as the American Yamaha web site does not list them in is parts section.
My friend in Dallas used to work for a Yamaha/Honda dealership in Cincinatti until a couple of years ago and he used to say we had a lot larger range of Jap bikes in Europe than was available stateside.
Still at least you can console yourself in the fact that you have more Harley's their

Keith

[Bill Jurgenson]

The srx and xt were available in the US as are all the quads using any of the xt/z engines: Grizzly and Raptor. THe TT I think, too.

The SZR was not officially available, but it was built by Belgarda in Italy and this explains a lot of the differences.

Of course Yamaha did not make any concessions in design to MZ, on the contrary. MZ didn't even request the engine without the completely unnecessary puel pump. Let alone a different, higher 1st gear like the SZR then had.

OTOH, there are more Skorpions in the US than there are in Germany!

Decisions about what gets imported are made by the Importers, not the manufacturers. There a many many examples of really interesting stuff being sited at international trade shows or in Japan that are not imported, some not even inofficially. The Suzuki Goose comes to mind.



or a SDR200



Many more like that delectable VTR250 V-2 from Honda.
or the NSR 250
Or the GB500 which strangely enuf was imported into the States but didn't sell. Most of the US model was then trashed on the continental european market, miles speedo and all. Wher it also didn't sell much. Now that they are gone, the price is up.
The SZR didn't sell, either, although it is basically a very good mount, better than the Skorpion is many ways.

And why KTMs sell so well is anybody's guess. It is certianly not becuase of dependability.
The BMW single sells as fast as they can be produced and, again, it is anybody's guess why. Certinaly not because it is particularly good or dependable, let alone good looking.


Ever since Ralph Nader, US regulations have ruled, for good or for bad - or rediculous. Or why do you suppose that all bikes shift on the left with first gear down?

b

[keithcross]

Bill

I didnt say the SRX and XT models wernt imported into the USA, I wrote the SZR660 XTZ660 wernt imported into the USA, after all it is the XTZ that has the same engines as our MZ bikes, and consequently the same anti pollution measures. Also on this forum it would appear that MZ have, in the past put additional bits on the bikes for the USA market. I am aware that at least the XT600 was imported into the USA as I have ridden one there.
Its the engine/gearbox from the XTZ660 model that MZ use, so your right the first gear is different to the SZR660. I have known of owners putting the 1st gear parts from the SRZ into their MZ's.
As for the Grizzly and Raptor engines, they have some diffences to the XTZ660 engines as well. Looking at the Yamaha spares fishes on the American Yamaha site, the crank is different as are the rear sprocket splines. I have also read somewhere that the Raptor uses Ti valves. So it would apprear that the quads only use the same barrel/piston/cylinder head as the MZ. As Yamaha quote different power outputs for the 2 engines, I suspect the camshafts ay also be differnet. The Raptor also rev higher than the MZ engine as standard.
Also as a matter of intrest to some, the new 660 4 valve engine/gearbox unit as used by Yamaha/Aprilia/Derbi etc is made in Italy.
As for what does and doesnt get imported, you are right that this is decided by the importer - up to a point. A manufacturer may decide not to make a model avaialble to some markets by not designing a bike to meet the necassary criteria to meet the laws of that land. I think thats one of teh reasons the XTZ was not made available to the USA market. After all one of the reasons we no longer have the XT600 available is becase it doesnt meet current emission regulations for the UK and I think Europe.

Keith

[AtomicSpew]

OK, so what's the net-net here? I have a 2003 Baghira that came with an M4 carbon can on it, and I'm told the jets were done, but I don't have proof of that.

Here's my question: What minor things can I do to improve performance of the Baggy but still keep it reliable and only needing typical required maintenance? I have a VStrom 650, so I don't need to run the Baggy on the highway at all. I live among some of this country's best twisty mountain backroads and SuperMoto tracks, so I'm thinking drop the front sprocket down a tooth to a 14. I already find myself hitting the rev limiter quite often, so I'm curious about the CDI units I read about. Can I install one and keep the cam and valves, etc., stock? Also, is there a carb mod or replacement that's suggested?

Keith, Bill and Phlat (if you're reading this), I trust your opinions--what say you?

[Bill Jurgenson]

As long as the engine is stock or nearly so without a high compression piston, you can go to a TDM 3VD box, the simplest change.
Do not use a 14 tooth sprocket! that is the surest way to shorten the life of the layshaft bearing. Much better to change the chainwheel and if you are looking at a new chain anyway, the sprocket as well to 16t.
43/15 or 46/16 is a good starting point. Right now, I am running 44/15 and finding that even better. Much better acceleration and flexibility. A real - not speedo- 185kmh is fast enuf on the road. I know it would be faster than I would want to go on any enduro.

[keithcross]

Bill

I'm impressed,m a genuine 185kph. Thats about 20kph higher than I tink I have ever seen on my Baggi with final ratios of 14:43, 14:45, 15:43 and 15:45.
You mods must work really well. Wonky is claiming 125mph (just over 200kph) out of his much modded Baggi.

Keith