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cat
Joined: 30 Nov 2005
Posts: 398
Location: South Africa
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 Posted: Fri Dec 22, 2006 8:33 am Post subject: |
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| Wonky wrote: | | Yep the colds gone thanks to some seriously hot chillies, |
sheessh, way off topic, but...ya. chillies. you should...you know when you eat chillies like that - pickled chillies - how it can make your nose run. it's good for clearing the sinuses, which is good, probably, for not getting colds in the first place. but anyway, what i wanted to tell you, is ginger. ginger tea. ginger in your food - it's in most indian /curry - is very good for you. it's a heating thing, so it's very good in a cold, damp climate. it improves digestion - the "digestive fire". so...(try this, really, you're in the middle of..that dire winter)...get some fresh ginger (not ginger tea or dried ginger, fresh ginger, like you use for curry) chop or thinly slice about a teaspoonful, a heaped teaspoonful. pour it in a cup with boiling water - you need one of those tea-ball things, otherwise you can strain it - and leave it for 3 or 4 minutes. then microwave it to get it hot again. then put sugar or honey. you'll find it works - not like the Med-Lemon stuff. try it you'll like it. you can squirt a bit of lemon juice in it if you like, but it's the ginger that's the main thing. and it must hot. |
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Wonky
Joined: 14 Sep 2006
Posts: 224
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| Posted: Fri Dec 22, 2006 9:58 am Post subject: |
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As for the Chilli and Ginger business, great stuff! The chilli n cheese sarnies burnt the hell outta my mouth but were superb, boy did i get some burning but it has sent my lurking cold into the firey depths of hell!!!! All good...
As for CDI unit, modify the standard one to get a tad more revs is fine, but forget the dredded TDM CDI route, it's bad news all round! (We can modify the standard CDI for you if you need it! A good idea with a tuned engine but you will lessen the life expectency but not drastically on a 102mm bore, rod,etc. On a 105mm race bore that's a whole different kettle of fish!)
As for rebuilding engine and replacing bearings, that's a great idea if you have the time and resources to do it. If not then just keep up the servicing and your thumper should keep on thumping....  |
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hb7
Joined: 16 Jun 2004
Posts: 89
Location: Los Angeles
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| Posted: Fri Dec 22, 2006 12:48 pm Post subject: |
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I know of one Skorp with 100k+ miles which is still running.
No rebuild.Oil changes were done every 5-7k I believe ...with Walmart 10-40w. In fact, he did oil analysis which indicated he could why he run his oil ~7k miles....
What is your science for oil changes every 1500 miles ? |
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Wonky
Joined: 14 Sep 2006
Posts: 224
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| Posted: Fri Dec 22, 2006 5:52 pm Post subject: |
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The science is simple....if you can afford it....£15 a time....fresh oil changes every 1500-2000 miles means that you'll have fresh new oil in the engine pretty much all the time, which is obviously extremely healthy for the engine. Theres no big scientific analysis behind it, just logic buddy!
Some engines run for almost what seems a lifetime without being rebuilt. It depends on how it's ridden, some of the guys here ride their bikes damn hard, and to the limit, you wouldn't be able to ride an XT660 engine that hard for 100,000 miles without a rebuld that's for sure! Try it and see what happens, now THAT would be a test and a half!!!!
I'm not saying that you absolutely HAVE to rebuild every 30,000 miles or you HAVE to service every 1500-2000 miles either, if you ride hard and your a type of bike enthsiast that likes to tinker with your pride and joy then it's advisable to do so to help life expectancy! Nailing these bikes hard is so much fun but you inevitably will break something so just be as caring as you care to be along the way.  |
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Bill Jurgenson
Joined: 18 Nov 2006
Posts: 113
Location: D-74348 Lauffen am Neckar
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| Posted: Sat Dec 23, 2006 4:02 am Post subject: |
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As far as oil changes are concerned in this thread, I agree completely with Wonky.
I do not share his dislike for the TDM 3VD box or OEM boxes modified to put the rev limiter up to 8400. Just because you can rev the engine byond the 7200 of the OEM box doesn't or shouldn't mean to are obliged to do so all the time.
Revs are not the only determining factor and the small end shown farther up didn't happen cause of too many revs. Mean pressure and bearing load are just as important and that is one reason why I advocate a short final ratio.
Too high pressures at low RPM are at least as bad for the entire drivetrain as high RPM over the top.
Around here there are two or three XTZs with more than 100000km and a rat-bike Skorpion with over 100000km, several winter crashes and otherwise only a minimum of maintenance. Not that I advocate that...
My own '94 Tour which I bought new has over 80000km and it is pushed reasonably hard where necessary. It is still running its first OEM valves, guides, crank and conrod. I put in a oversized piston this year because the bore looked pretty rough. But this engine is not stock as I have explained before, having had either dual 34mm Mikunis or Miller's TM42 kit which it has now. And it has had either TDM or a modified CDI most of its mileage. And a larger bore racing exhaust. And a Megacycle stage2 cam. And the final drive as always been 43 or larger. I also removed the counterbalancer 45000km ago and lightened the flywheel/freewheel assembly. Lots of no-no things, but then it is my bike, I have the mechanical resources to fix it and it runs as testbed for some of my stuff. Anybody can testdrive it if they like...
It has needed precious little fixing, tho, apart from one capital street crash and two or three spills on the racetrack, 'cause I try to treat it right, even tho I do sometimes rev it over 8000. It did need new 5th and 2nd gears a couple of years ago, well known problems with the XTZ engine. At that time I replaced the cluster with the SZR unit.
Of courseWonky's right that a performance engine needs an reworked crank with Carillo (or similar) conrod and a forged piston and the best C3 bearings. And lots and lots of other goodies, too.
Such a motor is a money pit - and time consumer of the first order. Try to do it right the first time to save some of that money in the long run. As long as I have been running the racing engine, 5 years now, I have had no trouble with the crank, bearings or rod or piston. Lots of problems with the timing chain and valve train, surely due to RPM and valve spring load.
Slipstream doesn't offer the rollerchain conversion for nuttin! and I have it installed. Since then no problems. Next was ignition; I finally gave up on the magneto and installed a Silent Hektik battery ignition and since then have had no problems of any kind. We'll see how long the thing hold up next season...
But oil? there is no excuse here and Wonky is right.
Only the best is good enuf and that frequently.
_________________
Bill,
http://www.william-jurgenson.com
http://www.zabernet.de/bill/tuning.html
http://www.appel-tooling.com |
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Wonky
Joined: 14 Sep 2006
Posts: 224
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| Posted: Sat Dec 23, 2006 7:54 am Post subject: |
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Hey Bill, i was thinking of you the other day, i came across an article online about the Skorpion Replicas that MZ produced. Only 16 went to the US apparently and i think Ray Dentith owns one over here in the UK. The review was singing the MZ's praises. It's based on our Factory MZ! Martin Sweet, my boss and owner of Slipstream Tuning, also part of the original team behind the beginning of the MZ Factory Skorpion, which inevitably led to the Skorpion road bike and who led the development of the XT660 for MZ way back in the mid 90's before the money ran out, still maintains his word that these bikes have outstanding handling, as you already know! This article just varifies this and i thought you and evryone else here may be interested. Check it out...
http://www.motorcycle.com/mo/mcmz/replica.html
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keithcross
Joined: 20 May 2004
Posts: 870
Location: Hampshire England
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| Posted: Sat Dec 23, 2006 2:49 pm Post subject: |
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Wonky
Ray Dentith owns the shop I got my Baggi from and it was him that refered me to Slipstram for any tuning work I might want.
I looked over the replica he has and it not quite standard you know With a big bore kit fitted and many up rated parts including a rather special front brake.
The last I heard, about 2 years ago, the bike was up for sale.
Keith
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cat
Joined: 30 Nov 2005
Posts: 398
Location: South Africa
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| Posted: Sun Dec 24, 2006 3:06 am Post subject: |
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| Bill Jurgenson wrote: | Revs are not the only determining factor and the small end shown farther up didn't happen cause of too many revs. Mean pressure and bearing load are just as important and that is one reason why I advocate a short final ratio.
Too high pressures at low RPM are at least as bad for the entire drivetrain as high RPM over the top.
...
And the final drive as always been 43 or larger.
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ahh. Very interesting. So you are making it rev. High pressures at low rpm... you mean the "jerky thump effect", that sometimes used to cause old XT's to stall at low revs, the reason for the dual cv carbs. ...?
| Bill Jurgenson wrote: | | I also removed the counterbalancer 45000km ago and lightened the flywheel/freewheel assembly. |
I'd like to hear more about that. How to remove a bit of weight on the 660 flywheel.
The reason for removing the counterbalancer...? Just less reciprocating weight, I suppose?
| Bill Jurgenson wrote: | | the best C3 bearings. |
Yes. Why go cheap on bearings. Does the C3 grade also apply to needle rollers like small-end bearings?
| Bill Jurgenson wrote: | | Next was ignition; I finally gave up on the magneto and installed a Silent Hektik battery ignition and since then have had no problems of any kind. We'll see how long the thing hold up next season... |
What problems did you get with the magneto?
Silent Hektik good stuff - the best cure for the pathetic stuff on the old BMW GS's. |
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Wonky
Joined: 14 Sep 2006
Posts: 224
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| Posted: Sun Dec 24, 2006 5:31 pm Post subject: |
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| keithcross wrote: | Wonky
Ray Dentith owns the shop I got my Baggi from and it was him that refered me to Slipstram for any tuning work I might want.
I looked over the replica he has and it not quite standard you know With a big bore kit fitted and many up rated parts including a rather special front brake.
The last I heard, about 2 years ago, the bike was up for sale.
Keith |
That's awesome! Bike sounds nice, haven't seen an original replica  in the flesh, sounds wicked. Wonder if he sold it? I'll get the Martin Sweetmeister on the case...
Merry Xmas buddy! |
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keithcross
Joined: 20 May 2004
Posts: 870
Location: Hampshire England
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| Posted: Sun Dec 24, 2006 7:07 pm Post subject: |
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Marry Xmas and a prosperous New Year to you and all of the other members of this forum.
Keith
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Bill Jurgenson
Joined: 18 Nov 2006
Posts: 113
Location: D-74348 Lauffen am Neckar
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| Posted: Mon Dec 25, 2006 3:35 am Post subject: |
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Hi,
| Quote: | | you mean the "jerky thump effect", that sometimes used to cause old XT's to stall at low revs, the reason for the dual cv carbs. ...? |
Two different things here: chain lashing is one thing - if that is what you mean and loss of manifold vacuum is something very other. The CV carbs of the Raptor ( and KTMs, too) and the dual register carb of the Skorpion/SZR/SRX etc combat this by not being able to open without manifold vacuum regardless of how hard one twists the grip. Chainlashing -drivetrain backlash - is a problem of all big bore engines, whether singles or twins, have. Modern injection mapping helps a lot towards relief. Some like the current Ducati 4 valve twins are almost free of chain lashing. The brand new Morini is pretty good, too. The press made a big thing about the supposed undrivability of the MZ1000S below 3000rpm - chainlashing again. You don't read diddlysquat about the same bad habits in the Aprilia Mille which is in reality much worse than the MZ, even the every first one. And the 1200 4 valve BMW twin is no exception either, despite shaft drive. Their new 800 twin has, like the single, a cog belt!
Of course big singles all have the problem, more or less. Classic thumpers - the MZ and SZR are not really thumpers - with their long stroke (undersquare), low compression, low performance and extremely heavy flywheel are soft on the throttle and easy to drive. A short stroke (oversquare) engine like ours with much higher compression even in OEM state must chop at low RPM when the trottle is opened too agressively. Especially since they also have, compared to a real thumper, a light crank and flywheel assembly. The flywheel of the dated SRX is much heavier, needs to be, too, since the thing has a kickstarter. Even so, it is a notoriously bad starter. This is more due to the CV carb and automatic deco than the flywheel, however.
Removing the counter balancer: I do NOT recommend this unless you are ready to take a beating and ride very actively, sporty, even agressively. With correct riding position and good physical condition, the vibes are not a problem - for the rider. They tend to loosen and drop almost anything on the bike until one has learned where and what and what to do about it. In the old days of real thumpers, this was commonplace. With any 50ies British bike, even parallel twins, you spent as much time looking after it as riding it, sometimes even more until you had learned the ropes. Been there-done it. Remember I am over 60. And I have a BSA A7 running now as well.
Until the newest models, KTMs had no counter balancer and the early 610 and 640 models had no oil pump, either. A pure racing engine, meant to broken after every outing.
enuf: the counter balancer needs up to 5hp to rev up and down. A lighter one needs less of course and OVER used to offer three (I think it was) different sizes. Of course none at all needs even less, namely nothing. There is a lot more to it, and this getting long.
Acceleration and braking is quicker. The motor responds like a twostroke - almost at least. Reducing the flywheel mass does the same thing to a lesser degree. But also makes the bike less drivable if one is prone to low RPM riding and an uncontrolled right wrist. The reduced mass increases the chainlash. THe CV carb is per se uncontrollable, so that augments the problems which Wonky alluded to a while back. A finely tune flatslide and good riding habits get around this. In fact, I can coast thru town at 2200RPM in top gear as long as I don't need too quick response. Can even accelerate (slowly) out thru the city limits without changing down. No chainlash. No chopping: no counterbalancer, lightened flywheel and freewheel, quickturn grip, flat slide, 60hp at the rear wheel but also 43 chainwheel on a much lighter Brembo wheel and 155kg with gas in the tank.
C3 is the rating of "space" between the balls or rollers and the races, tolerance, but not in terms of manufacturing quality. One reason to use C3 bearings is because the casings, when they get hot, tend to cinch up the outer races and the tolerance is reduced. Another is alignment. Another is changing axial tolerance at different temps.
One of the cardinal points in gettng performance and longevity is to get everthing to spin as freely as possible: reduce friction!. In racing two-strokes (125, 250, marine engines) C4 bearings colloquially know as outboard bearings are used. Not a good idea for 4 strokes with their much higher loads per cc, but where lubrication is only supplied by the fresh gas and the engine gets dismantled after every race...
Magneto problems: this was the PVL magneto used by many. In my case the circuitry was finicky. The beast started up alright - out onto the track and after one round at best dead. Turned out, that the circuitboard must have had a thermic problem; as soon as it reached a certian temperature caused by the circuittry itself (not from the bike), it quit. PVL flatly states that they are finicky and never ever should be turned without a plug attached and grounded. I assume the main transistor (thyristor?) was damaged. This happened without apparent cause from one day to the next. The magneto worked fine for a year or so. We looked for days for a cause, thinking it was fuel starvation since that was how the bike acted. nada. Found lots of little things, too, but not the cause.
Such a small magneto has potential advantages: very low rotating mass, very small and light, no battery, thus selfcontained.
It also has the usual magneto disadvantages of being dependent on RPM to deliver any noteworthy spark. Below 500 is nothing, so starting a very high compression big single can get to be a problem. Without a starting machine you can forget it. My bike, without deco, could not be jumpstarted regardless of how many were shoving.
A battery igniton like the SilentHektik delivers max spark at any RPM, the SilentHektik delivers 3 sparks in milles. series. The ignition is even lighter than the magneto and the rotating mass is nill. Disadvantage is needing a battery and of being dependent on its charge to run. Or you modify a small light ca 100W generator to run the system, necessary for fuel injection if you have it, but then you have the higher rotating mass you were trying to get rid of. Drivability of the SilentHektik ignition is much better, not to mention starting, which is now child's play.
All three bikes I use on the track - the 1978 1200cc Laverda triple, the 1986 Bimota DB1 and the Skorpion SOS - have constant loss battery ignitons now. The Bimota never had anything else and was raced in the BOT that way. Just a little 4,5ah battery like the little one now in the Skorpion. The big triple needs, due to its three current-devouring coils, something a bit bigger.
Merry Christmas.
_________________
Bill,
http://www.william-jurgenson.com
http://www.zabernet.de/bill/tuning.html
http://www.appel-tooling.com |
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omrra91
Joined: 19 Mar 2006
Posts: 36
Location: Portland OR
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| Posted: Thu Jan 18, 2007 11:04 am Post subject: |
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Wonky, YOUR WRONG!
Congratulations on the response to your post. Fear is always an awesome motivator.
Some people like myself who don't have piles of cash to pay Slipstream or Galen Miller for a motor have to take the chance. My team mate and I have constructed two race motors without any mods to the bottom end. We intentionally limited the output to 70hp. Yes that is just a little less than the very best MZ motors. But the track we race at has a very long front straight so reliability was also a goal. I use the TDM850 CDI and it is an important part of the overall package. To date we have experienced no mechanical failures. But we do have quite a pile of trophies after four years of racing.
If my motor goes bang tomorrow it won't be because I used a TDM CDI without a Carilo rod. It will be because it's a race motor and that's a hard life for any motor.
I will not banter back and forth with you on this issue. I have work to do in preparation of the 2007 season. You see an excellent local racer just acquired a Tigraft with a Slipstream 720 motor. It will not be an easy bike to beat. But when I do I promise that you will hear about it.
Jeffrey Thompson - OMRRA #91 |
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keithcross
Joined: 20 May 2004
Posts: 870
Location: Hampshire England
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| Posted: Thu Jan 18, 2007 2:47 pm Post subject: |
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Jeffrey.
As you state, you have carried out other mods to you engine unit to get 70bhp, and as a race motor its probablly been rebuilt very carefully and maybe even stripped for inspection on a regualr basis. All this is of course normal on a race bike.
Wonky's comment was I think with reference in the main to road bike, those that can end up being used hard for thousand of miles, not teh few hundred miles ridden really hard on a track.
I could of course be wrong, but logic dictates that more revs on a big single has got to result in less relaiability.
I am not to sure about Yamaha, but Honda design and build their engines with a particular power output in mind, and that includes bearings an the major stressed componants like pistons and connecting rods. After all the standard 45-50bhp is a lot different to the 70+ that some have.
One example of this was in the old days of Ducato vee twing, one racer had been told to keep to a certian repm. After seeing that he was loosing ground, the chief mechanic put out a board indicating that he use an extra 500 rpm. Result, one piston in several pieces.
Keith
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cat
Joined: 30 Nov 2005
Posts: 398
Location: South Africa
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| Posted: Thu Jan 18, 2007 2:59 pm Post subject: |
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| keithcross wrote: | | I could of course be wrong, but logic dictates that more revs on a big single has got to result in less relaiability. |
yes, definitely. especially given what you say about what it's deisgned for. high revs, high power = modern 4 cylinder engines.
you want high revs and more power in a single, better to just get the KTM or husaberg in the first place and do the maintenance. and know where you stand. with the MZ, we've basically got a cruiser/commuting bike with an SM orientation, where SM stands for Street Moto, not supermoto. |
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omrra91
Joined: 19 Mar 2006
Posts: 36
Location: Portland OR
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| Posted: Fri Jan 19, 2007 11:04 am Post subject: |
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| keithcross wrote: | Jeffrey.
As you state, you have carried out other mods to you engine unit to get 70bhp, and as a race motor its probablly been rebuilt very carefully and maybe even stripped for inspection on a regualr basis. All this is of course normal on a race bike.
Keith |
Hello Keith,
Your whole post was quite reasonable. Yes, I made a fair amount of modifications to my bike. As I did it on a tight budget it was done in little bits along the way. If I listed off the bits and pieces and where I got them I think a lot of people on the board would think my racer is a bit unconventional. I go over the bike before and after every race, but a tear down just for the sake of inspection never happens. That's probably due to a combination of confidence in the bike and outright laziness.
Regards, Jeffrey |
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