OzVMX Forum
Clubroom => Tech Talk => Topic started by: firko on July 16, 2009, 12:26:12 pm
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With flat slide carburetors being declared ilegal for pre 75, where do I stand with my under construction 650 Benelli flat tracker? The engine is a legitimate '74 model and is factory fitted with a pair of 29mm square slide Dellortos. There's no way I wish to change them as the engine is remaining stock so therefore the carbs are already jetted right and a matching pair to suit that engine. They're obviously not round slide carbs so are they regarded as flat slides?
What do the rulebook junkies think?
(http://img.villagephotos.com/p/2005-8/1062154/dellorto%20004.jpg)
(http://img.villagephotos.com/p/2005-8/1062154/dellorto%20002.jpg)
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A parts fische or manual will sort the issue but if they are on a standard bike how could anyone argue they are not from the period? With the proof they would be 100% legal IMO.
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I've got all sorts of written proof Lozza but the rulebook specifically states that flatslide carbies aren't allowed for pre 75.
It doesn't matter too much to me as the bike won't see too much official championship racing but on the off chance that
I do race a title meeting I'd like it sorted befor it gets ugly and violent in the scrutinnering line ::).
I seriously think the vintage carburetor section of MoMs needs some further work. There's no way late flatslide carbs should be allowed in Evo except for Lectron, EI, Blue Magnum and such. No way are late Mikuni, Keihin or Dellortos correct but you watch the punters go for them now. In pre 65 Gardner flat slide carbies should be allowed as they were around in the early 60s but as the rule is currently worded, you can't use 'em, yet you can in pre '62 road racing.
I'm only mentioning these hyperthetical situations to demonstrate the lack of serious research that went into that section of the rulebook.
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You like to stir the possum don't ya Firko ;D.
These carbies open a new chapter of controversy - are square slide carbs included in the flat side rule?
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Agreed on that firko(WTF ???) true rules don't exclude carbs like PWM or a PWK with a TPS/Power jet soleniod and anyone can have a box of tricks to run them.Even if I run the black box I wouldn't run the carb.
With the Dellorto's I think again unfortunately if there was an 'ugly scrutineering incident' it would taken to the enth degree be a ruling on the definition of 'flat'. True Gardners were available in the 60's and plenty of evidence of them being used in open competition and available for sale.
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mid 60's Ducati singles started running square slides,it shouldn't get ugly,especially if they're original fittment Firko,no wukkers with "gardiners" in pre 65,but pre 62 P3 RR is a bit iffy,theres no (apparently) written info predating that period, but hey,the powers that be are letting round slide mikuni's in pre 62 (P3) to redress the balance as Amal MK2's are allowed,(ie 2 wrongs do make a right??),so 40mm Mikuni stocks just went up in value bigtime ;)
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Mick's right Mark.
SQUARE slide 29mm Del'ortos were std issue on Ducati 450's which first appeared in 69.
They are less than spectacular in performance and are better replaced with 30mm or 32mm ROUND slide Delortos which date back to 71 as far as I know and have accelerator pumps. Square slide carbs aren't worth the effort and getting slides is not easy unless someone has taken to making replacements.
If taking on the hierarchy you can tell em hey are DEFINITELY pre 75!
Cheers,
Dave Mac :D
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Just ride ya bike firko and tell'm to F-R-O!!
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don't take this the wrong way Firko,but the only thing ugly at scrutineering will be the square body delorto's,i think the conversation will go along the lines of ,"is that the best you could find",(snigger snigger) :P :P :P
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good one Mick. you're right
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Yeah I know they're shit boys but that's not the point I was trying to make. I've got 'em on the engine and I don't want to change anything until the bike's finished and winning races ;D. I was merely bringing up the point to show the discrepancies in the rulebook. I've got a pair of 30mm Mikunis or a pair of Amals from a Triumph Bonnie for down the line..
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bugger!,that'll teach me to be a smartarse, :-[ my 2stroke 36mm delorto dosent fit the new ossa,if it makes you feel any better Firko,(karma?) it's rubber manifold has benelli italy on it ::),only thing that fits up crankcase to inlet manifold is a keihin off a CR250 i had 30 something years ago,(knew there was a good reason for keeping it ::),hope the jettings close ;D
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THread hijack but where or what can i use on the RT/Dt piston port barrell that is a flange that will go over the 2 bolts so i can slide a normal MUk in there, VAndy what did you source and where ?
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Baaaaad thread hijack! You just used my Del Orto link off the Benelli thread rather than start a new thread! No wonder people get confused you naughty boy. ::)
Freaky, try a TM Suzuki rubber manifold. I'm fairly sure that's what I used.
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Sorry just you where all in here talking boout carbs, though it was the perfeect converstion slide, I did try a TS250 (assume same as TM) but the base steel section is too small its out by a few mm so the bolt holes are about 5mm too short, you might be able to eliptical the holes wide out but then it would open up and be only held on by only half of the bolt/nut.
Any Other ideas what fits up properly ?
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Maybe this may help.
Whats the stud spacing on the the intake manifold? What size is the spigot and the bore on the Mikuni ?
(http://farm4.static.flickr.com/3224/2895375556_ef891b9273_o.jpg)
(http://farm4.static.flickr.com/3263/2895375364_1e69a75fe4_o.jpg)
We ran into the same kinds of problems here in the States with Different bikes and what class they can run.
Rokon's came with disk brakes. They are allowed to compete. We have a similar rule on Flat Slide carbs. , but Lectrons are allowed in our Historic class because the late Pentons / KTM's came with them stock. Hope some common sense will prevail where you folks are , our bunch has pretty much lost any semblance of that . Chuckle Chuckle !!!!!!!!!
john d.
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Firko - maybe that is one of those cases where it actually gets pointed out to "the powers that be" for an adjustment to our rules?
Just a thought
Rossco
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Firko my little Indian was made in 1973 and it came stock with a 26mm square slide del orto carbie :o jimson
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OK repost change the suzi carby rubber is too small as in the bolts brush up against the rubber, what did you use other than nuts to secure it so they didnt tear into the Rubber ? i was trying to think or a captive nut with smooth sides and the allen bolt lid ? ideas or VAndy post a piccy of you intake.
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it wasnt so much that there was a lack of reaserch on the flat slide issue, there was and through this forum considerable information was supplied, considered and discussed.
The reason why it was decided to cut off the eligibility at pre 78 was it was undeniable that flat slides were generally available in the pre 78 period. We were correcting the "you cant use flatslides - period" rule that technically prevented bikes fitted standard with them using them!
The problem with pre 75 is more about management, they were not readily available and they are / were rarely used pre 75 and although it can be argued that some were available like early Mk1 Lectron etc there had to be a decision made.
How do you determine what flat slide is OK or not? Are the riders calling for the inclusion of specific indervidual units to be included in the MOMs? Its up to the riders, put forward the case and your voice will be listened to.
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"Flat side carburettors are prohibited unless originally fitted to the machine in question".
You could include a bit about needing to be the original type of flat side, if anyone thinks that a 1973 Indian 125 or a 650 Benelli fitted with a period Lectron is going to upset the apple cart too much...
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freakshow,
This is what we did on a 1973 , 125 cc Wombat we installed a reed kit on.
We had to use a new style 26 mm Mikuni in place of the old 26 mm flange type carb.
(http://i439.photobucket.com/albums/qq113/sachs175/cylinderwithreedinstalled002.jpg)
(http://i439.photobucket.com/albums/qq113/sachs175/cylinderwithreedinstalled003.jpg)
(http://i439.photobucket.com/albums/qq113/sachs175/cylinderwithreedinstalled006.jpg)
We had to use one of the Amal manifolds because of the stud mounting widths.
We used allen head screws and turned down the head diameter to clear the manifold and the clamp.
If you don't have access to a lathe you can use a drill mounted in a vise and a good sharp flat file to do the turning.
john d.