Modern Carb On A 340

[dsa]

hi all, just sorting out my 340 and would like to fit a modern carb. i have a new dellorto bhbl 26 this is from a 300 gas gas, it fits perfect to the air filter rubber hose with the gas gas adapter but the bultaco stepped inlet rubber for the amal carb is too large 35mm to 31mm on the dellorto. what inlet rubber can i use or should a i switch carbs to 28mm keihin. what are the set up jets for the dellorto or keihin. thanks

[pschrauber]

You need to turn you a bushing that has the outer diameter of the Bing and the inner diamter of the Dell' Orto and then it will fit very good. I used polyamide for the bushing. Inner diameter of the bushing was turned very close to the Dellorto so it sits very thight. For the intake side of the carb I made a srew on bushing where the inner side is curved:

Comparison carbs, Bing and Dell' Orto:

Dell' Orto with bushings on both sides:

The transparent bowl is just an add-on, contemporary!, as I don't like the black plastic ones, these transparent

plastic bowls where reprted in German Trialsport magazin in 1981, you still get them from Malossi in Italy,

the given adress in the 32 year old article shown below doesn't exist any more:

[woody]

You can also get a step down inlet rubber which will fit the Dellorto/Mikuni/OKO inlet stub. Bultaco UK should have them. Saves the job of making the sleeve.

[big john]

You can also get a step down inlet rubber which will fit the Dellorto/Mikuni/OKO inlet stub. Bultaco UK should have them. Saves the job of making the sleeve.

Hi Woody,

Is that the one that is for the Montesa 348 with Amal Mk2 Concentric?

I have measured the Mikuni VM26 it is 34mm inlet; the PHBH28BS is 36mm and the Bing a whopping 40mm.

I know we have a PHBL26BS fitted to a 325 motor at the moment and its a sloppy fit in the step down, I think its a 31mm inlet.

I'm going to try a PHBH28BS on my 199 Sherpa when I get the engine finished.

Big John

[nigel dabster]

Dellorto on a 340 satanic thoughts you are all devil worshipers!!!

[wayne_weedon]

Dellorto on a 340 satanic thoughts you are all devil worshipers!!!

Just doing as the Spanish do! Mind you that may change with their new ultra strict rules for classic classes.

[woody]

Hi Woody,

Is that the one that is for the Montesa 348 with Amal Mk2 Concentric?

I have measured the Mikuni VM26 it is 34mm inlet; the PHBH28BS is 36mm and the Bing a whopping 40mm.

I know we have a PHBL26BS fitted to a 325 motor at the moment and its a sloppy fit in the step down, I think its a 31mm inlet.

I'm going to try a PHBH28BS on my 199 Sherpa when I get the engine finished.

Big John

I have a Dellorto on my 340 with the step down rubber but I don't know if it is a Montesa one or not to be honest. I don't know what size it is either as I've never needed to measure it but the carb is a snug fit. I will be doing some final fettling on the bike sometime in the week for the Normandale next Sunday, so I'll measure it up then.

As far as I can recall, Dellortos do have differing inlet stub sizes as I'm sure I have one from a GasGas lying around somewhere that is smaller than other carbs.

I have a 28mm OKO on the other 340 and that performs well too.

[pschrauber]

The Dell'Orto PHBL is an old mate in carburation, you could buy this carb in the 80's, the carb was already used on Bultacos back then too, (as f.e. the Lectron carb in the end 70's), so I think it is contemporary. The carb is at least where I live easier to set up/jet, then it is so much easier too to get spare parts, different jets, for a Dell'Orto then for a Bing 54.

The smaller rubber intake for the carb sounds interesting, but I will stay with my standard one, so if I need to swap the carb again, (for setting up the bike in delivery condition or the frequently technical inspection from road and traffic authority in D, (the reg. papers have the Bing recorded), I don't need or have to hassle around with any other extra pieces.

Another + point for the Dell'Orto is the combination with the transparent bowl that is as Felix wrote in the Trialsport article something for lazy guys that want to know in forehand if there is a need to clean the bowl or not, (beside the tricky look).

There is not such a big difference in power output between the both carbsin my personal experience, beside that the engine does respond better and runs more even, (consistent), with the Italien carb .

Edited January 29, 2012 by PSchrauber

[woody]

Just doing as the Spanish do! Mind you that may change with their new ultra strict rules for classic classes.

I think it is the flatslide they can't have as the roundslide Dellorto is a contemporary carb that was fitted to 70s and 80s twinshocks

Unless their rules have changed again...

Edited January 29, 2012 by Woody

[wayne_weedon]

I think it is the flatslide they can't have as the roundslide Dellorto is a contemporary carb that was fitted to 70s and 80s twinshocks

Unless their rules have changed again...

Javier will know more. But there's some new changes which seem to be outlawing a fair few of the modified bikes.

Via Google translate this is what I get. Seems there's an OPEN class so I guess those heavily modified bikes compete there.

The asset Sotobike Moto Club has created a new trial championship national classics, teams and with coefficients depending on the age of the bike.

The new championship will be governed by the following rules including:

The MC Sotobike organize the 1 st edition of SOTOBIKE OF CLASSIC TROPHY TEAM, based on these Supplementary Regulations:

1 - 3 races will be scoring the two-day Sotobike organize the MC in 2012 (Robregordo, Pobladura and Los Angeles), scoring 5 days individually for each team, and is therefore facing 5 races you get points for the Trophy. Scoring on Saturday and Sunday and Pobladura Robregordo and Saturday in Los Angeles, performing the award of the Trophy at dinner on Saturday in Los Angeles de San Rafael. It may deduct one result for the Team Trophy total count.

2 - Teams will consist of 3 pilots the same level of difficulty of zones (Yellow, Green and Blue).

3 - Registration of the 3 tests will be mandatory for pilots to 3 teams ranked in the Trophy. The 3 drivers from each team will be starting together. Pilots who wish to participate in the Trophy and fail to form a team, indicate the organizer that includes a "bag of drivers" that can be used to form dichoequipo with other participants who are in the same situation.

4 - There will also be an individual classification in each event for each level (Yellow, Green and Blue), so that every pilot, regardless of being on a team for the Trophy, will have an individual classification in each competition for two days.

5 - trophies in each event will the first-placed team in each level (trophy for each component) and 3 pilots individual finishers in each level.

6 - Each driver may participate with any motorcycle, classic or Postclassic, and perform the chosen level areas, but according to category (old) of the motorcycle is multiply each rider's score by a correction coefficient. The coefficients are:

PRE 65 0.6

PRE 72 0.8

PRE 80 1

80 1.2 POST

1.4 OPEN

1.7 Postclassic

* Example of Equipment. A team consists of the following lights: PILOT, with PRE 65 that does 17 points, PILOT B, POST 80, for 12 points, and C DRIVER, with Postclassic makes 8 points. Team points will be: 17 x 0.6 = 10.2 + 12 x 1.2 = 14.4 + 8 x 1.7 = 13.6 and Team scoring will be: 38.2 POINTS. In the case of individual pilots will use the same coefficients as your motorcycle.

7 - Technical Rules shall apply to the award of coefficients to assign categories to each motorcycle and therefore its pilot.

8 - Regardless of the team and individual classification of each test made ​​on the basis of this Regulation and in the case of scoring for another championship, there will be an Individual Classification and without applying the coefficients that allow each pilot to score at the championships that scores for each race.

9 - In case of withdrawal of any component of a team and looking to the total score of the team, will be awarded to the pilot's last score of its highest rated 20 points, but not declassify this computer the competition.

Technical Rules for the award of coefficients. In applying these rules and scores coefficients, what we try is a simple and practical way, the fact that motorcycles in each category are as similar as possible in performance. But we have also tried to affect as little as possible to changes in fact already under way in classic races.

Article 1 Motorcycles admitted. Generally, for the purpose of consideration and trial motorcycles Classic motorcycles will be accepted equipped with drum brakes and rear suspension two dampers, where no substantial changes have been made ​​with respect to models series produced at the time (which may not therefore equip hydraulic clutch, liquid cooled, etc..) for all categories, except for motorcycles Postclassic to be air cooled, but not required to meet the limitations of drum brakes and rear suspension two buffers.

The Open category will consist of classic motorcycles take to be a component of other motorcycles after the end of the classical era (about 1985) but keeping drum brakes and rear suspension of two buffers.

It is solely the responsibility of the Race Director or Technical Commissioner in his absence, the decision on the admission of each participant in the motorcycle category.

The specific characteristics of motorcycles to be included in each category are determined by these Rules on the basis of its definition in the following technical sections:

-Frame and swingarm (rear fork)

-Motor

-Carburetor

-Front fork and Seatposts

-Wheels and tires

As regards the inclusion in each category (Pre65, Pre72, Pre80, Post80, Open and Postclassic), the organization may decline your acceptance if, during scrutineering changes were observed or assembly of elements belonging to the motorcycle models manufactured in later years and specified in these Regulations, which lead to the inclusion in the category they belong to the modified elements. (For example, riding a motorcycle carburetor Pre72 to Pre80 category will be included in the motorcycle Pre80. And so on with other modifications). Everything that is not specifically stated in these Regulations shall be free in their use.

Article 2 Chassis and swingarm. Both the chassis and the swingarm of the bike are original period as to material composition. Therefore not allow aluminum swingarm Post80 preceding categories, and if the modern rocker is included in the Open category. Changes are permitted level geometry, or rear subframe cuts, but can not be interrupted or cut the chassis under the Pre65 and Pre72 engine. Allowing for modification of the footrests, as well as its attachment to the chassis.

Section 3 Engine. The engines will retain their original design and appearance (cylinders and crankcase covers), himself mounted on the motorcycle model of the time trial. Engines in later models determine the change of category. (For example, the engines of post Aprilia TX 300-Climber-bottom step will determine the Open, like Fantic motors after the 300-303 engines, 305, etc .-). Not permitted in the reed valve Pre65 and Pre72 category.

Section 4 carburetors. Carburetors should be used by trial bikes at the time of each category. So the MKI Amal carburetors mounted Pre65 not handle air, or 65 models from British Villier type, etc.. In Pre72 may also use the Irz, the Amal MK I with handle air and VH Dellorto. In Pre80 be used MKII Amal (square pan), Bing, Dellorto PHBH, etc.. Mikuni and Keihin and the time for Japanese motorcycles. To be able to mount Post80 PHBL Dellorto, Mikuni, etc.

Article 5 and Seatposts front fork. Seatposts and forks holding the front cylinders, both top and bottom, must be original designs of the time. Thus, in the forks will Pre65 pre65 design and centered axis. Marzocchi forks take a single screw Pre80 lower for motorcycles, etc.. All forks later models to those used for classic bikes are included in the Open category. No bottles will be allowed a greater diameter than 38 mm. in classic bikes.

Regarding the seatpost in Pre65 must have both a single screw at each bar or none in the upper yokes older. In Pre72 Bultaco not be mounted lower yokes newer models of Bultaco

Section 6 wheels and tires. The wheels are kept in appearance and materials, the components of the time. So the brake drums are the originals of the time. In the categories Pre65, Pre72 and Pre80, the tires will grip (even tubeless) and will set jaws to the tires with or Papillon.

Article 7 Amendments. But the foregoing, any modification to the specifications of this Technical Regulation, could be approved in advance by the organization in case of doubt or error.

LIST OF MODELS OF MOTORCYCLES (indicative):

- Pre-65: Motorcycle factories trial before 1965.

- Pre-72: Bultaco: Sherpa models 10, 27, 49 and 80. Montesa: Trial 250, Dimensions 247 MK I, II and III (up to Chassis No. 21M6600). Ossa: 4 MAR 1 marches and meetings (chassis No. B340001 and up). Other pre-1972.

- Pre-80: Bultaco: Sherpa models 92, 125, 151, 159, 183, 191, 199 and 199A. Montesa: Cota 247 (all), Cota 172, Cota 348 and Cota 349 1 st series. Ossa: All MAR 250 and 350, and TR77 (green). Honda TL 125, TL 250 and Seeley 200. Yamaha TY 250, TY 350 and TY 175. Suzuki Beamish RL 250 and 250 and 325 (up to Chassis No. 101 601). Kawasaki KT 250. SWM: TL Guanaco (red). Other pre-1980.

- Post-80: Bultaco: Sherpa 199B. Montesa: Cota 349 White and 349 / 4, Cota 350, Cota 200 and 242, and Cota 330. Ossa: Yellow and Orange TR 80, and 303. Merlin: DG 3.50, 350 Gallach Replication and DG 7. Honda: TLR, RS and Reflex. Suzuki Beamish (from Chassis No.: 101 602). SWM: Yellow and Jumbo TLNW 350. Fantic 200, 240 and 300. Aprilia: TR 320 Red, 320 White, and TX 300. Beta: 240 White. Italjet: TR 350 T-350 Green and White. Garelli: Trial 320. Other classic bikes.

Postclassic: Montesa: Cota 304, 125, 335, 307, 309 and 310, JJ Cobas: Trial. Merlin: FIUs and DG88. JP: 325 tr. Alfer: TX 300 Red and Green. Mecatecno: MR 326, Dragonfly and Skywalker. Gas: Halley and Trial 327. Fantic: 301, 303, 305 and 307. Aprilia TX 311, TX 311M and 312M TX. Beta: TR 32, TR 33, TR 34 and TR 35. Garelli: Trial Section 323 and 323. Honda: RTL, TLM and TLR250R. Yamaha TY 250 Mono, TY and Tyz 250R. Other air-cooled motorcycles.

Edited January 29, 2012 by wayne_weedon

[old trials fanatic]

Javier will know more. But there's some new changes which seem to be outlawing a fair few of the modified bikes.

Be interresting to know what they are, preferably English trnslation as i found it difficult to follow the Google translation, as i'm always interrested in how different rules are implemented. Always admired the way the Spanish policed Twinshocks. We can always learn something.

Edited January 29, 2012 by Old trials fanatic

[pschrauber]

There were some Sherpas fitted with flat-slide carbs in the end of the seventies, they used the carbs from Lectron:

I believe the use of this flat-slide carbs came more from the MX and Enduro before the better Japanes carbs like Keihin showed up. As the Lectrons showed good results for the MX and Enduro bikes some rides tried them out on their trials bikes too.

Here a Pursang that comes with three carbs, the Bing, (original), the Lectron which they will have used as an improvement and a Keihin when these showed up in the mid 80's.

A very nice bike, with Simmon fork's! and long travel Koni's it was prepared by Gary and David Bailey, sadly it is on sale over the pond and no bargain. Baileys Bultaco on sale

Anyway the Lectron carb is best for bikes that runs in mid to upper rpm, I do not believe that you have any benefits with this very special carb mounted in bikes that produces their power from idle up???

Would be interesting to hear any experience from someone, maybe from USA and Australia as there where most Lectrons sold?

Edited January 29, 2012 by PSchrauber

[wayne_weedon]

Would be interesting to hear any experience from someone, maybe from USA and Australia as there where most Lectrons sold?

They were used a lot in Karting circles as far as I remember.

I certainly remember a flatslide that was plastic bodied used on Karts.

[bogwheel]

There were some Sherpas fitted with flat-slide carbs in the end of the seventies, they used the carbs from Lectron:

The Powerjet carb is a 30mm (i think the smallest back then), and has a bush inserted into the outlet to reduce the diametre. The carb worked very well at all throttle positions, but alas the slide is now too worn out, and plastic float bowl has died from modern fuel. According to Lectron, bowls are not available as the new carbs are slightly different. Also slides and metering rods are $$$$.

Also in the throws of fitting a Dellorto to my M158 - same problem, how to adapt.

Edited February 1, 2012 by BOGWHEEL

[greeves]

Javier will know more. But there's some new changes which seem to be outlawing a fair few of the modified bikes.

Via Google translate this is what I get. Seems there's an OPEN class so I guess those heavily modified bikes compete there.

At the moment this are just the new rules for the brand new "Sotobike Trophy". This rules will just be used to grant a handicap to the bikes depending in their preparation. The new "Sotobike Trophy" will be a teams trophy, based in teams of 3 riders and scoring in the 3 Two Days International Trials we arrange for in Robregordo, Pobladura and Los Angeles, with also an individual classification.

The handicaps will be:

PRE 65 - 0.6

PRE 72 - 0.8

PRE 80 - 1

POST 80 - 1,2

OPEN - 1,4

Aircooled Monos - 1,7

The innovations here are

1.- Everibody will have a place in our trials; tuned, original and even Mono´s bikes.

2.- With the exception of handlebars, shocks, modified footrests and other small stuff; your bike will be penalized or favored with a handicap depending in the components you have. For example; a pre65 with a PHBL carburrettor will be considered a Post80, and consequently have a handicap of 1,2 - with an Amal Mk1 the handicap for the same bike will be 0,6. If your bike is a Fantic 240 with a 307 fork, it will be send to OPEN and have a handicap of 1,4. A Bultaco model 92 with an aluminium swingarm will be sent to OPEN category... and so on.

3.- Aircooled monos are admitted, but will race with the same non stop rules.

BUT as I wrote this rules will be just for our trials and will only be used in our trials and to assign a handicap.

In the Federation; both Spanish (RFME) and Cataluña (FCM) are preparing new rules for their championships, and it looks (obviously I don´t want to use the word rumors....) they will be quite hard.

Well see and I will let you know as soon as I know about them.

EDIT to add that the warning red light you can read in Todotrial is:

No vendáis ni tiréis las piezas originales de vuestras motos que hayáis sustituido por otras más modermas, puede que tengáis que volver a ponerlas... Ni modifiquéis demasiadas cosas si alguien se está haciendo una moto en estos momentos, porque es posible que tenga que rehacerlas...

DO NOT SELL OR WAIST THE ORIGINAL PARTS OF YOUR MOTORCYCLES IF YOU HAVE REPLACED THEM BY MODERN ONES AS MAYBE YOU HAVE TO GO BACK TO THEM. IF SOMEBODY IS STARTING A PROJECT, BETTER DON´T MODIFY THINGS, AS MAYBE YOU HAVE TO REDO THEM...

Edited February 1, 2012 by Greeves