carl ekblom

I have done about 10 hours of riding with the R9359 carb and I like it. I prefer to keep the needle in 4th or 5th groove as I felt it was a little bit lean with the needle in the middle position. With the original 111 main jet the engine was four stroking at full throttle runs. The cure was a 105 main jet. No four stroking or hesitation at all in 2nd or 3rd gear full throttle road runs. Now it really revs out. So far I have not felt any pre ignition under any conditions or throttle openings. About the R9354 carb: I have got the information that this was the old VHST carb for Beta. It has now been replaced with the R9359 which is intended to be an improved version with larger fuel valve etc. I have found that dust may pass straight through the air filter, into the idle system air jet and then block or partially block the idle jet causing idling problems and small throttle running problems. So from now and on I regulary do some air filter maintenance. Keeping the filter clean and lightly oiled. Carl

A friend of mine (a very good rider) have done it. He claims he don

First impressions of the R9359 carb std jetting, throttle neddle in middle position: This is after a very short (15 min) test run. After first start up I had to remove the carb and carefully blow the jets and passages (once again) with clean compressed air. It feels softer and not so strong compared with my R9354 carb. I feel that the mixture is slightly weak at small throttle openings. Not true. If this was true the Beta 125

Carb outlet is machined down to 35mm with a new groove and inlet is machined down to 46.5mm for good fit into original rubber mounts. I will test the R9359 Beta Factory part in a few days time. I use the Champion N7YCC plug. Never had any spark plug problems at all. Carl

Yes, specially in low and midrange. Yes. Its more sensitive to dirt and dust. I had some cold starting problems before but changing pilot jet from S37 to S38 and choke jet from 60 to 70 seems to have sorted it out. Now it usually starts from cold in 1st or 2nd kick. Carl

Betarev3: I

Choke and idle/idle mixture screws are on the right side. Betarev3: When you got your jetting right you will not be dissapointed. I can

For those who are intrested..... I felt that the mixture was slightly rich at small throttle openings so I changed the throttle from 50 to 55 (=slightly leaner) and got better throttle response and a cleaner, less dull exhaust sound which is an indication of more effective combustion. Current jetting: Main jet115 Pilot jet S38 Idle mixture screw 1.5 turns out Needle D47 4th groove from top Needle Jet 272H Throttle 55 Float valve 250 Choke jet 70 Carl

Neonsurge, I had the same problem as you have. I found out (as someone already have suggested) that I had disconnected the earth connection. A two pole switch and a new earth connection is a good idea. I have put mine to the upper engine mounting as I don

Jetting update: Main 115 Pilot S38 Idle mixture screw two turns out Needle D47 4th groove from top Needle Jet 272H Throttle 50 Float valve 250 Choke 70 Cold starting problems is cured and I feel this jetting offers better performance than the previous 120 main/S37 idle at all throttle openings. Parking downhill or long steep downhill runs is no problem with this carb. Carl

Here is the Beta Original Factory 250/270 Tuning Part data: Dellorto VHST26BD R9359 Main Jet 111 Needle Jet 272H Needle D48 Idle Jet S38 Throttle Cut Away 55 Choke Jet 60 Spider 2.5mm The Air Jets also appears to be of different size from std carb R9354 Carl

Front 5mm Rear 5.5mm regards carl

I have recently run -04 250 (my old bike), -04 270, -05 270 and -06 270 (my current bike) and I think the main difference between the -05 270 and the -06 270 is that the -06 has a more powerful engine. carl

Ok, Choke test=engine stalls. To me this tells rich mixture and no blockage in the idling system. If there is a blockage the engine usually runs better when the choke is opened. Chocke closed=running lean but idle mixture screw has an effect when needle is in 5th position. I would try one or two sizes larger pilot jet. I think you can get jets from here http://www.dellorto.co.uk Good luck. It

In theory the main jet has no effect at all at small throttle openings. The depression simply isn

You are correct. I have 120 and a 170 seems a bit large. Sorry for that carl

The idle mixture screw has no effect telling us that the idling system is out of range . You say it surges. I guess you are correct when you say it runs lean. Try and open the choke at low throttle openings and see what happens. Try and run at slow speed. I have had new out of box vhst that need cleaning You may try and carefully blow all passages and jets with compressed air. Just a thought. The vhst is standard fitting to Beta 125

Hello If I read you correctly: Idle jet S35 Needle jet 270K Needle D49 Main Jet 170 (seems small to me) Choke Jet 60 Float Valve 270 Firstly with a sharp knife cut the two pegs away on the inlet rubber. This is to assist carb removal and reassembly. Some oil on the carb inlet and outlet will help when putting it back. Taking the carb off, rejet and mount it back again can be done in 10 minutes. I would try the carb as it is. The first check the idle system. The idle should change when adjusting the idle mixture screw. 1-2.5 turns out is good. Then try to establish the correct main jet size by full throttle runs in 3th-4th gear. Four stroking tell you that the main jet is to large while hesitation tell you that you need a larger main jet. I guess the needle/needle jet combination is just about right and the only adjustments needed is the needle position. The engine must be in working temperature (check the fan) before performing any fuel set up tests. By the way, the VHST is sensitive to dirt. Use a fuel filter and keep the petrol clean. Hope this helps. Regards carl

With the VHST carb the exhaust note of the Beta changes to be more like a gasgas or sherco . The dull Beta sound is almost gone. Dull exhaust sound is generally an indication of fat mixture or a carburation problem. Perhaps the Mikuni needs a leaner (2.5) throttle cut away. But I guess that would cause more pinging problems. Anyone knowing? After a couple hours of riding today I have noticed that it

Hello It is not the Beta factory part. Mine is a std carb bought from a local motorcycle dealer. The bike revs out easily. It is more or less depending of finding the correct main jet size. 120 seems to be just about right. I think that the 270-06 is the most powerful Beta ever. It certainly has more power than the 05 270. Carl

Last year I tried the VHST 26mm for my 250 -04 and found it to be a real improvement over the stock Mikuni. I started this year with a new 270 -06 and have covered about 2 mounths of riding with the stock Mikuni and found that the new bike was difficult to handle. Riding with slipping clutch in 2nd gear was difficult and the general feeling of the bike was that it felt nervous. Now, I have replaced the Mikuni with the VHST and covered about 10 hours of riding....and what a difference. 2nd gear riding with slipping clutch isn

My current jetting for Beta 270-06 altitude 50-300 meter Main 120 Pilot S37 Needle D47 Needle Jet 272H Throttle 50 Float valve 250 Choke 60 Carl

Great! Is cold starting a common problem with the VHST? The chocke jet and passages is clean and the lever mechanism and piston is in perfect condition. Otherwise the carb is perfectly working exept from a slight pinging after a short full throttle run (fuel valve size to small?). Carl

Interesting information . For my Beta-06 270 the VHST was so far a great improvement over the stock Mikuni. The light throttle spring offers good engine control and overall performance and throttle response is much better than with stock carb. However, for cold starting it needs a few kicks more. I guess that the choke jet(size 60) need to be slightly larger. The right hand carbs is called BD and the left hand is called BS. Now, I have to check the size of the fuel valve. I think I have the brass fork so it is probably 200. carl

For the 06 the main berings are Ball Bearing 30x62x16. I guess its the same for the 04. The oils seals are 25x40x7 viton. Carl