Beta Rev 3 Carb Fault

[wilsoff]

I recently set up my carb on my rev 3 250 2001,as explained by Billy T found on a previous post. since setting up i'm having trouble starting when cold. Have i over adjusted or under adjusted, or done something else wrong. Also is there a preset setting for the screw to the left of the idle screw. Any help would be greatly appreciated.

(the carb has been cleaned and new air filter fitted the fault only been on since i adjusted)

[billyt]

Jets with adjustments

#35 Min pilot 40> 45 reccomended.

@140 Main Jet.

Air screw 2.5 turn out.

BillyT

[hrc1]

Billy,

Seems odd those pilot jet sizes....I've had 4 Rev-3s now & all ran superbly on one size under stock jets. i.e. 27.5 & 145.

Thats one 200 & 3 250s.

Or maybe its UK fuel & weather?

[wilsoff]

Thanks for your help i'll strip the carb out again and check what jets are in at the minute. I'm the uk will that make a difference.

Were is the best place to buy the jets or are they available at most beta dealers.

[totalshell]

if it wasn't too far wrong before you 'adjusted' the carb dont go changing jets yet, play with it some more, pull it apart and put it together again, make small changes one at a time then ride it,

get the bike to start dependably first then tackle tickover, then rideing away from tickover your not aiming for perfection at this stage just 'almost there' once your at that stage across all throttle openings the thing then comes together and only minor adjustments should be necessary at specific parts of the ranget

a manual or this forum will give you a good starting point but each bike, each fuel, every mixture you make up every filter are all slightly different before you even get to the carb!!

although each jet/slide /needle effects differnt parts of the throttle opening their relationship to each other is important to how the bike works as a whole, so the main jet will have some effect on the whole throttle action not just when its wide open

[neonsurge]

Hmmmm. All my Rev3s have had a 150 main and 30 pilot installed. I usually go up to 32.5 on the pilot to eliminate the occasional pinking that these bikes seem to be prone to. Like hrc1 says, maybe it's the British climate that makes the larger jets more appropriate. Allen's Performance are Mikuni specialists and sell parts for all models. They're very helpful with general jetting questions as well.

Anyway, with regards to your original question if you've adjusted the float height slightly too far, it can prevent sufficient fuel from reaching the carb to start the bike from cold. The solution is to either readjust the float height (doh!) or simply rock the bike from side to side a couple of times before kicking. This seems to "prime" the carb with fuel and make cold starting much easier.

Edited January 4, 2006 by neonsurge

[gkp413]

Do any of you Rev3 experts change the spring in your carb? I have a 02 200 which is about 3 times as heavy as the spring in my daughters 125 GG pro. Is it likely that someone has changed the spring or are they all like this?

If you change them where do I get one and what do I need?

Thanks guy's,

[neonsurge]

Beta throttles are usually very light - you sure the cable's not binding somewhere?

I believe that there's an alternative carb spring available on the "factory" parts list. Lampkins should be able to help.

[kinell]

Do any of you Rev3 experts change the spring in your carb? I have a 02 200 which is about 3 times as heavy as the spring in my daughters 125 GG pro. Is it likely that someone has changed the spring or are they all like this?

If you change them where do I get one and what do I need?

Thanks guy's,

<{POST_SNAPBACK}>

I use the softer carb spring from JLI's

http://www.beta-uk.com

[wilsoff]

Stripped out carb it has a 150 jet and what looks like 2.5 jet is this the problem all the above are 30 or above.

[billyt]

Your cold starting is due to a #25 jet if that is indeed what you have in the bike.

Switch to a mininum of #35 pilot jet. Mikuni jets only go down to #10 on the pilots so it could not be "2.5". GET A BIG MAGNIFIER AND LOOK CLOSER.

Trust me.......

Cheers

BillyT

[hrc1]

Neon .....I use a Smaller pilot jet.

& yes a light throttle spring helps too.

Also none of my Betas have "knocked" or Pinked either (off road)

[wilsoff]

I fitted the 35 pilot jet but bike is still the same, poor starting when cold but ok warm. The bike still performs well, any other ideas anyone.

Wilsoff

[rev3guy]

Wilsoff:

I would follow the advice of Billy T on carb set up for the Mukuni and the Beta in particular. I also sort of agree with Neonsurge that rocking the bike when cold might help. When I got my first Beta in 1999, Ishy showed me the correct way to start a cold bike and I swear it works. First turn on fuel, set choke on, put bike in 3rd or 4th gear, with clutch in, roll bike back and forth breaking the clutch plates loose (getting oil in them)and also pumping a little bit of fuel into cylinder, once you can roll, rock bike back and forth easily, give er a kick and I would be surprised if it doesn't fire on first or second kick. Just took out my Rev3 after 5 weeks and fired on second kick.

Good luck and let us know how you make out.

Anthony

[clarkp]

I would set the floats back to their original position and check the starting... my guess is it will be back to normal.

Follow the advice of 'totalshell' change only one thing at a time (this applies to computers as well...)

And lastly, for 'gkp413' heck yes! Take that carb slide spring out, grab your wire cutters and snip about 1/3 off the length of that sucker! (or more). Makes a world of difference! I, like you, prefer a delicate, light, super smooth throttle action. Cutting the stock spring off (the stocker is as tough as a die-spring...) really helps - no need to spend your beer money for a light spring.

Edited January 10, 2006 by clarkp