mcman56

http://www.ebay.co.uk/itm/261981283404

The other CDI has no curve and the bike runs the same. I still do not know if the OEM CDI should have a curve or not. The aftermarket was on: http://www.regulatorrectifier.com/catalog/20032008-Beta-250-Rev-3-CDI-Unit-1

The aftermarket one is a combo CDI/ coil but has the same lack of a curve. The Beta CDI has 4 wires vs the 6 wires I have seen on a diagram listed by Dan W. There is one two pin connector and two seperate wires, one of which looks like the kill button connection.

I have found a couple of advance curves on line for trials bikes, one for Beta and one for Sherco. They show curves like a 4 stroke so I guess mine should have something similar. I could not find a Beta OEM CDI online but did find an aftermarket one. They could not tell me what type of curve it has but I ordered one anyway and will see what happens. http://www.leonelli.com/english/028%20CDI%20DIGITAL/028%20INGLES/028%20VOK.E-ING.pdf

Compression is 155 psi. I measured the stroke. Beta USA was also nice enough to confirm with the factory before I did the swap. On some official Beta publications, the bore/ stroke numbers are misstated for the 200. (maybe from 2008) Working out the numbers shows that they do not equal 200. That had me confused for a while.

The problem is that I have already barked up every tree I can find. It has the fast throttle. Carb cleaning, carb jetting rich to lean, OEM and Boysen Reeds, Keihin 28 and OKO 26, pack muffler, inspect head pipe, alter static timing at stator and probably a number of things I can not remember at the moment. Some of these had an effect but still did not change the basic flavor. The advance curve thing is one thing I had not considered. Maybe I'll try a CDI from a bike breaker. Actually, it is a very sweet bike, perfect for a rider that takes points in turns due less that perfect throttle control. (starts easy, etc.) I'm just at point where I could use better response.

The Beta 200 is a sleeved down 250 not a big bore 125. At one point I actually split the cases to see if there were any stuffers in the crank but there are none. As far as I can tell, the only difference in the crank assembly is that the 200 assembly has a bronze bushing in the small end of the rod to size it down for the smaller gudgeon pin of the 200. The Gas Gas 200 (175) is a big bore 125. I believe Sherco is/ was the same.

Looking at the parts list, all ignition, intake and exhaust components are the same for the 200 and 250. I bought the 250 top end on ebay so am not sure of the year. There is one thing I have never been able to figure out. Beta used to sell 270 kits for the 250 Rev3s but there were several different versions depending on the model year. Externally, all of the Rev3 top ends I have seen look the same reguardless of year so I don't know why there were different kits.

Here is the stator. There seems to be more than one brand of ignition on Betas. I believe this one was made in Slovenia. It has been rewound since the picture. I have heard that all lignitions with triggering coils have an advance curve . This is a 2008 200 with a 250 top end installed.

I have an 08 Beta Rev3 250 with poor throttle response. (much much softer than a well worn GG200) I have tried all sorts of things and someone on here suggested that there could be an issue with the ignition advance curve. I ran a timing light and got 15 degress BTDC at idle and reved up got 20 degrees. This seems like too much advance at idle and I believe 5 degrees of additional advance is a byproduct of the circuit and not a planned advance curve. For comparison, I once did this on a 97 techno and got 6 degrees at idle, 20 at mid range and 25 to 30 at full scream. I can't find a specification for this anywhere. Does anyone know what it should be? I'm wondering if the CDI is bad and stuck at semi full advance. I hate to buy a new one and find out that they are that way by design.

I ran a timing light on it and got a very odd result. Idle is about 15 degrees BTDC. Reving up the engine pushes this up to 20 degrees BTDC where is stays. Could this mean the CDI is locked in full advance mode? Does anyone know what this should be like? I have to run rich to avoid pinking when just creeping along. I checked this a long time ago on a 97 Techno and got 6 degrees at idle, 20 at mid range and 25 to 30 at full scream.

My only Beta comparison is a 2014 Evo 300 Factory. Throttle response is much much better on the 300. I'll try a timing light and see if there is any advance. A CDI is $255 US so a bit expensive to try.

I don't understand the statment about a site glass. This has the standard plastic cover over the flywheel. I'll try it with a strobe. If it is an advance problem, is it the CDI unit that is bad or could it be somthing else?

There is no flywheel weight.

I have a 250 Rev three and the response (pick up) of off idle is very very soft. It there anything that can be done to improve? It does not feel weak in that it will pull tall gears at low revs but the engine just winds up very slowly. A GG200 has significantly quicker response. This is a 2008 with later 250 top end. Timing is on the advanced side. I have run a 28 mm Keihin and 26 mm OKO and it is the same. Jetting richer and leaner does not alter the response much. I have also run Boysen dual stage reeds and OEM Beta reeds but it still feels the same.

What does teg GB flywheel cost?

I tried a boost bottle on on a Rev 3 and it did have some effect. I would not say there was more power but it would take very large throttle openings at low rpms and condinue to pull cleaning.

The one fork cap looks like it needs a pin type spanner wrench to remove. Will a couple of dowel pins pressed into an aluminium plate be strong enough to remove or is there another recommendation? (At first look 1/8 pins on 24.5 mm centers would fit.) The other cap has a pretty small square for a wrench so both look pretty easy to damage. Do these come out easy or are there some tricks to avoid damage? This is a 2014 Beta Factory 300.

It would be worthwhile to inspect the piston and exhaust. I once bought a Techno that ran as you describe. The power was sort of like a TLR200 but it would rev a higher. After checking everything, I pulled the cylinder and found the bottom of the skirt on the exhaust side was bent in. This must have disturbed the port timing. It looks like someone had the cylinder off, rotated the crank and crashed the skirt into the case. The bend was maybe 3/8" high and complete with a crack but was not loose or broken off. Cylinder compression felt good when kicking and there were no weird noises. A new piston was the cure.

Does it take long to "break in" the forks on a new bike? I have a 2014 Factory 300 with a several hours on it now but the forks feel much stiffer than my old Rev 3. I would like it absorb impacts better. Looking at the specs, it uses the same fork spring as the 125 but the 125 uses 5 mm lower oil levels. Does that really make much difference? Is a softer spring available? My Rev 3 started life as a 200 and I see that that some fork part numbers are different between the 125/200 and 250/270 (2008) although the spring is the same.

I also had a Shiro Trials Helmet but the shape did not fit my head well. (It was more rounded.) It is not as well made as the Airoh but is much less expensive. I was able to improve venting further by cutting away some of the black plastic trim that was blocking some vent holes. I don't think I would recommend it but have seen helmets where the owner created additional venting with a hole saw.

The Airoh has decent venting. The lining is a very soft cool feeling fabric. The lining is removable for washing. Still, helmets are hot.

I have nothing to campare this to but the fins do not look particulary large. Could this be an ATC200X cylinder?

How can you identify the 83-85 ATC200X cylinder? I have an old ATC200 top end to get rid of but am not sure of the year, mabe 82. It has a recess in the piston, sort of a negative dome if that helps to identify. The cam along with the journals is gone so I can't go by that.

Splatshop sells the Keihin. You will also need a new throttle cable. The intake manifold (carb to reed block) is longer for the Keihin so you need the later manifold. If you are really ambitious, you can make a spacer for the original manifold. You can get a Keihin with a right side idle speed screw or modify an existing carb. However, you can not reach the idle mixture screw. Splat shop sells a mixture screw with a piece of flexible cable attached so it can be wrapped around and used from the other side. (Hard to explain but easy to understand once you see the picture.) mid-atlantictrials sells an OKO version of the Keihin for much less money. Quality not quite up to Keihin standards but still quite good. I have run the 26 OKO and 28 Keihin. They run about the same but the 28 may give slightly more acceleration. (There are lower quality "look alike" copies of the OKO and I suspect that is where some people have found really bad quality.) The conversion is not cheap and plenty of people seem to have good running Rev 3s with Mikuni carbs.