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Franklin9000

Hard to start beta rev3

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Worn rings will lower cold compression to the point they are a pain to start. If the stator is good and the carb is clean you probably have low compression. It is an 18 year old bike and I doubt the previous owner was going to freshen up the motor before selling.

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22 minutes ago, dan williams said:

Worn rings will lower cold compression to the point they are a pain to start. If the stator is good and the carb is clean you probably have low compression. It is an 18 year old bike and I doubt the previous owner was going to freshen up the motor before selling.

That's true, but the engine still looks brand new. All the paint is good on it, and there's barely any scratches. I don't think this bike was used a lot. If it was I don't think it was used heavily. I'll test the compression on it and see what it's at. Any idea what the compression should be on these engines?

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Your bike sounds a lot like mine, I just bought my 2001 Rev 3 back in August, and when I went to see it the seller said:"Take it for a spin!"

So I straddled it, looked down in horror at the left hand kick start and proceeded to wear myself out over the next 5 minutes kicking it, without it even coming close to starting.

Feeling like a fool, i asked the seller to start it for me, it took him about 4 kicks. Bought the bike and took it home.

Figuring I needed some help to start it, I looked around the acreage and saw a few stumps that looked like they might make a decent bike stand.

Pushed it up onto the stand, now I was able to stand on both pegs without worrying about balancing.

I could now jump up and fall while kicking through with my left leg, lo and behold, it started on the second kick.

Since then I use that technique when the engine is cold, when it is warm I simply lean the bike over and push through with my leg and it starts first kick.

I still can't start it cold unless it's on the stand, and so today, just for a lark, since it hasn't run in a couple weeks due to the cold weather here,,

I pulled it out, set it on the stand, and it started on the second kick (32F outside).

As a right leg kick starter all my life, I have to use a stand to get the proper speed and power into the kick to start it with my left leg.

Anyway, good luck on it! I'm really enjoying my bike now....

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19 hours ago, Franklin9000 said:

I tried moving it forward and hitting the brakes 3 times before starting it and then kicking it really hard. I was able to get it to start the 2nd kick. Thanks for the advice. I've been trying to mess with the air screw. It doesn't seem to do much. It only wants to die when you put it all the way in. but from 1/2-2 1/2 there isn't a noticeable difference. Usually I can hear a big difference each half turn. The cold might have something to do with it. I know the circuit and jets are all clean. maybe it's sucking air from around the boot. I'll test it with some starter fluid. 

I don't really like the gearing on this bike. Third gear doesn't have enough range, and then fourth gear is too high. It makes trying to do things like slow wheelies difficult. Maybe I just have to get used to it. On my little gasgas 160 I did most things in third.

It's all snowy here. I'm trying to ride around in the snow, and sliding all over the place. Much better than sitting inside waiting for it to melt though.

 Much better than mud too, improves the balance without the dirty stuff being thrown about.

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13 hours ago, Franklin9000 said:

That's true, but the engine still looks brand new. All the paint is good on it, and there's barely any scratches. I don't think this bike was used a lot. If it was I don't think it was used heavily. I'll test the compression on it and see what it's at. Any idea what the compression should be on these engines?

I believe I was seeing about 145 PSI but it does vary. I usually get about four years out of a Beta before I notice it's a little soft off the bottom and harder to get  started. They still run fine once going so it's a little deceptive until the new rings are in and then you realize how much power was lost. As noted crank seals and reed valves can also cause a loss of cranking pressure which will affect starting.

As for kicking it isn't a big deal to me as I had a 400 Maico as a kid and anything after seemed easy, even 40 years later. It is fun letting someone who isn't used to a trials bike try to start my 300 as they often can't get the starter to move. I did have one guy test ride a bike to see if he wanted to buy it. Supposedly knew how to ride. He stood on the pegs, wound up his leg and jumped full force... ON THE SHIFTER! The assembled group of riders just watched horror struck as I yelled, "WHAT ARE YOU DOING?" He calmly replied, "Trying to start it, DUH." He didn't buy the bike.

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14 hours ago, ahh_me2 said:

Your bike sounds a lot like mine, I just bought my 2001 Rev 3 back in August, and when I went to see it the seller said:"Take it for a spin!"

So I straddled it, looked down in horror at the left hand kick start and proceeded to wear myself out over the next 5 minutes kicking it, without it even coming close to starting.

Feeling like a fool, i asked the seller to start it for me, it took him about 4 kicks. Bought the bike and took it home.

Figuring I needed some help to start it, I looked around the acreage and saw a few stumps that looked like they might make a decent bike stand.

Pushed it up onto the stand, now I was able to stand on both pegs without worrying about balancing.

I could now jump up and fall while kicking through with my left leg, lo and behold, it started on the second kick.

Since then I use that technique when the engine is cold, when it is warm I simply lean the bike over and push through with my leg and it starts first kick.

I still can't start it cold unless it's on the stand, and so today, just for a lark, since it hasn't run in a couple weeks due to the cold weather here,,

I pulled it out, set it on the stand, and it started on the second kick (32F outside).

As a right leg kick starter all my life, I have to use a stand to get the proper speed and power into the kick to start it with my left leg.

Anyway, good luck on it! I'm really enjoying my bike now....

I've been setting it next to a quad so I can put my right foot on the quad and then put all my weight into my left to start it. It's just awkward because it's on the left and once you get to tdc if you put just a little weight on it it goes past tdc to a point where you can't kick it. So once you go one click past it basically locks up to where all you'll do is hurt your foot. My yz250 takes a lot of force to start, but once it's at tdc you can rest your foot on it without it going past that point. Once I'm at that point I usually jump off the ground with my other foot and put everything into the kicker. Then it starts right up. This beta is just different, and I'm getting used to it. I think I figured it out with help from everyone here. That rocking the bike and hitting the brake seemed to help. I think my fuel flow problem was also making it difficult at first.

 

1 hour ago, dan williams said:

I believe I was seeing about 145 PSI but it does vary. I usually get about four years out of a Beta before I notice it's a little soft off the bottom and harder to get  started. They still run fine once going so it's a little deceptive until the new rings are in and then you realize how much power was lost. As noted crank seals and reed valves can also cause a loss of cranking pressure which will affect starting.

As for kicking it isn't a big deal to me as I had a 400 Maico as a kid and anything after seemed easy, even 40 years later. It is fun letting someone who isn't used to a trials bike try to start my 300 as they often can't get the starter to move. I did have one guy test ride a bike to see if he wanted to buy it. Supposedly knew how to ride. He stood on the pegs, wound up his leg and jumped full force... ON THE SHIFTER! The assembled group of riders just watched horror struck as I yelled, "WHAT ARE YOU DOING?" He calmly replied, "Trying to start it, DUH." He didn't buy the bike.

I'll check the compression and see what I get. That's a funny story. Some people are just too proud to admit they don't know what they're doing. If you always act like you know everything it's really difficult to learn something new. I'm pretty confident I know how to kick start things, but I knew something was wrong when it took 20 kicks before I could start it. Glad I figured out the trick. Hope that guy didn't mess up the spindle  for the shifter...

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On ‎12‎/‎14‎/‎2018 at 12:28 PM, dan williams said:

I believe I was seeing about 145 PSI but it does vary. I usually get about four years out of a Beta before I notice it's a little soft off the bottom and harder to get  started. They still run fine once going so it's a little deceptive until the new rings are in and then you realize how much power was lost. As noted crank seals and reed valves can also cause a loss of cranking pressure which will affect starting.

As for kicking it isn't a big deal to me as I had a 400 Maico as a kid and anything after seemed easy, even 40 years later. It is fun letting someone who isn't used to a trials bike try to start my 300 as they often can't get the starter to move. I did have one guy test ride a bike to see if he wanted to buy it. Supposedly knew how to ride. He stood on the pegs, wound up his leg and jumped full force... ON THE SHIFTER! The assembled group of riders just watched horror struck as I yelled, "WHAT ARE YOU DOING?" He calmly replied, "Trying to start it, DUH." He didn't buy the bike.

I tested the compression and was getting in between 125 and 138. I took off the head to look at the cylinder. It had a couple of very light scars. Nothing I'm really worried about. Where can I find rings or a piston and rings for this bike? I measure the cylinder and came up with 71.9mm.

 

I know I need 72.5mm rings. Some rings you can't use on some pistons. So I'm thinking I should just get a piston and rings kit. Can I just put in a 2t namura 72.5mm piston kit in it like this one?

https://www.ebay.com/itm/Namura-020-Over-Bore-Piston-Kit-Polaris-250-2-Stroke-ATVs-72-5mm/352542217677?hash=item52152755cd:g:AJUAAOSw~odcEFVd:rk:29:pf:0

Edited by Franklin9000

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Just rings I think. If you don't hear a slap you're usually good on a trials bike. They just don't stress pistons like other bikes. You can get rings from just about any Beta dealer or the beta importer at betausa.com 

Your parts diagram

https://www.betausa.com/sites/default/files/pdf/2012Support/Parts Diagrams/Mototrial/Full Size/2000 Rev 125-270 2 stroke.pdf

Looks like your rings are part# 28.52200

Edited by dan williams

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9 hours ago, dan williams said:

Just rings I think. If you don't hear a slap you're usually good on a trials bike. They just don't stress pistons like other bikes. You can get rings from just about any Beta dealer or the beta importer at betausa.com 

Your parts diagram

https://www.betausa.com/sites/default/files/pdf/2012Support/Parts Diagrams/Mototrial/Full Size/2000 Rev 125-270 2 stroke.pdf

Looks like your rings are part# 28.52200

Thanks for that. I'm finding a hard place that sells them, but I emailed several beta dealers. Hopefully they'll get back to me today. I told them that if they don't have them to please let me know who would. There's also a place here in the states that specializes in trials parts. You have to call and talk to them though, so I'll try that tomorrow too. I needed to get another front fender for my gasgas anyway. Thanks again.

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It looks like Trials and Tribulations has them in the UK. I’ve ordered some stuff from the UK and it’s been a little pricier but not too bad.

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2 hours ago, dan williams said:

It looks like Trials and Tribulations has them in the UK. I’ve ordered some stuff from the UK and it’s been a little pricier but not too bad.

Ya. I saw that, but that's crazy expensive for a set of rings. I would just be angry at myself for getting ripped off. Beta responded to me and said that they have them, but I have to go through one of their dealers close to me. I already emailed them, but haven't gotten a response. I guess I'll have to call.

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4 hours ago, dan williams said:

It looks like Trials and Tribulations has them in the UK. I’ve ordered some stuff from the UK and it’s been a little pricier but not too bad.

I talked to jim at trials parts usa. He's the guy that makes all the videos for working on trials bikes. He said 125 compression is normal for a trials bike. I think I'm just going to leave the rings. what was your compression after changing the rings?

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Any Beta I’ve tested was up over 140. If you really are curious the typical way to check is take the rings off and put them in the cylinder and measure the end gap with a feeler gauge. Trials bikes parts are expensive in general. The cost of owning specialist machinery. I still think 125PSI is low compression for a Beta but I’ve been wrong before so...

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I  couldn’t find specs for a 2000 but the compression ratio for an ‘04 is 11.4:1. I remember it was quite high on the older Betas. The main reason they run lousy on regular fuel. At sea level pressure of 14.7 PSI even without any boost from scavenging effects of case reeds and exhaust you’re still looking at ~150 PSI relative to atmospheric. Jim knows a lot but he does tend to give the, “Go away boy, ya bother me.” answer when he’s in a cranky mood.

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Just to go into the theory a bit what happens with low compression is the speed of the flame front in the combustion chamber is slower so a significant part of the fuel mixture doesn’t burn before the exhaust port opens. Unburnt fuel is unused power since it never gives its latent energy as heat so never contributes to the pressure above the piston on the down stroke. You can compensate somewhat by advancing the ignition timing but that only helps a little as the shape of the head is optimized for an expected burn duration. 

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