jimsshed

We've had the experience of both Beta and Gas Gas (and Montesa 4RT) in our family. In terms of maintenance, I actually found the Rev-3 slightly easier to work on eg; carburettor removal and replacement. In terms of build quality, I consider them even. You can pick flaws in both. In terms of riding...that's up to you. go to a club day and ask someone for a ride on their bike. They're both good trials bikes. If you want the best build quality and ease of ownership then buy a 4RT. People just don't appreciate how different the 4RT is in this area until they actually own one.

I tried a similar concept on my son's Beta Rev-50. They're awfully tinny and loud (bad Beta Motor Co.). I got a roll of 50mm exhaust header-wrap and tightly wrapped it around the expansion chamber from where the header pipe is welded onto the expansion chamber, right back to just behing the chamber's mounting bold. I secured it at each end using strong zip ties. The noise reduction was enormous and he could comfortably ride around the back yard, and the header wrap was surprisingly durable. It never fell off or became loose at all. Even the pressure cleaner didn't budge it. FYI: Exhaust header wrap is a soft woven fibreglass fabric ribbon used on drag cars etc to shield parts in engine bays from high radiated exhaust temperatures. You buy it from performance auto stores. Jim

I think you mean you have a Beta 50 Mini-trial, not a Rev-50 (which has a clutch and manual gearbox). There is no air screw, and you will find that this carb, with it's plastic slide and single jet (yep, there's no pilot jet either) is a cheaper item than you'll find on most lawn mowers and something Beta should be ashamed of.

A shrieking clutch would indicate something is wrong with it. I've never heard a 4RT clutch do this. The on/off clutch on my 06 4RT was cured by a tip given to me by Tarp, our Australian importer. It was simply to back off the actuating pin's adjusting screw at the lever as far as possible. This has the effect of changing the leverage dynamics as you pull in the clutch. I was astounded at the difference. My clutch is now nicely progressive whereas before it was very on/off. There is still plenty of room to disengage with one finger without crushing my other fingers between the handgrip and lever. It did not affect the ability to start in gear. Tarp says if I want even more adjustment, to remove (grind off) 1 to 2 mm from the actuating pin. I haven't needed to do this cos' I like it as it is. I also slid the clutch lever assembly further in along the bar so that when I reach out with two fingers, they touch just inside the knob on the lever's end. This of course increases the arc length, and reduces required effort. Jim

I went through a few plugs initially, but since then I always let the bike sit and idle from start for at least one minute. Let it idle, don't blip or rev it when stone cold. My last plug lasted about 10 months. I live in Brisbane Australia, so those of you living in colder climates should extend this warm up time. Jim

Sorry, who are Birketts? Do they have a web site? Thanks, Jim

I read somewhere once that someone manufactures an 80cc kit for the Rev50. Does anybody know if this really exists and who sells it ? Cheers, Jim

My son has a 2006 TXT50 Boy. I've made all the mods as suggested by Tonyp884 and am glad to say it performed beautifully at our last trial. Max 2 kicks to start it, and we now kick it with much much less effort. In summary I did Following... * Cut away airbox baffle and also drilled holes in airbox lid * Dropped needle another notch. Clip is now in the topmost position. * Air screw is backed out 2.5 turns * Fitted iridium plug Engine now idles better. Responds smoothly low to mid range. Very noticeable increase in grunt and overall power. We rode the entire trial and didn't have to replace the spark plug. Even when he dropped the bike the engine was less prone to cutting out, and when it did, it still only took one or two kicks. Woo hoo !!!! Thanks Tony. Jim

Ned, I'm glad you liked it and I hope you buy one. You've made a valid point about the suspension. Given that, I'd really like to ride another one sometime with a standard setup. You are right in your assessment of low vibration. Compared to the 2T bikes I've ridden, it is as you say 'super smooth'. My comment was based on getting on/off each bike and riding exactly the same terrain and I felt, the 4RT was even smoother. I don't have a brand loyalty. Witness my family's current garage; a Beta, a Gas Gas, and a 4RT. Each bike bought by me because I felt it was the best bike at the time for the intended rider. Last 2 years I rode a Beta, this year a 4RT, and I have no qualms about buying a Scorpa in the future if I feel then, they have a bike I like best. So far, based on my ride of the 2006 250f, the 4RT is easily the bike I like best, and I'm glad I didn't wait for the 250f, even though I too admired the pre-release photos. One thing I am biased towards these days is the 4T motor because it is so clean and smooth, although I hear at least one brand is developing an EFI 2T, so you never say never. Cheers, Jim

I had a test ride on an SY250F last Sunday on a demonstrator bike supplied by our local dealer (6-Aug-2006). I own an 06 4RT but feel I can be objective if I don't write too much. My comparison was very direct as I was able to get on/off either bike and ride exactly the same terrain or section. It was very easy to start. As easy to kick as a my 4RT. Maybe a touch easier (believe it or not). Much lower geared than 4RT, 2nd gear was like 4RT's 1st gear. As such, I felt 1st was wasted. Would be ok for lower grade riders I suppose, but others will rarely use it. Compared to 4RT, response was much softer down low, although I suspect that was due a lot to the very low gearing. Certainly didn't punch like the 4RT does with a standard map. Some people might like that. Tractability in slow going was very good. Clutch lacked feel somewhat. Slow turning was surefooted. Suspension not as plush as 4RT. Didn't get a chance to ride hillclimbs so can't comment there. Had to fight it riding up running rocky creek section (round slippery rocks 3" to 8"). Just couldn't keep it straight and stay in the section. By comparison the 4RT was on rails and I cleaned it every time. Handlebar angle or suspension tuning may help (I hope). I was shocked by the difference here. 4RT feels smaller and more nimble between your legs, with less vibration and fuss (not only my opinion). I see marketing of the 2007 SY250F is already out and touting various improvements, so lets hope the gap closes a bit next year. We need more 4T bikes in trials. The 4RT has been the benchmark, and it still is. Cheers, Jim

I like the 4RT's because they don't stink...or blow smoke. I'd be worried about any unnecessary additive glazing the bore and causing power loss (two stroke or four stroke).

When the Rev-50 is in gear, with the clutch pulled in, the kickstart will not engage. Does anybody know what needs to be done to remove this restriction? My son now finds it very annoying having to always select neutral in order to start the bike. He can at times kick it over with the clutch out and then quickly pull the clutch in as it starts, but this is not always convenient according to the predicament. At the moment we have removed the clutch-side sidecover off the engine, but cannot see anything apparent. On another topic, I saw reference in the past to a 75cc kit for the Rev-50. Can anyone point me to some info on this? Thanks, Jim

Does anyone know what the Iridium equivalent is, and have they tried it ? Cheers, Jim

We don't want an MX style guard for reasons given above. We're also talking about a typical 8 year old child that does not always have the reflexes or experience to control a fall. Our riding days are typically hot and humid, and of course we are riding trials, so open vision is essential. MX helmets are very hot at slow speeds and hinder peripheral vision. This is obviously a product opportunity for helmet or accessory manufacturers, because EVERY parent I've talked to about this situation are worried about their children's teeth getting damaged or knocked out. Jim

Does anyone know of a face guard that can be attached to an open face helmet? Not one of those plastic bmx/motocross things from yesteryear, but maybe a wire cage style guard like cricket or baseball players wear. I'd really like to protect my son's face and teeth a bit more, whilst still giving him most of the ventilation and vision that open face helmets provide. Thanks, Jim

My 4RT requires a new spark plug more often than my previous 2 stroke Beta. By my analysis, it appears the iridium equivalent of the NGK CR6EH-9 is the NGK CR6EIA-9. Has anyone tried these? Getting longer life? Starting any easier? (not that I'm complaining...such a great bike to start) Cheers, Jim

Peter, did the bike run okay before the new piston etc, or did you just acquire it? For my part, I have returned the bike to the dealer for a refund, and he will in turn return it to the importer. My last ditch debug effort before returning it was to remove the reed valve block. The reeds were seating perfectly. I did notice that the machined crancase facing which the reed block bolts into had a slight surface mismatch where the two crancase halves come together...maybe 0.25mm. There was no visual evidence of intake manifold gasket leaks though. This mismatch could also be felt by running my finger around inside the intake, although this is a bit moot because the internal surfaces aren't machined. On reassembly I chose not to seal the gaskets with a sealant (there was none applied at the factory) because by now I was now fed up with the whole thing and didn't want to tamper with it's original build. Just one more observation...the crancase halves had no gasket between them. This is normal, but I saw no evidence of sealant anywhere. Always when you reassemble two crankcase halves, you get at least SOME sealant being squeezed out. I could be wrong, but I can't remember seeing or feeling any when I was running my finger around checking the mismatch. We've now ordered a Gas Gas TXT 50 Boy. Consequently we may never know what the problem truely was. Regards, Jim

Thanks KTMSprocket. We've been away for a long weekend, hence the slow reply, but I'll have to contact my Beta dealer again and get this sorted out. I will let the forum know what happens. Cheers, Jim

KTMSprocket, yes I agree with you on all points. I did the tank removal thing on Saturday to eliminate anything in that area. It all points to the carb, and the next logical step is to swap it out. I had entertained thoughts of puting our Rev-50 carb on it to try it out, but as you too probably know, it uses a different style of inlet manifold. Does anybody else following this forum actually have a Beta 50 Mini-trial, and if so, how does your engine behave?. What do you use for an air cleaner?. What other issues am I likely to face with this bike?. Thanks, Jim

My 2003 Rev-3 developed this pinging. It occurred when rolling off the throttle at mid to high rpms. Upon removing the barrel, a lot of carbon and laquer buildup was found on the piston, rings, and barrel surface. This really surprised me as the bike had been ran on unleaded premium and Motul 800 for all of it's (then) 18 month life at a 60:1 ratio. The carbon and laquer was easily removed and no damage had occurred, so the only parts needed were a head and base gasket. After reassembly the knocking was completely gone. Afterwards I also switched to Bel-Ray 2 stroke oil, as I found out some other people had had a similar experience. I will point out that I often rode it for short periods in the back yard, and this may have exacerbated the condition. The knocking used to vary in severness. After seeing the carbon layer on top of the piston and head surface, I attributed this knocking mostly to the carbon impacting the piston & head surfaces together around the edges. I have seen this in other motors before, especially stationary motors on pumps etc, wherein the carbon swells due to humidity etc if the motor is not used. That's my 2 bob's worth. Cheers, Jim

I'm not sure about the KTM ad I've never see one, although one of my trials buddies told me the engine is used in a KTM. The engine sidecovers have the words "MX Racing" on them. Auto clutch. Single speed, but noisy/whiny transmission. Carb is definitely SHA 15/15 as stated in the owner's manual..and I measured it to confirm. Main jet is definitely intact. Bike has no injection and runs on premix. We assume the gearbox oil ran out thru the breather. Cheers, Jim

Thanks everyone for your suggestions. * I've checked the fuel cap. * No water or dirt in fuel tank. * Air box is clean (btw the only air filter is a metal gauze wtf!!! but I'll deal with that next). * charliechitlins: interesting...what brand, bike or carb?. This carb is a Dellorto SHA 15/15...cheapest carb I've ever seen: No pilot jet, no air screw, plastic slide. * Fuel flows freely thru tap even when rear is up. * KTMSprocket: Odd idling occurs straight away when the rear is up. Problem occurs most noticably when hot. I changed the fuel pipe to a shorter one yesterday and the problem appears diminished a little in that the idle speed still goes down when the rear is up, but not as quickly. Could this be related to vapour lock?. I will investigate your fuel in the crankcase theory; the crate it arrived in had been on it's side somewhere in transit as all the gearbox oil had leaked out into the cardboard. Bike is not blowing smoke as I would expect in this case though, and I feel he's already ridden it enough to consume any residue that might have been there. Will also check the stator. Lastly, if you leave the bike idling on flat ground, it will eventually idle right down then stall in about 30 seconds. It's a journey... Cheers, Jim

Hi, My son has a new 2006 50cc mini trial and it wont idle properly. When riding, it idles high, but after 15~20 seconds it will idle right down then stop. * Have re-cleaned the carb with compressed air * Checked the inlet manifold for leaks. Checked bolts. * Confirmed that slide closes and opens fully and that steering movement does not interfere. * Needle and seat looks new (as it should). The fuel tap runs freely, but have noticed that fuel line constantly has a long air bubble inside it after the bike has ran for a few minutes (fuel pipe is clear tubing). I don't know why. Stalling problem interferes with his riding as we noticed it always does it when he rides down a slope with the throttle backed off. Motor will remain running if you work the throttle whilst on the slope. After seeing this in action, I can replicate the problem and make it immediately idle down and stall simply by lifting the back wheel 6 inches in the air. Motor otherwise starts easy (hot or cold), runs clean, and produces good power even with me on it. Does anyone have any ideas or experience with this problem ? Cheers, Jim