dan williams

None of these bikes adjust ignition timing based on temperature. Certainly not something with razor thin profit margin like a tiddler. Your problem is either a faulty ignition or more likely carb/mixture possibly an air leak. Is the current jetting set to stock values? Are you certain the carb is assembled correctly? Have you tested for air leaks with hot start? Are the reed valves intact? Is there anything blocking the exhaust? It’s important to start from stock jet values with a properly cleaned and assembled carb. It’s very easy to chase around in circles if you don’t have a known starting point. Not diagnosing but just reference, a cold engine requires more fuel in the mixture to help vaporization. Do you have to use the choke to start it cold? If not that would indicate a blocked air passage or a choke circuit that is not shutting properly.

SIT REP as Jeremy Clarkson would say. Second day out on the bike with custom indexer installed and stock cam. No false neutrals and shifting on the loop very positive. A couple of times a shift wasn’t right on and a split second later the box snicked into gear on its own. Strongly points to my original issue being the wonky bearing on the indexer.

Fair enough. I was happy to see a pinch bolt on my ‘18.

Place your finger on the area between the pinch nut and the top triple clamp and rock the bike to feel for motion. Some standard Beta top triple clamps pre-18 had too much clearance in the spindle hole. Tightening the nut would help for a few hours but the only way to fix it was to shim the spindle. I don’t know about the Top Trial clamps but if they don’t have a pinch bolt that might be your problem. I chased that clunk for months tightening the bearings and re-seating the head bearings over and over until I figured that one out.

Well yes and no. How's that for commiting to an answer? Typically in a cam follower needle bearings are used with a thicker outer race because the force is concentrated at one point on the outside of the race. A typical ball bearing isn't meant to have the outer race under constant asymmetric pressure so there is a concern long term of unusual wear when a ball bearing is used as a cam follower. But I agree that in this situation the concern is probably minimal. I don't like that there may be torque on the bearing that could twist it.

That would do fine for how often I change my oil?

It's kind of ironic that when I first got the 2018 I posted on here that it was the best shifting Beta I've owned. I suspect that as the indexer bearing has worn the position of the shift drum has been allowed to move leading to the problems I had. I was thinking about this a bit more and I think one of my assumptions may have been off the mark. Since it pops out of gear usually on a hit I thought it was probably the lever deflecting that was moving the shift drum. The problem with that idea is the lever sits centered position on either side of the cam and would have to travel with sufficient force to move the cam off the indexer. Now I'm wondering if the indexer was so loose that what was holding it in gear was the friction under power of the dogs. When the rear sees a bump the loading on the transmission is momentarily released allowing the dogs to disengage. The custom cams should be in in a few weeks. I have to press the pins in and then I can try one to see how it works. I wish I had taken it apart before I had the cams made to see the offset but hindsight... Obviously if I were a professional I'd split the cases and make sure the drum/forks were in the optimal position but that's a lot of work. I've tried several oils but currently Castrol edge 10W-30 titanium. Once the clutch mod is done the oil just doesn't seem to make much difference. The bearing overlap is about 2mm. Kinda sub-optimal with a 5mm wide bearing and a 5.5mm wide cam.

I'll wait to see the first revision of the custom cam. I may go for a modified version if there's clearance for the actuator.

Well still working the problem but here’s the latest discovery. I ordered a cam indexer to make measurements on since it was winter and I didn’t have a warm place to pull the motor apart. Last week I did pull the shifter assembly apart to put in the indexer I had made. So here are the indexers. The first is what was in the bike. 14mm diameter, 3mm wide and loose as can be. The replacement from Beta, 16mm diameter, 5mm wide. The indexer I put together, 13mm diameter, 5mm wide. What I learned seeing the actual assembly in situ is the indexer is offset from the cam and only hits the very end of it. A situation made worse by the offset of my design. I have to rethink that a bit. Beta seems to be using collections of whatever parts are in the bin. The stock bearing on my bike was crap. I put in my replacement indexer anyway and went riding. It popped out a few times when I did halfhearted stabs at the shifter but never popped out when I did a proper shift. Shifting also felt more positive snicking neatly into place when done correctly. So it is improved but not perfect. So where to go from here? I have custom cams machined that’ll be arriving in a few weeks. Deeper re-profiled notches and extra holes to move neutral between any two gears. Unfortunately they are not offset to match the indexer so I may have to rethink their design.

The older spacers had a metal ring on the end the sat on the spring. I don’t think the new ones do (I could be wrong). If not, the force from the spring might be deforming the plastic enough to make it jam.

I’ve noticed some odd tolerance type issues with the Sachs/Paioli forks so maybe they just didn’t machine the spacer right and stuffed it in figuring it would wear into size.

Yeah that’s weird. That bushing should just slide out. If it’s binding you might not be able to adjust your preload properly. Thinking a bit further it’s not even really a bushing. It’s just a spacer so they could use a shorter spring. Just out of curiosity did you loosen the top pinch bolt on the clamp when you tried to take it out? It shouldn’t make any difference as the tube should be strong enough to not deform from the clamp but stranger things have happened so...

That’s a new one. The spring is just loose in there and should just pull right out. If you compress the leg it should poke out the top.

If the UK importer can’t help you you might be stuck having a custom spring wound. There appear to be four different spring rates above stock available from Beta. Suspension spring chart-2016 EVO_0.pdf

Woodruff key is still your best bet. Nothing should vibrate apart no matter how high you rev. You could pull the reed block to make sure they weren’t damaged but it’s unlikely as when the bike is at high rpm the reeds just sit full open so they aren’t really stressed.

Not surprising. The reed cage is from a KTM 65.

Awesome. Nice catch!

Spring has sprung. Let the fettling begin. Clutch holder tool fits perfectly. (Edit) Oh this is getting interesting. After pulling it apart the stock indexer is different than the “stock” replacement. Where it contacts the cam is way off from what I expected. The shifter indexer/cam looks a bit like a thrown together assembly of mismatched parts. I’ll post an update later.

From the varied responses you’ve probably figured out we’re all just guessing too.? It’s not too complicated a system and I’m sure you’ll figure it out after noodling around with it a bit. Welcome to Beta.?

Won’t turn over as in motor locked up and won’t spin? Then seized which is unusual. Won’t turn over as in won’t start? Sheared woodruff key on ignition flywheel. Fairly common.

I’ve only had to have main bearings done once on a bike that sat in storage for the better part of a year. Just sitting did more damage than regular riding. When the Beta mains go there’ll be no question as it’ll sound like a rock crusher. The whirring noise is on every Beta I’ve ever owned and after a while you just tune it out.

10t, carbon reeds and a low compression head on mine. Not keen on extra flywheel as they tend to run on a bit more than I like. 13t is a street sprocket.?

The Beta gearbox is pretty robust. I had a prospective buyer (not the brightest bulb...) wind up and stomp on the shifter much to the horror of those of us watching. When I said, “What are you doing?!” His reply? “Starting the bike. Duh” Fortunately the bike just shrugged it off. He didn’t buy it either.?

I would not worry about a stand. Just take the bike with the engine off and roll it a bit back and forth while putting a little pressure on the lever up and down. It should be able to shift the gears pretty easily. If not then there is something bunged up with the mechanism. Is it stuck in neutral or a gear? Does the engine turn over? Your description isn't clear whether it's stuck in first and won't shift out of first or won't shift into first. Engine running or not running? It's a pretty simple mechanism so if it fails to work there's usually something like a part been dropped into it. Hopefully your mechanic gave you back the stock parts and you have six of each bolts and washers.

Is the lever moving? Can you feel the cam drop into place? It sounds like your mechanic might have pulled the shifter assembly out if he pulled the whole primary side cover off. To replace the clutch preload washers you only need to pull the round clutch cover which doesn’t involve disturbing the shifter assembly.