Jump to content

Beta Techno Shallow Fork Angle


ssaulnier
 Share

Recommended Posts

 

 

Dan thanks for the suggestion to pierce a small hole in the carburetor vent lines above the float bowl in order to stop fuel being siphoned out.

I used a sharp pick to pierce the two vent lines without destroying their integrity too much.

I tested this modification by cleverly falling over twice yesterday while practicing my off camber slow turns on dry dirt hillsides. With the bike laying on its side, fuel was flowing out of the vent pipes as expected. But after righting the bike there was no siphoning action and the fuel flow stopped (unlike previous rides when siphoning was observed).

In addition the clutch drag was much reduced throughout my 2 hour practice session as a result of adding the two 0.005” spacers under the clutch needle bearing. 

And my knees were more tired than my clutch finger so I suspect reducing the preload on the clutch springs by 3mm helped with no downsides noted.

The clutch still grabs just a little more aggressively than I would like so will try some of the Mobile 1 0W-40 European engine oil and only fill to the middle of the sight glass, about 475ml I think.

Link to comment
Share on other sites

 
 

As I think of things on your Techno I’ll try to add to this. The stock pilot jet for this bike was a 30 but most people ran a 27.5 as it made response off idle a little crisper. If your bike is running fine you probably already have one though. Your bike looks to be in excellent condition with no apparent wear on the titanium nitride fork coatings. You might want to find some fork guards. They’re cheap insurance to prevent a nicked fork stanchion.

For basic techniques there are other threads but stay centered. Steer with your feet. Keep your weight low and over the rear wheel when climbing... Have fun. It’s a silly sport but you can have stupid fun fur hours on a small pile of rocks. 

Welcome to trials. You’re now one of us.?

Link to comment
Share on other sites

 

Move your bars forward. Perpendicular to the ground or even slightly forward. Yeah it’ll make you wobbly at first, especially on loop trail, but you get used to it. You also want your levers much closer to level with the ground. If they point down you can’t control the bike as well on drop offs and steep downhills. You also run the risk of rolling your wrists on downs and that’s bad. Really it’s bad.

Link to comment
Share on other sites

 

Dan, I see what you are saying about the handle bars and levers. I have already rolled the bars slightly forward from the previous photo and they feel better. I suspect that they are still too far back so will roll them forward a bit more per your observation and adjust the levers a bit as well.

My biggest problem at this point is that when slow turning the front tire slides, scraping sideways over the top of the dirt, as I slip the clutch. I am trying to be more gradual with clutch engagement and have been trying to lean forward doing these full lock turns to put a bit more weight on the front wheel (but not sure that is helping). Have also taken a turn less preload out of the front fork spring adjuster so the bike has a bit of free sag in an effort to get a bit more weight on the front wheel for better traction. Preload adjuster has almost 5 turns of adjustment and I am at 4 turns of preload.

Front tire may need a bit less air as I think I am presently running about 8 psi, I think I will try 6 psi next time.

Front tire is also very old. Not cracked or worn but is a Made In Spain Michelin so I suspect it is likely pretty old. I am suspecting a new tire might give better traction on our dry South Texas dirt.

Are the Michelin trials tires the go to trials tire or should I be looking at something different for Texas dry powdery dirt, rocks, trees and cactus?

Link to comment
Share on other sites

 

Michelins are the gold standard but the 803 Dunlops are very good and cheaper. I find about 1 pound less air in the Dunlop gets traction similar to the Michelin. I tend to like to crawl over stuff and it's usually muddy or deep leaves/pine needles here so I'm typically at ~3PSI in the rear and 6 in the front. The pushing the front end is normal for a new rider especially with a Beta. Don't think about weight front or back. Think about centering and using pressure into the pegs to let the bike turn. A twitchy clutch makes it really difficult to turn as the abrupt grab/release loads and unloads the front making it skid. You can help this by feathering the rear brake against the clutch but the real key is to bend your legs and steer with peg pressure while keeping your torso straight. You may have noticed most of your dabs are on the inside of a corner. That's because you keep your legs straight leaning your body with the bike which is fine on a street bike or an enduro bike but doesn't work on a trials bike. When you lean the bike and keep your knees straight you compensate for this by twisting your torso and sticking your ass to the outside of the corner. This does a couple of things; first it keeps your core muscles in torsion so it's fatiguing and second you have no flexibility to deal with any situation that knocks the bike off line. To get an idea what I'm saying try this. Find a hill side and stand perpendicular to the fall line of the hill so one foot is higher than the other. Your weight is centered between your feet because this is the natural stance. This is how a turn should feel. You lean the bike and the outside leg bends more and the inside leg straightens a bit but your center hasn't moved from a line between the contact patches of the tires. Still on the hill try straightening the uphill leg. You will twist your body and stick your rear out to counter balance. This is an extremely weak position. Have a buddy poke you in the shoulder in both positions and you can see how little effort it takes to move you when you're twisted. Centering is the key. Unless you're doing a dynamic move you always want to be centered. This holds true for up and down too as you let the bike come up to you or let it drop away. You'll hear a lot of silliness about weight the inside peg or the outside peg but it's pointless since any imbalance in peg pressure has to be countered with bar pressure and you're right back in that core torsion situation. So let's assume you're centered and want to initiate a turn. Think pressure not weight. Apply a little more pressure to the inside peg to make the bike lean keeping your torso straight and your shoulders level. Once the bike is at the desired lean angle back to center and the bike will turn. Once the turn is done apply pressure to the outside peg to straighten the bike and back to center. Once you get the hang of it full lock figure eights are good practice and you can impress your friends by tuning around in a tight trail while they're bulldogging their non-trials bikes around. Thinking pressure can help on a steep uphill too. New riders will typically throw their weight forward thinking they need to hold the front end down. That unweights the rear wheel and they get wheel spin while the experienced guys just crawl up the hill. Watch videos of the top riders and you'll see on steep hills they squat low over the back wheel for traction. It takes practice to get used to this idea of weighting the rear wheel on an uphill but it works. The secret is getting low over the bike. When you stand up tall and accelerate you are a big long lever that wants to turn that acceleration into rotational force and going uphill that means a loop out but if you are right down on the "seat" of the bike the moment of inertia is greatly reduced and so is the tendency to loop out. A good way to practice is going slowly up a slippery hill and when you feel you're losing traction pull on the bars. Once you get good at it you'll find you can walk up slippery stuff at a crawl and since your knees are bent you can turn and go over things while still centered. OK it's late so I'll leave it at that for now.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

 

Dan, thanks for the trials clinic! I was looking for some Ryan Young videos on line  but thanks to you now I have lots to practice! 

After initiating a turn with peg pressure on the inside peg I was confused about the advice to weight the outside peg throughout the turn so I am glad that doesn’t make sense to you either. I like your picture language about centered weight balance and no contortions.

I will try your trick of pulling on the bars to improve traction on an uphill. I have some 3 or 4 foot tall steep soft dirt ditches that would be perfect to try this on.

I have tried alternately squatting down and standing up during the same hill climb and felt much more stable squatting. Your description of the physics explains that. I am an electrical engineer so relate to physics pretty well and appreciate a good first principles explanation.

You are right about the grabby clutch engagement causing the front tire to skid on the soft dirt while practicing slow off camber turns on the hillside. Will report back if the 0w-40 mobile 1 euro oil helps with that along with dropping front tire pressure to 6 psi.Waiting for the Amazon truck to arrive with my oil.....

 Thanks for taking the time to explain all that.

 I will have to get the Beta out of the shed and do some figure 8s today!

Cheers Steve

Link to comment
Share on other sites

 

One electrical engineer to another.? There is the clutch fix thread pinned to the top of this forum that helps smooth the clutch and stop the cold clutch launch. Long thread with much learndings as Ralph Wiggum would say. I didn’t expect it to become a magnum opus but it kinda grew wings and took off. Most people seem to like the fix. Some think it’s a load of dingo’s kidneys. 

Link to comment
Share on other sites

 

Dan, yes I have read though your procedure several times and performed that clutch plate glue removal and tab filing/polishing, totally eliminating my really bad cold launch issues. The clutch engagement action was also improved, but still to abrupt for my liking. 

Clutch drag was then improved by spacing the clutch pressure plate out 0.010" and clutch pull was reduced by installing 3mm washers under the clutch spring bolts. Note that the Techno manual states that there should be between 0.4 and 0.6mm free play in the clutch disengagement pushrod assembly, so you need to be careful not to add too many of these 16mm ID x 0.005" thick shims.

The Amazon delivery guy left 5qts of Mobile 1 0W-40 Euro oil on my porch this morning as I left for work! I think my "Italian Princess" is going to get an oil change tonight. 

Hopefully this Mobile 1 Euro will make the clutch just a little less grabby and will be the icing on the cake. We will see.

My Techno manual calls for 500ml of 20w-30 clutch oil, but I have read that ends up being too much oil as it increases clutch drag. 500ml seems to bring the oil level to the top of the sight glass on my engine case. The Techno manual says to keep the oil level at the bottom of the sight glass or higher. I will try 450ml this next oil change and see where that falls on the sight glass and add oil if needed to get in the sight glass window.

 

Link to comment
Share on other sites

 
 

Clutch drag was further reduced by spacing the clutch pressure plate out a total  of 0.015" (by adding a third 0.005" spacer washer under the clutch pressure plate bearing washer).

The 0W-40 Mobile 1 Euro motor oil actually INCREASED clutch drag significantly over the GM AC Delco Transfer Case Fluid Auto-Trak II. Using the mobile 1 I was unable to shift gears or find neutral while stopped and shifting was more difficult even while moving.

So I have gone back to using the 450ml of the GM AC Delco Auto Trak II fluid in the Beta Techno gearbox so am able to shift gears and find neutral with the engine running while stationary.

I rolled the bars further forward to good effect, per Dan's suggestion.

I left the Beta in the shed last Saturday and rode my 2004 KTM 200EXC on a very muddy work day at our local Dirt Bike Ranch. Due to my trials practice on the Beta I observed improved balance and confidence in the sloppy mud and water ponds whilst riding the Enduro bike. 

Looks like even Old Dogs (62 YO) can learn new tricks!  :)

 

  • Like 2
Link to comment
Share on other sites

 

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...