2020 Beta 300RR wont start

[RR 300]

Looking for ideas of why it wont start
I have spark and fuel
Drained fuel and replaced and also removed jets to check if blocked
Swapped of spark plug with a spare

Bike was started 2 weeks ago with no issues

Any help would be appreciated

[F5 Dave]

Roll it down a hill.

Pwk carbs some people lay the bike over to flood the carb a bit more. But 2 weeks should be nothing.

I'd try a 3rd plug.

Check choke is holding up OK.

Float level should not leak on sidestand, but start to if tipped a bit further.

[RR 300]

Roll it down a hill.

Pwk carbs some people lay the bike over to flood the carb a bit more. But 2 weeks should be nothing.

I'd try a 3rd plug.

Check choke is holding up OK.

Float level should not leak on sidestand, but start to if tipped a bit further.

Thanks Dave,

New spark plug fitted and still not going

Chock is clicking up so I say its working correctly

I have tried to bump start in driveway but it didn't work... not a hill but differently fast enough to get it started

Some things i have noticed is when I give it a bit more fuel it sounds like it want to go but to much throttle and it backfires. When i drain the bowl more fuel runs out of the overflow... is that normal?

[F5 Dave]

Hmm. OK going out on a limb.
Is the throttle closing properly? Like if you snagged the cable loading it up on the trailer, pulling it out so it hangs up on the adjuster?

Either end.

Closing it should bonk on the carb body.
Reason I ask is that it can feel ok at the throttle, but if the slide is hung up 5mm, you won't start it until you get it spinning fast enough for long enough. Unlikely off the start button. Dangerous if it does. Should have mentioned that before I said crash start it.

[RR 300]

Hmm. OK going out on a limb.
Is the throttle closing properly? Like if you snagged the cable loading it up on the trailer, pulling it out so it hangs up on the adjuster?

Either end.

Closing it should bonk on the carb body.
Reason I ask is that it can feel ok at the throttle, but if the slide is hung up 5mm, you won't start it until you get it spinning fast enough for long enough. Unlikely off the start button. Dangerous if it does. Should have mentioned that before I said crash start it.

I think it is, when I had the carb off the other day i did check the throttle was was moving but didn't pay to much attention to the gap. I'm thinking of check the reed valves too.

[F5 Dave]

You'd be seriously unlucky for the reeds to break. Betas are usually pretty reliable.

[pete376403]

When you tried bump starting, what gear did you have it in? First or second is too low and will probably just lock the wheel. Try third or fourth. push the bike up to speed, dump the clutch. Might help, couldn't hurt

[Kickaha]

I have seen reports of wires chafing though on the headstock, although I think that was the model before, I'd also check the flywheel hasn't come loose

[RR 300]

You'd be seriously unlucky for the reeds to break. Betas are usually pretty reliable.

You'll right, the reeds are fine.

The carb is making that donking noise when I close it but it looks like there is a small gap at the bottom.

Spoke to bike shop and suggested to take spark plug and tip the bike over and see if fuel comes out, he is thinking fuel may have got into the bottom end.

[RR 300]

I have seen reports of wires chafing though on the headstock, although I think that was the model before, I'd also check the flywheel hasn't come loose

Thanks Kickaha, wires are ok and it has had the loom changed because of that happening.

If the flywheel was loose wouldn't I hear it when I try to start it?

[F5 Dave]

OK that's OK for carb position.

GG have a removable bung bolt so you can drain cases if drowned. Or gas flooded. A lot of Euro bikes did. Was a bit surprised my Beta doesn't.

[Kickaha]

If the flywheel was loose wouldn't I hear it when I try to start it?

Nope, we were on a ride when that happened to a guy on a Sherco, it wasn't obvious until the cover was removed, we had stopped and we went to move on his bike would not start

[RR 300]

Nope, we were on a ride when that happened to a guy on a Sherco, it wasn't obvious until the cover was removed, we had stopped and we went to move on his bike would not start

Had a look today and flywheel in tight and has all teeth.

thanks for the suggestion

[RR 300]

Update:

Still not luck but do have 1 question.

Does fuel spray in to the carb when it is removed from its boots. The bowl is full but when I open the throttle no fuel is enter the carb. I have cleaned the pilot jet but am thinking it maybe blocked some where else.

[F5 Dave]

Does the what, when it what? Boots?

So, no it doesn't have an accelerator pump like some foulstroke carbs used to.
Engine has to spin to suck gas up into the airstream.

Wow this really is getting perplexing. I'd be driving to a long downhill at this point.

Ps helmet always, pull clutch anytime it gets away and let it Rev if for some reason the throttle is stuck, even though you pretty much discounted that.

[jato]

sounds like its time for some basic checks... give it a teaspoon and-a-bit of fuel down the plug hole and see if it trys to run for a few seconds.( you might need to kick it 5 or 6 times with a handful of throttle) if so, you've narrowed the problem down

[RR 300]

Does the what, when it what? Boots?

So, no it doesn't have an accelerator pump like some foulstroke carbs used to.
Engine has to spin to suck gas up into the airstream.

Wow this really is getting perplexing. I'd be driving to a long downhill at this point.

Ps helmet always, pull clutch anytime it gets away and let it Rev if for some reason the throttle is stuck, even though you pretty much discounted that.

HAHA.. I knew I didn't explain it right but I'm glad someone understood what I meant.

[RR 300]

Update....

finally gave in and took the bike to the shop.

They found the Keyway for the flywheel had broken. This let the flywheel move which messed up the timing.

I never would have found that, even when I checked the flywheel and it seemed ok.

Anyway, its going now

Thanks for the help everyone

[F5 Dave]

Cool. Chocolate fish to Kickaha for guessing correctly.

Pants to Luigi for not tightening it up at the factory properly.

[pete376403]

Update....

finally gave in and took the bike to the shop.

They found the Keyway for the flywheel had broken. This let the flywheel move which messed up the timing.

I never would have found that, even when I checked the flywheel and it seemed ok.

Anyway, its going now

Thanks for the help everyone
Point of order -the key sheared - the keyway is the slot the key goes in. If the key is semi circular then it is a woodruff key

[Kickaha]

Cool. Chocolate fish to Kickaha for guessing correctly.


The bikes I have seen do it were obvious once the side cover was removed though

[F5 Dave]

It will be a woodruff key, yes.

It is only there for easy exact assembly of course. The taper locks it in place. I've assembled racebikes without keys out of necessity, but it is a pain so I've got the flywheel broached in correct location and filled the old one once settled.

[pete376403]

My F9 Bighorn used to shear keys regularly, until i lapped the rotor to the taper with fine valve grinding paste.

[Grumph]

Surprising how many people use woodruff keys that are too tall. The flywheel ends up running on a small piece of shaft and the top of the key
Doesn't last long.

Saw just that at one Lady Wigram meeting. Freeth was running the Starlet and had sheared a rear hub key. Sprint car quickchange solid axle.
So naturally he comes into the bike pits and asks who's got a box of woodruff keys with them ?

Jungle McGregor was standing there so I immediately said - You know Jungle don't you Roger, he just lives literally round the corner - and i'm sure he'll have everything you need. Away they went to Jungle's place.
Talked to Jungle later and he told me they'd lapped both hubs and put the correct keys in. Both had been too tall for the keyways. DNF just waiting to happen.

[F5 Dave]

Ahh can see how that happens. It won't wobble because it's centred by the washer and nut.
Thanks will look out for that. They usually only go 1/2 way up groove but that makes sense now.

I have a small selection in my race/dirt toolbox.

I've used fine valve grinding paste (also in toolbox) to clean up suspect tapers. Obviously it's never been used on valves. They live in inferior engines.

[Kickaha]

The taper locks it in place. I've assembled racebikes without keys out of necessity,

I sheared one in first practice on my IT200 at a VMX, I didn't even try and find another one, lined the flywheel up on the shaft, tightened it with an impact gun and finished another 5 races

[merv]

I sheared one in first practice on my IT200 at a VMX, I didn't even try and find another one, lined the flywheel up on the shaft, tightened it with an impact gun and finished another 5 races

Kick it seemed to me back in the day it was a 2T problem because I never saw a 4T Honda have a flywheel move. Is there an explanation as to why the 2Ts do this?

[F5 Dave]

Probably a combination of heavier flywheel (foulstrokes hide their inertia in associated reciprocating components) and

home mechanics doing rebuilds on the more simple 2 stroke bottom end, but having nothing to properly hold the round flywheel, much less own a torque wrench.

Our friend here suffered from Giuseppe being distracted by the delectable office girl and then rushing off for a lunch of. . Actually, I have literally just finished last night's leftover spaghetti and Italian meatballs so I've fallen into my own stereotypical trap set to slur anyone else but my culture.

Oh the shame.

But if it happens again (unlikely) I'd be reaching for the bearing blue to test the taper has wide engagement, then the valve grinding paste.

Machinery tools lathes etc rely on tapers and are quite reliable.

[jato]

Just a fine point on lapping flywheels on to tapers - when you've finished lapping you need to relieve the ends of the flywheel bore a few thou to allow for the fact that with the paste cleaned off the flywheel will advance up the taper further. if something like a gp bike i will have it's rotor heated in hot water before fitting to give a secure "bite". peace of mind ...

[Grumph]

Kick it seemed to me back in the day it was a 2T problem because I never saw a 4T Honda have a flywheel move. Is there an explanation as to why the 2Ts do this?

I don't think Kick's old enough to know this one.

2T's have a lot less advance than 4T's. It is quite possible to wind up with a cylinder full of hottish gas ready to light and have it fire at low enough RPM that the flywheel mass does not carry it past TDC. It then kicks backward. This can of course loosen the flywheel nut which leads to the already seen sheared key.

4t's don't generally do this because they have well defined intake, compression and ignition phases.

Back in the day when 2T oils were depositing thick crusts of crap on anything they came into contact with it wasn't unknown for this hot crap in the ports to fire any mixture whic came in contact with it. One instance the old man used to quote was a mate riding a Scott. Held up by traffic at one of ChCh's bridges and stalled.
Let it run backwards to give himself some room, let the clutch out to slow down - and it fired - and ran backwards. Till he fell off.

[F5 Dave]

Meh. He'd just set the timing too retarded. Hilarious but avoidable.