Water In Gearbox And Other Problems

[hrmad]

video problem sorted, soz!

[hrmad]

Have you repacked the tail pipe? If not then you will probably find the smoke you are getting is from years of unburnt oil, if the tailpipe is chocked with oil this will also stop the bike running correctly.

You can get a replacement packing cartridge from lampkins for about £15.00 and it's a 5 min job to fit it may sort out both problems in one hit (smoking and running poorly).

Worth a go, thanks

Most of us do carry some small bag with spares and a few tools. Add some zip ties.

The video says it is private so I could not watch it.

You ran with the filter out and had no improvement so yes, you can rule out a plugged filter.

From your description, it does sound like the bike is getting too much fuel. Yes, the screw circled in red is the idle stop screw and the blue one is the air screw. The air screw does change lean/rich ratio but mostly at idle. It doesn’t have much affect at high RPM. Up and to the right of the red circle is the “choke.” I can’t tell if there is a lever on it. It should have a plastic lever that you flip so it is pointing up to start. Then once the bike is running and warmed a little you flip the lever down. If you don’t flip it down, or if it is broken in the up position, it will send lots of extra gas into the engine causing exactly the conditions you are reporting. There are other carb problems that could also cause the rich condition.

If the “choke” lever (its not really a true choke it is an enrichment circuit that serves to give more fuel when cold to help it start) is OK, it does sound like you will need to get into the carb. I know there are a number of youtube videos on how to rebuild Mikuni’s. Get the model number of yours and do a search. Good news is it is often just a good cleaning and proper adjustment so it’s pretty cheap to do. Pay particular attention to setting the float height and adjusting the needle in the slide.

Running the bike a bit rich will not damage it, just make it not run cleanly so keep on riding!

Sorry about the video, it should work now. The choke doesn't seem to be a switch as such. You pull it up to open, and push down to close as far as I know- it doesn't seem to go any other way. I don't know how it is on other betas of this type and with this type of carb. Time to do some research... Thanks again for all the advice, I will get the problem sorted out one way or the other!

[worldtrialchamp]

sounds like it choking on raw fuel....fuel in crankcase from leaving tap on?

[hrmad]

sounds like it choking on raw fuel....fuel in crankcase from leaving tap on?

Maybe, I have remembered to turn the tap off when she's not running, but I don't know what sort of treatment the bike had before

[thats_a_five]

Hi Heather,

Sorry for the slow reply. Once in a while I need to take time to make a living. L

From watching the video, it looks like the bike is getting too much oil. This could be from several reasons:

1) left over 50:1 mix when you added 70:1.

2) Excess fuel/oil mix (carb letting too much through). Excess fuel is a common cause of fouled spark plugs. This can come from clogged carb, incorrect jets, or leaking “choke” (enrichment) circuit. This is why I asked about the choke. If it is not shutting the enrichment circuit fully, it will pass extra fuel. Also, inside the carb is a slide that is connected to the hand throttle. On that slide is a “needle” that moves with the slide and opens and closes the main jet. If that is adjusted wrong it will let in excess fuel. There is also the float which allows the fuel to enter the carb in the first place. Adjusted wrong it can also cause excess fuel.

3) Plugged exhaust as mentioned by Worldtrialchamp. Badly plugged will cause the engine to not run well in upper RPMs. Heavy smoke from old oil in the exhaust usually happens worst after long pulls up hills or high RPM running which puts lots of heat into the exhaust. This happens even with new, well adjusted bikes.

The operation of 2 stoke engines is really a combination of the whole system, including intake, combustion and exhaust. Changing one has an effect on the system. The good news is that most of the things that can get out of adjustment can be readjusted.

Start with the easy stuff. Hotter plug first. Make sure the choke is fully off after starting. Let us know how that works.

Bill

[hrmad]

No worries Bill, we've all got to fund the bikes somehow, hehe.

My friend took the carb apart today and showed me how to do it and put it back together correctly. The carb looked clean, Jets weren't blocked up, we adjusted the tabs slightly. The main jet is 140, we're considering going to a 130 to see if it improves matters. We also checked the choke, it was working correctly and closing correctly.

We also took off the reed valve, there was a problem there. The petals weren't fully closing, so I am going to try to find some new ones online, along with the gasket. We took a look through the gap where the valve was, the cylinder and piston were both in good condition- one thing to be thankful for!

Number 6 plugs have been fouling within an hour, if it continues after the reed valve fix we could try a 5.

[jfc]

The bp5es is the plug you need, but before you start to re-jet the carb check that tail pipe as you will be chasing you tail if you do the jetting first.

[thats_a_five]

If the reeds are not sealing properly, it is more likely to run lean than rich. Same thing with the gasket. If it is leaking the bike will run lean. From all you have described, the engine is running rich (too much fuel). Unless the reed is cracked or chipped, I would not worry about that right now.

I am a big believer in doing one thing at a time and starting with the easy (and cheap) stuff first. I also like to think that the bike used to run well so before I start changing parts I want to try cleaning and adjusting things. I think I remember you commenting that the previous owner had put in the wrong plug. Do you have the old plug? If it ran good with that plug, put it back in. Or get a new one of the same number.

I want to be sure that the parts are in good condition Here is the sequence I would try:

1) Replace that plug. Preferably a new one. (Cheap)

2) Clean and repack the silencer to get rid of the excess oil buildup. (Cheap)

3) Drop the fuel needle in the carb. (Free - just time). Good to hear that the carb looked clean. Before you start changing jets, you can adjust the needle in the slide. Unscrew the top on the carb, pull up the slide and needle. Compress the spring and disconnect the cable from the slide.

The brass needle can be adjusted by changing the position of the little C-clip. Be very careful when removing the clip because they seem to enjoy flying off and hiding. There are several grooves in the needle. Moving the clip toward the pointy end will make the bike run richer, moving it toward the flat end will drop the needle making the bike more lean.

When reassembling the slide be sure to align the slot in the side with the little index pin inside the carb. Before you start the engine be sure to check the smooth operation of the throttle. If you turn the throttle then let go, you should hear the slide click when it contacts the idle screw.

4) Sometimes you can flip the reeds over and they will fit and work. Free to test.

5) After all these things are checked and good, then you can starting changing jets.

[hrmad]

jfc: Thanks, I will try the bp5es. I'll have a look at the packing in the exhaust when I get to the bike again, she's down my friends workshop at the moment.

If the reeds are not sealing properly, it is more likely to run lean than rich. Same thing with the gasket. If it is leaking the bike will run lean. From all you have described, the engine is running rich (too much fuel). Unless the reed is cracked or chipped, I would not worry about that right now.

I am a big believer in doing one thing at a time and starting with the easy (and cheap) stuff first. I also like to think that the bike used to run well so before I start changing parts I want to try cleaning and adjusting things. I think I remember you commenting that the previous owner had put in the wrong plug. Do you have the old plug? If it ran good with that plug, put it back in. Or get a new one of the same number.

I want to be sure that the parts are in good condition Here is the sequence I would try:

1) Replace that plug. Preferably a new one. (Cheap)

2) Clean and repack the silencer to get rid of the excess oil buildup. (Cheap)

3) Drop the fuel needle in the carb. (Free - just time). Good to hear that the carb looked clean. Before you start changing jets, you can adjust the needle in the slide. Unscrew the top on the carb, pull up the slide and needle. Compress the spring and disconnect the cable from the slide.

The brass needle can be adjusted by changing the position of the little C-clip. Be very careful when removing the clip because they seem to enjoy flying off and hiding. There are several grooves in the needle. Moving the clip toward the pointy end will make the bike run richer, moving it toward the flat end will drop the needle making the bike more lean.

When reassembling the slide be sure to align the slot in the side with the little index pin inside the carb. Before you start the engine be sure to check the smooth operation of the throttle. If you turn the throttle then let go, you should hear the slide click when it contacts the idle screw.

4) Sometimes you can flip the reeds over and they will fit and work. Free to test.

5) After all these things are checked and good, then you can starting changing jets.

Hey Bill.

The reeds are definitely not as they should be, I've ordered some boyesen trials ones which weren't crazy expensive. Still waiting for them in the post. We'll have to see how it affects things when she is running.

The old plug had also gone black and was too short. Maybe it was an attempt to treat the symptom not the cause, or ignorance on the previous owners part. I don't know.

I went through 4 plugs just testing if the plug would foul without the air filter, which it did and tried a 6 instead of a 7, next will be a 5.

My Dad and my friend are quite dismissive of the exhaust packing being a problem, but as the packing is generally 12 pounds or under I do personally think it is worth doing. I just don't want to do it wrong and cause more damage on my own.

I took a look at the online manual for this beta, the standard jets were 150 main, 30. I think there was a 140 on there when we checked, if all else fails I suppose we could put it back to standard- although am I right in thinking a bigger number = richer?

Can't find the standard set up for needle, will try out what you have suggested.

Tried flipping the reeds round, still worn and not looking right. Not a difficult fix.

So, will try bp5es in bike, change reeds and adjust needle. If problems persist, I will change the packing once the bike is home. If plug fouling still occurs after that jet changes as suggested.

Thanks everyone

Edited October 16, 2014 by hrmad

[thats_a_five]

Heather,

It could be you found the problem with bad reeds. It will be interesting to hear the result.

I suspect the previous owner did go to the hotter plug to try to fix the rich running. That is usually the first thing to try. You know you can clean the plugs to keep for spares, right? People use various techniques for this. I tend to use lacquer thinner and a wire brush but have also used the gas torch method (search Youtube cleaning spark plugs).

The packing in the silencer is not exactly the heart of the exhaust problem. The real problem is the closing up of the small holes in the baffles or spark arrestor screens. It varies by the design of the internals but if the exhaust gets plugged up, it will be sort of like trying to blow up a balloon while squeezing the neck of the balloon together. The air just can’t flow through freely.

This will cause the bike to not be able to rev up cleanly. Too rich of a mixture will cause a build-up of oily residue and carbon inside the exhaust system. The system includes 3 parts: head pipe, center silencer, and rear silencer. There are threads and many techniques for cleaning each of these parts. Most people do just the rear silencer with good results but ultimately it makes sense to clean them all for optimum results.

One clue that the exhaust is clogged can be that exhaust is trying to leak out at the connections between the 3 pieces. Another is the weight of the unit when removed. The silencer is basically an aluminum tube with fiberglass packing and a center steel perforated tube. All lightweight materials. I think it should only be less than 2 kilos. If it is heavy, it is packed with oil and carbon.

To do the rear silencer, you have to drill out the rivets that hold the end cap on. Then pull out the packing and the perforated tube and any screens or baffles. This is a messy job. Bin the packing and clean the tubes and screens thoroughly. I had a GasGas that was so plugged it didn’t even look like there were perforations. If there is a spark arrestor screen, make sure that is thoroughly clean as well.

You could try running the bike with the rear silencer removed but it will be loud.

The main thing you need to be careful of is getting the perforated pipe correctly aligned to both ends when reassembling. Not hard to do. There is really not much you can do wrong. If it fits together easily you got it aligned properly. Reassemble with new packing material and new pop rivets to hold the end cap on.

You are correct, the larger the jet number the larger the hole that allows fuel through so the richer it will be. I think the number is the hole size related to millimeters. #150 = 1.5 mm. 140 = 1.4 mm.

You did check the float height in the carb, right? A float that is too high can cause flooding because the excess fuel has to go somewhere and it usually goes to the engine rather than out the overflow.

As always, keep riding and letting us know how you get on with the bike.

Cheers,

Bill

[worldtrialchamp]

any update HRMAD?

[hrmad]

Hey Bill,

Thanks, I'll have a look for spark plug cleaning tutorials, might come in handy. As for the silencer, we took it off when replacing the bones around the air box and I don't recall it being overly heavy. It's something to try if the reeds and 5 plug don't solve the issue. Thanks again for the advice. We did check the float height and made minor adjustments to the tabs. The chamber wasn't flooded with fuel when we removed the carb, don't see a problem there.

Hi Worldtrialchamp, the boyeson reeds finally came today. I've left the bike at the workshop, I will get down there on Monday, fit the reeds and try the new plug then. Hopefully she'll be running well by next Sunday, a local trial is on that I want to try the novice line on. thanks for asking

[b40rt]

For plug fouling in the ngk range, the lower the number the hotter it runs, burning off excess carbon etc.

http://www.ngksparkplugs.com/tech_support/spark_plugs/p2.asp?mode=nml

Edited October 19, 2014 by b40rt

[hrmad]

Thanks for the link b40rt, very informative

Put the new reed plates on today, put the carb back on, turned the air fuel mix 1 and 1/2 turns, lowered the idle speed slightly and put in a bp5es plug.

The bike has improved a lot, went well today for two hours practice or so. I'll ride the bike again tomorrow and see how it goes. It's a lot smoother at lower rpms and isn't smoking as much as before. You can really tell the difference, it's much nicer to ride.

[burns1989]

Hi just a pointer running less oil will make the fuel mixture rich and running more oil will lean off the mixture so if you want to use less oil you should adjust your jets to suite plus different temperatures will affect jetting and running , the pilot jest screw is only going to richen or weaken the pilot jet off idle , you should ring beta uk to see what oil fuel ratio you should run with the jetting if its stock , plus two stroke engines don't like to be ticking over as you need to get the heat in to allow the pug to work correctly to burn the fuel off , a perfect air fuel mixture and right jetting should coulor the plug a biscuit brown and you know you are spot on . but I don't think you will be able to see that as the engines are never flat out . if it were a oily plug id say too much oil but your plug is sooty suggesting its too rich , id drop to the next two sizes smaller on the main jet and on the pilot jest and see what happens . I use rock air filter oil soak the filter squiz out the excess oil allow to dry for 24 hours and its all good and use the air filter cleaners as they do not melt the foam and get all the oil out. check the ignition timing is spot on as well could be slightly retarded

Edited October 20, 2014 by burns1989