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

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!

When you fixed the spoke you had to remove the giant rubber band from inside the rim, right? That rim strip must be properly installed into the groove in the rim. They can be very tricky. Jim Snell made a really good video that you can see on youtube. http://www.youtube.com/watch?v=1sAD6l0ORVg&list=PLfrG78Ca76TbmQbYODIpXU4Inj8Lpi8JT

Can you post a copy of the wiring diagram?

The 5 plug should be better. 7 is pretty cold. On my 2 strokes, I always carry a spare plug and changing tool. Even really well running bikes will foul plugs occasionally. They usually do it at the farthest possible distance from the truck or trailer. Mags is right about cleaning the air filter with washing up soap and water. Using petrol or solvent will shorten the life of the foam filter. A light coat of oil is all that is needed. I had some spray on oil but switched back to light oil massaged in as Mags described. Keep the spare filter clean, oiled and in a sealed zip-lock bag. Hopefully the better fuel/oil mix and hotter plug will cure the fouling but don't worry about tearing into the carb. After what you have already done, carbs are a piece of cake!

Threaded rod is available in different strengths and harnesses. Regular hardware store rods are usually pretty soft and can stretch when heated. The original bolts are probably the best choice but if unavailable get some heat treated, high strength threaded rod to make your own.

The bike is looking good. I wonder if the front fender is on correctly. I know some people who ride mud sometimes mount them with the back end of the fender close to the tire, like yours, to act as a scraper. That may explain the mounting. You may find better clutch control if you rotate the perch and lever up higher. This move the clutch from your fingertip to the first joint in your finger. I would suggest adding more oil so you can see it part way up the sight glass. Just draining the oil through the drain bolt does leave some of the old oil inside the engine and clutch housing. When you removed the clutch housing, more of that oil was able to drain out. As a result, it will take a little more to bring up to the proper level. The fouled plug does indicate an over-rich condition. Sometimes, with prolonged slow running, a plug can foul in even a perfectly adjusted bike. It is a good idea to rev it up from time to time to burn off some of the carbon. Wait until the engine is warmed up before doing this. I seem to recall you saying the previous owner had put in a wrong plug. That was probably an attempt to solve the fouling problem. Other possible causes are plugged air filter, incorrect jetting, improperly adjusted carb float, and improper fuel / oil mix. You can test for a plugged or over-oiled, air filter by running it dry or even without the filter for a short time. Get that mixture corrected to the 80:1 range. You mentioned replacing some fiddly parts near the rear shock. I think you are talking about the “dogbones.” They have bearings that can be replaced. These bearings have a tough life. They are down in the water, dirt, and mud a lot. I recommend at least cleaning and repacking with grease every 6 months. The bearings can also be pressed out of the castings for replacement. Bill

Recheck your wiring. It sounds like the fan wiring may be shorting to ground. 14 volts AC before the rectifier sounds right.

I applaud your willingness to jump in and work on the bike (with the help of a friend). It sounds like you are doing a good job of fixing up many things that have needed a better repair then they had in the past. It is a good feeling to know that things have been put right and they will be unlikely to fail for a long time into the future. I don't know the market value of bikes in your area but it doesn't sound like you made a bad deal. I do think you have given us all a good reminder to think and do some research before we buy a used piece of equipment. We are quite fortunate to have a resource like Trials Central to read old posts of what to be aware of when looking at a used bike. I look forward to hearing how you do in upcoming trials. Keep your feet up and keep smiling!

Check the bolt on the flywheel.

Did you get it fixed?

HI, Sorry for the slow reply. I think you already have answers from Mags and others. Their answers are accurate but unfortunately they are not good news. At the risk of being redundant, here are my answers. Yes, there looks to be significant corrosion inside the water pump portion of the housing. The surface inside the water pump area should look very much like the surface just to the right of the sight glass in the photo – more smooth looking like it has a nice coat of paint on it. In fact, it should have a nice coat of paint on it prevent the liquid coolant from touching bare metal. Once the paint loses a good seal on the metal, the coolant can start to “eat” the metal. Two problems exist: 1) The coolant “eats” the magnesium much faster than it “eats” aluminum. 2) Once the corrosion starts it can be very difficult to stop. Usually it is necessary to grind or cut away the corrosion until you get to good, solid metal below it with no signs of corrosion left. If you don’t get it all, the corrosion will continue, even if you put a good coat of paint on the entire metal surface. It is difficult to be sure just from the picture but it looks like the corrosion has eaten away enough material to make holes completely through the metal allowing the coolant to pass through the little holes it created in the metal. We previously thought the coolant was leaking past the rubber seal on the water pump shaft. It seems now that the coolant is passing through the holes in the metal. When things heat up, they expand. So, the coolant expands when hot and builds pressure while forces some of the coolant through the holes in the metal. When it cools, it gets smaller, creating a vacuum. This thermal expansion and contraction could explain how the water got into the gearbox when hot and possibly how the oil appeared to go down as the motor cooled because the oil got sucked into the cooling system. Now to the question of what to do to fix it. Choice A: Repair with sealant. Unless you can completely remove any existing corrosion and apply protection to prevent it from returning, any “fix” will be temporary. A poor fix could fail in weeks, a good fix could last years. A big part of poor versus good will be how well the existing corrosion is removed from the metal it is attacking, and how well you can seal that metal surface to keep the corrosion from “eating” the metal again. The other main part of the repair has to do with the heat expansion again. Because metal and plastic expand and contract at different rates with heat, the sealant can come unstuck from the metal allowing coolant to leak between them with the resultant leak and additional corrosion. Some of the epoxy type sealants have tiny particles of metal mixed in to try to make the epoxy expand and contract more like the base metal. One brand available in the states is called JB Weld. This is probably the cheapest fix in the short term. Choice B: Repair by grinding out the corrosion, welding in new metal and machining it back to the original size and sealing it against corrosion. To do this well, the complete housing should be removed and the welding done by a professional. It might be cheaper than buying a new housing, it might not. Research can determine that. If done well this repair could last longer than the epoxy repair but if done poorly might not last as long. Choice C: Replace the housing. If you do this, try to find a new housing made from aluminum (aluminium in the UK), rather than magnesium. See this link for a video of how to tell aluminum from magnesium. http://www.youtube.com/watch?v=g2A5o_MJ1-k . If you choose this option, be absolutely sure there is a good coating on the metal (even paint some extra layers on) because the slightest bit of bare metal that contacts the coolant will allow the coolant to start “eating” the base metal again. This choice is probably the most expensive but also has the best chance of lasting for a much longer time before failure. Whichever choice you make, be sure to check that oil sight glass every day before riding so you can see very quickly if another leak is starting to pass coolant into the oil. I am sorry that you are faced with this so early in your ownership of the bike. I wonder what recourse might be available to you with the previous seller. It is difficult to tell from the pics but if there had been a previous “temporary” repair, that previous owner had known, and did not tell you about, they might have some legal responsibility or even feel some moral responsibility to participate in the repair. Good luck and keep up posted on how you get on. Cheers.

Wow, 38 pounds. That's about US $61. Our club charges $25 for a trial. Come ride with us! Haha. Bit of a commute to Seattle from where you are.

Sorry to hear about your "off." Many of us have had similar experiences and you drew exactly the correct conclusion: Don't ride alone. But, if you are going to ride alone, drop down a few levels in the degree of difficulty of obstacles. I also always carry my mobile phone in a padded case but know that there may or may not be service in the remote locations. And trust me, at 52 it may be a bounce. At 62 it's a thud. Here's hoping you heal up quickly and get back on those pegs!

I am not a beta expert but I would start by making sure that you have correctly installed the shift shaft and the springs that position the levers and pawls that engage with the shift drum. These can usually be accessed inside the clutch housing without splitting the engine cases. I recently got a great deal on a Yamaha because it would not shift. Found that one of the small levers had a broken tab. Replaced that and it worked perfectly. $700 price discount for a $15 fix.

Don't beat yourself up over buying the bike with the bad seal. It would happen some time anyway so you would have had to learn sometime. After 4 oil changes, all the previous water should have been out so it clearly has new water getting in. If you decide to disassemble the clutch, be sure to keep track of the order of the plates for reinstall. You can clean up the steel plates with some #400 abrasive paper on a flat surface and slide the plates on small circles to keep them flat. I have had the fibers come unglued from the plates when water was in the oil for too long. They can also swell. If they seem OK, a light sanding the same way is OK. I don't know about Beta but my old Gasgas had an index mark to get the pressure plate clocked to the clutch basket during reassembly. Have fun!

The oil does look milky. That usually indicates water in the oil. If you had just been running the engine it can look a bit milky because there are many tiny air bubbles in the oil. Let it rest for an hour or so, then check again. If it is still milky it is probably water. You never get 100% of the oil out when draining. Most manuals say to drain the oil when it is hot do get a more complete drain. Be careful to not burn yourself. So when you refill you have a little old oil and mostly new oil. If it has water in the old oil it will cause the new oil to look slightly milky after it mixes during running. Usually 2 changes of oil should remove the old oil enough that it does not look milky. If it gets milky again after that, there is new water getting in somehow. (I just reread your original post and it sounds like it is getting milky after oil change so it probably is getting new water in). The slight loss of coolant water would support that idea. Usually the oil should be half way up the sight glass so it looks like you have too much oil in there. The bike should be level when checking, not leaning like resting on the side stand. Too much oil can cause some clutch drag also. It is rare that the oil level would go down unless it is leaking out somewhere. Do you see any puddle of oil under the bike? I suspect the water pump seal is leaking and needs to be replaced. It is not a hard job to do but do need to pry out the old one so it might be a good idea to have someone else with experience help you. ** You also mention that the bike is hard to kick. The very short kick lever on trials bikes makes then hard to kick so it is usually best to take the bike out of gear when kicking. Not a bad idea anyway if you have a sticking clutch so the bike does not take off when it starts. Even in neutral I always make sure to hold the clutch in and the front brake on when kicking.

It sure sounds like a plugged idle jet circuit to me. Clean, clean and clean some more. Soak or ultrasonic, then blow compressed air through all holes in both directions.

I know some guys who ride endures on trials bikes. If the trails are tight and twisty they kick butt. But when the trail is high speed desert running they simply don't have the high speed capability to keep up. Per your other thread, there is water getting to your oil somehow. Be very careful that you don't run the radiator dry or things could get expensive.

Congrats to you both. The first of many memorable trials days.

The water in the gearbox will make the clutch drag badly. Sorry, I don't have Beta knowledge. Common way for coolant to get into gearbox on other brands is leaking or failed water pump seal. If you disassemble the pump, check the impellor shaft closely for wear. If it has a groove from the seal, it should be replaced or the new seal will not fully seal. Remember to install the seal in the direction so water pressure will squeeze the seal tighter on the shaft, not the other way round.

I don't get any pop-up ads when on Trials Central. Thanks Andy.

There are separate windings on the stator for the ignition and the fan circuit. Please notice on the wiring diagram that the regulator which feeds the fan does not feed the ignition in any way. The ignition is fed from a different winding of the stator. It is highly unlikely that a bad voltage regulator or fan motor would cause the spark problem you mention. One sure way to confirm that, is to disconnect the regulator wire from the stator so the regulator and fan circuit are completely out of consideration. Then, wire 12 volts from batteries directly to the fan so it will run and cool the engine. Then ride.

Quote "its was almost as if the bike was running lean so dropped the needed still dose it" Dropping the needle will make the bike more lean. Or did you mean, you lowered the clip on the needle?

Hate to sound too basic here, but have you tried a new plug? Not a recently cleaned one but new from the box. Plugged baffles in the mid box could make for loud popping because the pressure wave is forced through rather that expanding through the baffles. Should not create the surging problem you reference. Did the previous owner lighten the flywheel? Does the surging only happen in corners? What about straight line at idle?