mcman56

Can you explain your reference to a hacksaw? I have seen pictures of bikes with the lower frame tubes removed but this bike has a sump plate that actually hangs down lower than the frame so I don't see how that would help. I also ride in areas with lots of rocks and things to bang on the bottom.

I have a C15 with Alpina forks and 13 1/2" shocks. The frame is a 1960 C15S, gooseneck type and I struggle with the lack of ground clearance. It is 2 or 3 inches shorter than a TLR200. I also have a spare, later model, C15C frame. Do these later model competition frames have more ground clearance? How do others deal with this lack of clearance? Probably due to the offset Bultaco forks, it turns pretty well so I'm reluctant to just jack up the back end. Plus, I don't have that much ground clearance myself.

I just did this work on a 2008. Clutch travel was 0.05" (1.27 mm). Runout was 0.005" TIR. To measure runout, I put the indicator near the OD of the pressure plate. With the clutch pulled in and the bike in gear, I rotated the back wheel to get the plate to spin. This is not a machined surface so I think 0.005 is quite good. The clutch worked OK but would not change gears when stopped. It was also stuck at start up. I have not ridden it enough to see if it is now different. If I remember correctly, my 2002 Sherco had 0.04" of travel. Update: I have ridden the bike a bit now. The clutch no longer sticks at start up and it is easier to change gears when not moving. With two springs out, the pull is a bit easier. It is also a bit noiser as the article warns.

I had a 2002. It had a pretty heavy flywheel so the power was very smooth. That is why I bought it but it copuld make it feel slow. There was a huge gap between 3rd and 4th gear that made any type of trail riding a little awkward. You may just be expecting too much from a trials bike. Compared to an enduro bike, I find that trials bikes have the bottom end power of an open class bike with a big flywheel, OK mid range and no top end.

Is the main jet the correct size? Could it have been drilled out to a larger size? Could you have somthing in the air box that becomes a restriction at high air flows? Is the issue above 75% under load? I once had a bike that ran fine and picked up rpm well with no load but would miss under moderate to heavy load. It turned out to be a wire under the flywheel with worn insulation. Underload, there was less resistance to jump from wire to ground than there was to spark the plug.

Is the smoke black or blueish white? 75%+ should be main jet territory.

Is this something that would fit through the oil filling hole? Do you have small kids that like to play near your bike?

Another option is bronze bushes with grease fittings. I have done this successfully on Gas Gas and Sherco. There were no seals and the concept was that the grease would push out water and dirt. Here are a couple of work in process pics. (They have not been cleaned up yet.) On Sherco, there was enough clearance on the front to thread from the front rather than the bottom and use a regular 90 degree nipple type fitting. This shows a needle type grease fitting.

Has anyone tried the Mikuni off a Beta on a C15 or other Pre-65? The 26 mm size seems somewhat appropriate but I'm wondering if jetting would be a major effort.

I had a similar event. After cleaning the carb many many times, I found that it was actually the stator. There are some resistance numbers you can check to verify the stator.

I have successfully used Marine Goop. It bonds all sorts of plastic. The marine variety works much better than the other varieties. http://www.eclecticproducts.com/ag_adhesives.htm

The Sherco data shows the 125 and 250 with the same bore and stoke. Does that mean the 250 is a twin?

I don't know about Mikuni but old Keihins use the same casting for different size carbs. The TLR200/ TL125 type carbs were made in 22 mm and 24 mm versions. The bores were machined differently and the only size marking is on the slide cap.

I sealed the exhaust and went up two sizes on the pilot jet yet the pop is still there. At 60 degrees F, it started without the choke but did sound lean until warm. Could it need to be richer?

I have heard that a solid bronze main bearings (plain bearing or bushing) transfers heat better than the OEM bushing. When I tore down my C15, I was surprised by the quality of the OEM bush. It was pretty bad. There was an outer steel housing with an inner bushing. The inner bush was not even a machined ring but had a split in it like it is just rolled in place. The inner bush looked to be plated with copper. I coppied the design in solid bronze. The bike is running but does not have many hours on it so I can't make statements about durability.

My fix only lasted until the next removal. After a little research, I found EZ Loc. They are large enough that the hole is fully cleaned up prior to tapping yet small enough to fit in the small mounting blocks on the frame. http://www.ezlok.com/Home/index.html

I will be interested in hearing how you make out with the pit bike ignition. I tried one of the pit bike inner rotor ignitions on a C15 but could barely get a pop out of it. They may vary in performance so you may be more lucky. To see what was going on, I set it up and ran it with a milling machine. For comparison, I also had a Honda XR50 and a Yamaha PW80 ignition. Both Japanese ignitions would fire a spark plug at lower rpms than the pit bike ignition. I put it on a fresh motor and just coil not get it spinning fast enough with the kicker. I tried to squeeze in the XR50 ignition but it just would not fit under the cover. It is surprisingly big for little 50 and would probably be too heavy also.

When my Rev 3 engine winds down off throttle, I'm getting a lot of Pop Pop Pop that sounds like gas going off in the exhaust. You don't have to rev it very high to get this result. Otherwise runs fine and starts very easy but this is annoying. Idle mixture screw does not have much affect until getting down to about 3/4 turn out when idle starts to drop. Plug looks tannish almost lean. This is a 250 with Keihin and stock jetting. Needle at mid position. What could cause this? Would it be a good idea to try a leaner pilot?

As copemech states, I would be sure about the big end bearing before changing. There should be no up and down play. However, there can be quite a bit of side to side rocking/ tilting. Put an indicator at the small end and measure side to side rock. I don't have a spec for a Sherco but some older Japanese bikes allowed 0.08". If you can find a Montesa 315 manual, it may have a good spec for reference. For main bearings, grab the flywheel and try to move it up and down. There should be no movement in that direction. There does need to be a little side to side movement. See 2-3 of http://dl.dropbox.co...15R_02_2002.pdf This shows big end tolerances.

These people may be able to help. http://www.westcountrywindings.co.uk/ If the plate is not available, a machine shop should be able to duplicate the one you have.

Someone was parting out a Rev 3 on Ebay UK. I believe the stator is listed.

Looking at more recent Beta cylinders, the number would represent the year the cylinder was cast. It would be for a bike manufactured in 91 or 92.

The idle mixture and idle speed screws for Betas are on the opposite side of the carb from most other brands so you would have to consider that. - EVO 125s come with the Keihin. Splat Shop sells Keihins and related items. - These guys sell Keihin knock offs but are expensive http://www.oko-australia.com.au/ - If you were happy with the original Mikuni, they show up on the UK ebay and you may be able to get one from a breakers. Beta would probably sell you one also.

I have had plugs that would fire in air but not under compression. Try another plug.

The holes were about 1.5 times as deep as the helicoil so I tapped them as deep as possible with the helicoil thread. Rather than installing up near the top per instructions, I installed the helicoils as deep as possible in the hole and was able to get good torque on the bolts. So far, it has held for one ride so maybe it will be OK. Is there a torque spec for these?