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Discussion in 'Thumpers' started by Bowhunter, Jul 10, 2016.
Fastenal, McMaster Carr or maybe KTM rotor bolts?
yea, I could pull one off my 690 and see how that fits. Or even our little KTM 50 ;-)
Or post a pic of what you need...
Why not just order from the dealer, Iv ordered parts recently though a beta dealer and some of the did arrive in only a couple of weeks? Or just get some DOT 21/18 tires for the enduro wheels.
Dealer? Ha, yes, tried a few. Its more about issues with Beta USA and their parts availability. Again, we've had about a 30% failure rate.
FOund a dealer in Reno that claims to be able to get most of the spacers and a seat, so we'll give it a try. If something's wrong, I have have a local source to make some spacers.
We have a 19" wheel that I had Woddy's make for the Beta, as well as the factory 18 rear dirt wheel. Just didnt come with spacers.
PM'd you about my extra seat.
Selling my 125. PM if interested.
$3950.00, located in Colorado Springs --> SOLD
2017 Beta 125RR-S (4-stroke)
50 state street legal
150cc big bore kit
Stage 1 performance cam
Tubliss front and rear
Moto Z 110/100 rear tire, Shinko 90/100 "fatty" front
Tusk hand guards
Custom skid plate
I'm the original owner of this bike, and have a clean Colorado title. All maintenance performed per manufacturer schedule. Great bike for any riding ranging from single-track to 60mph on the highway. Gets about 70 mpg on most dual sport rides I do, hits reserve at about 95 miles.
Bummer, why you selling it?
Lots of reasons, but primarily because I want to give E-mountain biking a try.
Helluva good deal CJ. Hope it goes to a good home.
Interested, I emailed you through your Craigslist ad.
Onward to another two wheel adventure.
I haven't been on in months and looking through the last dozen or two pages saw a number of posts about not being able to pull the front wheel up to clear an obstacle. The problem is the constant velocity carb that has been mentioned. They have their good points but quick response is not one of them. I worked in a race shop and started to explain why this is then realized that it would take a lot of space and bore most you into a coma. CVs work great at maintaining correct fuel air mix at high elevations as some of you report. After all they were originally developed for aircraft and their extreme elevation changes. Be warned though, they will also correct fuel air mix for a dirty air filter or one that has deteriorated. Check yours, keep it clean and replace it once in a while. I had a 1982 Kawasaki KLR 250 with a CV carb that over time was well down on power. Everything checked out. The filter was clean, properly oiled and the spark plug was the usual light tan color with no signs of richness that comes from a filter that was not passing enough air. That is like running with the choke on. Several times we had older bikes on the dyno that had gone rich for no apparent reason and the foam filter was the cause. I took the filter out and the power was there. Put filter back in and it was a dog again. A new filter was all it needed. Sometimes something happens to the pores of a foam filter where it will not pass air even though it looks great. But back on subject. This KLR had a CV carb and rated at 22 HP would not lift the front wheel either without a rev and clutch work. My first bike was a 1971 Honda SL 125 with a standard carb and a thundering 11HP. It would loft the front wheel easily and simply by chopping the throttle to slightly compress the forks then snapping the throttle open and with a tug on the bars. Later I had a Honda XL 125 with 12 screaming HP and standard carb that did it even easier. Looking at the vids from Europe and they are popping wheelies all over the place. They have fuel injection on theirs that we were denied. Who knows why. Our bikes will do it to and I strongly suspect a carb swap to a standard type and proper jetting is all that is needed. I hope someone finds one that will bolt up and give it a try. If you do let all of us know.
There is talk about replacement mufflers and how well or if they work. I put on a Scalvini system on mine which is both a stainless steel header and open silencer muffler. The header is one of those snake that swallowed the rat designs. It bolted up perfect. I had to go up two sizes on the pilot jet, one size on the main jet and shim my needle .015 for my elevation of 2200 feet. Otherwise the engine is stock and I am happy with it. I picked up noticeable low end torque, a little mid range and it opened up the top end. Its stronger low end still comes on to slow as before. *#&^%"> CV carb! This header does eliminate the baffle in the end of the stock head pipe and air pump inlet, and the muffler eliminates the cat converter so check your states laws.
I really appreciate the great pictures and scenery you post. We are not to envy others but I do. Here in massive Pennsylvania, home to huge tracts of forests, off road riding is gone to the point of almost being outlawed except on your own property. The few public trails there are are heavily crowded with 4 wheelers with I will not say what behind the bars. True squirrel holes they are and carnage reigns. My bike is mostly a runabout and dirt fire road explorer that fits in well with Pennsylvania's paved roads. It is said that we have bad potholes. That is propaganda. Our potholes are not that bad. It is the little pieces of pavement that sticks up between them that does the damage and makes long travel suspension nice. And we pay the highest gasoline tax in the country!
Nice write up @senecawarrior. I think you are spot on with your conclusion that the CV carb is the cause for the lack of low end response. In addition I think the 30mm size is too big for encouraging torque from a small engine. High RPM horespower maybe, but not grunt. Ive had a KLR650 and currently a KLX351 that suffer(ed) from the same thing. With that in mind I suggest this as a good candidate for a replacement: https://www.sip-scootershop.com/en/...+flat+slider+with+accelerating+pump+_40076000
Mikuni TM28 flat slide with accelerator pump. It even has a side pull throttle cable actuation. One potential limitation of the Beta 125 is the frame backbone which goes right over the carb and which, I would imagine, precludes the use of a standard carb with a top cable pull. The question with the Mikuni is whether it would fit and whether you could get the proper inlet and outlet flanges to line it up with the airbox and motor. And I bet the answer to all of those questions is yes. And maybe somebody can figure out a way to get a top cable under the frame backbone.
This bike originally came equipped with a Mikuni carb, I'm pretty sure, in 2016(?) when it was launched. So there is an alternative out there for the Keihin CV. But I don't know what model that original carb was. I called Beta USA and as I recall they were no help.
I had to check but the Honda SL - XL 125s I had sported a 26mm carb with no accelerator pump and they reved pretty high. The slightly smaller diameter would give a little better velocity off the bottom and and would not hurt top end enough for most to notice. Not many of us run wide open ( WFO. Now that is a blast from the past that dates me. ) at peak RPM for any length of time. A lot of the straight pull carbs back them had goose necks on the top of the carb for routing the cable. Haven't looked to see how much room there is and if this would be a possibility. The Mikuni TM 28-1 carb has a 40mm outlet and a 50mm inlet. Anyone have their carb off and can measure it? The TM carb is listed for 125 - 200cc four strokes so the 28mm seems to be on the larger size. I am going to check around to see what is out there for a 26mm. It may not be as high in the slide chamber. It is possible to make an adapter for the inlet to the airbox boot if we find something that is smaller on that end..
The current CV carb has a 40 mm outlet and a 55 mm intake, so a bit bigger on the intake side. The distance across from intake to outlet flange is 114 mm. The height of the CV carb is 131.3 mm. Those are my measurements and ought to be verified by someone else.
I agree that a 26 mm carb could work but all the ones I've seen have a top pull throttle cable. If that could be routed around the frame I could see even a cheap round slide working.
If we could find something like this. I have seen both 45 and 90 degree elbows. Too bad the old shop I worked at is gone. They had bins of carbs and parts. I believe they all went to the trash when they closed.
Down at the bottom of the page: https://www.pjmotorsports.com/mikuni-tm-series-carburetors.html There are other pages with conversion kits and also flange adapters - I think. I can't locate them at the moment so maybe I'm thinking of another site.
I've ordered jets from these guys and they arrive with an invoice hand-signed with a caligraphy pen. Nice touch.
I think one of us is going to have to pull the carb out and get some detailed measurements. For me that won't happen for maybe a few more weeks. This might be a winter project.
Also, regarding the Mikuni TM28-1, here's some detailed specs: https://www.allensperformance.co.uk/carb-kit/tm28-1-data-set/ . I suspect it is too tall.
Have been doing some digging around and found these 90 degree throttle cable elbows on ebay. https://www.ebay.com/itm/Sudco-007-...774630&hash=item5dab45f0e2:g:jnQAAOSw5Bde8qQg They were listed for both Mikuni and Kehin carbs but the ends were not threaded which had me confused for a bit until I found out how they worked. They slip into the stock cable adjuster that is threaded into the carb cap which would make them almost universal. If they are short enough and there is enough room under the frame this would allow the use of the Mikuni VM series carbs or one of the Kehins. Another possibility is to slightly angle the carb a few degrees in the intake and air boots to the left or right. I have seen carbs angled forward to around 20 degrees from factory and they seem to work fine. Early Honda 90s come to mind with their laid down motor. ( When I started riding the automatic clutches on those Hondas were laughed at by most everyone, especially true dirt riders and racers. Today all the rage in off road is automatic clutches such as the Rekluse which is the same thing with just enough refinments and changes to keep from being sued for patent infringement. What was old is new again and Honda was ahead if its time. ) Another thing to look at is how to operate the choke if it is one of the lever or plunger set-ups. So far I haven't found what Mikuni carb was fitted on the first few that came into the country.