spokerider

Sounds like you're covering the bases..........dunno. I haven't tried mine yet, but I sure hope it comes off easier than yours! I think I read that someone heated the gear hot enought that it was almost glowing? Hummm, wouldn't that take the temper out of the steel? I'll be fabbing up a puller myself, Sounds like it ought to be a big-ass strong puller to do the job. Do you have the means to fab a puller that'll allow more torque and thus pulling power?

Great post Tayld, Thanks for sharing your Amal 26 / 27 tuning technique.

After researching to the limits of "google", it appears that a "Keihin PWK 28 29S" carb is a direct fit for the 348. This flat-sided carb appeals to me as the swap should be *simple* The Keihin's intake and airbox diameters match that of the Amal MKII's measurements of 35mm diameter at the intake and 49mm diameter at the airbox. This means that the manifold and airbox rubbers will fit the carb. Anyone know if the [ oem as factory new ] jetting that the Keihin comes with will work for the 348? If not, which jets would need to be changed out and to what? Thanks.

Jaan, Did you ever get the mikuni carb on the 348?? If so, what methods / manifold and airbox rubbers did you end up using to get it in place? I'm also curious as to how to mount a PWK 29S to a 348, reguarding manifold and airbox rubbers. The Amal MKII has to go!

As a new Cota 348 owner, please don't quote me, but I think the 349 had a longer swing arm and thus a longer wheel base as well as being about 20 lbs or so heavier than a 348. The intake manifold on a 349 is a bolt-on manifold, where as the 348 is cast as part of the cylinder. The 349 that I have for parts has a heavy aluminum skid plate that is integral to the frame, bolted in place. 348's have steel tubing downtubes with a thin mesh skid between the two downtubes.

Thanks for the pics! Do you use anti-seize compound on the hex nut threads when reassembling and torquing nuts?

I took the cyl head off the engine today. There is some dusty rust / crud in the 7mm cyl nut recesses, so there's penetrating oil soaking things loose right now. The barrel will come off in a few days...... I bought a long 7mm alllen socket that'll work fine for the job once I grind the ball end off of the business end of it. I see that a previous owner has had the engine rebuilt once before, as there is a .025mm oversize piston in place. I can see the cross-hatch pattern in the cyl bore. The cross hatch is more visible on the sides of the bore and less obvious in the fore / aft cyl wall. No scoring or really shiney areas either. No carbon build up, just some thin oliy soot. Top ring looks fine from the inspection so far...... I can't make the piston move fore / aft in the cyl with pressure applied by two fingers on the piston crown, as in piston slap, but I CAN rotate the piston as if trying to spin it in the bore, with the same pressure from two finger tips. This holds true with the piston at all stroke positions that I tried. It moves about 1mm-1.5mm as a guess. Perhaps there's wear on the small end needle bearing? Big end bearing?? Is this movement abnormal? Thanks.

VintageCota, what about using an impact driver.......the kind that you hit with a hammer and it gives a partial revolution to the fastener......after using some penetrating oil [ x a few days ] and tapping the 7mm hex well into the nut recess? I'm in Victoria.

Good to know, thanks. Making a sleeve to accept the smaller diameter Mikuni carb bell sdhouldn't be too much trouble......... What are you doing to the Amal carb [ MK II ] ? to get it "to run right"? I've ordered a gasket kit for mine as it leaks a little fuel. I'm reluctant to put more $$ into the Amal at this point. The carb on my 348 seems to work just fine, for now, but alas, I hate having stuff on the verge of breakdown or on it's last legs..... I'd just as soon as put a new carb on it and be done with it. Of course, keeping the original for future resotration purposes is a given.

Right on, thanks. I'll search for a 7mm long hex socket and get the cylinder off for a look at piston, bore, clearances, and small end bearing condition. My bike has an engine sound similar to this; http://www.advrider.com/forums/showthread.php?t=365136 but not as bad, maybe one third to one half as loud as this guys rattle. More thoughts.......it seem that the Amal carbs on vintage bikes are pretty much worn out, even the MK II carbs are suppose to wear out easily.........before sinking any $$ into an old MK II [ on my bike ] how complicated is swapping a Keihin PWK 28 or Mikuni 26mm carb to the 348? Can the OEM manifold / airbox rubbers be used with these carbs or is there some other, different parts required for the swap? Can the same throttle cable be used? [ I just bought and installed a new Domino trials throttle and cable ].

Hummm, I guess that I can anticipate the same troubles as others when i's time to remove the cylinder on the 348........ Steve, if the problem is not drilling the stud threads from the nuts, and it's corrosion holding the now-drilled nuts in place, could you just get a pair of needle-nose vise grip pliers in there, grab hold of the nuts and tap / wiggle the nuts up and out? That along with a good soak of penetrating oil......... Not having had the head off the engine, I'm only guessing at what the situation looks like.

The oem Cota 348 shocks are long past their useful life, toast, kapput......... What is a good replacement shock for the bike? Falcon.....rather expensive...... NJB?....more affordable. Or? I ride trials for pleasure, not competition......

Here's an article on Montesa stuff, written by a fella who's had some experience.......... He explains the process required to drill out the nasty 7mm fasteners that have seized the cyl to the engine. Has anyone needed to do this to a 348?? Also, are these 7mm "nuts" or are they "bolts", that secure the cyl to the engine? http://rmmontesa.com/montesa%20articles.htm

Davedix, Hummmm. Perhaps it does need a small end bearing......... The "chirp" noise or "rattle" or "plink" noise is most easily heard at idle, or slighty faster rpm than idle. At higher engine rpm's the noise gets lost [ or diminishes? ] in the louder engine / exhaust noise. When I take the head off and then the cylinger, I'll inspect the small end bearing. Speaking of getting the cylinder [ barrel ] off, the 7mm allen socket, is it an allen key sticking out of a 3/8ths drive socket? Or is it actually a deep socket that accepts a 7mm bolt head? feetup, my bike doesn't pull that hard! Mind you, I haven't tried the 4th gear acceleration from stopped, yet! Thanks for the test-measurement info. It does have a 33 tooth sprocket. beldane, thanks for the kind gesture.......I just may email you with a few questions / advice. helm, the bike doesn't have a decompressor, just two spark plugs. Great thought / advice however, thanks. I would like to put a compressor on it one day. Tony, thanks for sharing your 348 experiences. I haven't had to expand my "french" [ curse ] as of yet while working on this bike, but when a difficult circumstance arrises, it's nice to know I'm not the only one who has struggled with it!

Fellas, great posts! PLease, keep them comng...... Mattylad, I was thinking of doing something like that. I see that the oem straps are available on ebay etc, but not cheap! At this time I'm looking at spending the $$ to get the bike running "better". feetupfun, sounds like you know your Montesa's! Thanks for the great tips. When I was repairing the hole in the case from the kickstarter, I was trying to figure the best way to position the kicker, so as not to re-hole the case. Seems to be a design-fault with that little bump-stop even being able to contact the case...... I'll try orienting it so the foot peg limits the kick stroke, as suggested. Great fork tip. I'll use some heavy oil.......I'm no welter weight lol. It has the air caps on the forks. When I drained the clutch oil from the case, only a small amount of very heavy oil came out, mabye 40-50 cc's.... I replaced it with 200 cc of synthetic Amsol 80w oil. I have yet to test the cluch now. It felt *fine* with that scant amount of heavy oil before. Yep, it has the Amal Mk II carb. I'll try and find the needle and needle jet parts........ Please elaborate on the top end rattle........ is there a way to determine WHEN it's time to do an overbore piston kit job? The compression feels good when kicking the bike over to start it. What shold the compression readings be per kick / max reading after a few kicks? At first, I thought the engine sounded like it had a "chip" to it when running. I asked my local bike dealer what 2-stroke piston slap sounded like and he said a rattle. Well, I guess the chirp sound could be described as a rattle, not severe, but it's noticeable. The engine seems to pull strong. First gear is very low, as you know....... it's sounds like the engine going to grenade when I sharply twist the throtte and accelerate, and I'm still hardly doing 10 mph! When standing to ride, should the bike pull a wheel off the ground when snapping the throtte open? even without pulling up on the bars? Cause it doesn't,......well, maybe an inch or two off the ground in 2nd gear, but no real wheely. Cheers.

I just recently picked up a Montesa Cota 348 and I am in the process of replacing some parts to make the bike tight and functional again. Alas, it show it's age and use, despite being well maintained by it's previous owners. To date, I've bought new brake shoes and installed, replaced the rear wheel bearings and seals, repacked the front wheel bearings [ they were still good ], replaced a badly leaking shifter-shaft seal, changed trans and clutch oils. I also lightly filed the points and reset ignition timing. I discovered that there was a small hole punched in the case from the kick-starter "bump / stop" on the shaft, allowing chain grease and dirt to enter the ignition case. After cleaning the inside of the case, flywheel and stator etc, I patched the hole with JB weld epoxy. Hopefully that'll fix the problem....... Now I'm waiting on a set of new points, once I locate a set to purchase. My local dirt bike dealer still had a few old Montesa parts about from years gone by, so I bought a 78.50mm piston kit, crankshaft seals, swingarm bushings, and a few other parts to re and re. There is a "rattle" in the engine that seems to come from the cyl head, so I'm thinking it's time for the piston kit........ The airbox has a few small cracks in the plastic, 1.5cm long or so. I'll seal them up too. It doesn't appear that too much dirt etc got into the engine and the inside of the airbox was relatively clean. The air filter was the original however, squished almost flat over the years. There's new air filter foam in there now....... The seat has a tear in the vinyl, so I'll recover it, and the fiberglass gas tank has a few chipped edges and a scorch mark where it touches the exhaust system. Iplan on touching up the fiberglass and doing a repaint. The rubber hold down straps are long gone......no kidding eh? lol. Bars are original. The levers are some cheapo plastic version that I'll replace. I just installed a new domino trial throttle and cable [ not oem I know, but try and find oem stuff!!] Have a carb gasket kit on order. I plan on replacing the carb gaskets soon. The exhaust is stock. There is surface rust on it. I'm looking into sanding the rust off then painting the exhaust with high-temp black paint. The shocks have no damping left, and will prolly be replaced. The forks will get new oil and seals. The wheels have been trued / tightened and have new Dunlop rubber. I don't know the condition of the inner workings of the engine and trans, such as con rod bearings, crank bearings etc........... I'm *hoping* that they'll be fine. Not wanting to delve into the inner workings of the engine as I've never split an engine case before. Plus, I'll prolly end up having to make all of the necessary gaskets by hand, as they seem to be very scarce. For those of you with 348 experience, do you have any advice or experience with this bike to pass on? There are no "how to" manuals for it, so I'm learning by the seat of my pants as I go........ Cheers and thanks! Spokerider in BC Canada