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oldjohn

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  1. There's something wrong if the seal housings are fully seated yet the crank is still off-centre. There should be very little crank end-float with the housings fitted and a standard case gasket fitted. With a cold engine 0.5mm is plenty and you wouldn't want much more than 1mm. You certainly shouldn't need to be tapping it with a hammer and it shouldn't even be getting close to rubbing on one side. If it's that far off centre there's something very wrong - incorrect seal housings perhaps, or gaskets behind the seal housing instead of just the o-ring, or maybe the housings simply aren't seated fully. You can check this with a thin feeler gauge (say .002") but be careful jacking things around with the seal housing bolts - the housings are a bit fragile. If the crank end float is excessive or it's off-centre you may have to shim or machine the housings but unless you have some oddball or mismatched parts it shouldn't be necessary.
  2. The crank is located by the seal housings. If the housings aren't fitted the crank can slide up against one side. Once you fit the housings the crank should be centered.
  3. I've always viewed the whole "hold-the-brakes-on-while-you-nip-up-the-axle" routine with extreme scepticism. I mean, if everything is in good condition you're going to have what, maybe 2 thou clearance between the backing plate bore and the axle - not enough to allow any significant movement. Likewise, if everything is in good condition you'll have nice square faces on the backing plate, the sleeve in the fork slider and the bearing spacers, so that when you tighten the axle everything pulls up squarely and securely with no scope at all for movement. But if things are so worn that you have to play these mickey-mouse games upon reassembly then I think some work to restore proper fits is in order. There simply shouldn't be any possibility of the backing plate being out of alignment once the axle is tightened.
  4. If I won 20 million in the lottery I'd spend half on coke and hookers. The other half I'd probably just waste...
  5. A source of material for cast iron drum sleeves is cylinder liners for diesel engines. If you know someone in the engine reconditioning business they may be able to get you an old liner from a larger diesel that you could use, but even new liners aren't that expensive and one cylinder sleeve will have enough material to line a few drums.
  6. There are a few methods. One is to have the shoes radius ground by your local brake place to match the drum diameter. Another is to chuck the backing plate with shoes attached in a lathe and turn the linings down to match the drum. You need to have the shoes shimmed out a little from the cam when you do this. Yet another old-school method was to chalk the surface of the drum then spin the wheel and apply the brakes. The chalk shows where the high and low spots are so you can then file the high spots down. If you repeat the process enough times you'll eventually get a pretty good fit. But I've found that no matter what method you use it still takes quite a few hours of riding time to really bed them in properly on the bike. They generally improve quite a lot once they're fully bedded in. My highly unscientific testing process consisted of riding on my concrete driveway and seeing how much pressure it took to lock up the front wheel (sitting down). I could never really get the Bul brake to fully lock even squeezing hard with four fingers. With the modified Yam brake I can lock it with two.
  7. I'll put up a photo or two later. I couldn't get bearings that fit the Sherpa axle directly so ended up using ones with a bigger ID with stepped spacers that sleeve the ID down to the axle.
  8. Agree, the main problem seems to be the chrome drum lining used on the later bikes, along with the grey cardboard that most manufacturers pass off as lining material these days. I'm not suggesting that we return to carcinogenic lining materials but I've never found the grey stuff to perform very well in any application. Even with the Yamaha brake, it didn't achieve full power until I fitted a set of NOS factory linings - none of the aftermarket shoes came close.
  9. 125mm, if its the same as the slightly earlier Sherpas. I got so fed up with the front brake on my 199 I ended up replacing it with a Yamaha DT/MX/YZ/IT hub. I stripped the paint off and polished it so it looks sorta-kinda like the original, but now I can stand the bike on its nose with one or two fingers; something I could never get the Bul brake to do.
  10. Wash the big end out and dry it with air then give it a squirt of WD40 or similar - if it's full of gluggy oil you won't feel the wear so clearly. Sit the crank on the bench and position the rod so that it's at or near the TDC position. Hold the rod between the thumb and forefingers of both hands, near the bottom of the rod so your hands are resting on the crank. Push the rod up and down and feel for any play in the bearing. Take your time doing this; if the rod isn't held perfectly perpendicular to the crankpin (looking from the front or rear) you won't feel any wear that's present. If you don't feel any vertical movement and the rod turns smoothly without any perceptible roughness and there's no sign of heat (like blueing) on the big end it's good to go. Don't forget to oil it before buttoning up the top end. Check the surface of the little end bore for wear and pitting while you're at it. The method I use is to fit the bearings to the crank first; they need to go right up against the shoulder. Warming the cases lets the bearings go in easily (there's a whole thread on this procedure here - everyone has their own preferred method) and a little oil on the case bores helps too. The seal retainers locate the bearings (and the crank) axially in the cases so that the crank is centred and nothing rubs. Replace the crank seals and o rings while you're at it.
  11. I think the Sherpa engines are very good for their intended purpose in stock form; I really don't think there's a lot to be gained and I can't remember ever wishing my 199 had more power. Apart from a decent carburetor they don't need much modification - I think your time is best spent on sharpening the tune-up. I experimented with different flywheel weights and found that it's a trade-off between responsiveness and traction. I swapped the big drive-side double weight for a smaller Pursang weight and found it improved response without impacting on traction too much. But when I fitted a lighter ignition side flywheel as well it became very much harder to maintain grip and the bike became exhausting to ride as it took so much more effort just to keep moving on loose, steep climbs. It seems that reducing the weight on one side only is OK but if you remove weight from both sides it destroys the bikes ability to find traction on loose ground - something they're very good at in stock form. Unless you're using the bike for something other than what it was originally designed for I don't think the stock engine needs much help.
  12. Maybe there are differences between your engine/carb and mine, but I'm sure that if I tried to run a 30 pilot in my bike it'd take about a week to warm up enough that it didn't hesitate on opening the throttle. I'd try the 45.
  13. That's what it sounds like to me, too. But if it turns out to already have a 50 or 60 in it I'd be having a good look for an air leak before putting an even bigger jet in. Probably sounds worse than it really is because the idle speed is set high.
  14. I run a VM26 on my 350 M199; it runs perfectly on this jetting so it might be a good place to start: 120 main (summer) 130 in winter N8 needle jet, 5DP39 needle (better from 1/4 to 1/2 than 5F21) clip in middle groove 60 pilot Screw 2 turns out 2.0 slide 0.5 air bleed Bear in mind summers here are around 25 - 35C, winters around 10 - 15C
  15. The slow return to idle speed is a classic symptom of an air leak - possibly from crank seals, the intake stub to barrel gasket, carb connector or centre case gasket. The 64mm stroke engines (eg. 350, 360 and 370cc but not 325cc) have a tendency to leak around the centre gasket as there is very little material between the crankcase and a couple of the stud holes. If it's very slow to drop back to idle - and especially if it makes that " imm bim bim bim" sound while doing so - then I'd be doing a pressure test. It's either very lean at idle or it's leaking air. And of course the other common symptom of an air leak is a cooked or seized piston....