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oldjohn

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  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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
  6. 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....
  7. Sounds lean. Edit: I don't know if this is of any interest to the OP or anyone else, but here's a link to a fairly lengthy guide to jetting that I wrote on another forum: Rookies Guide to Jetting If anyone thinks it's worthwhile I could post it up here.
  8. 130 would be very close, though you might want to try a 140 as well. You don't want to be any more than two steps leaner than a rich stutter, which on my 350 with the same carb is between 140 - 150 so I run a 130. It'd be a good idea to check a few other things out while you're at it, just to help prevent the same thing happening again. Eg. the ignition timing with a timing light, check for adequate fuel flow through the tap and filter and that an appropriate heat range spark plug is fitted. These engines will definitely preignite with a 5 on a long uphill or with prolonged full throttle riding, especially on a hot day. I won't use anything hotter than a 6. Make sure the exhaust isn't partially choked up and check that everything is sealed up nicely and that there are no air leaks, and don't be too stingy with the 2 stroke oil. Properly set up these engines will go a very very long time between rebuilds.
  9. The smart thing to do would be to leave the nuts the full width but make the machined section wider, so it spigots more deeply into the spring. You'd hold the nut on a threaded mandrel to machine it.
  10. The damper rod is stuck in the bottom of the slider. Pull the top plug and the spring out if you haven't already, push the tube into the slider then pull it out sharply, like a slide hammer. A few quick blows should have it apart. Be careful pulling the old seals out - don't pry against the top of the slider as it's very easy to damage. Use a slide hammer or sheet metal screws to extract the old seals. I find Ariete seals to be better than any others I've tried. Put the spring and cap back before reassembling to hold the damper rod down. Sometimes when you're tightening the bottom bolt the damper rod turns in the leg, preventing you from fully tightening the bolt. If this happens you can screw a long M6 bolt into the drain hole and this will push against the side of the damper rod, holding it in place while you tighten the bottom bolt.
  11. I've used Caswell on a poly 199 tank. I did it a couple of years ago and the lining is still in one piece but it isn't completely attached to the inside surface of the tank anymore. In other words the inner epoxy shell is still fuel-tight but it's becoming loose inside the tank. The cured epoxy is quite tough. I followed the prep procedure to the letter but it's very hard to roughen the inside of the tank and it's difficult to get anything to adhere to poly even with the best prep. I only lined it because of some cracks in the tank (and to stop the decals bubbling). It doesn't leak but if it ever does I'll throw it away and put a new one on rather than mess around with relining.
  12. It makes sense that the Elf HTX 740 would work well - it was specifically designed to be used with bike clutches and transmissions. I found that these types of oil worked significantly better than any of the ATFs.
  13. Thanks to all for the replies. Interesting too that you mention going a bit longer to quicken the steering bodwheel, I'd been thinking of trying this. Might even throw on a pair of 365mm Chinese cheapies just to see how it affects the steering, and if I like how it steers I could then get something decent in the same length.
  14. What would you recommend as a good shock absorber for a 199? I'm not a serious competitor so don't need the latest and greatest, just something reasonable with a reasonable price. The Betor Experts on it now were fine when they were in good condition but now they're barely functional. And what spring rate for an 80kg rider?
  15. The bike unexpectedly starts in gear and runs away, throttle wide open. It careens through an outdoor antique fair before crashing into a building where it bursts into flames, burning the orphanage and its occupants to the ground. Lawyers get involved. Apart from that, not much.