Yamaha XC155 (SMax) thread

Discussion in 'Battle Scooters' started by Chillis, Aug 28, 2014.

  1. ScooterJon

    ScooterJon Been here awhile

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    Did the valves actually need adjusting? If so, how far off were they? Had they ever needed adjusting before?
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  2. GotMojo

    GotMojo Been here awhile

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    Please let us know if you run into any issues with belt rub. Sliders cause the belt to ride high on the vespas and it catches the oil pan gasket and makes a mess of things.

    I'd also be interested to see if you notice higher oil consumption with the increased RPMs. My smax came with a smaller diameter tire in the rear and a proclivity to run way up in the red area. It kept losing oil until I replaced it with the correct size. Oil level is steady and the tach needle stays on the white side now.
  3. Nick113

    Nick113 Been here awhile

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    Just installed new tires. Both front and rear. Michelin Power Pure SC. With dual compound structure, center tread compound is formulated for durability for longer tread life, while the shoulder tread compound is formulated for greater adhesion to the road in wet or dry conditions. The rear tire is 150/70-13 the front 130/70-13. Actually they're both listed as "rear" tires, so the front 130 dealer installed the opposite way, against the arrow indicating direction of rotation. First impression... I didn't notice any height increase, even though they're taller. Strangely enough it didn't cure the speedometer "too optimistic" issue, I was surprise to see that it was still too optimistic about 3-4 mph. Before it was 4-5 mph. I guess front tire 130 is too little of difference to read. Turning curves is totally different from old tires, but this it true for all new tires. I got used to it in 10 minutes. I feel less suspension oscillation on uneven road, it's good. Speed: Pushed it to 70 mph on GPS, speedometer indicated 74 mph. It hesitated to go any faster even though there was some 500 rpm to red line. Not sure what to make of this, need more testing. Maybe larger wheel diameter was too hard for the engine to push above 8500 rpm. But either way, need more time to see it in different conditions. But the engine did drop around 350-400 RPM while driving with same speed as on smaller tiers... Which is a good thing. So far so good!
  4. LidoCA

    LidoCA Been here awhile

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    Both intake and exhaust were way tight from the factory when I checked at 600 miles. I check them every 4k miles or so. I adjusted 1 exhaust again at 8k, as well as this time at 12k. One exhaust was at .008. I set to .009. The others did not move.
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  5. Fiftygrit

    Fiftygrit Been here awhile

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    Nick what was the reasoning for reversing the front tire, I would have thought if it was directional it should turn that direction.
  6. Nick113

    Nick113 Been here awhile

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    The reason for reversing is that the tire is built like a beaver tail interlocking. The plies are inserted into each other in such fashion that when you accelerate hard, the "beaver tail" connections are pushing into each other to stay together. When using in front, the opposite is true. When you hit the brake, it experience same forces as acceleration in the back.
  7. ScooterJon

    ScooterJon Been here awhile

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    Thanks for the input. I’m a bit lazy and cheap so I haven’t checked the valves at all in 4100 miles. I guess I’ll be the poster child for what might or might not happen....so far, she fires right up so I’m assuming it’s not too tight. I bought feeler gauges for it but I’ve never done any valve check in my life and would rather do it the first time with my dad’s help. The problem is he lives 2.5 hours away which means I’d have to stay overnight and need at least a half day to work on it. I’ll get around to it one of these days.
  8. Nick113

    Nick113 Been here awhile

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    My dealer says, if it starts in cold weather instantly, there is no any emergency to start checking valves. If valves were off, it would be harder to start in cold weather, especially that is has one cylinder only.
  9. AJ32162

    AJ32162 Been here awhile

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    Actually, it would he harder to start when the engine is hot as the valve stem and rocker arms would have expanded due to engine heat and reduce the valve lash clearance. An engine should be easier to start when the engine is cool but not extremely cold as the valves will have more clearance at a lower temperature. That is why you are supposed to let the engine cool to room temperature before checking valve clearances. Have you ever noticed how valves on some engines sometimes 'clatter' a little on a cold engine after starting? That's because the valve clearances are greater than normal after a cold start but quiet down once the engine warms and the valve train components expand to the specs. required for normal operation. A warm or hot starting problem is a better indicator of insufficient valve clearance (especially the exhaust valves) than a cold weather start. It would be my guess that your dealer is more of a salesman than a mechanic. But, hey, what do I know?
  10. Moat

    Moat Been here awhile

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    AJ's ^^^ correct. Not only that, but an exhaust valve who's clearance is a bit under spec could run just fine 99.976% of the time, yet "grow" in length on that one, looong, WOT run up over that mountain pass (where the exhaust valve stems are literally glowing hot)... growing in length just enough to lose seat (cooling) contact and erode/burn, quite quickly, under that heat load.

    IOW - You'd never know until it'd be too late.

    Or... until you check 'em!! Highly recommended, IMHO.

    Bob
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  11. LidoCA

    LidoCA Been here awhile

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    Those were good explanations on the reason to reverse a rear tire used on the front and the reasons for checking valves.
    I checked The valves because my daddy, John David Yamaha, said I should. Although the manual states to check them every 2k miles or so, I have found that they don't move that much, at least on my scooter. YMMV.
  12. Nick113

    Nick113 Been here awhile

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    Called a dealer to see if they're available to check valves... They said it takes 4 hours to complete the job, including 1 hour for cooling the engine before starting the job! Is that how long it takes? 3-4 hours of labor? It's like $400 !! Any info on that? Thanks.
  13. Nick113

    Nick113 Been here awhile

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    So, I called another Yamaha dealer, I know they're very straight forward. They said it takes all day and will cost $400 !! Gee... But also they say if I don't hear tick-tick-tick noise I don't need adjustment. They said it with confidence. And they're the Platinum Badge Yamaha dealer! One of very few... Decisions, decisions...
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  14. grandpoo

    grandpoo n00b

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    Took me a couple hours to adjust valves the first time so a bike mechanic that's done a few should do it in an hour.

    It's pretty hard to tell if your valves are out of spec. You may notice increased power as the valves tighten. The cold start valve clatter will disappear.

    Eventually, due to wear, your valves will not close. This can cause burnt valves and seats which will be an expensive fix.

    My valves had tightened up significantly in the first thousand kms or 600 miles. I won't be ignoring valve maintenance.
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  15. AJ32162

    AJ32162 Been here awhile

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    The tick-tick-tick can be an indication of valves that have excessive clearance, and hard starting on a hot engine can be an indication of insufficient valve clearance. Slightly excessive out of spec. clearance, while not optimum, would cause far less damage to an engine in the short term (provided the engine is not operated at high RPMs) than valves with insufficient clearance. That being said, the only way to know the status of your valve clearance is to check it. It takes me less than an hour at a leisurely pace to check the clearance on a single cylinder engine (intake and exhaust valves can be checked at the same time at TDC) providing the engine is already cool. I've been checking my own valves for nearly 50 years, it's a simple procedure on a single cylinder engine.
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  16. AJ32162

    AJ32162 Been here awhile

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    Do a search on this forum "valve clearance check" the procedure has been discussed several times in the past.
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  17. AJ32162

    AJ32162 Been here awhile

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    If you do decide to do the valve clearance check yourself, there are two important points to remember:
    1. Once you find TDC both the intake and exhaust valve should have a small amount of play in them when you move them up and down. If only two of the four valves have play in them, you are not at the correct TDC position and need to rotate the crankshaft 1 more turn or 360 degrees to achieve TDC on the compression stroke (all valves will be closed and have freeplay).
    2. Once you achieve the correct TDC position, check all four valve clearances. DO NOT loosen the lock nuts until AFTER you have correctly checked the valve clearances. When checking the clearance, if the clearances are not close to the correct specs, off by no more than a thousandth or two, you have probably done something incorrectly.

    You might also find some of the YouTube videos useful.

    Even if you have your dealer do your valve adjustment, you have no way of knowing if it was ACTUALLY done. Learn to do it yourself and you will know it was done and done correctly saving you $400.
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  18. Nick113

    Nick113 Been here awhile

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    Thank you! Will look into it.
  19. ScooterJon

    ScooterJon Been here awhile

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    I got similar quotes from multiple sources as well. I’m not spending that kind of money on a check of a simple single cylinder engine. The dealer even asked why I felt it was needed, as if they don’t normally do it. Thus why I determined I’d do it on my own...at some point.
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  20. niknok9

    niknok9 Adventurer

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    Thats true bro.dont adjust the valve.when it starts in cold weather and dont make that tic-tic sounds.you can adjust your valve by yourself save lots of time and money.
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