DonW Posted September 1, 2009 Share Posted September 1, 2009 Just curious. Saw an ad for someone wanting a low milage replacement for a throttle body and TPS. I've never had mine apart, but... Are there bushings or o-rings that wear with the change in throttle, and therefore more throttle changes over more miles would wear it out? Surely the air passing by doesn't wear anything? And the TPS? Does it get tired of sensing after 100K miles? Link to comment
smiller Posted September 1, 2009 Share Posted September 1, 2009 The oilhead right-side throttle body shaft likes to wear, enough that most high-miles bikes will show a fair amount of play. For some reason the left does not seem prone to this effect, and the TPS itself usually lasts a very long time as well. Link to comment
Tank Posted September 2, 2009 Share Posted September 2, 2009 Don, My right TB shaft wore beyound help at 85,000 miles...I replaced the unit with new and at the time replaced the left side..( I ordered both) The left side TB was still serviceable and i have it on my shelf with other useable stuff. I'm not sure I'd change it out if I had it to do again. Anybody know a tech reason to change both at the same time??? Link to comment
smiller Posted September 2, 2009 Share Posted September 2, 2009 Anybody know a tech reason to change both at the same time??? It's generally considered good practice when replacing components to to replace both units of a pair, but it's not an absolute. In this particular case the left throttle body seems to commonly outlast the right by a wide margin and I personally see no reason to replace/rebuild it if it is showing no play. Link to comment
Shaman97 Posted September 2, 2009 Share Posted September 2, 2009 Slight hijack... What's a symptom of a throttle body shaft wearing out? Link to comment
smiller Posted September 2, 2009 Share Posted September 2, 2009 What's a symptom of a throttle body shaft wearing out? In mild cases the slop in the throttle shaft will make a ticking noise at idle (although it is also possible for healthy throttle bodies to do this, extra play just exacerbates it) and in more severe cases air can leak around the shaft causing an unsteady idle or difficulty in synchonization. Link to comment
DonW Posted September 2, 2009 Author Share Posted September 2, 2009 OK... how do you determine if you have sloppy shafts? Link to comment
KDeline Posted September 3, 2009 Share Posted September 3, 2009 OK... how do you determine if you have sloppy shafts? So many comments.......................... Link to comment
OoPEZoO Posted September 3, 2009 Share Posted September 3, 2009 OK... how do you determine if you have sloppy shafts? So many comments.......................... Yeah, but a good question. I'd like to know as well considering I'm about to do a major service on my bike and it is sitting at just a hair under 120k miles on the odometer. Link to comment
smiller Posted September 3, 2009 Share Posted September 3, 2009 Checking for throttle shaft wear is pretty straightforward... if it is significant you will be able to wiggle the shaft around by grasping the cable guide (you may have to release tension on the throttle cable.) The play won't be enormous (or at least one would hope), but any noticeable radial play is too much. It's not a 'park the bike' sort of problem but if detected you probably should get around to ordering a new throttle shaft/sleeve bearings (covered in other threads) sooner or later. Link to comment
Jerry Duke Posted September 3, 2009 Share Posted September 3, 2009 It could become a 'park the bike' problem. A friend was riding her RS to the Georgia Mountain Rally when she stopped at a traffic light. The shaft was so worn it cocked the plate open and caused raw gas to run out the throttle body and hit the catalytic converter which caught fire. Good thing there was a mud puddle nearby otherwise they might have had to waste a few beers to put it out. Link to comment
snod Posted September 3, 2009 Share Posted September 3, 2009 On my '97 it got to the point that the shaft was rattling at idle. A very noticable tic, tic, tic. By placing my index finger on the pulley I could feel the pulley moving around. I was unable to obtain a smooth idle. When I sprayed WD-40 around the pulley the idle would change for a few seconds. I replaced both shafts (left and right) at about 105k or there abouts. Cleared up the tic, and made smooth idle the norm. Link to comment
NonComp Posted September 3, 2009 Share Posted September 3, 2009 I may have this problem on my '96 with 62K miles on it. I do notice the ticking, but thought that it was the injector. I have noticed recently that the new closed loop manometer that I built tends to creep at higher RPMs, so that it does not return to balanced when you close the throttle. Having read this, I would attribute that to vacuum loss on one side. I'll check again and see which side ends up with more fluid. That might consistently point one side, but up to now I wasn't paying attention. Link to comment
smiller Posted September 3, 2009 Share Posted September 3, 2009 Note that there are two reasons for right-side TB ticking... one is a worn shaft, but a tight throttle cable can cause ticking as well so check it out thoroughly before making any assumptions. Link to comment
NonComp Posted September 3, 2009 Share Posted September 3, 2009 I'm pretty sure that the throttle is closing all the way. At the moment, my roadster is running better than it ever has since I bought it two years ago. I think that I've found a good combination of TPS voltage (.375), TB sync, CCP (removed), and spark plugs (Autolite 3923 iridium - gap .035) that seem to complement the GS intake manifolds that came with the bike. It's running so darn good right now that I think I will just leave it alone for a while and enjoy it! Link to comment
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