1981 YT125 Stud Duck Questions

[Highhorse78]

For the rear brakes, there's a stud with a jam nut in the caliper that is used to adjust the pad clearance. Once you adjust that, adjust the cable itself to get your lever/pedal throw. See if that helps any.

[generallee2005]

I'll do that first, I did just realize looking at the bike bandit schematic that I don't have the return spring on the perch at the caliper. With the kiddos birthday Saturday this may be a good project for Easter Sunday for us to look at.

[generallee2005]

Got the brakes going a few days ago. Still feels like the clutch is slipping a little bit too much. What kind of oil do y'all prefer? Right now I've got Castor SAE30 in the crankcase.
I've been doing some searching here about clutch setup/tuning, from the sounds of it my centrifuge clutch is good, since I've got the clutch slipping a little throughout the start until its up & running. Right?

[old-yellow]

I run castor gtx 10w30 in mine with no problems, but as far as your clutch slipping when does it happen when you take off or when you are getting on the throttle at speed, just make sure that you have the clutch adjusted right if you still cant get that to work, you might have to pull the clutch side cover off and check the the friction plates and metal clutch plates with a digital caliper to make sure that there all within spec, the friction plates thickness new 0.090in (2.4mm) to used service limit 0.080in (2.1mm). Next check the metal clutch plates for warpage on a flat surface (i use a thick piece of glass for any flat surface work) with a feeler gauge they are allowed 0.002in (0.05mm) of warparge at any given point. remember do not mix the order of the friction plates and metal clutch plates up. Had to pull the specs for this out of my Haynes paper manual because the link for the online manual that i gave you before does not have the specs on this dont know why. you might want to pick up a Haynes they helpful as hell.http://www.amazon.com/Yamaha-ATVs-Ow...+three+wheeler i have never had a bad YT clutch so this is all new to me to. good luck Alex

[old-yellow]

just stole this info from pat AKA vealmonkey so it might be a little harder then i was thinking to fix this.

What year is your 125 engine? If your 125 engine is 80 or 81, that clutch pack doesn't use as many clutch plates and friction plates as the 82 and later clutch pack. Don't ask me why, it just is that way. Also, I found out that yamaha used different thickness clutch plates. The total clutch pack has a tolerance for thickness that is made up by using the different thickness clutch plates, neato huh? If your clutch pack ends up too thick, it won't fit right into the clutch basket and you won't get the large steel clip in to hold it all together. Too thin, and either your clutches slip or your steel ring can pop out, once again, neaty petey! And then you have the 80-81 clutch pack that uses less clutch plates and clutch frictions-ARRRRGGGGHHHH! If you don't have a manual, you won't know this. That's why I always recommend a factory manual to anyone that has a trike, not an off brand manual, a factory manual. And be happy that it's not a Tiger or Rotax manual, what a piece of work they are. According to the manual, you should have 8 clutch frictions and 7 clutch plates, for the 82 and later clutch basket. The earlier 80 and 81 clutch basket has less. There are alot of dimensional measurement tolerances, too many for me to type them all out. And my manual is showing only 8 balls, but there are no mention of the number of the balls in the manual! Also there is an adjustment gap between the last clutch friction and the outer clutch plate that has the clutch springs in it. The manual says if you don't have the proper gap, that is when you have to mix and match the clutch plates. This is why you need a manual. Like I said, there are alot of measurements that you have to refer to a area to get them all. Also you would have to use a set of dial calipers to check the thicknesses of the clutch plates. You should also use a dial to check for the clutch spring "free length" and the length of the outer tiny springs of the clutch pack. Precise measuring is required here, much more so than other clutches I have had the oppurtunity to work on. That is why I have manuals, no way to remember all this info. You might have several problems with measurements being out of tolerance, parts just worn beyond their tolerance. If you have weak clutch springs, that will help your clutch slip too. It looks like you may have to pull the clutch all the way back apart and start over with alot more attention to detail. I might have to do this with my buddys yt125 also-Yay. Oh well, live and learn again. I thought we had it put back together right last time, but the third time is a charm, right? LOL

heres the link to the thread i stole it from http://www.3wheelerworld.com/showthr...ight=yt+clutch

[barnett468]

Hello


“The transmission oil had that milkshake look from water in the oil, but I don't know how long since it had last been changed & I believe the 3 wheeler lived outside & uncovered.”

The centrifugal clutch takes the brunt of the wear so it typically goes first.

I’m coming late so please excuse any duplicate questions.

The water did not help your clutches it could have trashed them.

Is it too expensive for you to simply replace both clutches?

Did you replace either clutch?

Were they replaced with Barnett’s, Japanese or Chinese?

Depending upon your std clutch design you can often pre-load the springs a little to reduce slippage by using either metric or AN washers or SAE, maybe .020” thick If you do that and slippage is same then centrifugal clutch is the only problem.

Oil should be oil designed for a WET clutch. Available at ALL motorcycle shops. The other will "work" but is not the best and since you have a clutch problem why take chances?

[generallee2005]

I don't mind duplicate questions, they make me go back & rethink what I've done. That is never a bad thing, I try to be 100% on all that I do, but I know I get in a hurry from time to time. This machine has lasted 32 years, I'd like to see it last double that.

Its not necessarily an expense thing as much as a time thing, I'm about to move & start grad school, so I'd just like to putt around in the yard & go riding on occasion before I leave the area. I have not replaced any clutches. The reason I took them off/out is to change the crankshaft seal behind them. I'll stop by & get some oil & try to tune the clutch again. It keeps getting better every time, so perhaps I learn a little more each time!

[barnett468]

Hello

Yes, perhaps the correct oil MIGHT give you slightly less slip. Either way it is best to use. If you fail to fix as I suggested just replace them both, doesn't take much longer than just doing one.

[generallee2005]

I think I got my clutch issue licked! Tomorrow is the day the plastics go on for a good buffing with the car buffer, then I'll wait patiently for my seat to arrive!

I had to just turn the adjustment screws an 1/8th of a turn until I like the way it felt. In 4th gear, it still kinda felt like it wanted to slip, but I can live with it until I have time & funds to build it good. I did put in the Yamalube 10w-40, guy at the Yamaha shop told me let that oil sit in for a couple of days & it would either solve my problem, or let me know its time to replace everything for sure.

I did take these pictures of the spark plug, since today was the real first time when I've rode the Stud Duck for at lease a solid 45 minutes. This is what the plug looked like when I cut the motor in a rev. What do you guys think? I think it looks good, but I'm a first time double stroker.

[generallee2005]

New clutch discs & springs are on the way. I rode the duck yesterday & just wasn't satisfied.

[generallee2005]

Discs & springs arrived today, springs were beautiful. Wrong discs!! Curse you eBay!! I did find this out after impatiently soaking them in oil before cross checking the part numbers.

[old-yellow]

sorry to hear good luck to you

[generallee2005]

I was messing around with the pressure plate, decided while I've got some time waiting on the right discs, I'd replace the little bearing in the middle, since it felt rough. Also, I've got this lock washer that I thought I knew where went. The more I think about it the less sure I am about the washer, so two questions. I tried to push the bearing out with my hands, but it didn't move. What's the best way to get this little guy out? Then, does anyone know off hand where this lock washer goes? I can't find it in my manuals, or in the schematics.

I feel I'm so close to whipping the Stud Duck into shape I can taste it!

[generallee2005]

My my my. Bike Bandit sent me the same kit as the eBay store did. EBC CK2303 is what they are sending me, it has 6 discs, I need 7. The inner diameter where it mounts to the gear are right, but the outer diameter is too small. More google-ing is in store I suppose.

[generallee2005]

Done! Minus the decals.