rs125 beginner questions

[feralchimp]

1. Minimum (within reason) toolkit required to wrench on one?

2. If it "needs a top end" and I take it to a Penguin class before doing that, how serious a game of russian roulette am I playing with the motor?

3. I'd love to see a set of preflight-style "checklists" for procedures like pre-mixing fuel, inspecting brakes, adjusting jetting based on OAT and humidity, etc. Is there an app for that?

[Awesome]

1. Basic tools, 8, 10, 12 sockets and wrenches, torque wrench. 6mm wrench I think for the jets. Top end tools, calipers and some solder if you're paying attention to squish, file set for prepping the piston and rings.

2. If it's due for a top end, do it. The recommended interval holds very tight to when it's required and the 125s only make power at high revs, so you have no option for taking it easy on the engine.

3. Check everything.

["Dangerous" Dan K]

1. Basic tools, 8, 10, 12 sockets and wrenches, torque wrench. 6mm wrench I think for the jets. Top end tools, calipers and some solder if you're paying attention to squish, file set for prepping the piston and rings.

2. If it's due for a top end, do it. The recommended interval holds very tight to when it's required and the 125s only make power at high revs, so you have no option for taking it easy on the engine.

3. Check everything.

to #3. Especially brakes. I've seen too many brake issues in the past year or so, one of which was my own.

[feralchimp]

1. Basic tools, 8, 10, 12 sockets and wrenches, torque wrench. 6mm wrench I think for the jets. Top end tools, calipers and some solder if you're paying attention to squish, file set for prepping the piston and rings.

2. If it's due for a top end, do it. The recommended interval holds very tight to when it's required and the 125s only make power at high revs, so you have no option for taking it easy on the engine.

3. Check everything.

Torque wrench recommendations?

How does solder fit into the equation?

Whoa whoa whoa...I'll be taking a metal file to my new top end parts? Seems I need to RTFM in a hardcore manner before my first track day. On the upside, that'll give me some breathing room in the schedule for the top end etc.

[feralchimp]

to #3. Especially brakes. I've seen too many brake issues in the past year or so, one of which was my own.

The bike is coming with a brand new (not installed) front caliper, and I'll be doing a bleed also.

[Kurlon]

Solder is used to measure the 'squish', or the clearance between the top of the piston and the underside of the head when you roll the motor through TDC. The solder string gets flattened and squeezed in the process, by measuring the resulting thickness and using a conversion table you can determine how much clearance you have.

[Paul_E_D]

Do the top end by the book. You can skip the filing of the ring and ring land for now. Lots of folks never do that and have no probs. You can also wait on checking the squish as long as you re-use the base gaskets, or replace with the same exact thickness.

Applying a thin smear of waterproof grease to the base gaskets makes them re-usable for 3 topends.

It will take you 2 hours your first time and 1 hour after that. Follow the manual! And put a papertowel in the bottom of the motor to catch errant circlips!

[Awesome]

Oh yeah, a set of picks for those damn circlips. If you can find something with a teflon coating or something that'd be good not to mar any of the components.

[Scottg22]

I know guys that used to run a whole season of LRRS on one top end. Running it semi rich and just having fun. Granted...it sound like a cement mixer near the end of the season. Then I remember my brother doing topends like crazy.

Probably best to be by the book to start, keep track of laps and mileage etc. Once you have done a few you can probably determine if you can go longer than the recommended book settings by the wear and the look of things.

The old joke in the garage back when my brother and a few friends were racing 125's was... "What main jet?" and the one guy that never wanted to work on anything would yell out "172"!

needless to say, when I got my 125 last year, I put a 172 in.

[Paul_E_D]

Exactly Scotty! I forgot to say put a 172 main in it and run it that way for the first season or 2.

[Pigman]

Buy and Hour meter and trow it on there.......keep track of the time on the head and change as needed

[TTD]

by the way, I still have some of my TZ250 stuff that I don't use anymore.

All stuff for measuring humidity, doing pressure checks on motor after rebuilds, etc.

If interested, I will be at the track for next races (in the Pirelli Garage) and can bring the stuff?

[rolker]

1. Minimum (within reason) toolkit required to wrench on one?

In addition to the above suggestions, I'd add safety wire pliers and lok-tite.

2. If it "needs a top end" and I take it to a Penguin class before doing that, how serious a game of russian roulette am I playing with the motor?

Well, I attempted to do a season of racing plus trackdays last year on a single top end and made it to the second to last trackday of the season before the piston disintegrated on me. So I'm guessing you would probably be ok, but the risk of something failing is there.

3. I'd love to see a set of preflight-style "checklists" for procedures like pre-mixing fuel, inspecting brakes, adjusting jetting based on OAT and humidity, etc. Is there an app for that?

Developing a good checklist is a good idea! Some things that should go on a pre-race or pre-session list are tire pressure, radiator (has water, taped for temperature), enough fuel for the session. A daily checklist would be more extensive, including checking the brakes!

The jetting app? I'm working on it!

[Kurlon]

Can you get forged pistons for these motors? They're heavier than cast typically, but they'll just get louder and louder as they wear instead of cracking up.

[Paul_E_D]

You can get them, but the cast stockers are the most trouble free. The so called A-kit pistons are forged, but can be made lighter with clever grinding. If I remember, I ran them for 20 hours with a re-ring at 10. They are more than double the cost now, and use a less reliable flat ring. Not worth it by any stretch.

[DynoTune]

Get a shop manual and join af1 racing forum. simple to work on, you will only mess it up once.... welcome to the dark side