Yamaha R6 Forum: YZF-R6 Forums banner

Motor refresh interval?

20K views 85 replies 13 participants last post by  Goatse 
#1 ·
Curious what system people use (if at all). I have a GPX Pro so it tracks hours and mileage for me. It's 100% track so easy enough.

I sometimes see posts where people talk about how many "seasons" they get out of their bike, but that's a pretty useless metric. Does anyone track their refresh intervals by race hours and, if so, what interval are you using? (and what are you doing after X amount of hours)
 
#2 ·
Would totally be dependent on build of the motor. Stock? Run her till she blows...or starts to use excessive oil, etc. If it's built, generally the builder of the engine will give you a window of when you should look at refreshing the motor.

If the engine builder cannot provide you with an estimate on when it should be rebuilt, that is definitely a red flag not to go with that guy...
 
#4 ·
Usually rings or valves go before the coating. My 81 BMW still has coated cylinders.
FWIW, a guy I know had about 40,000 miles (maybe half were racing and coaching) before his leakdown test showed something wrong in #3. Still ran and he has it as a back up motor until he can rebuild it.
 
#8 ·
no way does a street bike see the wear/abuse a fast rider puts on a track/race only engine. The valves are a weak link in a 3rd gen r6 motor, especially if you run mr12 or some other race fuels. The exhaust valves specifically get pitted on the seat face, and once the coating on these TI valves is compromised, they are not long for this world. exst. valves must be replaced on a race engine using race fuel every season or 2..

a leak down test is the first thing i would do. more than 5% leak down? not too bad.. but as a front running expert, i don't wanna see more tan 5-6%, and i wanna see consistency across all 4 cylinders. 10% ? most experts will rebuild but for most track day riders or AM racers, not a huge deal.. one friend of mine had 25 % leak down on his engine (1st year expert and had 3 seasons on his engine) and it still ran decent, but obviously well down on power. My guy did the rebuild for him. Rings, bearings, sent the head to KWS for seat cutting, all new valves and springs.

road use and pump gas.. not nearly the problems with valves that you will see with a race engine regularly 9000rpm or higher, and using race fuel. Race fuel leaves a horrible reside that as stated before, pits the exst valve faces..

do a compression test (min spec for a STOCK motor is 185psi, with less than 10psi variation from cyl to cyl).. comp test needs done with the butterfly plates on the throttle bodies held open somewhat, and all spark plugs out (so it cranks faster) and a good and charged battery. Slow crank, and/or butterflys closed, will show low psi !
a leak down test is better.. but need a mechanic with the leak down tool and know-how to do it. This test indicates not only the amount of leak-down, but WHERE it's coming from. If you hear the hissing air from throttle bodies it's intake valve leak, at the muffler it's leaking past exhaust valves, if from the ignition cover area (and have to have off to move engine to TDC on each cyl) it's leaking past the rings..

hard core racing, every season should do a build. (rings, pistons, bearings, valves, springs, seats cut, hone cyl). every couple sesasons for AM racing to be safe..

ALSO! i don't see any reason why a "built" motor should be rebuilt any more often than a typical race engine. A good superbike build, with carrillo rods, won't need rebuilt any more often than a typical supersport build (just thinner head gasket and cam timing).
 
#9 ·
So...what about the track day heros/racers that use bone stock engines with pump gas? ;)
 
#11 · (Edited)
I've never done a leak down test on mine, probably should ...

This bike was custom dyno'd on Sunoco 250 from an AMA round it was used for. Not sure how the integrity of the engine was other than the tune that it was running....118whp on a bone stock motor with 260 fuel.
 
#14 ·
rhouck , the leak down test should be done before tear down. If there is very little leak down, no need to even pull the motor apart. Valves are VERY expensive ($1000 minimum for a full set of 16). And you are crazy to buy new valves, if you don't spend $250+- to have the seats in the head cut...

intakes generally don't show too much wear, even with race fuel. It's the ex valves that take a beating and get a buildup on the stem and top side of the face.. and there is a buildup of crud in the exs. port of the head too. it's way worse, if you don't chase the mr12 or any oxygenated fuel out after a race weekend with pump gas for a good while. I drain the tank (have a bung welded on teh bottom with a quick disconnect), then take off the fuel line and drain both fuel rails (have to used an air tip sometimes to coax the fuel out .. ) then hook it all back up and run some non-ethanol fuel through for a good while. THEN , i fog the motor if it 's gonna sit a couple weeks or more. I use wd40, but there is actual fogging oil spray you can buy. With the air box lid off, you spray a little into each velocity stack while running the bike. DO NOT spray a bunch into any one cyl at a time, as you can literally hydro lock the motor.. so just go back and forth real fast across all 4 v-stacks then shut the enigine off. the ports and cyl are then coated a little and resist the oxidation that forms on the exst valves and exst ports..

the crud that forms if you don't chase race fuel out is real.. chase it out, fog the motor. if you run mr12 or some other race fuels. YOU WILL NOT get this stuff forming if you use pump gas.


 
#15 ·
Yeah, eff all that. I'll stick with pump gas until I'm actually a threat to getting consistently on the podium. I'm all about normal bike tear down between races, but fvuck all that noise. :lmao
 
#16 ·
^^ yup.

going faster is fun and all, and the chicks seem to dig it :) but it can cost silly money (unless you are just some uber talented phenom). More tires, more engine rebuilds, better suspension, etc. I sometimes miss the days of just doing track days, and getting 2 days out of a rear tire, running it one way one day and flipping for the next...
 
#17 ·
Off topic, but I decided to get my suspension refreshed by the man, the myth, the legend, Thermosman this year. Talked to him a good bit on the phone. Without me saying anything, he asked me "Do you have problems getting the bike to finish turns?" And I was OH MY GOD... yes!!! I thought it was some kind of black magic, he knew the problems I was having and I didn't even mention it...

Anyways, I'm looking forward to this year. :)
 
#23 ·
Thanks, Melka. I wasn't sure if the leak down was sufficient to show ex valve coating wear but sounds like that's all I need. I'll be sure to do that in a few months. Is a leak down tester not worth investing in as an at home tool?

I'm certainly not itching to spend $1k on valves! Just don't want to end up having to a rebuild mid season if I can avoid it (especially if it proves more costly because I put it off).
 
#25 ·
leak down will show, but also if you are in dire need of a valve adjustment ! once the coating wears off the ti valve, they are not long for this world. They mushroom quite fast, and clearance is diminished.. soon, the valve is held open a tad, since there is no clearance at the cam lobe, and bucket. less compression, harder starts, all bad. So, if your valves are all in perfect spec, and you have good leak down numbers, that's at least a good sign the valves are in good shape.
 
#26 ·
Correct me if I am wrong, but does the old school diagnosis process still work? IE: couple drops of 2 stroke oil in the cylinder. If leakdown improves you have ring/ cylinder wear. If not it's valves.
Used to do this with boat engines. Granted the clearance was not as big a deal if you got generous with the oil.
 
#27 ·
pretty much. The manual outlines this process... min spec is 185psi doing a compression test (stock motor, not higher compression pistons and/or thinner head gasket). if it's lower than this, put a teaspoon of oil in the spark plug hole. double check the manual, but pretty sure it states if the compression increases, the rings are worn.
 
#28 ·
Any thoughts on the differences between different leakdown tester kits?

Motion Pro ($145) http://www.motorcycle-superstore.com/4814/i/motion-pro-4-stroke-leak-down-tester

Pit Posse ($90) [ame]http://www.amazon.com/Pit-Posse-PP2723-Tester-Motorcycle/dp/B004N6EEPY[/ame]


Harbor Freight ($40) http://www.harborfreight.com/cylinder-leak-down-tester-94190.html

Bit of a price range there, and all it seems to be is a gauge and hose to thread into the spark plug hole... Worth it to pop for a nicer one since a couple % accuracy actually matters here?
 
#30 ·
Any thoughts on the differences between different leakdown tester kits?

Motion Pro ($145) http://www.motorcycle-superstore.com/4814/i/motion-pro-4-stroke-leak-down-tester

Pit Posse ($90) http://www.amazon.com/Pit-Posse-PP2723-Tester-Motorcycle/dp/B004N6EEPY


Harbor Freight ($40) http://www.harborfreight.com/cylinder-leak-down-tester-94190.html

Bit of a price range there, and all it seems to be is a gauge and hose to thread into the spark plug hole... Worth it to pop for a nicer one since a couple % accuracy actually matters here?
will need an air compressor that can make 100psi, or you need to be good at math, to calculate the % of leakdown at say 75psi..
considering you will likely use this tool once or twice, in many years, it MAY be worth having a reputable builder doing the ld test. this way, you can get a bunch of good advice along with having the test done correctly.. just one idea anyway.
 
#36 ·
BYOE (bring your own engine) :)
 
#37 ·
Well this thread was somewhat prescient. Motor blew up yesterday... while in second place with 5 corners left :'( sounded like bottom end let go, loud "clunk clunk clunk", no power, and when I shut it off it wouldn't crank over again later. Having it looked at to see if it's rebuildable. Bummer of a way to end the season with only 2 more races left, but at least it didn't oil the track or cause me to crash.
 
#44 ·
The more I started thinking about it, the more I started to worry that's what it was... I didn't remember it continuing to run so long after it lost power. I admit I have no experience (thankfully) in this arena. I'll find out soon. :( Trying to research whether it'll be worth trying to repair or just junk it and buy a used motor, seems like it may be the latter.

Typical causes? Needed a valve adj? Rev limit was 16k, but too much time on the limiter? Wondering how to hopefully prevent in the future.
 
#50 ·


Broken crank.

Suggestion to rebuild was:
- new crank
- replace 1 rod
- all new pistons
- all new rings
- all new bearings
- new gaskets

Should I try to have head down now since it's apart? Replace ex valves and springs?

I'm on somewhat of a timetable since I'm trying to race again on May 2-3 (and need to leave on May 1), but I also would rather do this right since it's all apart and out of the bike right now...
 
#56 ·
you need a LOT of stuff.. surprising a rod didn't get kicked through the case, so that is SOME good news.
You need a good builder, and a lot of money.
Valves and springs $1100 (too many miles to just do ex )
Crank $700 retail hopefully your guy can cut you a break as $400 is cost
Pistons/rings $300
Rods $300
timing chain,bearings and misc gaskets $350
Head seat cutting $270 , no way do you put new valves in and not do that
assembly/labor $600

these are rough numbers off top of my head. but not far off. Also assumes you didn't break anything in the head if a piston kissed some valves.
 
#55 ·
http://www.ebay.com/itm/R6R-ENGINE-...-07-/201320734846?hash=item2edfa6a07e&vxp=mtr

Not ideal but here is a quick ebay search candidate.

$1200 is about my limit on a stock used motor and the mileage has to be low.
Im sure the supply is kinda slim at the moment as race season has begun.
Anyone that had an R6 at Road Atl last weekend had at least 1 complete motor in their trailer. :lmao Id guess the bigger teams (Graves, Meen) had a handful!
 
#65 ·
Well, as an update, I had my motor rebuilt and I also bought a spare motor (with recent leakdown results). Did the break-in at Sonoma this weekend and was good enough for a win and a 3rd, so it seems to run alright so far. :D We'll see how long it lasts. I at least now really know what the motor condition is like (though I should have reset my GPX mileage before Sonoma), so I'll apply this thread's advice re yearly checkups going forward. Thanks, all.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top