250-500cc 360, top end, when?

Guys, the '96 360 I have, may have between 60-85 hours total, never raced. I believe the motor is 100% original.

Bike runs pretty dang good, and also switching over to the Lectron carb here in the next week or two.

Was wondering, since I'm going through the bike for general maintenance, etc, is now a good time to test compression and open the top end and take some measurements of things?

Do some just replace the rings if piston still in spec, and re-hone the cylinder?

I don't mind refreshing what needs refreshing... just checking opinions on that, esp around hours.

Also, when does the power valve need any love, never?

60-85 hours? thats it? thats a real gem you have then. i would suspect you have next to no wear inside. never hurts to check compression. if it helps you any, when i redid mine last summer with a fresh wossner, it had just over 160 psi..after about 50 hours last summer its still at that. there is not really much to hone in a plated cylinder, and surprisingly my bore still looked new and took the smallest piston. it probably helps the 360 is a capable lugger and only sees higher rpm for bursts when needed..
it is acceptable to replace only the rings if everything else measures ok but personally i replace the piston as well and call it done. piston skirts do fatigue and crack in high hour situations...i would not worry about anything under 200 hours if the compression is good..

Thanks Justin! Great info! I'll test compression and see where its at. I'll report back in the coming week or two. I'm stoked....won't take much to refresh this thing then. Cool!

i have well over 200 hours on my 88 250 i bought as nos..i keep think its getting weak or wearing out but its still at 215 psi....stock ring. i dont race but i certainly dont baby the thing. castor oil klotz certainly does not hurt. that bike sees a lot more revs than the 360 as well. way different motor but my point is clean air and good oil go a long way. i know theres some 125 engine bikes here in 144 and 165 form as well with waaay over 100 hours on their pistons.

when i redid my 360 i followed the shop manual procedure on setting squish clearance, also adjusted the power valves per manual. i know the squish could be pushed harder but it runs plenty good and starts easy..

i have 10 years on my 93 360, not positive of the hours but ride it more than the others
never did a thing to it and it still runs great
but it was fresh rebuild when i got it
they are durable

Great stuff guys, thank you! Sounds like if anything, just check it out, but possibly nothing is needed from the sound of it. Thanks for the reference.

I do ride 100% open desert with it since getting it in late '07 (might do a little more local stuff, but we'll see). And when riding along side my friend's FC501, we're more or less neck and neck towards the top of 6th and I take most of the lead in getting to 6th, but he leaves me by just a hair at the very end.... well, my point is, I do rev it out some, don't over rev or top it out, as I know these engine internals are not lightweight and have some extra mass to them, so I ease up quick, but I do rev it out on the dez trails more often than a lot of guys riding backwoods trails and single track stuff. Usually run around 50:1 Amsoil Interceptor Premix, and I change the oil every trip, which means about only 4-8 hours between oil changes, and running 10-40 Full Syn Amsoil. Air filter in great shape too, and will be changing out this next week or two when it gets torn down for these upgrades and basic maintenance.

Doesnt sound like you need to do much i personally would slip a tad more oil in the mix if your hooning it in desert but if it aint broke dont fix it, ive set my squish to .50 thou and my rings are old, on original piston to bike and original barrel, did swap to 1993 lined but i seized it from being to impatient on warm up.
Solid bike when alls said and done love the looks and always turns heads.
This is a pic of piston with smaller squish you can actually see the scavenging marks on the carbon build up i run at 33:1

interceptor is great stuff, ive run the amsoil bottom end oil quite a bit as well. its still what gets run in my street bike and cars.

Solid info guys. I'll up the pre-mix as well.

i have always used 40:1 for liquid cooled, 32:1 for air cooled...i know some get by with much less oil but it works for me, and i have little spooge or buildup. i buy by the gallon so i put the oil to 'er!

Guys, compression is 162. Should I do the rings?

No! Waste of time mines about 90 and she runs fine got some piston slap but the rings are 70hours old and the same piston i bought the bike with, stop looking for excuses to strip the beast down and run her till she screams no more!

here is a quote from myself earlier with the readings i got from my compression check after i just assembled a new piston and ring....sounds about the same as yours, but it sounds like you really want to tear it down

Juicy. You're hilarious! Haha

Justin...yeah, I remember that. OK....so its still great, just not perfect. I'll leave alone for this season then, top end wise, got it.

Lectron going on now....as well.

Tehee will let you guys know when my piston eats itself. Lol
162 good compression in my opinion.
High revs mine hit the rev limit everyday the past month not having a van and commuting on the bike will do that.
Oh 15.48 gearing tops out flat full chat the balls to the wall wait.... Wait for it 70 mph, i know odd its exactly the amount as our speed limit but coincidence hay (shrugs) may be a few give or take but thats off garmin sat nav

well i would say its close to perfect. i took my cylinder down to machine shop, had them inspect it(measure size and roundness), tell me its basically perfect, order the smallest piston. installed everything, set squish per book spec, kicked and got 160 psi. your bike has same compression as a brand new wossner topend so i would say its good to go. i had checked again at the end of summer, maybe 40 hours later? and it was up a pound or two. just over 160. i guess it was broke in at that point.

Now thats a good reading justintendo i now have a book spec for my new wossner piston on my 93 cylinder, what clearance you running the 0.06mm reccomended?
Mines a cast liner running 78.44mm piston think after first seize i need to increase clearance to 0.07ish, what say you?

Great stuff as always guys! Solid info and thx for the quick replies. I was sure if you were doing it at 162 or it was 162 after the build. Thx for clarifying!

Ok, this is great news. This bike is amazing to be in this condition. As far as i know, it's original. Makes me even more impressed with that thing. I had a a slight seep with the water pump o-ring.

Called MotoXotica to get it quick and since lately I've done a lot of business with them, as with others this month, they just sent it to me for free. What a shop I tell ya! Great people, Dan and Ann.

Ill of course post pics in the coming week of the 360 all shined up, with new parts on it, incl pics of the Lectron.

Love this darn bike!!

i cant remember to be honest, i can tell you i went by the spec that was listed in my owners manual for clearance. i gave the specs to my machine shop and showed them what pistons were available to me i.e. (a/b/c/d). they said my plated cylinder looked excellent and called for "a", the smallest piston!..i can check outside in my manual for you tho. i think it matches up with the wossner spec.