butcheryboy

Rotors both measured 69.85mm at the thickest point, with side plate clearance of 0.08 rear rotor and 0.09 front rotor..pretty much factory specs.

butcheryboy

butcheryboy

*Correction* Land clearance of 0.08 on the rear rotor and 0.09 on the front rotor..pretty much factory specs otherwise.

j9fd3s

sounds like its a runner then....

butcheryboy

She's a runner

benedunn

Figure this might be the best place to put this!

ive been rummaging about everywhere to find an answer to my woes, bearly got any bloody hair left ive been scratching my head in deep thought over this for long.

Ive built a few engines over here on this side of the pond and love it :-)

im in the process off getting my 1st half bridgey (MSP) together for a friend of mine, ports are cut and the housings went off for surface grinding, 3 thou taken off all 4 faces and they came out amazingly flat 30 mins of hand lapping using 600 grit valve grinding past has left us with a very nice dul srface with a rating of about 9 - 11 RA. good stuff, all seems set to go!

BUT and its a big BUT since i did this ive encountered problems with 4 other engines ( not mine the bridgey was the 1st to be lapped of mine) that have had surface treatments 3 lapped and 1 surface ground.

the 1st time i noticed a problem i had an engine shipped to me to use as parts, when it arrived it had been painted, so obviously not a factory build. upon strip down it looked like it had been built with a granade inside exept the housings are in remarkably good nick. the iron on the other hand were severly scored and the areas were the rotor gear runs is blue with heat and got some pretty but nasty patterns going on. the front rotor is in good nick although the front iron is chewed up to hell. the rear rotors gear is mangled unbelevably bad and the iron its self looks like its been half digested and spat back out. after a bit of brake cleaner it became clear that the irons had been surface ground as the grinding marks were still there over the whole surface of the irons. so i measured them up against stock irons and the rear iron is short by 6 thou the front 7 thou and the center iron a full 13 thou (6.5 a side im guessing)

this is blatantly too much removed and explains the rouble with the large steps on the housings from wear as there is no nitride treat areas left i cannot understand however why this would cause the rotors to touch the housing

the next time i saw it i was at a track day and friend from down south who built his own engine's car started smoking quite badly at idle, hed done a couple of thousand miles on the engine. when he built it he had the side walls lapped. i cannot remember the exact numbers but not much was removed, im quite sure this is the same problem again (and obviously the same problem the OP of this thread had)

my 3rd contact with it was on an engine being run in an off road race buggy, the engine had been built quite recently by pip gardner who had given the plates a gental lapping before the rebuild .... i doubt he removed much material at all as the engine was an S2 engine that had done about 14k miles tops ... when i went to see the car it had been built just 200 miles and both rotors were nackard with VERY low compression although no signs of oil coming out of the plug holes on cranking it was a bit smokey again at low revs.

Then just yesterday another of my southern mates rang me, he'd just finished running in a low power reni but needed to pop some new stationary gear bearings in it (he didnt have any on the build) before he could sell the car. when he went to take out the front gear nothing would get it to budge so he set in stripped the engine back down with the intention of finding out why, what he found was again a bit disturbing. both the front and rear side walls were showing wear, the front in particular. although you couldnt see any damage to the rotor gears the wear on teh side was definatly down to the gear touching it!!!

here again he had had the plates lapped, and bearly removed any material at all. it was his test lapping engine if you like. he got kinda lucky that he stripped it down i guess

anyway so thats 4 engines, all have been lapped in some form or another and all are having problems with the gears touching the size housings!!!

its worth noting also that me and james among many others (including the many real specialists in the states as you know) have had great success rebuilding renesis engines without having the side irons lapped


PICS COMING SOON

Lynn E. Hanover

Again, when any rotor is in the open, put it in a press and give the gear a good push. Then measure the land height. Then reduce (grind) the land height to just below minimum spec. Then install 6 little set screws into hole that intersect both the gear and the rotor. Red Loctite and stake the hole after installation. Now the gear cannot walk out again. Notice that gears tend to walk out with long term high oil temperatures, and ,or, high revs (over stock red line). So, now you have a rotor that will not screw up your irons. For lots of time above 9,000 RPM, shave the rotor down .010" between the outer oil scraper groove ant the tip. For use above 10,000 RPM remove .012". Use a sharp bit so as not to screw up the corner seal holes. Debur and smooth everything. Polish the combustion surfaces like chrome. Looks great. Easy to clean. Very little carbon will stick to it.

Once you have ground the irons or, lapped extensively you are through the Nitride. Now the wear life will be shorter. A few years depending on the quality of your air filter and your top oil. A name brand SYNTHETIC 2 cycle
oil in a premix at 1 ounce per gallon of fuel or using an OMP adaptor to feed the 2 cycle oil from a bottle on the firewall. Rotaries do not toleate dust or dirt in any size.
So grease the gasket surfaces in you air cleaner so nothing gets through to the engine.

Lynn E. Hanover

banzaitoyota

Lynn, I absolutely agree with your advice on greasing the air filter and using 2 stroke

benedunn

sound advice indeed lyn ... and advice i adeer to religusly in my own car! thank you

i like the mod idea too!!!

what im wondering is why these engines arnt having problems on the factory build, why they are ok if you dont touch the housings and why they suddenly all have problems when you do

got me thinking tho, wonder if the finish is not good enough and its causing exesive friction and inturn heat build up which is causing the gear to move out as you say

cheers for getting back to me anyway

PhillipM

Or the nitriding process has been changed and is thinner than previously, remember we've had a bit of this issue with the '09 motor from the start - it had some marks already, although did a lot more than 200 bloody miles last time (although the actual failure was warped apex seals last time)
I'd be very surprised if it were dirt in the engine given the intake air is filtered twice through 3 filters, and the filters are sealed in, lubrication shouldn't be an issue given the amount of 2-stroke we run. Pity I don't still have access to the TiN coating plasma spray at WPS