Cr 85 Help!!!

[bigdaddy77]

We picked up a 90 mod. Had a good running motor in it. The 1 st owners had just started modding it and bought a used stroker motor 2003-2004. They ran it at one national " the motor " and decided to sell . The only thing i did was add a larger radiator same style just a better than stock that advertised 30% more cooling and we changed the jetting from a 42 pilot and 142 main to a 40 pilot and 132 main the carb is a 28 round slide keihin with a 2" uni pod filter and outerwear. The original owner thought he had it running fat. We ran it probably a total of 3-4 hours. The expansion chamber got a tear in it from a little crash so we welded it up and put a patch over the repair and reattached the mounting bracket.
So any how here is the problem we go to the track last Sunday August 18 make it a lap and 1/2 in practice and we loose the topend. The days we first rode it is was 108 degrees. Sunday it's 86 degrees! WTF? So get a piston and rings and all the goodies. Take it to a buddy that owns a shop. HE takes some muratic acid and cleans the cylinder. Should be good for some practice this weekend and we will decide if it needs the cylinder renickled sealed or what. Get it running Thursday , buzz it around the yard oh and change the jetting back to 142 main and go with a #9 plug instead of #8. runs fine . Go to the track 1/2 lap quits making power. Running vp 110, belray synthetic two stroke oil mixed 32 :1 . New Reed cage, and intake and exhuast gaskets when put back together. I drained the gas out of tank this morning to make sure i didnt put in the 4 strokes gas by mistake . Def premixed. Now when i bought the new can and fuel they premixed it but it has burned up at 2 gallons of it before failure.
What gives the piston is failing on the exhaust side. I know it was questionable to put the motor together with out getting the cylinder nickled sealed or replaced but i was just trying to get it up and running. My son is 8 and is a marginal rider, has been on shifters since 6 and we were just trying to get him seat time.
Any help or input would be great. I ordered a new cylinder this morning and im going to put it on our otherbottom end. The mechanic at the honda dealer said they can run lean through a crankcase seal. Has anyone ever heard of this. Please guys steer me in the right direction , we have a big 3 day weekend and cant afford not to at least make one complete moto! LOL

[bigdaddy77]

Upon further tear down it was the lack of a functioning waterpump that caused the melt down. Actually the lack of installing the nut, that holds the gear that spins the waterpump , to the crankshaft.
Now it looks like a total rebuild since the end of the crank is destroyed. Almost checked the waterpump the first time but didnt have a gasket.
What is your guys opinion, to go back with stroker crank or just put a stock crank in it?

[Logan #34's Dad]

Glad you figured it out at least.
Did your stroker crank go bad? Or just a lil worried cause everything got hot?
Stroker will give you SOME gain but IMO they are not worth the extra money. $600 vs $90.....
Your 132 main is way to lean. Stock bike jetting is usually pretty close. With a D slide it seems the norm is from 138 to 142 with 40 or 42 pilot and needle clip in the middle.
Now, If your rider is needing that little more power then maybe....
You can get a get deal on a stock crank through Honda of East Toledo.
We just raced a kid on what his dad said was a pure stock cr85 with a Pro Curcuit OR Bills pipe and some V-force reeds and it was every bit as fast as my ported stroker.

[doonanracing]

you can get a stroker crank built or rebuilt for under $400. there is case work that was done to get the proper clearances if not already done. I must we had 2 motors with one being a stock crank ported motor that was build by reputable engine builder and son also head a stroker motor with porting. the power was allot smoother with the stroker crank and actually he was a little bit faster with the stroker comparing lap times. here is a link. not the max rpm involved with mini. but no one could match their price of building a stroker crank from what I found and they have a kit for under $1,5k to build a National motor. I think I paid around $350 to have a crank rebuilt when bearing went out in it. simply send them a stock or stroker crank and they will remove rod and re-build a crank completly and can weld and true it or whatever you desire. hope this helps. link: http://www.maxrpms.net/shop/index.php/motorcycle-kits/mk-honda/cr85/cr90-big-bore-3.html

[Ryko racing]

we always ran a 40 pilot, clip in middle and 125 main in our 90 stroker. w oxygenatd fuel. ( it was Gilchrists and ran 2 full seasins with no issues)

You may be real rich on top.

[bigdaddy77]

Hey guys thanks for the input. I have a second motor that was stroked by Joe Wolton at Titan Motorworks. He really knows his stuff. The problem with it is the previous owner over ported the top end . Joe was amased it had as much on the bottom end as it did. Which isnt much. So I ordered a cylinder from Motosports. Suppose to have it in stock and it will get to the house Wednesday. Honda Toledo East didnt have it in stock and didnt think I would have it by Friday.The local Honda shop could get it next day but it was $321 with my 15% off. Actually Motosports wasnt much more than Honda Toledo East.
So the plan is to put the stock cylinder on the stroker bottom end that right now has the heavily ported cylinder on it.It all sounds good except I drove up to Chicago today { where I have been working all summer because the Pipefitter construction bussiness down by St louis is in bad shape} So I go by the union hall this morning to check in and hope to get out on a job shortly after Labor Day and what do you know it they send me to US Steel tomorrow. So now I dont even know if I will get to come home this weekend and race!! But pipefitting pays to drop all the ignorant money I have spent the last year and a half.LOL
Anyway the original stroked motor is junk as of now. The end of the crank is in the bottom of the case in shavings and it seems the bearings were getting alot of play in them. I think im going to put a stock crank in it . Unless it isnt possible with the work that has been done to the cases to stroke it. Going to renickel seal the cylinder and run it for practice and local races. after the season im going to have this new cylinder nickel sealed and a little port work done on it and put it back on the stroker motor and leave it for a handful of nationals and the bigger races we run in Illinois.
One last ? if I get to come home and get the motor put together what is the break in period and any other tips for a fresh topend?Thanks again and Im going to stick with 142 main and 40 pilot.

[qcitytile]

I always do three idol heat cycles then a fourth but running it half throttle. Then let er rip. I am close to you guys and we ran 140 main and 42 pilot with u4 on a ported motor. 138 42 on stock. We are within 3 hrs. of each other I believe. Our kids raced at bet I think. Dalton was on a cr85 cobra #306

[Yuk33]

We just toasted our stock crank running to lean with clip in the middle on the needle, 42 pilot & 142 main. Dyno guys at the track said we were running lean, but I didn't listen to them. We are now, needle clip one from the top, 42 pilot & 150 main. Seems to be running fine.

[Hetrick Racing]

D slide carbs 142 main and I run a bit rich on the pilot so you can choose that,, if you have a cr motor that idles real well with a kid that runs the pipe all the time you will hurt the piston on deceleration
Round slide carb 125-128 same idea on the pilot. what I do is make it idle nice and rev nice then move it up one size the motor will still idle for a short time,this just adds some fuel at 14000 when the throttle is closed

[bigdaddy77]

We are running a round slide carb. With 40 pilot and 142 main. Is this 2 rich? The plug looked lean when the topend first went and looked about right when it went out again. But of course we now know it was do to lack of cooling . Would this cause the plug to look lean?
I have a flat slide 28mm keihin but don't have a ton of time to get it all adjusted for this weekend. It ran really good before the crank issue. Just needed a little gas when you fired it up which tells me it was rich.
Looks like they want us to work 12 hours all weekend ! Told told the boss can't do it. If the wife finds out she going to string me up. Passing up a 12 hour time and half day and 2 - 12 hour double time days. But you got to have your priorities.

[bigdaddy77]

Hey gcitytile are you guys going to Richwoods Saturday ? When you guys ran the BET I was working , so my wife took him. We live about 5 minutes from the BET. Also we are racing at Casey LTM Sunday and Monday . You guys should come out . Some really fast kids and we would love to have some more mini quads. It's a free for all 90 class 8-15 age group. That's why we went with a mod . Going to try and run both production and mod at Richwoods .

[Ryko racing]

We bought Colby Gilchrists in 2009 and he ran a round slide carb w 42 pilot ( fat on the bottom, idled poorly..) clip in center and 125 main w u 4.2 oxygenated fuel and never had to touch it and it ripped. ( ran 2 full national seasons without rebuilding the bottom end.)

tHE OXYGENATED FUEL BURNS LEANER SO IF YOU ARE RUNNING C12 YOU CAN PROBABLY GO LEANER. BUT THAT SET UP IS FOOLPROOF. GOOD LUCK

[qcitytile]

Going to richwoods for sure, Dalton will be running a jb150 this time. Decided its 4 stroke time, because he is starting to race his 300 and it was causing a little conflict. Don't think we can make Casey because of other commitments, but I hear its a awesome place. Hope you get everything ready and We'll see you at romp.

[Ryko racing]

where is this track we would like to come this weekend. do they run mods and superminis too ?

[qcitytile]

Richwoods,Mo is sat and Casey,IL is sun. and mon. i think casey only has a 90 class not sure if they seperate. I think they have good turnouts in the 300 class. There both big tracks

[bigdaddy77]

Richwoods is a hour south of St Louis and the name of the track is ROMP . You can find info on district 18 website. They have 90 production, 90 mod and supermini class
Casey is located half way between Terahaute In and Effingham Illinois on I-70. They have a 90 class and we have run the boys in the 300 class because nobody else runs it. So you would be fine on the supermini. Actually Cyler Jackson runs all of the district 17 on Chloe buersters super mini. We would love to have you guys you can find info at LTM (lincoln trail motosports) web site . The name of the series is motooutcast. They would probably even let you run the 450 not real sticklers for the age deal if your pretty close. Casey is sunday and monday and they have descent facilities . Give me a call or text if interested and that goes for anyone else. Brian 618-975-7303

[bigdaddy77]

Just wanted to thank everyone for their help. Got the motor fired yesterday and pur a d-slide carb we had on it. Jetted 142 main 42 pilot clip in the middle and she sure does fire easy and idle nice. Hopefully the rain will hold off and we can race it Sunday and Monday. Thanks again

[bigdaddy77]

Spoke too soon ! Took it out to ride and was smoking quite a bit and didnt want to rev. thought it was loaded up from heat cycles. Ran it down the street and it didnt want to get on the pipe. After several runs we ended up at 132 main 40 pilot and this is a bone stock cylinder new out of the box. The lower end has been stroked and epoxied but this is all we have to run. What do you think seems to run real good up top but has a little mid range stutter. up one on the needle to lean it it?

[bigdaddy77]

Its official Im A Idiot!! Upon further review of our motor situation i realized I hadnt even checked the air fuel mixture screw. It was cranked all the way in.The carb came with a bunch of Pitster motor parts I picked up a couple months ago. So we put it all back to 42 pilot, 142 main, needle on center clip, air fuel screw 2 turns out. Did a couple plug chops with a brand new plug. Seemed to be pretty close , half the electrode was a coffee color the other half didnt really have any color.
We couldnt get it past third gear because our street is pretty short and we decided to stop because the one crabby old neighbor was giving us the look. The only thing that baffles me is that around the exhaust flange we still have a wet oily reisidue. wipe it off and run it and it comes back. We have a Bills Pipe that slips over the flange.
When I it idoling for a while ( to adjust the idol and air fuel mixture) it seemed like it was running a little hot. Or maybe Im just paranoid because of the way the other motor cooked.
Does anyone know what needle is suppose to be in these things. On a couple of dirtbike forums they make mention to a nfsn but I cant find that part number with keihin anywhere.

[Ryko racing]

we ran the stock needle from a cr 85. actually i had the best luck with acarb off a cr 85. round slide 125 main, 40 pilot clip middle or number two. d slide 140 main 42 pilot clip in 2nd. If the oil is dripping its too rich. If its around slide i think you are way rich .

actually i was down to a 120 at lorettas on he round slide and a 132 on the d slide last year and it was perfect.

[Logan #34's Dad]

D slide carb needle: NFSF

[bigdaddy77]

Ryko we are now running the d slide. I don't have the jets to get the round slide going. Need to order a jet kit.I'll go by the Honda dealer today and see if we can get that needle. Mine was a jjh or something. Thanks for the help were on the right path now. It seemed to rip pretty good. Hopefully we get to race it in a week or two.