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Engine Rebuild 101

126K views 211 replies 46 participants last post by  deepaksh 
#1 · (Edited)
OK, this is a 2002 RC51 SP2 engine rebuild and the steps that went into it.

My engine has about 1.5 seasons of racing on it so we figured it was time for a freshening up. Also next season, I'm going to be playing with the experts so a little more HP would be nice. It would have been nice for this previous season but that's life.

First things first, drain your coolant and oil. Remove the bodywork, exhaust, radiators, rear wheel, shock, and swing arm. Also you will need to remove the airbox, throttle body, and all electrical connections. I have a bike lift so the front wheel was held in place by the clamp. We were then able to rotate the frame up off the engine which was on top of couple of small scissor jacks. Be careful, a RC engine is pretty heavy. It helps to have a couple of buddies around.

(Side note) While your shock is out, now would be a good time to send it out for a rebuild. I expect mine back in a couple of days from Traxxion.

Make sure you have a nice area to work in and be able to store all the parts from your engine. It might be apart for a little while before it's back together, waiting on parts etc. etc.

You might want to figure out ahead of time what you are planning on doing to the engine before you take it out. My plans include removing any of the quieting gears, port the heads & valve job, hi compression pistons, under cut the transmission, and any other little thing to hep make some HP. Also looking at the HRC RC51 service manual, they show a few spots to port in the engine cases. I'm going to do that also.

I'll be updating this as we go along. I'll also add pics when possible.
 
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#69 ·
Quick note-

It might be worth looking into a different option regarding the rotating assembly. I would always recommend knife-edge, polish, and balancing the crank. I dont think that lightening it is the best way to reduce mass.
Consider a Thorsten alternator/flywheel instead. There are 2 versions available so you have a choice of how much weight to remove.

Remove it from the crank and you are stuck with what you get.:twocents
 
#70 ·
I'd love to get Thorsten's alternator set up however, I love sleeping in my own bed too. My Wife would kill me if I ordered that up!

She's been very patient with my "hobby" and I don't want to push it any more.

Quick note-

It might be worth looking into a different option regarding the rotating assembly. I would always recommend knife-edge, polish, and balancing the crank. I dont think that lightening it is the best way to reduce mass.
Consider a Thorsten alternator/flywheel instead. There are 2 versions available so you have a choice of how much weight to remove.

Remove it from the crank and you are stuck with what you get.:twocents
 
#72 ·
We're currently waiting on the crank to come back from Falicon. They have the crank, rods, and pistons. BTW: Falicon will not do the ultra-lite supercrank on a RC51. They'll only do the "regular" supercrank.

Make sure you clean your upper case when you get it back from Millennium. Mine had some gunk in the oil passage ways. The wife actually let me put them in the dishwasher!

I've got the gaskets, bearings, and such too.

The ported heads have also come back also. Alex Fornelli took care of the porting.

I'm still waiting on the Akro Ti left midpipe from LP also.
 
#73 ·
Can you please post pictures of the falicon crankshaft when it gets back? I'd love to know also how much weight they shaved down. Keep this post going GPZ :notworthy :clapper :rockon
 
#74 · (Edited)
GPZ11, are you using the stock rods?

I just didn’t have the time to tear my motor apart so I drove it out to Mark Ledesma (formally of North Valley Honda). I like his approach and engine building philosophy. Here is a quick rundown of what we are doing for comparison.

-New stock rods
-Custom dome JE's with moly coated skirts (12.5:1 with OEM Heads, not 11.3 like the off the shelf High Comp parts), OEM Rings
-Cases re-plated back to STD bore by Millennium and honed to the pistons
-STD Dia Morawaki supplied endurance racing steel valves, polished and some other trick work (Thanks to Bob Hayashita)
-HRC SP1 Aluminum Retainers
-HRC SP1 Springs
-New OEM Keepers
-Custom Billet cams, The cams give 1mm more lift, 11.4mm vs. 10.4mm std and have more duration,267* vs 251* std @1mm lift. (Dale Warren Cams)
-J.D. Hord ported heads
-Morawaki aribox
-Akropovic full system
-VP U4.2
-Carmo Electronics extended rev limit ECU (11,000RPM)
-All quieting gears stock
-SP2 T-Bodies (this is a SP1 motor)

I have talked with everyone in length, Rick Hobbs, John Ethel, Bob Hayashita, Hord, Make Norman, Kiyo Wantanaba etch. Everyone has a different way of doing it and there own experiences, opinions. Some say you must run Carillos because they are lighter and stronger, yes they are, but do you really need them and will they make for faster lap times? The HRC crank and rotating assembly was heavier then the stock parts. Testing shows the bike simply went around the track faster with more rotating weight. I also could not find fault with the OEM rods, they just don’t seem to be a failure point. The problem with the RC motor is valve train harmonics. Hopefully getting rid of the hollow cast cams this wont be an issue for me, time will tell. I have been told the Falicon service is similar to the Carrilo rods. It’s nice but I really should not worry about it at this level. If I went by just my own opinion I would have it done, but I am relying heavily on Marks experience, so I will go with what he says. I have a dyno of this motor just before we pulled it apart. It will be very interesting to see how she runs when where done.

Here is my (not so up to date) website with some more info Stewart Racing, WSMC 551

Damon
WSMC #551
 
#75 ·
Wow, thats alot to undertake on the RC. Watch out with rasing the rev limiter on the RC. I saw your website a while back are you on Rogue too? So your engine builder said not to go with a Falicon crank? Well keep us posted and i'd like to see pics and good luck.
 
#76 ·
Yes, I’m on Rogue. I’m not too worried about a stock the bottom end even at 11K, it’s the top end where you run in to problems. My engine builder said "it was not necessary and I recommend spending the money where its needed". He had several fully kitted RC's, one made over 165HP, all with stock bottom ends. So, who am I to argue?
 
#80 ·
OK, you partially lost me on this statement.

I get the part about Falicon not removing as much weight at Thorsten's stator but It doesn't cost twice as much.

It actually is about half the cost of his stator. The Falicon Supercrank for the 51 is $428. I thought his stator set up cost about $1000

Please correct me if I'm wrong cause if his stator set up is $250, I'll order it up in a heartbeat.
 
#79 ·
I’m not too worried about a stock the bottom end even at 11K, it’s the top end where you run in to problems.
Damon is correct.. the RC's bottom end is actually good for 12K. Currently my MOTEC is set for 11.4K also Thorsten has run his @ 11.5K for 3500 miles & zero problems. I too have talked to many of the names Damon has all with the same info.. RC bottom end is very strong. Also John told me that there was VERY little difference in the HRC bottom end & the stocker. The wink link is the top end for anything above 11K.
 
#81 ·
It actually is about half the cost of his stator. The Falicon Supercrank for the 51 is $428.
GPZ... your right.. but I was thinking more along the lines of folks that dont build their own engines like you & I. By the time you get the cases split, crank done, re-instal & all else that is involved your looking at $1200-$1500. All you have to do w/ Thorsten's set up is remove the stator cover pull the flywheel & install. Most shade tree mechanics can do this job in a hour or so... & his cost $700. Dont get me wrong though.. I think it is awesome that your doing this & sharing w/ everyone. :clapper My motor build is very different than yours so it will be cool to see how they compare... I just wish I was as far along as you are.. :(

Cheers!
 
#82 · (Edited)
Ah, I understand.

Yes, it would be alot cheaper just to install his stator to loose mass. I'm rebuilding my motor because it's got alot of racing miles on it. I also am looking for a bit more power since I have to play with the experts from now on.

The total bill to redo my motor is going to be pricey even with me doing the labor.

Rough prices:

Porting the heads ~$600
Recoating the cylinders ~$400 or so (don't remember exactly)
Wiseco Pistons ~$350
Under cut trans ~$700
Falicon Supercrank ~$428 plus shipping
Misc. gaskets ans seals ~$250
Oil, Filter, Plugs, Coolant ~$150

GPZ... your right.. but I was thinking more along the lines of folks that dont build their own engines like you & I. By the time you get the cases split, crank done, re-instal & all else that is involved your looking at $1200-$1500. All you have to do w/ Thorsten's set up is remove the stator cover pull the flywheel & install. Most shade tree mechanics can do this job in a hour or so... & his cost $700. Dont get me wrong though.. I think it is awesome that your doing this & sharing w/ everyone. :clapper My motor build is very different than yours so it will be cool to see how they compare... I just wish I was as far along as you are.. :(

Cheers!
 
#84 ·
Finally, we start the reassembly!

OK, the time has finally come around. I've been waiting for this day for awhile.

All the parts have showed up from the various places and are all back under one garage.

Last night was spent deburring the cases and measuring the clearances of the connecting rod and the main bearings with plastigage. Everything was within spec.

We used the old rod bolts as well as the old crankcase bolts for checking the clearances. You also use different torque specs when using the old bolts. :rtfm When we assembly the motor for good, we will use new rod and case bolts as they are not reusable.

I've also included a pic of the crank as we took it out of the box from Falicon. We then spent awhile cleaning it to make sure it was spotless before we checked the bearing clearances. Also if you send your crank to Falicon, MAKE SURE YOU WRITE DOWN THE BEARING NUMBERS OFF THE CRANK!! They wil be polsihed off as you can see. I took a picture of the crank, dropped it into Powerpoint, and added the bearing numbers in text boxes in the correct spot otherwise you'd be SOL.

You can also see the upper case which has been through the dishwasher while the lower case has not. We also put the shift forks / rod back in and the middle fork was replaced due to a little bit of wear.
 

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#86 ·
Sweet Job Man!!

Hey Chuck, did I read you had changed your mind about doing the 2nd "Big Breath Vent"... Or was that some one else.... It's been awhile since I read through this post... it's just too damn late and I'm baked again... Baked as in tired.. Not as in high...:p


Peace Buddy, Jeff
 
#88 ·
Yeah, we decided to go a different route instead of the big breather. We're going to install a Krankvent (Krank-Vent.com) which will create a vacuum in the crankcase. Kinda like what JD does with the Duc crank vent for his bikes.

Unfortunately we didn't weigh the crankshaft before we sent it out so I can't answer that. It's still pretty heavy but everything in these motors are heavy.
 
#89 ·
I would be glad to host the HRC manual for others if you like. Just let me know where I can get a copy at and it will be as good as done.
 
#90 ·
Cases Assembled

First off, I'm sorry I didn't get any pictures while we were assembling the cases. :(

So in assembling the cases, we measured the ring gaps and adjusted them. They all were too tight so each one was adjusted accordingly. The rods were cleaned up and the pistons attached. The wrist pins clips were a PITA to install. The wrist pins and piston pin bores were wiped with oil before installing the pins. The pistons were attached to the rods. The cylinders were wiped with oil until the paper towels came out clean.

The pistons were then installed in the cylinders. We wiped the rod and main bearings with oil and installed the crank. The rod caps were then installed and torqued. You also need a angle gauge to properly torque the rod bolts as well as 4 of main case bolts.

The transmission was then dropped into the case with a new seal for the sprocket. We also installed a new seal for the clutch push rod. The sealant was then applied to the cases in the correct location as per the manual.

The two case halves were put together. The case bolts were then installed. This also included the 4 new case bolts that you have to replace. The connecting rod bolts were also replaced. We torqued the main case bolts and tightened up the rest of the case bolts.

We called it a night after that.

I snapped some pics this morning. I included a close up pic of the where I cleaned up the lower case according to the HRC manual.
 

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#95 ·
We had some unfortunate family things to take care off out of town. I was able to get out in the garage last night and assemble some more of the engine.

I'll post up some pics later.

We'll do some more tonight.

One thing that I kinda messed up one was not running a tap in all the bolt holes in the top case. This is after I got it back from getting the cylinders replated. I went to tighten down the gear train for the front cylinder and felt the bolt tighten up before it was threaded all the way in. I then figured out there was crap in the bottom of the bolt hole. This is after I ran it through the dishwasher, hand cleaned it in the parts washer and in the heated parts washer at work. I then ran a tap in all the bolt holes and cleaned everything out. I did have to replace the one bolt that got tight on me. I just grabbed one out of the motor I popped when I got the bike.

I did get the gear trains installed and most of the right side of the engine. I need to finish assembling the clutch and put the covers on. Still have the left side which won't take long at all. put the heads and such on, and the bits on the bottom of the engine.

We are having a shop night tonight so we'll get some more done.

My hope / goal is to get it finished and installed so I can get it out to a practice day at Blackhawk before the 1st CCS round down at Topeka.

I also have to finish up our SV650 that I found out last night won't shift passed 2nd gear. It was a crashed insurance write off that went down on the left side. I'm hoping and praying that it's something simple like a bent shift shaft and we don't have to split the case on that one. I pulled the clutch cover off that one and will be checking it out tonight also.
 
#97 ·
We got some more done last night. The heads are on it and the left side is all buttoned up. I didn't have a case sealer so I couldn't install the right side cover.

All that's left is the cams, valve covers, oil pick up & bypass, and the oil pan. Hopefully, I'll get some more done this weekend.
 

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#99 ·
Well, it's pretty much buttoned up now. I'm leaving the oil pan off since the engine is more stable while we're trying to install it.

I had to adjust one valve's clearance. All the rest were within spec. I was able to snag a shim out of the old motor.

You can see in the pics that I did leave the quieting gears on the cams. I also replaced the gear train with some stock ones.

We're going to put it back int he frame tonight and hopefully by this weekend, it be running.
 

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