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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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#3 ·
Dan, those Q Gears have a pretty good amount of weight to them, that is why, to get rid of spinning Weight.. IF I was racing my RC51.... I'd Do It but for 90% street use and 10%: EVEN 50/50 Track Day useage or whatever it is... I'll pass on that mod. as I like the gear whine!

Hey Chuck, I'm really looking forward to this, as I know of only one other guy here that did a similar "hop up" but he doesn't come around here hardly anymore and has Never answered my request about his RC51 Engine build up...:(

Anyway, According to my Honda Service Manual: says the Engine weights in at 155.4lbs or 70.5kg dry weight...

Peace Jeff
 
#5 ·
I was going to ask the same thing, gpz can you tell us more about this HRC service manual? If its real HRC could you possibly PM me some of that info as im going to do an engire rebuild soon. Im sure some of that info would be helpful for me as well. Thanks
 
#6 ·
I've bought the HRC RC51 service manual from Thousand Oaks. It is not the regular service manual. I don't know if you can still get it from them. In one of my other threads with pics, you can see it sitting on my workbench. It is the book with the bright yellow cover.
 
#9 ·
Hi there,
I got my engine apart for this winter. (maintenance and mods too)
Read your info and I was about to ask the same as the guys above :)
Could you possibly describe what they suggest to port ?
they show a few spots to port in the engine cases. I'm going to do that also.
As for "Thousand Oaks"; what is it ? an online book shop ? or a Honda dealership ?

Thanks a million !
 
#13 ·
This is grinding the primary drive gear. I am not going to be reinstalling the quieting sub gear or springs so we ground the gear down to 12mm as per Thorston. In looking at the HRC parts sheet, they do not install the quieting sub gear either.
 

Attachments

#16 ·
To those of you that PM'd me, please accept my apologies for not being able to send this file. It is quite a large file and my ISP won't allow anything more than 10MB to be sent.

So, having said that, I will be arrangeing a special download address, which i will provide over the next couple of days.
If this is still a problem for some of you, i can burn copies of this manual to cd and mail them.

I hope this helps.
Cheers.
 
#17 ·
Nice! thanks Mondial

Also GPZ the grinding of that gear is that the remaning quieting gears that your talking about? Ive removed the ones from the cams but i know there are a couple more are those the ones in the pics.
 
#21 ·
This is kind of a weird area of discussion. Lots of people have been fine with removing the lash gears from the cams.
Many other people have seen all manner of issues with broken cams, and so forth.
FWIW, the HRC bikes did not remove the lash gears in the cams, but did everywhere else, generally.

My thoughts are that the high pitch frequency generated can cause he cast cams to break. Just my theory, nothing more. All engines are very sensitive to harmonics, and this is no exception.
 
#22 ·
Ill chime in on this issue saying that ive taken out the lash gears from the cams only and i havent had an issue yet. Its been a year now with them removed and have done 7 track days and alot of spirited riding with no problem, and ive riden her hard. My concern when doing this mod was that reliability as ive heard good and bad things for this mod. So i ended up replacing all the bolts that i took out with all the gaskets as well. The reason why i replaced all the bolts is that with time bolts happend to strech IMO. I used molylube (assembly lube) as i put things back together and tourqued everything back to spec as per what the manual said.
 
#27 ·
Hey GPZ now the increase of these holes are for what exacly? What does the HRC manual say this will do? Sorry if this sounds like a dumb question but im really interested in all these engine mods so keep the explanations and pics coming please :clapper :notworthy . And thanks for starting a thread like this as ill be needing something like this within the next month.
 
#28 ·
Here you go everyone.
I hope this works.
http://hrc_spw.webgate.net.au/hrcpdf/HRC%20VTR1000%20SP-1%20Owners%20Manual%20&%20Parts%20List.pdf

I've sent afew emails to those that contacted me via pm's with this exact location.
As all of the picturs are black and white, they didn't transfer all that well in my opinion. My apologies.
Now, this download is only up for this week, as it is costing me to have it setup.
If anyone misses out, unfortunately, there will be a small fee to pay for me to send it to them after the cut off.
I hope you all understand.

Cheers.
 
#32 ·
OK, here's the latest. I just dropped off the trans at my buddy's shop. He's going to ship it to Fast by Gast to for the undercutting. We're going with the road race cut. He's used them for over 10 years and has been extremely happy with their work.

Fast By Gast - High Performance Motorcycle Parts

I'm also going to drop off the injectors at a local shop to get cleaned and given a once over.

He's also looked at the cylinders and we've decided that I'm going to send them out to Millennium Technologies to get cleaned up and re coated.

Millennium Technologies

I'll have to find out if they need pistons first before they can do the cylinders. If they do, I guess I better order them too.

BTW: I got my shock back from Traxxion also.
 
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