July 20, 2013 at 9:46 pm #4276
Which way is the best way (and why) to install the crank seals on a CR125.After the crank and halves are assembled or before the crank is installed? Both ways are possible but I wanted to know from the experts which is bes tand why.Thanks!July 20, 2013 at 10:58 pm #4279
I really don’t think it matters. Just make sure they aren’t pressed too far in.July 21, 2013 at 4:57 pm #4374
Its easier to press them in without cranks, tranny shafts etc in the way.. U can either use a seal.pressing tool or a socket that is the same.circumference as the sealJuly 22, 2013 at 10:18 pm #4541
Nigel crank seals should always put in after the cases have been put back together. small rubber hammer and socket or a 3/4″ punch. You should be able to press them half way in with your fingers.July 23, 2013 at 6:46 am #4552
I always install the seals after the cases are assembled. I fabricated a “tool” just for the job. Basically it’s a hunk of tubing that fits over the crank, and a large washer that lays on the seal. On the primary side use a bolt that threads into the crank end to draw the seal in, and on the stator side, use the nut on the crank to pull it in. Works perfect, pulls them in nice and straight every time.
CRJuly 23, 2013 at 11:30 am #4573
Chris, would you be so kind as to post a few photos of this fab’d tool?
~AJuly 23, 2013 at 4:07 pm #4628
Thats a great idea on the tool Chris! I`m going to make them out of scrap emt tubing and various washers. This is much more “controlled” than my previous tapping with a hammer and socket. Thanks for sharing.Any more home made tool ideas for 125 and 250 engines?
ncJuly 23, 2013 at 5:18 pm #4647July 23, 2013 at 11:06 pm #4688
Some people really like to over think simple tasks…..
Jesus guys, its a seal that needs to by put in reasonably straight. It is extremely easy to do with a socket and hammer with light taps.July 23, 2013 at 11:21 pm #4690
A hunk of tubing and a washer, real complicated!!!! You can’t “over think” a motor build, that’s how you improve it…. You’ll find out that the straighter the seal is, the better it will seal, the less it will drag, and the longer it will last….
I know, it’s not measurable, but that’s how you blue print a motor, all those little things add up….
CRJuly 23, 2013 at 11:44 pm #4694
Gonna bust out the dial indicator on it to make sure it is perfect?
Look, I’m not saying it’s a bad idea. I just can’t imagine why anyone can’t get it basically perfect with a socket.July 24, 2013 at 12:02 am #4695July 24, 2013 at 10:57 pm #4830
Since this is about Crank Seal installation for CR125, the cranks are not slip fit from OEM into the bearings and the bearings are not slip fit into the cases. Therefore something needs to be heated up to assemble the cases shut and you wouldn’t want heating being done while new crank seals are in place, so the crank seals go in after the cases are closed.
What this also allows is the check the crank spins freely with cases torqued up which otherwise could not be felt if the seals are in there creating some resistance.
I like the idea that Chris R has for crank seal installation, while it may be a little overboard for someone who does this job once every 2 years, it’s certainly a effective tool and nice way to do it if your doing this on a regular basis. The last thing you would want is a seal popping out on the transmission side to suck in oil into the crankcase at a race meeting. Maybe even recommend some loctite sealing compound between the seal and cases even though I’ve never used a sealing compound on CR125 or personally had a crank seal pop out of any of my CR125 rebuilds, however free insurance if you have some laying around.
Ohhh and some advise that I’ve always taken from a reputable engine builder, always lube the inside of the crank seals that makes contact with the crank shaft with some Moly grease. Slips though nice to avoid damaging the lip and creates great sealing while bedding in. 😉July 25, 2013 at 9:54 am #4915
The Honda crankcase assembly tool will install the seals after the cases are bolted together.
Rapid Racing Inc.
"When in doubt Gas it, It won't help but it ends the suspense."July 25, 2013 at 9:34 pm #4990July 26, 2013 at 10:14 am #5010
You still have to use a washer under, otherwise it’s trial and error, and you risk damaging the seal
Uh Huh, Yeah of course. I didn’t feel I needed to state the obvious.
Rapid Racing Inc.
"When in doubt Gas it, It won't help but it ends the suspense."July 30, 2013 at 6:40 pm #5387
um correct me if im wrong but doesnt the tranny side crank case halve lift off the crank? the stator side of the crank is pressed in… not sure why you guys are heating the cases to press a crank in? ive done numerous cases for cr motors and a press does fine with no heat.
a seal tool kit will press int he seal nice and even without the crank in place.. why would you complicate such a simple installation? I understand about seal alignment and do so with the seal tool kit and mic it after???July 30, 2013 at 10:02 pm #5403
um correct me if im wrong but doesnt the tranny side crank case halve lift off the crank? the stator side of the crank is pressed in… not sure why you guys are heating the cases to press a crank in? ive done numerous cases for cr motors and a press does fine with no heat. a seal tool kit will press int he seal nice and even without the crank in place.. why would you complicate such a simple installation? I understand about seal alignment and do so with the seal tool kit and mic it after???
Broke, I have no idea what you just said!!!! Neither side slips in from the factory if that’s what you were referring to….
How does your seal instal tool work with the crank installed? I can pop almost any Honda seal in with my thumb if there’s no shaft in place, straight as an arrow, no worries. The issue is when the shaft is in place.
Necessity being the mother of all invention, I had a bad stator side crank seal that I needed to install with the crank in place at the track. Pull the seat out, pop the stator wires out from the cutout in the case, pull the flywheel, carefully remove the old seal with a flat blade, install the new seal as I’ve described with the home made tool, done! After seeing how easily it actually works, and how perfect the seal goes in without worrying, I do them all like that every time.
People can do it this way, they can not do it this way, use a BFH and a rusty socket, whatever floats your boat….
CRJuly 30, 2013 at 11:25 pm #5413
you never heard of a seal tool kit? who said anything about rusty sockets?
no slip fit crank halves hmm? oook lolJuly 31, 2013 at 6:58 am #5431August 1, 2013 at 6:17 pm #5741
listen chris my name is broque.. i bet you cant even pronounce it correctly and if i said it to you wihtout knowing the spelling I highly doubt you can spell it correctly. HA!
I got some seals for you to press to chill that arrogance with.August 1, 2013 at 6:59 pm #5752August 6, 2013 at 6:23 pm #6266
I did a full rebuild on the weekend for a friend, installed the seals AFTER the cases where closed up with some loctite with my thumbs and a piece of solid timber/lumber and my steel hammer…..tap tap tap tap.
I wish I had that special tool to make it a bit easier but as people have said, its not rocket science and I only do this job on people’s CR125’s maybe 3 times a year.
Bro, bearings/crank are not slip fit from factory, if it was meant to be slip fit don’t you think the factory would have done so? Same goes for CR250. People may prefer the slip fit mods for convenience.
PS….Bro, does the pronunciation of your name sound similar to the 44th President of the United States?August 6, 2013 at 7:06 pm #6276
No its not barack its one syllableAugust 6, 2013 at 8:06 pm #6280
Well since my first guess pronounced as “brark” is incorrect, I’m now guessing it’s pronounced as “brock”.
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