The Hodaka Club Forum

So I decided to look into this whole no compression thing I have going on. Well... it looks like at some point the rings got eaten by the engine because the was just two little pieces left. The piston has a .040 stamped on the top so I am guessing it has been bored .040 over or is that stamped on the original piston? It does not look/feel like the cylinder walls are scared up or anything. Think I could get away with just cleaning it up, putting on some rings and new gaskets and giving her a go? The guy who put it back together must have reused the old gaskets with some silicone sealer, it is pretty bad. I have to do this on the cheap because the wife just lost her job and she would kill me if she knew I was still playing with an "old dirt bike" .

Use no silicone, your piston looks new. usually when when a ring breaks and the engine eats it, the piston is really torn up. Make sure no metal pieces are in the lower end. I think new rings would be a go piston tight and all. Clarence

No Silicone- Check

I think the last guy put the entire engine together with silicone so it looks like I am going to be doing a total tear down, cleanup, and reassemble. This is my first attempt at this but I am pretty mechanical so I am going to give it a shot. I will be looking for a lot of advice from the members through this process. Any idea on the piston size so I can get some rings ordered? Thanks for the help thus far!

This is a great place for advice on your rebuild - keep everyone posted and good luck.
Yes, the .040 is a 4 over piston, so assuming your tolerances are good for that piston and cylinder, all you'll need is a 040 ring.
Here are some clearances for an Ace 100.
You'll need a flywheel puller to get that flywheel off - don't try a gear puller. Remember the clutch nut is a reverse thread, and a shop manual would be a worthy investment.
Have fun!
-Laurie

Thanks that is encouraging! I need to get a shop manual for sure. I might be able to sneak that in

Yep, as long as you're in there, new gaskets and seals, new rings, when you order tell 'em the numbers on the piston. While it's apart check all other wear items, bearings, crankshaft, clutch plates and basket. Might be an idea to look into some mechanical updates that may be available.

I got the side cover off of the ACE 100 yesterday and it is really clean in there, except for all of the silicone sealant that is gunked up in there. If you look at the pic you can see the large piece hanging off the engine. the flywheel also has a large amount on it. I am not sure why this would have used in place of a gasket, am I missing something? Someone took a lot of time making sure it was spotless in there, and then was really sloppy with the sealant. I had to use an easyout to get 3 of the cover screws out because the were stripped when I got it but that was not a big deal, now I just need to find new ones. I am still in the disassembly phase but I will keep the post updated. Thanks!

Workshop Manual- Ace 90/100 /100MX- Part# 209000

Has anyone used this manual to rebuild their motor? Is the best one to use for a simple rebuild? Thanks!

Just as a FYI, you can order kits that contain all the screws, seals and bearings required for an engine overhaul. Look under the bundles section of the Strictly Hodaka site.

Also, when you replace the clutch cover gasket make sure that the clutch actuator lever in the clutch cover has the correct amount of free play. It is adjusted by installing or removing the shims under the actuating disc. The manual should provide instructions on setting this up.

Brian

Are there nuts on the clutch screws? If so, you need to toss them and use safety wire. There should be holes drilled in the ends of the screws for this purpose. I can hardly imagine the internal engine damage that would result when those nuts unscrewed themselves.
Tom

I keep seeing comments about the nuts on the clutch screws. They are lock nuts if you are using the ones that Paul sells. I know some like the wires but I just wondered if anyone has had a nut come loose.

I have used nuts with captive external tooth washers on my race bike. I have raced it for two seasons and not had any problems. If they are tightened correctly and not reused (lock washers are not intended to be reused), there should not be any issues. I suppose you could use thread locker for extra security if desired.

Brian

Personally I have not had any issues at all.
I borrowed the idea from Hodaka/Pabatco as I have still new in the bag "Hodaka super strong Clutch Bolt Kit" part # 202500
They look like hardened clutch bolts (full thread) and nyloc nuts.
Paul

. . . and my recollection is that the screw sets with "Nylock" lock nuts came about partly because there were some incidents of safety wire breaking and contaminating internals with gear mashed bits of wire AND (and I think this 2nd item was the more important issue). The original design screws were small diameter smooth shank screws with rolled threads (thread OD considerably larger than shank OD). This configuration was more expensive/harder to obtain from multiple suppliers . . . whereas "regular screws" and nylock nuts were pretty easy to source.

Both concepts work just fine.

Ed
PS: Going back to the question asked a few posts ago. Yes the Official Hodaka Workshop Manual for 90/100 is what you want. Any manual published by anyone else is far-and-away your last choice (but probably better than nothing).
PPS: So far as I can tell, safety-wire breakage was primarily related to flubs in safety wire installation technique and not any inherent fault with the materials.

Just to carry this thread a little further off course...

Ed, if the smooth shank clutch screws are used, would there still be any benefit in "blueprinting" the clutch? (filing the clutch plates for additional clearance around the screws).

Since we have mentioned failures of the clutch safety wire, I have seen two engines where the safety wire has broken. One of these engines had bits of wire mashed into the primary gear and the other engine the wire just sat harmlessly in the bottom of the clutch cover. As was already stated, the failure was likely an installation problem rather than an actual desing issue. Make sure you use the correct wire (don't even think of reusing the old wire), and make sure the wire is installed correctly.

Brian

Thanks or the reply's. My engine has the safety wire and not the nuts. It just looks like small cotter pins to tell the truth, but they are bent over and look like they are in great shape. I am not planning on taking it apart if I don't need to. Everything looks real clean in there, I am not sure if it has ever been started since it was put back together. There was no exhaust and the rings were blown out, so maybe someone blew the rings and sold it off and then the next guy tore it apart and started the rebuild and lost interest. It is a mystery for sure. It does have a .40 over piston already installed, but it only had a small piece of the ring left. I found the bundle kits and I am sure that is what I am going to go with, it make sense since I need all of that anyway. As always though, I hope I don't end up with a $500 stereo in a $100 car. I am doing the work myself with the help of all of you so that should offset the cost a little Thanks everyone. Off to order a manual to start!

Your description of your clutch wires bother me. The wire needs to run from one screw to another all the way around the clutch and then twisted together at the ends. The purpose of the wire is to keep the screws from loosening, so they need to be laced in a manner to resist the loosening direction (I think there is a picture in the shop manual). It sounds like yours has a separate wire on each screw and that will not work as the screw can probably loosen a full turn before the (cotter pin) stops it. The picture you posted does look like cotter pins on the end of the screws.

Anyone got a picture you can post of the proper wiring?

Here are a couple of pictures that might help you with your clutch. Safety wire should be routed so it pulls the screw in the tightening direction. Wire should be reasonably tight. As you can see from the picture I used an old crankshaft throw held in my vise to assist.

Danny Cooke

Nice post on proper safety wiring!

Since I am "old school", "blue printing the clutch" means dressing the sharp burrs off the stamped steel plates so they won't gouge into the clutch cage . . . and dressing any gouges which have been dug into the teeth of the clutch cage. In the "old days" there was no need to file extra clearance in the steel plates for the screws. (and there still isn't a need for that IF you are using the OEM screws)

However, if you are using clutch screws which are threaded for their full length -- then it is vital that you file clearance for the threads such that contact between the steel plates and the screws is eliminated.

Finally, the use of little bitty cotter keys in the ends of the OEM clutch screws is just a baaaaaaddddd idea.

Ed

I am glad I said something! Looks like I will be taking the clutch off for inspection to see what else has been done. Thanks for the great info. I am going to try and get some garage time tonight so I will take some more pics. Thanks for the great photo!

Here is a clear shot of what is holding my clutch together. I could see how it could be problematic. It looks like an easy fix while I have the cover off. Thank for noticing!

I flipped the engine around to see what I am facing on the other side and things don't look much better. There are a couple missing screws that the last guy just filled the holes with silicone. I measured the bore and it is right on 2" but I can feel a couple digs on the walls. So how deep it too deep? Can I hone out the bore? I am already at .40 over and do not know how much more I can go. I am also on a shoestring budget so having to bore this out and needing a new piston might be a game ender for me for quite some time. Thanks!

That's what's nice about pics, this is how it should look, you know right away if you have an issue.
Your case screw issue will be better known if you split the cases. If the screws are broken off, then you might be ble to get them out and put in new, if the holes are stripped, then you can reclaim them by helicoil. You're this far in, won't hurt to that little extra. And besides, then you'll know what the condition of the internals is. And it gives you the chance to renew gaskets and seals.

So I was able to get the case split without any trouble this weekend. The bearings look good and everything was pretty clean. There is a ton of silicone that is sitting in the case so I am glad I split it. I see why the silicone was used, the previous owner did not want to mess with the two broken screws and a gasket. I was able to get 1 broken screw out without much trouble but the other one is being a little more stuborn. I tried to get it out with an easy out but it did not take. I have carefully drilled out the old screw and not I going to run a tap down it and see it that works. Worse case is I have to tap it out to a 1/4" and use a bigger screw. Helicoils can get expensive so I don't think I want to go that route if I don't need to. I guess all I need are now rings and a gasket set (and lots of flushing and cleaning). I will update when I get to the next step.

OK So after a long military weekend I am able to get back to my engine in the evenings. My son asked me why I was washing the dirt bike engine in the sink downstairs and I replied because your mother would catch me if I was upstairs.

Anyway.. I got everything cleaned up and the parts in the mail (thanks Bruce) I have gotten everything put together the way it was except I cant get the two case together. Is there a trick or am I just missing something? I have tried rotating the gears and wiggling it just a little. Are there any tips on getting the two halves back together? I don't want to break something by forcing it and thus costing myself more $$. Thanks Everyone!