Honda Twins banner

1 - 9 of 9 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
We purchased a 1971 Honda CL450 about 5 years ago with the intent of making it a cafe racer. With the enthusiasm of a kid on Christmas my wife started stripping the bike down. With everything removed from the frame the project took a little bit of a break... Five years later I have picked the project back up and I hope I stay on task a little better than we did last time.

The second round of restoration began with a complete tear down of the engine. The engine looks to have not had a single non-leaking seal on it. It is a mess.

My plan at this time is to only buy parts as I get to the stage where I need them. I have the motor completely tore down. Please forgive me if I call something by the wrong name. I am not a mechanic by trade.

Some issues I am running into are as follows: The cylinder sleeve has seemed to come out a little. I used snap gauges and a micrometer and my measurements are either consistently inconsistent or someone re-sleeved the cylinder head without having it bored out to the correct size. I checked my micrometer and it seems to be right on. My cylinders seem to be 5-7 thousandths under spec range. Some replacement parts are currently out of stock which makes my hunt more time consuming.

I am having a hard time deciding on going back with the stock look with upgraded parts such as electrical and suspension, or just go all out custom scrambler. The original chrome and painted parts are in relatively good shape, but a tank is impossible to find that isn’t dented or a fortune.

I am currently getting ready to take the case, heads and all those other outside engine parts to a media blaster to have them blasted. The intent is to paint them with duracoat, unless other, more attractive, suggestions come along. For now, here are some pics of the progress.
 

Attachments

·
Administrator
Joined
·
13,089 Posts
There are no pictures of the cylinder separate from the engine, so it's impossible to tell you anything by your description until we can see it. The sleeves are pressed into the cylinder and should not move, but they can be bored to one of 4 Honda oversizes (0.25mm increments up to 1mm over) to clean up excess wear but a machinist (who would do the boring if necessary) should be consulted to measure your existing pistons and cylinders to see if everything is in spec (and you'll need to furnish them with the specs from the FSM [factory service manual] so they will know the correct service limits). The cylinder head is another matter, and the DOHC 450 engine is unique in its design... if you're not familiar with it, you may have already done some things that are not recommended during disassembly (especially if you watched a popular video online). Also, since you mention that you have limited mechanical experience, be absolutely sure to align the bearings on the transmission shafts with the set rings and locating pins in the upper case when you put the bottom end together before you tighten the case bolts or you'll do damage.
308778
 

·
Registered
Joined
·
8 Posts
Discussion Starter #3
Here is a picture of the cylinder sleeve. Notice the other one is flush. The picture was on my phone. As far as the cylinders go, spec in the service manual is 2.7560-2.7564(if I remember correctly). Mine is at 2.7556 or there about sin places. I measured l-r and f-b at 3 different depths. All measurements were fairly close but a lot were under spec. There was a lot of sloppy gasket making material which suggested someone, before me, has been in the engine. I was wondering is they possibly had new sleeves pressed in and didn’t have them bored. Also, if you would be so kind, what things should I have not done, and is there a fix.
308783
 

·
Administrator
Joined
·
13,089 Posts
Where to start on that list... without seeing how you disassembled the engine, it's hard to be specific - but most importantly, if you removed the cam bearings (end covers) before breaking the cam chain at the master link - if it turned over and was not seized - then that is the first mistake. Order of disassembly and reassembly is more important on the 450 than many engines and I pointed out another thing that is critical in my picture above of the transmission locating pins and set ring grooves. As for the cylinder... you need to take your pistons and cylinder to a machine shop for proper measurement, but I would not use that cylinder as it might have been re-sleeved incorrectly. Used cylinders are available on eBay for these engines, and expect to get the one you buy bored to whatever oversize necessary to clean them up unless you get lucky and find a set that is serviceable
 
1 - 9 of 9 Posts
Top