View Single Post
Old 11-27-2011, 02:35 PM   #13
Kestrel OP
Gear Driven Cams!!
Kestrel's Avatar
Joined: Apr 2008
Location: North Carolina
Oddometer: 181
At this point, I reinstalled and rebled the rear brakes. Given that three out of the four posts were sheered off, that method of removal was no longer viable for me. Family rumor mill had it that my uncle was passing through town, and it turned out he had a few electric impact guns, and would be more than willing to loan one to me. Score!

He swung by the house a week later, and while holding down the rear brake, I stuck my Motion Pro clutch nut socket on the end of the impact... and.. clickclickzip, off came the clutch nut, followed by the clutch hub. I used a couple of pennies to jam the gears, and had the cam chain removed a few minutes later. Called it a night at that point and exited the garage feeling much more positive about the progress I'd made. Entirely too much had been going wrong with this project, as one crappy discovery led to another, but from this point on, it was fairly smooth sailing.

After a few days of real life, I managed to find a little time and headed back into the garage. First, however.. Valve stem seals replaced and valves reinstalled with a little moly lube on the shaft, as per the Honda manual.

The final steps of reassembly took place over a couple of days. I was close, but a couple of small issues sprung up that slowed progress. The piston wrist pin did not want to come out very easily, but after a quick trip to Ace Hardware, I had constructed a wrist pin puller using a long bolt, two washers, one nut, and a couple of choice length sockets from the toolbox. Five minutes later the wrist pin was out and the piston was free.

After careful inspection of the old piston, I realized the piston I pulled was NOT the stock cast Honda OEM piston, but rather a Wiseco, identical to the replacement I'd be installing! Odds are that whoever installed this piston before went through a ton of work, but still never rejetted the bike to take care of the lean running issue, and thus it ended up eating that replacement piston too. Amazing that such a large bit of work could be done, but they never bothered to fix the actual root issue!

At that point, I checked the ring end gap in the freshly bored cylinder (All were within spec!) and after installing the rings on the piston, applied assembly lube to the piston/wrist pin area, as well as the end of the connecting rod. Another circlip later and the piston was on there for good.

At this point, I called it a night again. Swung by the local Yamaha dealer the next day for some Yamabond 4 / Threebond 1194 / Hondabond etc etc. (It's all the same stuff..) to use in sealing the cylinder head cover. I hadn't realized it at the time, but the giant o-ring on the bottom of the cylinder jug was missing! Oddly, I don't think it was ever really on there to begin with! Previous owners must have removed without replacing it during the original rebuild. I opted against waiting another week and a half for a simple o-ring to arrive, and used the aforementioned Yamabond to seal the base of the cylinder. Common practice on many other bikes, and it worked like a charm. After installing the base gasket and dowel pins, the cylinder head was slipped over the piston with the rings aligned in proper position, and secured into place.

After a little oil on the cylinder stud bolts, as per the manual, I torqued them all to spec (29 ft/lbs) and prepared to install the cylinder head.

And it was here that I ran into another brick wall

I thought I had perfectly cleaned the cylinder before.. but apparently not. The threads had superfine grit in them from sandblasting, and the cylinder head would not have gone on without a fight, and possibly stripped threads. Not a chance in hell that was going to happen... I wasn't about to throw away all of my progress by trying to rush to through to the finish...

The bad news? It was Thanksgiving... My goal had been to get this thing finished by the end of the holidays, no matter the circumstances. I tried to clean the threads but to no avail, the damned studs wouldn't screw in. I desperately tried to look around to find a M10x1.25 tap, but no stores were open who actually carried the damned thing.

Pretty damned near defeated at that point, I started to think about ways that I could clean those threads out. The threads were in good condition, and it was simply the grit that needed removed. A tap and some oil would have done that without a problem, but I didn't have that on hand.. and all of the q-tips and paper towels seemed to be doing nothing. I cut the tip of an old toothbrush in half, and it removed a significant portion of the grit, but not enough... Think think think.. What else could I use? What would be open on Thanksgiving that might have it?

And then it hit me. Braces brushes! God knows I remember those from my days in braces as a kid... I removed the cylinder once more, and made a quick trip down the street to Walgreens. After a couple of passes with hot soapy water and the tiny brushes, I had clean threads! Game on!

From there, it went like clockwork... Back on went the cylinder, and then the cylinder head & gasket. Installing the cam chain and cam on the XR is extremely easy compare to other multicylinder bikes I've had.. Simply put the piston at TDC, and stick the cam in with lobes facing downward, line up the two lines on the cam gear at 9 & 3 o'clock, and screw it all together. Dab of assembly lube on the middle came journal before starting, of course... and with the cam chain in place, I pulled the pin from the tensioner and voila! We were in business, with plenty of travel left in the tensioner courtesy of the new chain.

(Note: When I first purchased the replacement chain and held it up to the old chain, the lengths were near identical... However, under stress, the new chain had significantly less stretching, whereas the other chain had the tensioner piece below and inside the tensioner, completely worn and making it impossible for me to grab with a set of pliers. New chain totally took care of the issue!)

At this point, I sealed my cylinder head gasket with some Yamabond, and installed it.

Next would come the clutch... Plates appeared to be in good condition, and I reinstalled them along with the new springs and new clutch nut. While holding the rear brake, I installed the nut with the impact and tapped down the stake on the nut in order to keep it from rotating out of place.

With everything torqued to spec, I then cleaned up all of the clutch cover bolts by running them through a die, and double checked to make sure all of the engine case clutch cover threads were in good condition, running a tap through those that were not to ensure cleanliness. With the new gasket in place, the clutch cover was reinstalled, along with a new oil filter and new oil pan bolt/washer, as the older bolt had been badly stripped. Rear brake lever and kickstart were reinstalled, and we were good to go.

The last step was to install the new exhaust, which I am unhappy to report did NOT fit. It had been reported that the CRF250X exhaust was plug and play, but it makes contact with the subframe and will not fit without an extension. I am pleased to report that the R header does in fact fit the L exhaust, though I had to construct a makeshift gasket of sorts. I'm still deciding whether to stick with the L exhaust, or trying in the future to make the nicer CRF unit work. We shall see.

I'm sorry to report that I'm a little short on pictures after this point... At this point, it hit me that the bike would be ready to start up soon. I was a bit nervous; I'd been working on the damned thing on and off since June, and this was the big moment.. Would it work? Would it not work? I've worked on cars for a lot of my life, and also assisted my father on a couple of engine & transmission rebuilds, but I had never done a complete rebuild completely by myself.. and here we were, moments from startup...

I took 15 minutes to readjust the valves, threw in some Rotella for break in, grabbed my gear, and gave a salute to the moto gods...

Kicked over once... Kicked over twice... and on the third kick, she fired up!

I think I sat there at that point sort of in shock, thinking... 'Wow, it actually worked...'

At that point, I threw on my gear as quickly as possible, and began the process of constant acceleration / deceleration and varying the RPMs for break in. I rode for about 12 miles over the next 30 minutes, and immediately dumped the oil and changed the filter. Tiny little microscopic sized glitter made for some pretty cool swirls in the oil pan... Almost like the swirls in a nice cup of espresso! During the short time I rode it, I could definitely feel the engine loosening up. But even during those first few miles, the bike was already stronger than it had ever been in the past.


Today, I took the bike out for another 50 miles of countryside twisties and mild gravel road exploration. She's feeling stronger than ever, and easily pulls up the front wheel in first on throttle alone, and also in 2nd with a little effort. The exhaust note sounds deeper and significantly more 'solid' than it ever did pre-rebuild. A little fuel screw adjustment had it running near perfectly, and I'm pleased to report that everything is working fantastically at this point. I replaced many of the rear fender bolts with some more appropriate fitting hardware, and plan to install the Buell turn signals in the near future as well.

As far as I'm concerned, mission accomplished! This bike was much more of a project than I had ever wanted, but I learned a *lot* in the process and am looking forward to a lot of dual sport fun in the near future.

Kestrel screwed with this post 11-27-2011 at 07:17 PM
Kestrel is offline   Reply With Quote