Getting Down to Work

Now you can get to work on the reason(s) why you took all that stuff apart. The following list highlights common reasons for engine disassembly, and what to do next:

Big Bore (Greater than 110ci)-- In this case, you may be needing crankcase boring, and/or cylinder sleeving and boring. If you'll be doing the work locally, find a machinist experienced in sleeving cylinders with bores around 4 inches (100mm or more), as well as case boring.

I'd also recommend you pull the four transmission (ball) bearings from both cases beforehand. The machinist will create lots of metal chips and dust during machining. This debris will work its way deep into every nook and cranny possible, even if you tape bearings over. I didn’t do this beforehand, and I was sorry.

If you really don’t want to remove your bearings, at least thoroughly mask off ball bearings and oil-journals using lots of duck tape. Just remember, once everything is reassembled, you might never know if there is still a tiny particle lodged in a bearing, creating premature wear. See the Transmission Bearing Tips section below.

I'd also recommend you thoroughly clean and dry your cases beforehand. Oil attracts and holds dirt, filings, and chips; this might make it more difficult to extract contaminates afterwards.

My machinist used a heat process on the cylinders to help press the sleeves in. He heated my cylinders to 400* for 40 or 45 minutes. This resulted in slightly darkening their stock silver color. It looked very subtle in contrast to the rest of the engine, but it could have been cool looking. However, I had already committed to powdercoating.

Also, if there is a need to heat the crankcases and/or transfer case, you must pull out, and replace, the rubber oil seals for two of the large ball bearings. There is one seal at the transfer case, middle driven gear, output shaft (where the front final-drive pulley goes). The other seal is at the right-side crankcase, transmission drive axle. The Parts and Tools article in this series has the part numbers.

Powdercoating or painting-- In the case of powdercoating, or any process where sandblasting or other dusty process is involved, be sure you pull the transmission case-bearings beforehand. Bearings left in will pretty much be destroyed, even if you tape them over. It is much easier to remove the bearings beforehand. See the Transmission Bearing Tips section below.

Many machinists handle parts a bit too roughly to prevent scratches to the paint finish, in my opinion. So, if your plans include machining or welding, see if your shop is willing to complete all work before powdercoating or painting. Mine was not, partly because the work included doing a valve job which could not be done until after powdercoating.

Also, if you are having a machining process or welding work done which generates heat in excess of 300*, it must be done prior to powdercoating. Check with your shop to be sure. Some paints can withstand fairly high temperatures for short periods--just be careful.

One final note: Not all powdercoatings and paints can withstand the heat that a motorcycle engine produces--around 250*. If powdercoating, be sure you find a powdercoater familiar with motorcycle powdercoating. If painting, be sure you use engine (or stove) paint.

Engine rebuild-- In this case, all bearings will likely be swapped for new ones. Follow the service manual for main and rod bearings, as well as generator and transmission bearings. Also, don’t forget the transfer case bearings.

Transmission rebuild-- See the Transmission Bearing Tips section below. Also, everything in the transmission is replaceable except for the bearing surfaces of three shafts:

• Both shift-fork shafts. It is very unlikely that they would wear their bearings, since they do not normally rotate at all.
• The shift-drum. This is a bit more likely, as this shaft rotates each time you shift gears. However, it would still take a long time to create much wear, under normal conditions. If these bearings have warn, look for why the wear has taken place.

The service manual doesn't discuss this, but if you have excessively warn shift-fork or shift-drum bearings, you will have to take your case(s) to a good machinist or expert motorcycle mechanic. These aren't really bearings in the usual sense, as the shaft simply rotates on machined holes cut right into the cases. Ask for help in the best way to fix your problem.

Disclaimer: I have not seen this or done this. I am just telling you my opinion, based on my limited mechanical engineering background. Look at your parts. If you suspect you may have a problem, seek a local, experienced, Road Star mechanic for their opinion.

Oil pump rebuild/fix/replace-- In this case, simply do what ya gotta do, but do it well. Remember, the oil pump is a critical part, so don’t cut corners to save a few dollars or minutes. It does more than circulate lubrication. It's responsible for cooling the entire engine, since motor-oil is the engine's primary coolant. Yes, it's that important.

Case welding-- In this case, it's not just a matter of taking your broken case(s) to a welder competent in aluminum. You must be sure that all gasket and mating surfaces are completely flat and true once your work is done. The same goes for all bearing surfaces. Of course, you'll also want to be sure that none of the repairs create scars that could interfere with the free movement of internal components or external fitment.

Other-- Something I forgot to cover? Sorry... Good luck.