Friday, May 29, 2015

Pop Quiz

Here are some examples of difficult to notice damage to parts that can cause big problems. Look at the photos and see if you can spot the problems with each component. Answers are below. Good luck!




A. See the crack on this ignition coil? That's bad...if you are still getting a spark, the coil will imminently fail. This is especially a problem on bikes with the coils mounted very close to a hot engine.

B. See the crack on the overflow tube? That caused a fuel leak that can easily be confused with a bad float valve. Sometimes they can be soldered to seal the leak, otherwise you need to replace the float bowl.

C. Did you spot all the damaged teeth in these transmission gears? There are 5 that are especially bad, and a bonus sixth tooth that is marginal. The bike sounded terrible when running and couldn't shift properly.

D. This starter clutch has been working too hard...the springs are about to break through the outside, which is what has caused the hole that accesses them from the outside to become enlarged. This represents enough damage to keep the starter from engaging the motor at al.

Thursday, March 5, 2015

What We Did This Winter

So, Spring is (hopefully) around the corner, and we're back in the shop getting bikes tuned up for another year of riding. As we dream of warm weather, here's a look back at our adventures this winter:

Geoffrey went to California and worked on some motorcycles with friends from the shop where he learned the trade:

His first project was a 1981 Suzuki GS550 with an engine that snapped it's cam chain. The cases were damaged from the subsequent destruction, so we did an engine swap from a bike with no title that was at the shop.
Untitled donor bike for our engine swap
1981 GS550 - the finished project

Next up was a 1997 Suzuki TL1000 - it had problems with the fuel injection system and another shop had given up on it. We found some incorrectly routed vacuum lines and adjusted the throttle position sensor and it was good to go. The bike is a beast, tons of torque and probably the fastest bike Geoffrey ever rode.

Next was a 1988 BMW K100. The bike didn't run great at first because of a seized choke mechanism. It also had the absolute most worn down rear brake pads of any bike we've ever seen - the pads were gone and the wear was halfway through the metal backing. Miraculously the rotor was salvageable after some heavy sanding. Geoffrey also did a rear tire change and used the opportunity to perform the infamous final drive spine lube. Now it's ready for another 20,000 miles!

Finally, we pulled out a 1984 Honda XR600 that had been sitting outside for a year. It had an aftermarket flat slide single-carburetor setup, but the carb was totally gunked! The choke plunger was completely seized inside the carb body. After soaking it overnight in the legendary Yamalube carburetor cleaner, it was clean as a whistle. Geoffrey tried futilely to start up this kickstart-only bike, then his old boss showed him a few tricks and it fired right up. It's ready for Baja now!
Single-carb and aftermarket manifold
Gunked Carburetor
Choke finally free!

1984 Honda XL600 - legendary dual sport amidst resurrection

Then Geoffrey made a visit to San Jose where he helped out Laurent (a mechanic who has also done some work at Slagheap Cycles) to get a 2005 Ninja 250R running right. The bike had a weird problem: even after thorough carburetor cleaning, it still wouldn't idle properly, on an engine with only 6600 miles that started right up and had plenty of power. After eliminating everything else we could think of, we performed a valve tappet adjustment and found that, even with so few miles on the engine, more than half of the clearances were significantly tighter than spec. So, word of warning, those valve clearances need to be adjusted often! After doing the adjustment and putting everything back together, the bike idled and ran great.

Monday, December 22, 2014


We will be closed from December 22 - February 20th, taking time away from the shop, and working on some projects to be unveiled in the spring. We are still available via email and phone, and will be at the shop periodically during this time. However, we will not be able to do any work on your bike until after this time, but you are more than welcome to get in touch before then to schedule something for our return in February.

Some Motorcycles That Visited Our Shop In 2014

CB750 10th Anniversary Edition
CL360 in front, followed by CL350, XL350

XS650 bobber

Monday, November 3, 2014

Winter Storage 2014-2015

Well, it's getting to be that time of year again. Here's our storage rates for this winter:

  • Bike will be stored indoors and tarped to protect from dust/dirt
  • We will provide a battery tender for you for $5/month, or hookup your own tender for free
  • We will pro-rate your charge if you are ready to ride mid-month
  • Bikes can be retrieved at any time, but we ask for a minimum of 3 days notice in Winter
 Space is limited, so please get in touch as early as possible to reserve your space, thanks!

We also do full winterization services for long-term storage, and in the spring we will be offering specials to get your bike ready for the riding season. Please inquire about our rates for your bike if interested.

Thursday, June 12, 2014

Connection Problems

Here's something we've seen a lot of in the shop this year: melted and burned connectors, particularly the 3-wire connector between the stator -> reg/rectifier, and the four-wire connector that plugs into the starter solenoid. Amazingly, most of the bikes we've seen this on are still running/charging in spite of how burned up the wiring looks. However, we can assure you that it will eventually cause big, big problems. Bikes we've seen this issue on recently include a GL1200, GL500, DOHC CB 750, VT500C, amongst others. After 30+ years, dirt gets into the major charging system connectors and the increased resistance generates heat, and the cycle of connector meltdown begins. If the damage isn't too far along, our best advice is to clean thoroughly with contact cleaner and sandpaper or a small flathead screwdriver, then coat each prong with dielectric grease and reassemble. If it's too far along, we have found some sources for OEM-style connectors for many vintage bikes and can order them for you...or just use decent crimp-on ones from the hardware store, so long as you can get a tight-fitting connection.

Here is an example of when one finally fails:

Sunday, April 6, 2014

Honda DOHC Cam Chain Tension

So, here's something we've never found much information about, either from Honda, or online. Starting in the 1980s, Honda switched design for most of their motorcycles from manual cam chain tensioners to automatic models. Once they went automatic, it became a lot harder to know what was going on with the system when you started to hear cam chain noise. There is good information for some bikes on how to tell with the automatic tensioner, but not much on the DOHC inline fours. How can you tell if your cam chain is stretched? And how can you tell if the tensioner has reached its limit?

Having just successfully diagnosed and fixed this problem on a 1983 Honda CB650sc Nighthawk, here is what we learned:

* The bike in question had approximately 31k miles. There was noticeable, very loud rattle, almost like a buzzing/gurgling sound throughout the rev range. It wasn't bad when the bike was cold, but got much worse as the engine warmed up.

* The stock cam chain has to be broken to remove both the chain itself, and the tensioner. However, both jobs can be done with the engine in frame, and only removing the valve cover.

* The tensioner is known for the spring to become weak and/or fail. Also, the spring and the complete tensioner have both been discontinued by Honda, for the CB650sc and CB550sc models with hydraulic valves.

* It may be possible to remove the tensioner without removing the cams, but certainly very difficult. We had to unbolt both cam sprockets from the cams and then remove the intake cam before there was enough room to remove the tensioner.

* The only solution that doesn't require engine disassembly down to the crankshaft is to break the old cam chain at one link, also break the replacement cam chain at one link, temporarily attach to each other and run the new chain around the crankshaft sprocket by manually turning the engine, then remove the old chain and fasten the new chain with a special cam chain masterlink.

* If done this way, be sure to run the new cam chain through the cam chain tensioner before fixing it with the masterlink, much easier than dealing with the tensioner slipper clips!!!

* We replaced the original cam chain tensioner with a unit from a 1983 CB550sc with 10k miles. The tensioner is the same design for both models as far as we can tell.

As far as measuring cam chain wear, we sadly did not take photos or measurements of the old chain before removing it from the bike. However, here are some photos of a new chain and low-mileage tensioner. Photos are with crankshaft positioned at TDC. Note the following that can be used to measure wear:

* Deflection of the chain is very minimal between the cam sprockets, estimate less than 4mm.

* The tensioner has a rod that runs through a center hole in the fastener plate; the closer this rod gets to the upper hole, the farther out the tensioner is (hence, the closer to its limit). As you can see in the photos, the rod is far below this upper hole in our new setup, estimate approx 10mm gap.

Hope this helps some of you out there, good luck!