Motorcycle Classics

Q and A: Gauge Rebuilders, Oil Types, and CB350

Join Keith Fellenstein as he answers questions from readers about gauge rebuilders, oil types, CB350 issues, and much more.

Gauge rebuilders

Q: I have a 1981 Suzuki GS750L that I’m rebuilding for the 3rd time. I need to get the tachometer and speedometer rebuilt. Could you suggest a company here in the U.S.?

Steven Rondeau/via email

A: I didn’t know of any offhand so I had to search a bit and found this fellow who specializes in Suzuki speedometers. Contact him and see what he has to offer. I hope this helps:

Help this reader

Q: Hello Keith, I have a Rumi Formichino scooter that needs a crankshaft rebuild (seals and bearings). Do you know anyone in the U.S. who can do this? Thanks in advance.

Joe Mensch/via email

A: While I have seen these scooters in the wild, I have no experience with them at all. I’ll do what I usually do in these cases and throw the question out there to our readers. Someone out there will have the knowledge I lack. Readers, if you have a suggestion of someone who can help Joe, email me at the address at the end of this column.

Oil thoughts

Q: I’m hoping to get clarification on the oil types to use in the crankcase and the Autolube system on my 1965 Yamaha YM1. Regarding the Autolube system, the manual I have references using 10w30 motor oil while everything I’ve read (online) says to use a semi-synthetic 2-stroke oil. I would think that using 2-stroke oil would be the way to go? What brand do you recommend? Regarding the crankcase, what brand and weight do you suggest? The manual references 10w30 with no friction modifiers. Also, what is the capacity? There is no dipstick on my engine. I’ve read 1.5 quarts, 1.75 quarts, 2 quarts, etc. Do I just fill it through the breather hole? Or through the tiny fill plug on the side cover?

Your help is much appreciated.

Bill/via email

A: Manufacturers recommended regular oil for 2-strokes back in the day because it was more readily available. Modern synthetic 2-stroke oils are better in every way. They should work just fine in your Autolube system. Friction modifiers in your crankcase oil will possibly cause your wet clutch to slip, so that’s why they are not recommended. I generally use an older oil formulation like Castrol GTX for that purpose. The transmission drain is on the bottom of the engine, and the fill plug is just below the side cover on the left side of the bike. The ancient Clymer compendium I have says the transmission should hold just a smidge over a quart of oil.

CB350 issues

Q: I’m having trouble reviving a 1972 CB350 I bought it in 2002. It only had 3,200 miles on it. I rode it for less than 20 miles and noticed it lacked power, would not accelerate and died sometimes. I pulled the plugs. They were NGK B9ES and they looked sooty and black. I left the bike in the foyer as a decoration piece until recently. I did a wet compression test, 150 on the left, almost 180 on the right. I cleaned out the carbs and put in a carb rebuild kit. I noticed the O-rings on the jets were undersized and the jets were somewhat loose fitting during reassembly. I checked timing, valve clearance, float height, put in new and proper NGK B8ES plugs and a new battery. It started right up. I rode it on a wide straight road with very low traffic. Since I did not want to bring it up to full throttle in top gear, I only got it to about 3/4 throttle in a lower gear. The engine was warmed up, I pulled in the clutch, coasted to a stop and checked the spark plugs. The one on the left was very dark, nearly black. The one on the right was sooty black. By then it became difficult to start. The electric starter could not get it started. I had to kick it many times to get it started. I thought it was still running too rich. Could those loose fitting jets be the cause? Neither the old jets or those from the new kit have numbers shown on them. After I reassembled the carbs another problem showed up. There was a minor gas leak from the drain tube of the right side carb. After disassembling I found a tiny hairline crack in the brass drain tube. I could not find a used float bowl so I put one drop of thin Super Glue type generic quick drying glue over the crack, let it sit for over 24 hours and reassembled everything. It held for about two weeks then an almost invisible leak started. I am wondering if I may paint over the tube with some diluted epoxy type agents such as fishing rod finish to stop the leak. Any suggestions will be greatly appreciated. Thank you.

Bing Fong/via email

A: Those loose jets could certainly be causing the rich condition, they should be a sealed fit with tiny O-rings along with a spring piece holding them in the upper body. Brass drain tubes crack when water in the gasoline freezes and splits the tube. Super glue won’t hold because acetone dissolves super glue and acetone is present in gasoline. If you have a hardware store or hobby store that carries brass tubing you can possibly find a slightly larger tube that will snugly fit over the old tube, or you can use some epoxy like JB Weld to hold the tube in place. You should also remove the floats and give them a shake. If there is any fluid in the floats the float bowl will have too much fuel in it.

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  • Published on Feb 3, 2021
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