Problems.

Roy · May 22, 2023

I have a new to me 1971 xs1-b that I have been working on for some time, and now have it up and running. We (me and the bike) have logged 250 miles together so far with great success. Following is a list of minor issues That I need advice on.
1, the engine doesn’t return to idle as quickly as it should when shifting gears and setting at stop lights. This doesn't happen until the bike is completely warmed up. The advance seems to be working properly. I took it all apart and cleaned and lubricated it.
2, I can't down shift without engaging the clutch a tiny amount. If the clutch is totally disengaged I can't shift down to the next lower gear without letting the clutch out a small amount. This only happens when the engine is completely warmed up.
3, The tac and speedometer needles bounce up and down. The speedometer bounces about five mph above and below the desired speed. The tachometer does the same thing. Both instruments have new cables. Thanks.

Kevin Werner · May 22, 2023

A. Pictures

. B. Have you checked you carb sync? C. Many members here recommend ignition timing approximately 2 degrees retarded from the factory recommendation. D. Is this a stock bike? E. Pictures.

5twins · May 22, 2023

You said you cleaned and lubed the advance unit but did you clean and lube the advance rod bushings in each end of the cam? They need to be greased. The outer bushing on each end has grooves in it's I.D. .....

Fill them with grease. The factory recommends a grease with moly in it .....

WideAWAKE · May 22, 2023

Idle issues…
Carbs synched? Ignition timed?

Advance springs worn out??

Gear changes…
That’s pretty standard for an xs. Some people claim they can shift through gears (or into neutral) without the bike moving but I’ve yet to personally meet an XS that can do that. A little motion is usually needed.

There is a procedure you can find in your manual (or the tech section on here) that covers how to properly adjust a clutch which if you havnt done should help the situation.

Needle bounce…
I believe once these start to bounce there isn’t much you can do to fix the dampening (I could be wrong on that). Search the archives for xs1 speedo. Gggary just did a nice write up on how to properly pull those early ones apart.

I know on early CBs they have an oil bladder that can be cleaned and refilled to get dampening back. Don’t think it’s like that on these.

gggGary · May 22, 2023

Yeah un sync'd carbs will do that.
advance is easy enough to check with a timing light and yup stay on the conservative side, check both sides.
Early gauges tend to wear out the bushing. They can be repaired, our resident watchmaker @TwoManyXS1Bs pioneered the process.

WideAWAKE · May 22, 2023

gggGary said:
Yeah un sync'd carbs will do that.
advance is easy enough to check with a timing light and yup stay on the conservative side, check both sides.
Early gauges tend to wear out the bushing. They can be repaired, our resident watchmaker @TwoManyXS1Bs pioneered the process.

Learn something every day! I’ll track it down just to see how he did it.

Doesn’t seem to be a topic all that often.

gggGary · May 23, 2023

Twomany's gauge rebuild guide https://www.xs650.com/threads/early-model-70-71-instrument-rebuild-rejuvenation.31305/

Roy · May 23, 2023

Kevin Werner said:
A. Pictures . B. Have you checked you carb sync? C. Many members here recommend ignition timing approximately 2 degrees retarded from the factory recommendation. D. Is this a stock bike? E. Pictures.

Thanks for the recommendation. I'm not clear on how to sync the carbs. The throttle cables are in perfect sync, but I don't know about the rest of the adjustments.

I have very little information about the history of this bike. As far as I know, it's completely stock. The mufflers are aftermarket, and that's all I'm aware of. It runs so darn good before it gets completely warmed up, I hate to mess with it. It's a one kick bike, always.

jpdevol · May 23, 2023

I'll leave the synch drill for experts to explain, but I'd be checking for valve adjustment (.003"IN, .006"EX; regardless of what your book says) and intake air leaks first

Jan_P · May 23, 2023

Nothing further to add .But if the idle i set high it can delay the rev coming down

Kevin Werner · May 23, 2023

Nice looking bike. Study the tech section to properly adjust the clutch. Do it when it is fully warmed up. The steel clutch pushrod has a different coefficient of expansion than the aluminum engine cases.
There are several method of sync ing carbs. A manometer is the most reliable. A search in this forum will show several home made with just a few $ worth of clear fuel hose. Your symptoms mimic my own before I synced my BS 38s.

Jan_P · May 23, 2023

Yes the plastic tube is working excellent . I wont ever use anything else .. Mounted it on a plank via some bended nails
Used Motor Oil
Read about risk fluid getting sucked out of the tube into the manifold so i made a clamp restricting the area of the tubes.
Giving time to stop and adjust. BS 34 carbs.
Used it last week Cheap and Good

Kevin Werner · May 23, 2023

I found this searching "sync" on this forum.

jetmechmarty · May 23, 2023

The ‘71 isn’t set up to use a manometer. I synced one or two of the old bikes using the sync procedure in the service manual.

I’m wondering if “Joel Levine” services Yamaha clocks. Have any of you gone that route?

Sparkyduc · May 23, 2023

jetmechmarty said:
The ‘71 isn’t set up to use a manometer. I synced one or two of the old bikes using the sync procedure in the service manual.

I’m wondering if “Joel Levine” services Yamaha clocks. Have any of you gone that route?

He did my XS2 tach and speedometer, was pricey but when you’re riding they’re sitting right in front of you to look at

Problems.

Roy

XS650 Enthusiast

Kevin Werner

Amatuer

5twins

XS650 Guru

WideAWAKE

Single Fins and Twin Cylinders

gggGary

If not now, When?

WideAWAKE

Single Fins and Twin Cylinders

gggGary

If not now, When?

Roy

XS650 Enthusiast

jpdevol

Hacker of Frames,Wires and other things

Jan_P

Tool Owner

Kevin Werner

Amatuer

Jan_P

Tool Owner

Kevin Werner

Amatuer

jetmechmarty

Project collector

Sparkyduc

XS650 Addict

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