Motorcycle Classics — September-October 2017

78 MOTORCYCLE CLASSICS September/October 2017

KEITH’S

GARAGE

“Since it will start on the button,

it’s not likely an electrical problem.”

Hard to kickstart

Q:

I have a 1975 Yamaha XS650 twin.

It has had a tuneup and runs great.

My problem comes when I want to start it with

the kickstarter. Warm, cold or hot, it does not

matter. There’s no way it will start. All I have

to do is touch the starter button and it will start

immediately. The coils are still original. Are

they my problem?

Mike Trunk/via email

A:

I’ve had this question numer-

ous times the other way around,

where a bike will have a bad electric

starter, but will start fine when kicked,

but I’ve not seen one that won’t kick

but will start on the button. My first

thought is that kicking it may not be

spinning it fast enough, especially if the

compression is starting to fall off. Maybe

the valve clearances are too tight and are

letting the air out, so to speak. I had a

look at the wiring diagram, thinking there

might be a reason to be found there, but

it’s pretty straightforward in 1975. Since it

will start on the button, it’s not likely an

electrical problem. I’d check the compres-

sion cold and hot, and compare it to spec.

If it’s too far below spec, do a leak-down

test to see where the compression is

going, through the rings or valves, or even

a blown head gasket.

Electrical woes

Q:

I have a 1976 Triumph Bonneville that

I built into a bobber. The bike ran great

before I stripped it down and rebuilt it. I ran my

own simplified electrical wiring harness. It already

had the electronic ignition system installed. I didn’t

touch the engine. Now I do not get spark when

I kick it over. The battery shows 13.5 volts, the

resistance is good on both coils, and I have checked

all the wiring for continuity and correct connec-

tion. When I turn the key on and off, I get spark

at both plugs. I also installed a new key ignition

switch. What’s wrong?

Perry/via email

A:

The quick and simple answer is that

something is wrong with the wiring

from the pickup coils in the points case.

The black box is fine since you get spark

when you turn it on and off. Remove the

leads from the pickup coils in the points

cavity and with the ignition on, touch

the wire ends together momentarily. You

should get a spark at the plugs when

doing this. If you don’t, you have a prob-

lem with the wiring between there and

the black box. If you do get spark that way,

the problem is with the pickup coils.

Positively grounded

Q:

I just read your Triumph Bonneville wir-

ing advice in the March/April 2017 issue

regarding a 1979 Bonneville ignition problem

where you mentioned “ground the negative lead

of the VOM to frame ground.” I have a 1973

Triumph T150V which is positive ground, and I

believe all earlier Triumphs were positive ground

as well. I do a fair amount of wrenching on old

bikes, and it might be helpful for me to know: At

what point in time did Triumph switch to the more

conventional negative ground? Thanks for the

great column. I read Motorcycle Classics from

cover to cover, and your column is like the dessert

following a fine dinner!

Dave Dawes/via email

A:

Looking through the workshop

manuals I see the change hap-

pening with the 1979 models. They

got a new alternator that year also,

the RM24, and electronic ignition, the

Lucas Rita. It’s not uncommon to find

older Triumphs that have been convert-

ed to negative ground. It’s not difficult

for a bike running points, and it makes

it easier these days if you want to use

modern LED lighting. Thanks for the

kind words. I enjoy writing this column.

Honda gearing

Q:

I have a 1973 Honda CL350 that I

turned into a sort of bobber/café racer.

It presently has a 36-tooth rear sprocket and a

16-tooth countershaft sprocket. At 70mph it is

turning over 7,000rpm which is not far from red-

line. I’d like to get the gearing so I turn fewer revs

at speed, but I don’t really know what would be

best and I have limited funds. I’d like your opinion

as to whether to go to a 35-tooth rear sprocket or

a 17-tooth countershaft sprocket to lower the revs

yet still give me good acceleration. Sprockets are

limited for the CL350 and somewhat expensive for

my limited budget.

Skip Baldwin/Picayune, Mississippi

A:

The easiest way to drop the rpms

is going to be to change the coun-

tershaft sprocket from a 16- to 17-tooth

sprocket. As for expense, I found one

at BikeBandit for $16 under Aftermarket

Parts, Wheels & Final Drive. Of course,

raising the gearing is going to slow the

acceleration somewhat. There’s nothing

you can do about that.

Trickle charger update

Several readers have written to address

a glaring omission in my last column

regarding trickle chargers and 12-volt pos-

itive-ground motorcycles. Specifically, the

bare lead of the pigtail will be the hot lead

and must be prevented at all times from

contacting the frame or you will short the

battery to ground with no fuse to stop

you. I don’t know how I missed this, but

thanks to everyone who wrote to point

this out; it’s important.

Email questions to keithsgarage@

motorcycleclassics.com

Ready to take your classic queries: Old-bike

mechanic Keith Fellenstein.

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