GT250M roadside breakdown

All to do with wiring, charging or just trying to figure out whats gone wrong.

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redliner
On the street
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Joined: Fri Jan 19, 2018 4:52 pm
Country: United Kingdom
Suzuki 2-Strokes: GT250

GT250M roadside breakdown

Post by redliner »

Evening all - if I may, I just wanted to put today's conundrum out there to see if anyone has any ideas as to what was the cause of my roadside breakdown.

OK, GT250M, a nice quick 5 mile trip to the shops - just started for home when the bike started to quickly lose power on the RH cylinder. Pulled over to check, got out the toolkit, and found no spark to the RH plug. Changed plug - no spark. Checked HT connections - still no spark. Points cover off, checked points gap, condition - all ok.

Expecting the RH pot timing to have slipped, I got out the little static timing light that I carry, put the two lead clips on the RH points spring clip and to an earth point, and rotated the crank anticlockwise to rough-check timing. The lamp was illuminated and I was expecting it to go out as the points opened, hopefully at the point where the markers on the rotor/stator line up.

Points opened, but the lamp stayed on all the time, despite repeated rotations of the crank. Repeated the process with the functioning LH set of points as a check, and the lamp went out as expected as the points opened at the aligned markers.

Back to the RH side, but just couldn't get the RH points to do the same - the static lamp remained illuminated throughout, even when the points were fully open. Finally had to call for a lift home.

I've had bikes break down roadside like this on a number of occasions over the past 50 years, and this emergency get-me-home fix has always worked. Anybody able to shed some light (pardon the pun!) on what was going on with the RH pot? Was there something, or some component, I have overlooked, or failed to diagnose at the roadside?

If there's a simple explanation, I'll put it down to my age and rubbish close-up eyesight! :wink: Thanks for any help/input.
gammakeith
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Suzuki 2-Strokes: 1966 T20

Re: GT250M roadside breakdown

Post by gammakeith »

Two likely possibilities. Firstly the condenser may have broken down internally so its a dead short If you unbolt the condenser from the backplate4 and your timing light works OK then you have the answer. If its not that, you may have a damaged wire that is shorting to earth. Its worth checking the wiring around the backplate as that gets flexed and you may have some cracked insulation. It could also be a broken insulator in the points connection itself.

Keith
1927 Scott 3 Speed Super Squirrel
1948 Scott Flying Squirrel
1951 Cyclemaster
1966 Suzuki T20
1981 Montesa 349
1985 Suzuki RG500
1999 Honda CRM250AR
Definately NO 4 strokes :-)
redliner
On the street
Posts: 15
Joined: Fri Jan 19, 2018 4:52 pm
Country: United Kingdom
Suzuki 2-Strokes: GT250

Re: GT250M roadside breakdown

Post by redliner »

Thanks Keith

Removing the condenser from the back plate made no difference to the light going on/off - just stayed permanently on as before. I've swapped the condenser for a new one anyway. The black wire coming from behind the rotor to join with the black condenser wire looked ok - no fraying or cracks visible.

Also new RH points fitted/insulators checked/ok. Still only got spark to LHS, so thinking I need to be checking the coils/HT leads/caps/plugs next.

Any further ideas/suggestions welcome!
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jabcb
Moto GP
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Suzuki 2-Strokes: 69 T350 thru 75 GT750
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Re: GT250M roadside breakdown

Post by jabcb »

Do you have a multimeter? If so check voltage with points open for both sides. Also check voltage when points are closed for both sides.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
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GT550 72 & 75
GT380 72
T500 69 project & 73 project
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redliner
On the street
Posts: 15
Joined: Fri Jan 19, 2018 4:52 pm
Country: United Kingdom
Suzuki 2-Strokes: GT250

Re: GT250M roadside breakdown

Post by redliner »

Will do. Got myself a multimeter today - hopefully will get time to have a play with it tomorrow.

EDIT - sorry for delay, got a house move going on right now. Hopefully will get some time in the workshop over the weekend.
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