Gt 250k dies under load

[Tapnell]

I have an ongoing issue with my Gt250k and am running out of ideas. Basically it will not rev under load over about 5k and just bogs down and the engine dies until throttle is eased off again. Think I can rule out carburettor/fuel as have replaced everything inc the carbs themselves...all setting jets/needles are factory spec. I’ve rebuilt the engine so not a compression issue or crank seals. New points and condensers and battery. Just leaves the coils...I’ve tested them and readings look spot on. So I’m going to change them anyway. A question tho....will a dual outlet coil work ok or will the wasted spark ignite the fuel charge in the cylinder at BDC?
Any thoughts advice would help retain the small amount of hair I’ve yet to pull out over this bike!!

Many thanks

[daxman]

I might have suggested crank-seals - had you not eliminated them.

I might add that mine ran poorly until I set the ignition timing properly.. Regards the coil - I wouldn't - for the reasons you've anticipated, afaik those wasted spark jobs only suit four strokes.

[jabcb]

The GT500 uses a single dual-outlet coil. The wasted spark is not a problem.

Check for voltage drops in the wiring. There might be a problem in a switch, wiring connector, or etc.

HVC Cycle sells coils. (The triples & twins use the same coil.)
https://hvccycle.net/suzuki-gt380-gt550 ... 410-31010/
https://www.ebay.com/itm/Suzuki-GT380-G ... 1582420158

[titan performance]

Might be worth checking that the exhausts are clear.....

[dollydog]

question is: what's factory spec? i've seen main jet sizes at 87.5 supposedly factory spec, but i always use 112.5 mains and #30 pilot jets. airscrew 1 and 3/4 turns out, needles set in the middle notch
cheers, dd.
p.s. dax you should know better. wasted spark only good for 4 strokes. try telling all the t/gt250 engines i've built including the big bang, plus the t10, plus 185, plus dt125, plus rg250 [need i go on?] and all got my electronic ignition on them and all are wasted spark

[daxman]

p.s. dax you should know better. wasted spark only good for 4 strokes. try telling all the t/gt250 engines i've built including the big bang, plus the t10, plus 185, plus dt125, plus rg250 [need i go on?] and all got my electronic ignition on them and all are wasted spark

OK back of the class for me - what the OP wrote made sense when I read it.. I have wasted spark on my IL4 Yamaha and sparking on exhaust stoke is more obviously harmless.

[Tapnell]

Thanks all....yes DD 112.5 main and 30 pilot, 3/4 turn out and mixture looks spot on. Exhausts are clear and timing is good..thanks for the coil advice, just wasted some more cash on the wrong coil dughhh!! If that’s not the solution I guess electric ignition is the last call. Newtronic seem the only suppliers for this model.

[dollydog]

hope that was a typo mate? i did say 1 and 3/4 turns out - definitely not 3/4 turns, which would make it much richer. tbh, i would leave your standard coils on, if the readings are good with an ohmeter. can't remember offhand what the main circuit was, but positive to negative on each coil is usually about 4.6 ohms, way lower or way higher and it's your coils that's kaput. apart from that you have me stumped any gear and over 5000 rpm? it all points to an electrical fault to me, but the only time i've had anything like that was my ts250 engine wouldn't rev over 3000, but that was cdi ignition. have you tried changing condensors [easy enough]? maybe one or both are breaking down under high revs. sorry, but thinking out loud here
cheers, dd.

[alanr]

l would suggest float level.l read it as-you could ride all day at 4000 revs but go to 5000 and it dies-drop back to 4000 and carry on riding all day.fuel starvation,ie more gas going out of carbs and not enough replacing it at 5000.l would rule out electrics.if things run well at 4000 electrics will be fine.dont look for problems that dont exist.