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GT750 M carbs

Posted: Wed Jul 17, 2013 7:05 pm
by kawonda750
Honestly speaking, I'm a Kaw triple guy but I have this Gt750M. It pulls like a train up to about 5000 rpm then cacks out. Since I am not familiar with these bikes, how should it go and how far should it pull?
The timing seems spot on but the carbs are suspect. They are definitely clean though.
Can I synch them with a mini synch tool, or do I need a mercury guage? Once again, I am not familiar with the CV carbs.
Any ideas or input?
Thanks
Dave

Re: GT750 M carbs

Posted: Wed Jul 17, 2013 11:16 pm
by T350guy
Dave it's H2dude aka Ian
Carbs are real easy to do..you can use the mercury style or even a Uni Sync.
Do you still have the 3 into one pipe ?
Maybe the mains are too rich? Does it blubber or fall flat..maybe lean ?
These will pull to redline though not as hard as a H2.
With Stock pipes you will have 110 mains for the left & Right and 107.5 for the middle.

Re: GT750 M carbs

Posted: Thu Jul 18, 2013 9:20 am
by kawonda750
Still have the 3 in 1 and 120 mains as well as up one clip on the slides.
Plug colour looks good.
I will try the uni synch.

Re: GT750 M carbs

Posted: Thu Jul 18, 2013 11:29 am
by Old School
I would say that if you are running it at full throttle and having this issue, it is not a sync problem as the throttles for the most part are all wide open (or very close). My guess its a fuel mixture or delivery problem or maybe possibly a ignition issue.

Re: GT750 M carbs

Posted: Thu Jul 18, 2013 12:45 pm
by tz375
kawonda750 wrote:Still have the 3 in 1 and 120 mains as well as up one clip on the slides.
Plug colour looks good.
I will try the uni synch.
Sounds about right. A Strader 3 into 1 peaks at around 5300 and has a flat plateau after that. 120 mains are right for a Strader.

Jemco 3 into 3 makes more power and has more top end, but not as sweet around town and in traffic as a 3 into 1.

Re: GT750 M carbs

Posted: Fri Jul 19, 2013 5:32 am
by kawonda750
This is an Omar's Torque Cannon. Yes, it sounds like a porn star name. It claims more low end torque.
The synch issue is still there as at low throttle openings it is quite rough but smooths out wide open.
I will re-check the timing too.
Thanks
Dave

Re: GT750 M carbs

Posted: Fri Jul 19, 2013 6:55 am
by tz375
Do you have a DYno near you? It might be good to strap it down and see what the HP curve looks like and how the air:fuel tracks.

Re: GT750 M carbs

Posted: Fri Jul 19, 2013 8:29 am
by kawonda750
No dyno. i'm way out in the country. Lots of boats and Ford tractors.

Re: GT750 M carbs

Posted: Fri Jul 19, 2013 8:55 am
by tz375
Nothing wrong with boats and tractors I suppose.

I suspect that 99% of the issue is that the exhaust drops off at around 5,000. A dyno test would show what's going on there, but that's typical of 3 into 1 systems.

Where we live, that solid low end and midrange is more useful than top rev performance. The best compromise between a 3 into 1 and chambers is a stock exhaust, but they are so heavy that they kill performance, where a 3 into 1 is nice and light.

Re: GT750 M carbs

Posted: Mon Jul 22, 2013 9:25 am
by T350guy
Dave how you making out with the GT? Sync issues? is it the bucking/surging at low speed? or is it running rough?

Re: GT750 M carbs

Posted: Thu Jul 25, 2013 2:41 pm
by kawonda750
Hey Ian

did the carbs with the uni synch and set air screws. it's much better now. it just doesn't pull too much past the 5 G mark. it runs really well so I think it is just the pipe function. It is still good just entirely different from the Kawasaki.

Re: GT750 M carbs

Posted: Sun Jul 28, 2013 4:23 pm
by T350guy
kawonda750 wrote:Hey Ian

did the carbs with the uni synch and set air screws. it's much better now. it just doesn't pull too much past the 5 G mark. it runs really well so I think it is just the pipe function. It is still good just entirely different from the Kawasaki.
Good to hear Dave..Maybe that pipe makes Power/torque in the lower end..

I never rev mine much anyway , maybe 5000 so that pipe may just work for you .

Sorry for the delay as I was away at a Vintage bike rally.