GT750 Questions and Intro

[simmons1]

I recently bought Wayne Mueirs old Buffalo and need some help.

I have been riding for 47 years and this is my first Buffalo. I currently own 9 bikes including the Buffalo.



Not sure if I have a carb or ignition problem, or both.

1. Bike has a Dyna ignition.
2. Battery is a couple years old but still seems to be in good shape
3. Bike hasn't been ridden much in a few years.
4. Charging system appears to be charging fine.
5. Sparks Plug color looks good.

Symptoms:

1. Bike starts great and idles ok parked in the driveway. Idle is set between 1250 and 1500. Doesn't like to idle near 1000. Idle seems a little rough but I have nothing to compare it to.
2. Bike runs great on the highway. Way smoother than I expected, especially compared to my highly tweaked H2.
3. When coming to a stop the bike will regularly stall right as the RPM's drop and approach idle. It is like turning off a light switch.
4. Bike usually starts right back up and idles ok. A couple times it started up running backwards. I have read this is not unusual with the DYNA setup.
5. When I am in stop and go traffic is seems to happen more often. If I am at an exceptional long light it may stall multiple times.

Normally I would think dirty carbs from sitting, but if the pilots were plugged it I wouldn't think it would idle at all.

I have replaced the regulator and rectifier with Oregon Motorcycle parts. I was planning on doing this anyways but did it sooner to see if helped with problem I am having. There was no change in the symptoms.

I plan to replace the Dyna with an Accent Ignition but I a haven't heard back from Uwe let about purchasing one.

I am currently working a lot of hours at work at and I was hoping some of you guys with a lot more Buffalo experience may be able to suggest some things to check before I start shot gun trouble shooting.

Thanks in advance for the help!

[Coyote]

Sounds like nothing other than clogged or partially clogged pilot jets. Definitely check those. If the bike sits for long periods with today's fuels, the 'corn' likes to coagulate in the tiny holes of the pilot jets. Remove bowls, remove and clean the pilot jets and associated pathways. I would pretty much bank on that being your only problem.
What happens when slowing down from cruising speeds is the pilot circuit can't deliver enough fuel to "pull in from behind" so to speak. Been there - done that.

[simmons1]

Thanks.

I'll start there first. I have cleaned the carbs on my H2 a bunch of times because of crap gas causing problems. My H2 wouldn't idle at all when the pilots were plugged, but it has 34mm flatslides on it. I have owned a lot 2-strokes but this is the first one with CV carbs.

Thanks again!

[tz375]

I agree with Chris (Coyote). Sounds like partially obstructed jets. I'd start there.

CV carbs are pretty much the same as slide carbs except that the slide and throttle cable are not connected as directly. Think of it as the analog version of Fly By Wire.

[Coyote]

CV's are easy to work on. The big plus with those is that both the pilot jet and main jet are in the carb bowls, not in the bodies like most. Be careful when messing around with the diaphragms if you go in that far. You can still get new ones if you feel like spending $220 each for them. Gee, that's only $660! Not to worry though. They are pretty durable - unless you tear it. Also note that the slides are aligned by the tab on the diaphragm. No alignment pins or slots in the slides.

[simmons1]

These should look interesting inside when I pull them apart.

I'll let you guys know what I find.

[Suzukidave]

Carb info http://www.oldjapanesebikes.com/mraxl_G ... cover.html" onclick="window.open(this.href);return false;

[jeff kushner]

Congrats on the pickup!! Very nice looking bike. IF you need diaphragms(I doubt you do), you might want to look here....20 bucks each:

http://jbmindustries.com/Dimensions.html" onclick="window.open(this.href);return false;

Your size is the same as several other bikes.....M77 on their table

jeff

[Barry S.]

Have you checked the timing? I thought it had to be way off for a 2-stroke to run backwards.

[Suzukidave]

Have you checked the timing? I thought it had to be way off for a 2-stroke to run backwards.

My thought also Barry

[simmons1]

Now I haven't checked the timing yet.

I was reading the instructions for using a home built DYNA, and there was a caution about them being more prone to starting backwards. Something about the size and sensitivity of the pickup coils.

I would like to replace the Dyna with an Accent. I sent an email to Uwe a few days ago but haven't heard back from him yet. Does anyone have any idea how long it typically takes to hear back from him?

Thank you for all of your suggestions so far. I have to work Saturday, so right now I plan on cleaning the carbs bright and early Sunday morning. I'll see what that does first, and then move on to the ignition.

The bike is far from perfect, but it is a very nice rider, and very pleasant to ride. I m enjoying it very much so far. Wished I had bought one years ago.

[T350guy]

I have bought 2 Accents from uwe and he usually responds in a day or 2.
I would guess it depends how busy he is.
Great product and easy to install/

[T350guy]

Congrats on the pickup!! Very nice looking bike. IF you need diaphragms(I doubt you do), you might want to look here....20 bucks each:

http://jbmindustries.com/Dimensions.html" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Your size is the same as several other bikes.....M77 on their table

jeff

Good to know Jeff..Thanks for the Link

[tz375]

A DYNA S will trigger in either direction as the leading edge of the magnet approaches/crosses the leading edge of the pickup. That means it will run backwards or forwards, but to start running backwards, it has to be kicked barely enough for it to fire back down the bore and that typically means either a weak starter or ignition timing that's too advanced.

Other than that they are fine. I use one on my GT750 and this is the second one I have made. So far zero backwards running issues.

I like the look of the ACCENT unit but if it were mine, I would not remove a Dyna to fit an accent. Points - for sure, but a Dyna, not no. At the right price I'd take that DYNA off your hands though.

[simmons1]

A DYNA S will trigger in either direction as the leading edge of the magnet approaches/crosses the leading edge of the pickup. That means it will run backwards or forwards, but to start running backwards, it has to be kicked barely enough for it to fire back down the bore and that typically means either a weak starter or ignition timing that's too advanced.

Other than that they are fine. I use one on my GT750 and this is the second one I have made. So far zero backwards running issues.

I like the look of the ACCENT unit but if it were mine, I would not remove a Dyna to fit an accent. Points - for sure, but a Dyna, not no. At the right price I'd take that DYNA off your hands though.

The few (1 out of 20ish) times it has started backwards was right after it stalled and it doesn't exactly turn over quickly.

Still plan to clean the carbs first so I know the base line condition of them, then move on to timing and other electrical