Suzuki GT 250 fuel questions....

Siegmanandsons · Posted: Wed Aug 27, 2008 8:19 pm Post subject: Suzuki GT 250 fuel questions....

I recently purchased my first project bike for this winter - a 1976 GT 250. Everything is stock, original and in decent shape. I'm not very versed on 2 cycle motors, so I will be using this forum frequently during reconstruction. My first concern is the 3 positioned fuel cock. The positions are ON, RESERVE, and PRIMING. Fortunately the bike came with the original owners guide and indicates what each position means. My questions are:
1. Is there a total shut off position for fuel from the tank?
2. What position of the 3 should the lever be in when the bike is parked?

My other concern is after I brought the bike home and parked it overnight , there was a very strong gas smell in the garage the next morning. After investigation, I found that raw gas was literally dripping at a constant rate from both carburetor by-pass tubes. I tried moving the fuel cock lever to different positions, but in all cases fuel continued to flow out. I had to disconnect the supply line from the fuel cock to the carbs in order to stop the leakage. The only thing the previous owner "enhanced" was putting two aftermarket fuel filters on the supply line. The filters are dry and the lines at the connecting points of the fuel cock and carbs are dry. Questions:
1. Are these aftermarket filters causing some reaction that causes a continuous flow of fuel?
2. Do I have a faulty fuel cock?
3. Does this problem sound like it would contribute to hard starting when cold? (15-20 kicks)

Thanks for your help in advance. I will post some picts of Mr. Stinky soon. I'm looking forward to making it a fun project.

KirkN · Posted: Thu Aug 28, 2008 7:06 am Post subject:

First of all - welcome aboard! Sounds like a cool little bike, and yes, please, post some pictures!

Second - Brecksville, Ohio!! Wow, I was born and raised just to the south, in Richfield off 21 on Farnham Rd just south of the turnpike interchange, across from the Holiday Inn. We moved away in 1979 when I was 13. I can remember grocery shopping at the grocery store in Brecksville at the corner of 21 and 82. Country Counter? My dad and HIS dad built the house themselves in 1960 - 63. 3050 Farnham Rd. Smile

What a small world.

Third, your bike has a vacuum-operated petcock. It requires engine vacuum, typically from an intake manifold, to open the petcock.

Theoretically, it is shut off if the engine is not running when the petcock is in the ON or RESERVE position. In the PRIME position, it is open and fuel will flow, engine running or not.

When running, the ON position is just that - on. RESERVE is just like any 'manual' petcock - draws from a lower position within the tank, giving a bit of range / warning before the tank goes dry.

I hate vintage vacuum petcocks, because they almost always start to do what yours is - leaking thru. And there's no positive shut-off.

In fact, I don't like vacuum petcocks at all, because I like to shut the fuel off a block or two before I get home to drain the carb bowls. That way, if the bike happens to sit a while between one ride and the next, the fuel doesn't evaporate nor get a chance to turn gummy.

Sometimes, they can be bypassed internally by repositioning a small spring and they'll function like a normal petcock. Others can't.

On several bikes over the years, I've added a tiny 1/4-turn manual shutoff valve from a lawnmower shop in the line, downstream of the vacuum petcock. That way, I have a very positive shutoff.

Or, you might be able to just buy a new petcock, or new internals and fix it right... Smile

Good luck with it, and again, welcome aboard!

Kirk

Siegmanandsons · Posted: Fri Aug 29, 2008 11:33 am Post subject:

Thanks Kirk - your insight and answer was very helpful. I did go ahead and order the fuel cock re-build parts from Bike Bandit. I'm sure I'll be using them a lot more as well on this project. This bike also has an oil injection system. I've heard that a lot of 2 cycle owners bypass this and rely on mixing fuel and oil. I guess the thought process being that if the oil injection fails, your pretty much S.O.L. Any thoughts on this?

Your home town of Richfield has changed considerably. I don't know when you were here last, but certain areas (Wheatly Road and Rt. 21) have become prime corporate business parks. The Holiday Inn is now a Comfort Inn and Country Counter is now Giant Eagle. Several of the big trucking depots along Rt. 21 have been abandoned and are making way for housing developments.

Thanks again!
Glenn S.

KirkN · Posted: Fri Aug 29, 2008 12:09 pm Post subject:

Well, it's a true statement that if the oil injection system fails, you're S-O-L.

But, it sounds kind of funny to be "afraid them new-fangled injectors ain't gonna werk..." I mean, they're not rocket science or anything. And bikes have been built with 'em since about 45 years ago! Smile

And, in fact, on many bikes with such injectors, they actually inject oil right to this or that bearing and you can actually damage the engine by NOT running the injector and trying to just run premix. I don't know if the GT250 is such a design or not.

But, I'd certainly run the auto injector, if it were my project. They're actually easy to test and adjust. Then, you can pretty much forget 'em.

Huh, interesting about Richfield. I moved away in 1979, and I've only been back once, on a business trip in 1999 to Cleveland, and then it was just a quick drive-around. My older brother was there a year or two ago, and he, too, mentioned the corporate park type areas.

Kinda fun reminiscing. I even had to go spend a few minutes on Google Satellite maps and look around!

Kirk

Siegmanandsons · Posted: Fri Aug 29, 2008 12:36 pm Post subject:

Ahhh - again the light has been shed into the dark, oily caverns of the 2 cycle. There are small two tubes that run into the crankcase attached (for lack of better terms) by a mini brake-line fitting. This oil injection obviously serves more purpose that just mixture. Thanks!!!

One thing that you certainly remember is the old Richfield Coliseum... long standing home of the Cav's, Barons / Crusaders, and a million concert events. It was demolished in 1999 and the land was reclaimed by the national park service. It's very surreal to drive by knowing what was once there - but if you didn't know - you would swear nothing ever was there. Just a large grassy patch of nothing. You may also remember the iconic hamburger joint on Rt. 21 called Whitey's. Still going strong and growing - and only accepting cash! What a business.

KirkN · Posted: Fri Aug 29, 2008 1:19 pm Post subject:

OK, let's just skip the pretense of discussing motorcycles all together and focus on the important stuff: Very Happy

We lived there when the Coliseum was first proposed and built. My folks knew the farmer family that owned the land on which it was built. I want to say Emmitt?

Another older brother worked there when he was in high school. Around '75 ~ '76. Got into some slight backstage disrespect with Jimmy Page of Led Zeppelin and was nearly fired over it! Laughing

I had two cousins whose first jobs were dishwashers at Whitey's.

My dad owned a rental property home near the coliseum which was proved to be over 100 years old at the time. This was in the year of the Bicentennial when 'history' stuff like that was in vogue. They gave him a big bronze "Centennial Home" plaque for the front of it. Well, when we moved away, the property was sold off, and eventually reclaimed by that same park service, who subsequently bulldozed it flat, and let the weeds grow back and reclaim it. Not a speck left but some grape vines we had planted. I'm sure even they're gone by now. Laughing

Kirk

linehand · Posted: Sat Aug 30, 2008 7:07 am Post subject:

you need to replace float valves too "needle and seats"

Siegmanandsons · Posted: Tue Sep 23, 2008 9:56 am Post subject:

Well - Here's the update.... I rebuilt the 2 Mikuni's along with the fuel cock (with what parts are still available). The actual diaphragm inside the fuel cock can't be replaced - which I think is still causing my problem. After taking the fuel cock and carbs apart, I never understood how this thing ran in the first place. What appeared to be "coffee grounds" in filter bowl of the fuel cock, and grime in the bottom of the float bowls, it's no wonder this took 20+ kicks to get it going. I also cleaned and sealed the fuel tank with Bill Hirsch's 3 part motorcycle kit. Well worth the $29. I put everything back together this weekend, fueled up, checked for leaks, and ONE kick later it fired right up. Amazing! My 16 year old son even asked, "Was that supposed to happen?"

Unfortunately this morning I smelled and saw raw gas dripping at a slow pace from the carb bowl overflow tubes. Even though the seals, o-rings, and filters were replaced in the fuel cock, the diaphragm must still be open slightly with the engine off. I guess the only option is the addition of an aftermarket fuel shut off (or find a new Suzuki fuel cock - yeah right.) I'm just pleased with the ease of starting and the 10 extra years I've avoided in knee replacement surgery.

Glenn S.

Siegmanandsons · Posted: Sat Sep 27, 2008 6:47 pm Post subject:

As promised, here are some recent picts. I tried my hand at polishing the aluminum cases - not bad for the first time out. These were badly pitted and oxidized. My plan is to take it down to the frame this winter. Still starts on 1-2 kicks...

TahitianRed · Posted: Thu Nov 06, 2008 1:54 pm Post subject:

Wow. Beautiful Bike. What are you using/doing to clean your engine cases? I am not having nearly that kind of success with the two bikes I'm working on right now.

BTW, I have your bikes little brother. It's a '75 GT185.

Thanks,

-TR

Siegmanandsons · Posted: Thu Nov 06, 2008 9:41 pm Post subject:

Thanks for the comment. This winter, I'll take it down to the frame and go over it in detail.
The polishing process is simple, but a little time consuming. So pull up a chair and beverage when you're doing this procedure.

I start with 200 grit wet sand paper. Make sure its saturated and don't apply too much pressure - let the paper do the work.
Sand with the contours of the case, and get the heavily pitted areas as smooth as possible. Then move up to a 400 grit keeping the case
and the paper wet at all times. Thoroughly go over areas with even pressure. Then go to a 600 grit and repeat the process again.
You'll see the difference in the finish after the 600 grit application. Next, dry the parts (blow gun) and use a 0000 grade steel wool.
This will start to buff and remove any fine scratches from the wet sanding. So far you really don't have a lot of expense - just labor.
It took me about 2 hours total to do the clutch case. But it was badly pitted and dull. The only real "large" cash expense was a
bench top buffer - which I got a Harbor Freight. Decent unit with a sturdy stand, buffing wheels, and polish was $70.
I figured it would get a lot of use in the future.

The final application was lightly buffing all parts with a light coat of polish.
The results were better than expected - and probably better than half the cost of sending them out to a commercial polisher.

Good Luck!